JP4842598B2 - Printing apparatus and ink amount detection method - Google Patents

Description

The present invention relates to a printing apparatus and ink amount detection method comprising the hole plate printing apparatus.

  Conventionally, as a simpler printing method, a plate making apparatus integrated thermosensitive digital stencil printing apparatus (hereinafter sometimes simply referred to as “stencil printing apparatus”) is known. This is also called heat sensitive stencil paper with a laminated structure in which a thermoplastic resin film with a thickness of approximately 1 to 3 μm is bonded to a Japanese paper fiber or synthetic fiber as a porous support pair, or a mixture of Japanese paper and synthetic fiber. A stencil master (hereinafter referred to as “master”) is brought into contact with a thermal head in which fine heating elements are arranged in one or more rows, and the master is moved to a platen roller while energizing the heating elements in pulses. By perforating the master thermoplastic resin film (hereinafter sometimes simply referred to as “film”) in contact with the heat generating element of the thermal head by perforating based on the image information After a perforated image is formed on the master, the perforated / prepressed master is wound around the outer peripheral surface of a printing drum, also called a plate cylinder, and pressed The ink is oozed out from the opening portion of the plate cylinder and the perforation portion of the master in the printing drum by pressing the printing paper (hereinafter referred to as “paper”) against the outer peripheral surface of the printing drum by pressing means such as a roller or an impression cylinder, This ink is transferred to paper to form a printed image (see, for example, Patent Documents 1 and 2).

In a normal stencil printing apparatus, emulsion ink is mainly used. This is an emulsion ink in which water and oil are mixed as the main component (hereinafter simply referred to as “ink”) to reduce drying under exposure and standing conditions. It is a W / O type ink in a state.
This ink is stirred uniformly while maintaining a constant amount on an ink roller as an ink supply member constituting an ink supply device and a doctor roller as an ink amount regulating member or an ink amount measuring member inside the plate cylinder of the printing drum. After being kneaded, it is supplied to the inner peripheral surface of the plate cylinder wound around the outer peripheral portion of the printing drum, and supplied to the master on the outer peripheral surface of the plate cylinder through a large number of fine holes formed in the plate cylinder. Based on image information read from the original or image information sent from a personal computer, the master film is heated and melted and punched to create a path for the ink, and the ink is transferred and transferred onto the paper. ing.

Here, as a conventional method for detecting the amount of ink in a printing drum, for example, an ink reservoir is formed between a rotating ink roller and a doctor roller or the like arranged in parallel with a slight gap, and the ink reservoir For example, by inserting one or two needle-like members (hereinafter referred to as “ink detection needles”) having a diameter of about 0.5 to 1 mm as the role of maintaining a constant amount of ink, A method of detecting the capacity is adopted. The amount of ink in the ink reservoir is controlled to always be a constant amount by setting a predetermined capacitance as a reference value.
In Japanese Patent Laid-Open No. 2001-287341, in order to prevent overflow due to an increase in the ink reservoir, the detection of the normal ink amount by the conventional ink detection needle described above and the ink amount in the ink reservoir increased abnormally. Two types of ink amount detection with different purposes from the ink amount detection by the abnormal increase detection part (an inclined surface-like part provided on the top of the ink detection needle so as to increase the contact area with the ink) Techniques to do are proposed.

JP 2001-287341 A JP 2003-94789 A

However, in the ink amount detection method described in Japanese Patent Application Laid-Open No. 2001-287341 (Patent Document 1), since the surface area of the portion of the ink detection needle inserted into the ink reservoir is small, the condition that the physical properties of the ink change In this case, that is, for example, when continuous printing with a low image ratio with an extremely low master perforation rate is performed, the ink in the ink reservoir is not consumed easily, and the same ink is long between the ink roller and the doctor roller. When the water content of the ink evaporates and only the oil and pigment remain, and the capacitance decreases as the water content in the ink decreases. Is controlled so as to always satisfy a predetermined capacitance value, so that the amount of ink supplied to the ink reservoir is increased. By increasing the ink reservoir, more ink detection needles will sink into the ink reservoir and increase the amount of contact with the ink (increase the surface area of the ink detection needle in the portion inserted into the ink reservoir). It will be a control to replenish.
At this time, the aim is to stop the ink supply by increasing the ink reservoir and bringing the ink in that part into contact with the abnormal increase detection part for preventing overflow. If the ink is insufficient or the capacitance is extremely reduced, the increased abnormal ink may not be detected. Normal ink pool ink retains a certain level of viscosity, so it is retained by forming a pool of ink on the ink roller and doctor roller. When the printing machine is stopped due to the increased amount of ink, the ink flows down from the ink reservoir and ink roller onto the inner surface of the plate cylinder, and the machine is left unused for a long time. In the state, there is a possibility that the ink roller will eventually flow out from both sides of the printing drum to the outside of both sides of the printing drum.
In addition, as a condition for changing the physical properties of the ink, the case where the low-image-ratio printing as described above is repeatedly performed continuously is particularly remarkable, but the stencil printing apparatus is not used for a long period of time. In the case where the ink adhered to the inner surface of the plate cylinder is left unused for a long period of time.

The present invention, which was made in view of the above circumstances, particularly in the stencil printing device among the printing devices, if such continuously performed repeatedly printing a low image ratio, the ink reservoir of liquid turned into suppressing an increase in ink was shall be the primary purpose is to prevent the ink from leaking from both sides of the printing drum in advance.

In order to solve the above-described problems and achieve the above-described object, the invention for each claim employs the following characteristic means and invention-specific matters (hereinafter referred to as “configuration”).
The invention according to claim 1 is an ink supply member that supplies ink, an ink amount regulating member that is arranged with a predetermined gap from the ink supply member and regulates the amount of ink on the ink supply member, and the ink supply A detection electrode that detects a capacitance corresponding to the amount of ink in the ink reservoir formed between the member and the ink amount regulating member, and the detection electrode is constituted by a needle-shaped member; In a printing apparatus comprising an ink amount detection device having a configuration with an ink amount regulating member and a printing drum, based on an image ratio setting means for setting an image ratio, and a signal from the image ratio setting means, And fourth control means for switching to either one of the case where the ink amount is detected by the needle-shaped member and the case where the ink amount is detected by the ink amount regulating member.

The invention according to claim 2 is the printing apparatus according to claim 1, wherein an ink replenishing means for replenishing ink to the ink reservoir, an ink replenishing amount detecting means for detecting an ink replenishing amount by the operation of the ink replenishing means, Based on the no-ink signal from the needle-shaped member or the ink amount regulating member and the ink replenishment amount signal from the ink replenishment amount detecting means, the ink replenishing means is used to replenish a predetermined amount of ink to the ink reservoir. And a fifth control means.

According to a third aspect of the present invention, there is provided an ink supply member that supplies ink, an ink amount regulating member that is disposed with a predetermined gap from the ink supply member and regulates an ink amount on the ink supply member, and the ink supply A detection electrode that detects a capacitance corresponding to the amount of ink in the ink reservoir formed between the member and the ink amount regulating member, and the detection electrode is constituted by a needle-shaped member; In a printing apparatus having an ink amount detection device having an ink amount regulating member and a printing drum , a storage means for storing image data, and an image ratio is calculated from the image data stored in the storage means And a sixth control means for switching to one of the case where the ink amount is detected by the needle-shaped member and the case where the ink amount is detected by the ink amount regulating member. And butterflies.

According to a fourth aspect of the present invention, in the printing apparatus according to the third aspect , an ink replenishing means for replenishing ink to the ink reservoir, an ink replenishing amount detecting means for detecting an ink replenishing amount due to the operation of the ink replenishing means, Based on the no-ink signal from the needle-like member or the ink amount regulating member and the ink replenishment amount signal from the ink replenishing unit, the seventh ink supply unit replenishes the ink reservoir with a predetermined amount of ink. Control means.

According to a fifth aspect of the present invention, an ink supply member that supplies ink, and an ink amount regulating member that is disposed with a predetermined gap from the ink supply member and regulates the amount of ink on the ink supply member In the ink amount detection method for detecting the capacitance corresponding to the ink amount of the ink reservoir to be formed using the needle-like member as the detection electrode, the ink amount regulating member is used as the detection electrode in addition to the needle-like member. As a result, it is possible to switch between detection of the ink amount by the needle member and detection of the ink amount by the ink amount regulating member.

According to the present invention, the above problems can be solved and a novel printing apparatus and ink amount detection method can be provided. The main effects of the invention are as follows.
According to the present invention, since it is possible to switch between detection of the ink amount by the needle-like member and detection of the ink amount by the ink amount regulating member, the ink amount detection control and the ink amount by only the needle-like member are possible. the switchable in two ways of detecting the control of the ink amount by only regulating member (claim 5).

According to the present invention, in the case of printing at a high image ratio, by performing ink replenishment control corresponding to the ink amount detection using only the conventional needle-like member, the margin for occurrence of image blurring in solid image printing is remarkably increased. In the case of printing with a low image ratio, it is possible to prevent an excessive increase in the ink reservoir by switching to ink replenishment control corresponding to ink amount detection using only the ink amount regulating member, As a result, it is possible to prevent a problem that ink leaks from both sides of the printing drum (claims 1 to 4 ).

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention (hereinafter referred to as “embodiments”) including the best mode for carrying out the present invention and examples will be described below with reference to the drawings. Constituent elements such as members and components having the same function and shape throughout the embodiment and the modified examples are given the same reference numerals and will not be described after being described once. In order to simplify the drawings and the description, even components that are to be represented in the drawings may be omitted as appropriate without being specifically described in the drawings. When a constituent element such as a published patent gazette is cited and explained as it is, the reference numeral is attached with parentheses to distinguish it from that of each embodiment.
In “Best Mode for Carrying Out the Invention”, the first embodiment is referred to as “first reference example”, the first modification of the first embodiment is referred to as “reference modification 1”, and the first The modification 2 of the embodiment is read as “reference modification 2”, the second embodiment as “first embodiment”, and the modification 3 of the second embodiment as “modification 1”. I will do it.

First, referring to FIG. 16 to FIG. 21, an overall configuration of a plate making apparatus-integrated thermal digital stencil printing apparatus (hereinafter simply referred to as “stencil printing apparatus”) as an example of a printing apparatus to which the present invention is applied, and its configuration The operation will be briefly described.
In FIG. 16, reference numeral 65 denotes an apparatus main body frame. In the upper part of the apparatus main body frame 65, a portion indicated by reference numeral 80 is a document reading portion, a portion indicated by reference numeral 90 below is a plate-making plate feeding portion, and a portion indicated by reference numeral 30 on the left is a printing drum 31 or the like A portion indicated by reference numeral 70 on the left side of the printed drum portion is a discharging portion, a portion indicated by reference symbol 110 below the plate-making plate feeding portion 90 is a feeding portion, and a portion indicated by reference numeral 120 below the printing drum 31. Indicates a printing pressure portion, and a portion indicated by reference numeral 130 at the lower left of the apparatus main body frame 65 indicates a paper discharge portion.

Next, the operation of the stencil printing apparatus will be described including its detailed configuration.
First, a document 60 having an image to be printed is placed on a document placing table (not shown) arranged on the upper part of the document reading unit 80, and is placed in the stencil printing apparatus before and after this. After turning on a power switch (not shown) for turning on / off the power supplied to each device unit, the prepress key 41 of the operation panel 40 shown in FIG. 17 is pressed. A start signal generated when the plate making start key 41 is pressed serves as a trigger, and a plate discharging process is first executed. That is, in this state, the used master 61b used in the previous printing remains attached to the outer peripheral surface of the plate cylinder 6 of the printing drum 31.
When the printing drum 31 rotates counterclockwise and the rear end portion of the used master 61b on the outer peripheral surface of the plate cylinder 6 approaches the plate release roller pair 71a, 71b in the plate release portion 70, the roller pair 71a, 71b rotates. While, the one end of the used master 61b is scooped up by one of the discharged plate peeling rollers 71a, the discharged plate roller pairs 73a and 73b and the discharged plate peeling roller pairs 71a and 71b disposed on the left side of the discharged plate peeling roller pairs 71a and 71b, Is discharged into the discharge plate box 74 while being conveyed in the direction of the arrow Y1 by the pair of discharge plate conveying belts 72a and 72b laid between the two, and the used master 61b is peeled off from the outer peripheral surface of the printing drum 31 to complete the discharge process. . At this time, the printing drum 31 continues to rotate counterclockwise. The used master 61 b that has been peeled and discharged is then compressed inside the plate discharging box 74 by the compression plate 75.

  In parallel with the plate removal process, the document reading unit 80 reads an image of the document. That is, the document 60 placed on a document placement table (not shown) is conveyed in the directions of arrows Y2 to Y3 by the rotation of the separation roller 81, the front document conveyance roller pair 82a and 82b, and the rear document conveyance roller pair 83a and 83b. It is used for exposure reading. At this time, when there are a large number of documents 60, only the lowermost document is conveyed by the action of the separation blade 84. When reading the image of the original 60, the reflected light from the surface of the original 60 illuminated by the fluorescent lamp 86 while being conveyed on the contact glass 85 is reflected by a mirror 87 and passed through a lens 88 from a CCD (charge coupled device) or the like. This is performed by entering the image sensor 89. The document 60 from which the image has been read is discharged onto the document tray 80A. The electrical signal photoelectrically converted by the image sensor 89 is input to an analog / digital (A / D) converter (not shown) in the apparatus main body frame 65 and converted into a digital image signal.

On the other hand, in parallel with this image reading operation, plate making and plate feeding processes are performed based on the digital signalized image information. That is, the master 61 set at a predetermined portion of the plate making and feeding unit 90 is pulled out from the roll state wound in a roll shape, and pressed against the thermal head 91 as a plate making means for making the master 61 via the master 61. By the rotation of the platen roller 92 and the feed roller pair 93a and 93b, the platen roller 92 is intermittently conveyed to the downstream side of the conveyance path. A large number of minute heating elements arranged in a line in the main scanning direction of the thermal head 91 with respect to the master 61 conveyed in this way correspond to the digital image signal sent from the A / D converter. The portions of the thermoplastic resin film of the master 61 that selectively generate heat and are in contact with the generated heating elements are heated and melt punched. In this way, image information is written as a drilling pattern by position-selective melt drilling of the master 61 according to the image information.
The front end of the master-making master 61a in which the image information is written is sent toward the outer peripheral side of the printing drum 31 by the pair of feeding rollers 94a and 94b, and the traveling direction is changed downward by a guide member (not shown). The printing drum 31 in the plate feeding position state shown in FIG. At this time, the used master 61b has already been removed from the plate cylinder 6 of the printing drum 31 by the discharging process.
When the leading end of the master 61a is clamped by the clamper 32 at a constant timing, the printing drum 31 is gradually wound around the outer peripheral surface while rotating in the arrow direction (clockwise direction) in the figure. I will put it on. The rear end portion of the master-making master 61a is cut into a certain length by the cutter 95 after completion of the plate-making.

When one plate-made master 61a is wound around the outer peripheral surface of the plate cylinder 6 of the printing drum 31, the plate-making and plate-feeding steps are finished, and the printing step is started. First, the uppermost one of the sheets 62 stacked on the sheet feed table 66 is sent in the direction of the arrow Y4 toward the registration roller pair 113a and 113b by the sheet feed roller 111 and the separation roller pair 112a and 112b. Further, it is sent to the printing pressure unit 120 at a predetermined timing synchronized with the rotation of the printing drum 31 by the pair of registration rollers 113a and 113b. When the fed paper 62 comes between the printing drum 31 and the press roller 33, the press roller 33 that has been separated below the outer peripheral surface of the printing drum 31 is moved upward, whereby the printing drum 31 is configured. The plate master 6a wound around the outer peripheral surface of the plate cylinder 6 to be pressed is pressed. Thus, ink oozes out from the opening portion of the plate cylinder 6 and the piercing portion (both not shown) of the plate-making master 61a, and the oozing ink is transferred to the surface of the paper 62 to form a printed image. .
At this time, on the inner peripheral side of the printing drum 31, ink is supplied from an ink branch pipe (not shown) to the ink reservoir 10 a formed between the ink roller 5 and the doctor roller 4, and the same direction as the rotation direction of the printing drum 31. Ink is supplied to the inner peripheral side of the printing drum 31 by the ink roller 5 that is in contact with the inner peripheral surface of the plate cylinder 6 while rotating in synchronization with the rotational speed of the printing drum 31. As the ink, for example, a W / O type emulsion ink type is used.

The paper 62 on which the printing image is formed in the printing pressure unit 120 is peeled off from the print drum 31 by the paper discharge peeling claw 114 in the paper discharge unit 130 and sucked by the suction fan 118, while being sucked by the suction paper discharge inlet roller 115 and the suction. Due to the counterclockwise rotation of the conveyance belt 117 that is stretched around the sheet discharge outlet roller 116, the sheet is conveyed toward the downstream side of the sheet discharge unit 130 as indicated by the arrow Y5, and is sequentially discharged and stacked on the sheet discharge table 67. The In this way, the trial printing, also called plate printing, is completed.
The apparatus main body frame 65 is provided with a printed sheet counter (not shown) as counting means for counting the number of printed sheets. This printed sheet counter counts the number of printed sheets based on the number of on / off times of the paper discharge sensor 119 disposed below the conveyor belt 117.
Next, the number of prints is set with the numeric keypad 43 of the operation panel 40 shown in FIG. 17, a desired print speed is set with a print speed setting key (not shown) provided on the operation panel 40, and a print start key is set. When 42 is pressed, the paper feeding, printing, and paper ejection steps are repeated for the set number of printed sheets in the same process as the trial printing, and all the stencil printing processes are completed.

  Next, the periphery of the conventional printing drum unit 30 and the configuration of the operation panel 40 will be supplementarily described, and the ink supply unit 35 for supplying ink to the inner peripheral surface of the plate cylinder 6 of the printing drum 31 will be described with reference to FIG. Referring to FIG. 19 and the configuration of the ink supply detecting device 300 for detecting the ink amount of the ink reservoir 10a and the configuration around the ink supply control device 310 for controlling ink supply.

As shown in FIG. 18B, the printing drum unit 30 includes a plate cylinder 6 that winds the plate-making master 61 a that has been made and conveyed by the plate-making plate feeding unit 90, and an outer periphery of the plate cylinder 6. A printing drum 31 provided in the printing section, an openable / closable clamper 32 that extends in the axial direction of a part of the outer peripheral surface of the plate cylinder 6 of the printing drum 31 and sandwiches the leading end portion of the pre-made master 61a; The ink roller 5 serving as an ink supply member for supplying ink to the inner peripheral surface of the printing drum 31 while rotating in the same direction as the rotation direction of the ink drum 5 is disposed in parallel with the ink roller 5 with a predetermined minute gap. An ink reservoir 10a having a substantially wedge-shaped cross section is formed between the roller 5 and the doctor roller 4 as an ink amount regulating member for regulating the amount of ink on the outer peripheral surface of the ink roller 5, and ink is supplied to the ink reservoir 10a. And a supplying ink branch pipe 3 or the like.
In the vicinity of the outer peripheral surface of the plate cylinder 6 of the printing drum 31 facing the ink roller 5, a press roller 33 is disposed as a pressing unit that swings up and down and presses the paper 62 against the plate cylinder 6.

As shown in FIGS. 16 and 18, the plate cylinder 6 has a well-known porous cylindrical shape, and fastening means such as screws are provided on outer peripheral surfaces of end plates (not shown) disposed at both ends of the printing drum 31. It is concluded. The printing drum 31 is rotatably supported around the support shaft 34 through the end plates together with the plate cylinder 6. The plate cylinder 6 of the printing drum 31 is provided so as to extend in the direction of the central axis of the support shaft 34, and is made of a metal support such as stainless steel in which a large number of fine holes 6a having ink permeability are formed. A cylindrical body and a porous elastic layer (resin or metal mesh screen not shown) as a layer wound around the outer peripheral surface of the support cylindrical body, holding and diffusing ink on the outer peripheral surface, and discharging ink by pressing Layer).
The support cylindrical body has a printable area in which an aperture 6a is formed over a predetermined range on the circumference except for the periphery of the clamper 32, and an ink-impermeable non-passage in which the aperture 6a is not formed. A print area is formed. Non-printing areas are also provided at both side edges of the support cylindrical body.
The printing drum 31 is unitized similarly to the plate cylinder device (55) shown in FIGS. 2 and 3 of JP-A-5-229243, for example, and constitutes a drum unit. Through this drum unit, the printing drum 31 is detachable from the apparatus main body frame 65 shown in FIG. On the apparatus main body frame 65 side, an attaching / detaching means similar to the holding means (36) shown in FIG. 2 of the above-mentioned JP-A-5-229243 is arranged, and printing to be attached to the apparatus main body frame 65 is performed. The drum 31 is detachably held. The printing drum 31 is driven to rotate clockwise and counterclockwise by a drive motor (not shown).
As shown in FIG. 2 of the above-mentioned Japanese Patent Laid-Open No. 5-229243, both ends of the support shaft 34 are inserted into insertion holes formed in a front frame and a rear frame (both not shown). Then, it is fixed to the front frame and the rear frame by screws or the like using a fixing tool (not shown).

  The ink roller 5 is made of a metal such as aluminum or stainless steel, and rotates in the clockwise direction together with the printing drum 31 by a gear train (not shown). The doctor roller 4 is made of metal such as iron or stainless steel, and rotates counterclockwise by a gear train (not shown). The ink roller 5 and the doctor roller 4 are rotatably supported on an ink side plate (not shown) suspended from the support shaft 34 via a bearing (not shown).

In addition to the ink roller 5, the doctor roller 4 and the ink branch pipe 3 described above, the ink supply device 35 can reciprocate in the direction indicated by the arrow in the figure as shown in FIG. 18 (a). An ink pump 2 that has a piston rod and a base 12 and supplies ink to the ink branch pipe 3 via the ink supply pipe 13, and the ink pump 2 and the ink branch pipe 3 that are inserted and connected as described above. An ink container (not shown) that is detachably provided on the ink feed pipe 13 and an ink container holder (not shown) and that can be attached to and detached from the base 12 of the ink pump 2 and contains ink ( (Not shown), and a link (not shown) connected to a disk 16 fixed to a gear at the last stage of a gear train 15 to be described later, with a worm 14a attached and fixed to the output shaft thereof. ) An ink supply motor 1 for reciprocating the piston rod 11 of the ink pump 2 via, and a said link for connecting in a manner to be described later and the ink supply motor 1 and the disc 16.
The ink supply pipe 13, the ink container, the ink container holder, the ink pump 2, the link, the ink replenishing motor 1, and the like constituting the ink supply device 35 are arranged on the support shaft 34 ( The gripping frame, rear frame, and front frame (both not shown) are fixedly attached to a stationary member fixed to a fixed member (not shown in FIG. 18) and configured to rotatably unitize the printing drum 31. It is provided on the front frame side.

The ink pump 2 is a reciprocating pump, and the piston rod 11 reciprocates in the front-rear direction indicated by the arrows in FIG. 18A, so that the ink in the ink container is sucked and pumped out. Ink is sent out to the ink branch pipe 3 through.
The gear train 15 is composed of a worm wheel 14b that always meshes with the worm 14a, a small-diameter gear and a plurality of gears that are coaxially and integrally formed with the worm wheel 14b, and finally integrated with the last gear. The rotational driving force of the ink supply motor 1 is transmitted to the formed disc 16.
Between the disc 16 and the piston rod 11, for example, as shown in FIG. 9 of Japanese Patent Laid-Open No. 2001-315305, a pin (a pin implanted at a position deviated from the rotation center of the disc 16 ( 53a), a long hole (54b) into which the pin (53a) is loosely inserted is formed, and its central portion is connected to the piston rod 11 via the pin (54a) and swings about the fulcrum shaft (55). Possible links (54) are arranged. A filler 8 for detecting the number of reciprocating operations of the ink pump 2 through the piston rod 11 is fixed to the piston rod 11.
The ink supply motor 1 is a DC motor. An electrical connector (not shown) for electrical connection and connection to the input side of the ink supply motor 1 is attached to the outer surface of the rear frame. On the apparatus main body frame 65 side shown in FIG. 16, an electrical connector for supplying and controlling electric power for operating the ink supply motor 1 is attached by facing and engaging with the electrical connector. Yes. In this example, the ink replenishing motor 1 is described as operating at a constant rotational speed and with a constant period between pumping by the ink pump 2.
As described above, the ink supply device 35 has a function as an ink supply means for supplying the ink 10 to the ink reservoir 10a. The ink replenishment motor 1 has a function as an ink replenishment drive unit that drives the ink pump 2 and the like of the ink supply device 35 as an ink replenishment unit.

  Accordingly, in FIG. 16, the ink 10 is replenished / supplied by turning on and rotating the ink replenishing motor 1 to rotate the disk 16 and the pin (53a), and this rotational motion causes the swing of the link (54). The ink connected to the ink container via the cap receiver 12 at the arrow A portion is converted into motion, and the swinging motion of the link (54) is converted into the reciprocating motion of the piston rod 11 in the front-rear direction. After the ink in the container is sucked and pumped out and taken into the ink pump 2, it is sent to the ink feed pipe 13 and the ink branch pipe 3 and dropped into the ink reservoir 10a from the opened ink discharge port 3a. Become. Here, the amount of ink replenished / supplied to the ink reservoir 10a is configured such that the number of reciprocating operations of the ink pump 2 (hereinafter referred to as “pumping frequency”) is counted by detecting the filler 8 by the pumping frequency sensor 7. Yes. The pumping frequency sensor 7 is composed of a transmissive photosensor having a light emitting element and a light receiving element, and detects the amount of ink supplied to the ink reservoir 10a by the operation of the ink supply device 35 by counting the number of pumping times. It has a function as a quantity detection means. Thus, the pumping frequency sensor 7 is a simple means for detecting the amount of ink replenished to the ink reservoir 10a. Accordingly, the means for detecting the ink replenishment amount to the ink reservoir 10a due to the operation of the ink supply device 35 is not limited to the pumping frequency sensor 7, and the ink replenishment amount may be directly measured and detected.

FIG. 19 shows a conventional ink amount detection device 300 and an ink supply control device 310. The ink amount detection device 300 uses a needle-like member as a detection electrode for detecting a capacitance corresponding to the ink amount of the ink reservoir 10a formed between the ink roller 5 and the doctor roller 4. It mainly includes a needle 20 and an ink amount detection circuit 21 that electrically processes the capacitance detected by the ink detection needle 20.
Here, detecting the amount of ink in the ink reservoir 10a or the presence or absence of the ink 10 indirectly means the amount of ink supplied to the inner peripheral surface of the plate cylinder 6 of the printing drum 31 or the presence or absence of the ink 10 in the stencil printing apparatus. It is to detect.
The ink detection needle 20 is disposed so that the tip portion thereof is buried / inserted in an ink reservoir 10a having a predetermined amount of ink. The ink roller 5 is a counter electrode facing the ink detection needle 20 that is a detection electrode, and is grounded. Here, a capacitor (capacitance) C is formed by the detection needle 20 as the detection electrode and the ink roller 5 as the counter electrode, and the capacitance value is determined by the dielectric constant (ε) of the ink 10 between the two electrodes. The lower end portion, which is the tip portion of the ink detection needle 20, is arranged so as to be present in the ink reservoir 10a when the ink amount of the ink reservoir 10a exceeds a predetermined amount. In general, the dielectric constant (ε) of printing ink is about 100 times larger than the dielectric constant of air, so the capacity of the capacitor C is such that the tip of the ink detection needle 20 is in contact with the ink 10 in the ink reservoir 10a. It varies greatly depending on whether or not it is.

The ink detection needle 20 is connected to an ink amount detection circuit 21 via a predetermined wiring 19. The ink amount detection circuit 21 is, for example, a one-shot multivibrator (single pulse output circuit) 22 having an IC configuration as shown in FIG. 10 of Japanese Patent Application Laid-Open No. 11-101680 and described in paragraph “0004”. And a multi-vibrator 23 having an IC configuration, and a logical sum circuit 24 for taking a logical sum of outputs of the vibrators 22 and 23.
The one-shot multivibrator 22 is connected to be activated at an edge where the output of the multivibrator 23 becomes L level. The H level output width of the one-shot multivibrator 22 is set shorter than the L level duration of the multivibrator 23. Here, the time constant circuit 25 of the one-shot multivibrator 22 includes a charging resistor R and a capacitor (capacitance) C. For this reason, the wiring 19 of the ink detection needle 20 is connected to the charging voltage monitoring terminal 26 of the time constant circuit 25. Hereinafter, a method of detecting the ink amount (or presence / absence of ink) of the ink reservoir 10a using the ink detection needle 20 is referred to as an ink detection needle method.
According to the ink amount detection apparatus 300, the logical sum of the outputs of the vibrators 22 and 23 is monitored through the logical sum circuit 24, and the fluctuation of the L level duration time is observed, whereby the time constant circuit 25 of the one-shot multivibrator 22 is monitored. The fluctuation, that is, the fluctuation of the charging voltage V of the capacitor C accompanying the increase or decrease of the ink amount of the ink reservoir 10a can be detected. Since the capacitor (capacitance) C is charged through the charging resistor R in this way, the amount of ink forming the ink reservoir 10a is larger, and the larger the capacitance C, the longer the charging time. It will be.

In a broad sense, the ink supply control device 310 detects the number of reciprocations of the ink amount detection device 300 and the ink pump 2 (hereinafter sometimes referred to as “pumping times”, and one reciprocating operation is defined as one time). The above-described pumping frequency sensor 7 for counting and the ink supply motor 1 provided on the apparatus main body frame 50 side to drive the ink pump 2 based on the output signal (detection result output) from the ink amount detection circuit 21 It is mainly composed of a CPU (Central Processing Unit) 301 to be controlled.
In a narrow sense, the ink supply control device 310 mainly includes a CPU 301 and a ROM, a RAM, a timer, and the like (not shown) connected to the CPU 301 so as to be able to transmit and receive. This means that the same applies to the embodiments and modifications of the present invention described later, after changing the reference numerals.

  The operation panel 40 is disposed on the upper part of the document reading unit 80 shown in FIG. On the operation panel 40, as shown in FIG. 17, a plate making operation for starting a series of steps (operations) from reading of a document image to plate discharge, plate making, plate feeding, plate printing, and paper discharge steps. A plate making start key 41 as an activation means, a ten key 43 for setting / inputting the number of prints, and a print start key 42 for starting a printing operation for the number of prints set / input by the ten key 43 A printing speed display key (not shown) for notifying the printing speed setting key and the printing speed value set thereby, and how to operate various keys, various messages, selected functions, etc. And a liquid crystal display unit 44 and the like for displaying operation contents for selecting and setting the function as needed. The liquid crystal display unit 44 is driven via a liquid crystal drive circuit (not shown). When the power switch is turned on, the operation panel 40, the CPU 301 and the like are ready to be activated.

With reference to FIG. 3B and FIG. 18, the ink replenishment operation by the conventional ink detection needle method will be described.
When the same printing process as described above is performed, in FIG. 18B, the ink 10 of the ink reservoir 10a is gradually consumed and the size of the ink reservoir 10a is gradually reduced, so that the tip of the ink detection needle 20 is obtained. Is not in contact with the ink 10 in the ink reservoir 10 a, and accordingly, the ink amount detection circuit 21 transmits an “no ink” signal of “L” level to the CPU 301.
The CPU 301 that has received the “no ink” signal transmits a command signal for turning on the ink supply motor 1 to drive the ink pump 2 to the ink supply motor 1. As a result, when the ink replenishment motor 1 starts to rotate, the ink pump 2 pumps through the detailed operation described above, whereby the ink in the ink container is sucked and pumped out, and the ink feed pipe 13 and The ink is delivered to the ink branch pipe 3 and dropped from the ink discharge port 3a to the ink reservoir 10a, and is replenished and supplied to the ink reservoir 10a.
When ink is replenished to the ink reservoir 10a, the size of the ink reservoir 10a gradually increases, so that the tip of the ink detection needle 20 comes into contact with the ink 10 of the ink reservoir 10a again. The detected capacitance increases, and the ink amount detection circuit 21 detects “ink present” and transmits an “H” level “ink present” signal to the CPU 301. The CPU stops the operation of the ink supply motor 1 based on the “ink present” signal. In the printing process, the ink supply operation and the supply stop operation as described above are sequentially repeated.

  Thus, in the conventional ink replenishment control, when the ink detection needle 20 detects “ink present” via the ink amount detection circuit 21, the ink replenishment motor 1 is stopped to stop the ink replenishment, and the ink 10 is gradually consumed. When the ink detection needle 20 detects "no ink" via the ink amount detection circuit 21, the ink replenishment motor 1 is rotated to start ink replenishment. The ink amount in the ink reservoir 10a is reduced as much as possible. It was a control method that tried to keep it constant.

Next, with reference to FIG. 20 and FIG. 21, the state change of the ink 10 around the ink reservoir 10a by the ink replenishment operation by the conventional ink detection needle method will be described. 20 and 21 and each of the drawings showing embodiments described later, the ink amount detection circuit 21 showing only the charging resistor R and the charging voltage V for charging it is schematically shown in order to simplify the drawing. Has been shown.
FIG. 20A shows the state of the ink detection needle 20 and the ink reservoir 10a in the case of initial ink (ink 10 having a normal capacitance and high viscosity). On the other hand, FIG. 20B shows the ink detection when the capacitance of the ink 10 is reduced when water in the ink 10 is lost and only the oil and pigment are lost when printing at a low image ratio is continuously performed. The state of the needle 20 and the ink reservoir 10a is shown.
In FIG. 20A, it is detected that “there is ink” in the ink reservoir 10a in a state where only the front end portion of the ink detection needle 20 is in contact with the ink reservoir 10a. In the case of FIG. This indicates that since the capacitance of the ink is reduced, the ink reservoir 10a cannot be detected as “ink present” unless most of the ink detection needle 20 including the tip of the ink detection needle 20 enters the ink reservoir 10a. 20A and 20B, the ink drum 10a is in a state where the printing drum 31 rotates and the ink roller 5, the doctor roller 4, the plate cylinder 6 and the like rotate in the direction of the arrow. Show. Here, in the initial ink 10 shown in FIG. 20 (a), since the viscosity is high, even when the rotation of the printing drum 31 is stopped, the shape of the ink reservoir 10a is kept substantially the same. As shown in b), in the case of the ink 10 which has lost water and has a low viscosity, when the printing drum 31 is stopped, a state shown in FIG. 21 is obtained.
FIG. 21 shows an ink reservoir 10a in a state where the printing drum 31 is stopped (machine stopped) in the case of low ink viscosity that occurs when printing at a low image ratio is continuously performed by the conventional ink detection needle 20 method. ing. When the printing drum 31 rotates, as shown in FIG. 20B, the ink reservoir 10a is held in a substantially circular shape or wedge shape even though the ink 10 has a low viscosity and a large absolute amount. When 31 stops, the shape cannot be maintained as shown in FIG. 21, and the ink 10 flows down from the ink reservoir 10a to the ink roller 5 and falls to the inner peripheral surface of the plate cylinder 6. When the printing drum 31 starts rotating (printing) again, the state returns to the state shown in FIG. 20B again, but the ink 10 is left for a long time in a state where it falls to the inner peripheral surface of the plate cylinder 6. In this case, the viscosity may be low, so that the ink flows out from both sides of the ink roller 5 to both sides of the printing drum 31, and in the worst case, leaks out of the printing drum 31.

Next, the principle of ink amount detection of the present invention will be described in comparison with a conventional ink detection needle method.
First, as shown in FIG. 5 (a), in order to clarify the essence of the detection of the capacitance of the ink 10, the parallel plate model that derives the general formula of the capacitance is used to determine the ink amount of the ink reservoir. The detection is simplified and described. In the drawing, the area S of the electrodes 76 and 77 (surface area of the opposing surface of the electrodes 76 and 77) as a parallel flat plate composed of two opposing conductors, the distance d between the electrodes 76 and 77 sandwiching the ink 10, and the ink 10 When the dielectric constant ε of the capacitance is C, the relational expression C = εS / d holds for the capacitance C between the electrodes 76 and 77. That is, the capacitance C increases as the distance d decreases and the area S of the opposing electrodes 76 and 77 increases. FIG. 5 (b) to FIG. 5 (e) show this at a glance.

In FIG. 5, when FIG. 5B is the basic form of the parallel plate model, the gradient that is the gradient between the electrodes 76 and 77 represents the magnitude of the capacitance C as shown by the solid line. The d-shortened parallel plate model shown in FIG. 5C differs from the basic type only in that the distance d between the electrodes 76 and 77 is shortened to the distance d ′, and corresponds to the size of the capacitance C. The slope to be shown is indicated by a broken line. The S-enlarged parallel plate model shown in FIG. 5D is different from the basic model only in that the area S of the electrodes 76 and 77 is expanded to the area S ′, and corresponds to the size of the capacitance C. The inclination is indicated by a broken line.
FIG. 5 (e) shows a comparison of the inclinations (corresponding to the magnitude of the capacitance C) of the three types of the basic form, the d shortened form, and the S enlarged form. In the figure, the slope indicated by the broken line of the S-enlarged form is larger than the slope indicated by the solid line of the basic form, and the slope shown by the d-shortened broken line is larger than the slope of the S-enlarged form (steep slope). Therefore, it can be seen at a glance that the size of the capacitance C is the largest in the d-shortened type, and then in the order of the S-enlarged type and the basic type, and the contribution of the capacitance C is large in this order. I understand that.

  FIG. 6 is a simplified diagram when the parallel plate model of FIG. 5 is applied to the ink detection needle method shown in FIG. In the ink detection needle method shown in FIG. 6, with respect to the amount of ink in the ink reservoir 10a, the ink roller 5 as one electrode of the counter electrode facing each other and the ink detection needle 20 as the detection electrode as the other electrode are parallel plates. In addition, detection and detection are performed using the electrostatic capacity of the ink 10 that exists between the ink roller 5 and the ink detection needle 20 and is supplied.

  As shown in FIG. 6A, the area S on the detection electrode side is a region where the tip of the ink detection needle 20 is buried in contact with the ink reservoir 10a, and is a region indicated by a symbol L in the drawing. . That is, the dimensions relating to the area S of the ink detection needle 20 are schematically in the embodiment: width T = 0.2 mm shown in FIG. 6B, length L = 5 mm shown in FIG. This corresponds to the area of thickness B = 1 mm shown in FIG. The distance d between the electrodes is a distance between the ink roller 5 and the ink detection needle 20 and is about 5 to 10 mm. Further, in this example, as shown in FIG. 6B, in order to increase the area S of the ink detection needle 20, two tip portions that are buried in contact with the ink reservoir 10a are provided. In the same figure, it has shown that the two site | parts enclosed with the broken line are the area | regions which contribute to the area S and distance d.

Specifically, the problem described in the prior art is that the dielectric constant ε of the ink 10 changes to about 1/3, which causes problems on the apparatus. In order to compensate for the decrease in the dielectric constant ε of the ink 10, it is possible to increase the area S or decrease the distance d as is apparent from the shape and comparison of the parallel plate model in FIG. It becomes. As a method for realizing this, it is conceivable to increase the area S of the general formula by increasing the number of ink detection needles 20 or increasing the area of the ink detection needles 20, but then the ink 10 in the ink reservoir 10 a is increased. The side effect of preventing rotational flow will occur.
Note that the ink detection needle method has the advantage that the ink amount can be detected relatively easily by adjusting the depth L of the tip of the ink detection needle 20 to the ink reservoir 10a in FIG. 6B. Needless to say.

FIG. 7 shows an outline in which the ink detection needle 20 of the ink detection needle type is replaced with the doctor roller 4 so that the doctor roller 4 has the function of the detection electrode. Hereinafter, a method in which the doctor roller 4 detects the amount of ink in the ink reservoir 10a is sometimes referred to as a “doctor roller detection method”.
That is, in the doctor roller detection system shown in FIG. 7, with respect to the amount of ink in the ink reservoir 10a, the ink roller 5 as one electrode of the opposed electrodes facing each other and the doctor roller 4 as the detection electrode as the other electrode are parallel. A flat plate is used for detection and detection using the electrostatic capacity of the ink 10 that exists between the ink roller 5 and the doctor roller 4 and is supplied.

  As shown in FIG. 7 (a), the distance d between the ink roller 5 and the doctor roller 4 that is the distance d between the electrodes is about 0.1 to 0.2 mm (theoretical), depending on the model. In theory, 0.1 mm is used), which is theoretically about 1/50 of the ink detection needle method shown in FIG. That is, it is possible to obtain a capacitance C 50 times that of the ink detection needle method. In the doctor roller detection method, the area S of the detection electrode facing the ink roller 5 can be larger than that in the ink detection needle method. In FIG. 7 (b), it is shown that the part surrounded by the broken line in the long range in the respective axial directions of the ink roller 5 and the doctor roller 4 is an area contributing to the area S and the distance d.

  Further, according to the doctor roller detection method, the doctor roller 4 and the ink amount detection circuit 21 have the existing apparatus configuration, so that the rotational flow of the ink 10 in the ink reservoir 10a is detected as in the ink detection needle method. Since S / d in the above general formula can be increased without hindering, the detection of the amount of ink 10 in the ink reservoir 10a that does not depend on the change in the dielectric constant ε of the ink 10 (hereinafter simply referred to as “the amount of ink”). Detection ”), that is, detection of the presence or absence of the ink 10 in the ink reservoir 10a (hereinafter sometimes simply referred to as“ detection of presence / absence of ink ”).

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 to 4 and FIG.
In the first embodiment, as compared with the configuration of the conventional stencil printing apparatus shown in FIGS. 16 to 19, instead of the ink amount detection apparatus 300 using the ink detection needle method as shown in FIG. 19, As shown in FIGS. 1 to 4 and 7, the ink amount detection device 17 using the doctor roller detection method is provided, and instead of the ink supply control device 310 constituted by the CPU 301 or the like as shown in FIG. 19. As shown in FIG. 2, the main difference is that the ink supply control device 50 is composed of a CPU 51 and the like. Hereinafter, the difference will be mainly described.
The ink amount detection device 17 includes a detection electrode for detecting an electrostatic capacity corresponding to the ink amount of the ink reservoir 10a, which is constituted by a doctor roller 4 that is an ink amount regulating member (hereinafter simply referred to as "doctor roller 4"). And an ink amount detection circuit 21 that electrically processes the electrostatic capacitance detected by the doctor roller 4. Therefore, the ink amount detection device 17 is different from the ink amount detection device 300 only in that the doctor roller 4 is used instead of the ink detection needle 20, and the configuration of the ink amount detection circuit 21 is basically the same as the conventional one. Are identical.
FIG. 1 shows an example in which the detection electrode is constituted by a doctor roller 4.
The ink roller 5 is formed of an aluminum tube material which is a conductor in the embodiment, and is formed by press-fitting and fixing a steel shaft 5a to an end plate 5b made of a sheet metal (steel plate) fixed to both ends. Has been. Steel ball bearings 28 are press-fitted into both ends of the shaft 5a. A pair of ink side plates 18 made of sheet metal (steel plate) is suspended from both ends of a support shaft 34 (omitted in FIG. 1, see FIG. 16) inside the printing drum 31. On the other hand, the support shaft 34 is formed of a steel pipe material. When the drum unit is mounted in the apparatus main body frame 65, the drum unit is in contact with and engaged with a steel pipe bearing made detachably provided on the support body 34 on the apparatus main body frame 65 side. As a result, the ink roller 5 is supported by the pair of ink side plates 18 through the ball bearings 28 in an electrically conductive state in the printing drum 31 in the same manner as in the past. As described above, the end plate 5b, the shaft 5a, the ball bearing 28, the ink side plate 18, the support shaft 34, and the bearings, which are metal conductors, are grounded (grounded).
In the drawing of the ink roller 5, a steel gear 36 that meshes with a drum gear (not shown) fixed to an end plate (not shown) of the printing drum 31 is attached and fixed to the end of the shaft a on the back side.
The doctor roller 4 is formed of a steel pipe material, which is a conductor in the embodiment, and rotates to a pair of ink side plates 18 via a non-conductor resin bearing member 27 attached to both ends thereof. It is supported freely and electrically in a non-conductive state. A resin gear 37, which is a non-conductor that meshes with the gear 36 of the ink roller 5, is attached and fixed to the rear end of the doctor roller 4.
On the other hand, a resin insulating member 29 is attached and fixed to the front ink side plate 18 in a non-conductive state. In the drawing of the doctor roller 4, the front end of the doctor roller 4 is made of metal in which the base end is attached and fixed to the ink side plate 18 via a screw in a non-conductive state with the insulating member 29 interposed therebetween (implemented) A free end portion of a leaf spring 9 (made of copper plate, for example) is in contact. A wiring 19 connected to the input side of the ink amount detection circuit 21 is connected to the base end portion of the leaf spring 9. In this way, the voltage is input to the doctor roller 4 which is a rotating body by lightly pressing it with the leaf spring 9, and the doctor roller 4 is in a non-conductive state with the ink side plate 18, in other words, the ink roller 5. Both are electrically connected to the ink amount detection circuit 21 via the wiring 19 in a non-conductive state.

Compared with the ink supply control device 310 shown in FIG. 19, the ink supply control device 50 is replaced by the doctor roller 4 instead of the ink detection needle 20 constituting the ink amount detection device 17, as shown in FIG. The main difference is that the configuration is used and the CPU 51 instead of the CPU 301 is used. Others are the same as those of the ink supply control device 310.
In other words, the ink supply control device 50 includes the ink amount detection device 17 and the number of pumping times of the ink pump 2 (hereinafter, the piston rod 11 corresponds to one rotation of the ink supply motor 11 for simplification in the embodiment. The above-mentioned pumping number sensor 7 that detects and counts the amount of ink replenished / supplied to the ink reservoir 10a by reciprocating operation and setting the number of pumping corresponding to this as one pumping number) and the apparatus main body frame 50 side Based on an output signal (detection result output) from the provided ink amount detection circuit 21 and a pumping frequency signal corresponding to the ink replenishment amount from the pumping frequency sensor 7 (hereinafter referred to as “pumping frequency signal from the pumping frequency sensor 7”). And a CPU 51 for controlling the ink replenishing motor 1 to drive the ink pump 2. To have.

The CPU 51 is connected to the ink amount detection circuit 21 and the pumping frequency sensor 7 via an input port (not shown), and to the ink replenishing motor 1 via an output port (not shown). Or an on / off signal or a data signal to be described later is received.
The CPU 51 is connected to a ROM, a RAM, a timer, and the like (not shown) by a signal bus (not shown).
The CPU 51 performs the ink supply device 35 shown in FIG. 18 based on the “no ink” signal from the doctor roller 4 and the pumping frequency signal related to the ink replenishment amount from the pumping frequency sensor 7 via the ink amount detection circuit 21. First control means for supplying a predetermined amount of ink 10 to the ink reservoir 10a, in other words, the ink pump 2 shown in FIG. 18 (a) has a predetermined pumping so as to supply a predetermined amount of ink 10 to the ink reservoir 10a. It has a basic function as a first control means for controlling the ink replenishment motor 1 so as to operate several times.
In the ROM, related data for performing the control function of the CPU 51, a timing chart described later, a program related to an operation sequence, and the like are stored in advance. The RAM has a function of temporarily storing calculation results of the CPU 51 and a function of storing data signals input from the ink amount detection circuit 21 and the pumping frequency sensor 7 as needed.

Next, with reference to FIG. 1 thru | or FIG. 3 (a) and FIG. 4, about the ink replenishment operation | movement in 1st Embodiment, the ink replenishment operation by the ink detection needle system described with reference to FIG. The difference will be mainly described. Here, the basic first function of the CPU 51 is used.
When the same printing process as described above is performed, in FIG. 4A to FIG. 4B, the ink 10 in the ink reservoir 10a is gradually consumed, and the ink reservoir 10a is formed as shown in FIG. 4B. By almost disappearing, the doctor roller 4 passes through the ink amount detection circuit 21 (hereinafter sometimes referred to simply as “the doctor roller 4” by omitting “through the ink amount detection circuit 21”). The “no ink” signal is sent to the CPU 51.
FIG. 4B shows the state of the ink reservoir 10a when the doctor roller 4 detects “no ink”, but there is almost no ink 10 in the portion where the ink reservoir is formed. It shows that the ink 10 is uniformly attached to the outer peripheral surface with the doctor roller 4. Even in the state shown in FIG. 4B in which there is almost no ink reservoir, a sufficient amount of ink 10 remains on the inner peripheral surface of the plate cylinder 6, so that no image blur or the like occurs unless the solid image is printed. .

Upon receiving the “no ink” signal, the CPU 51 first transmits a command signal for turning on the ink supply motor 1 to the ink supply motor 1. Thereby, ink supply for forming the ink reservoir 10a is started through the detailed operation by the ink supply device 35 similar to that described above, and the doctor roller 4 detects “ink present” as the ink supply gradually proceeds. Still, the ink replenishment operation is stopped after the ink pump 2 has been performed a predetermined number of times (n times) by the n rotation drive of the ink replenishment motor 1, and the ink replenishment operation is always performed regardless of the capacitance of the ink 10 in the ink reservoir 10 a. A certain amount will be replenished. N is a natural number.
The state of the ink reservoir 10a at this time shows a state after the ink pump 2 has been operated a predetermined number of times (n times) by driving the ink supply motor 1 n times as shown in FIG. 4A. When the printing continues and the doctor roller 4 detects “no ink”, the ink replenishing motor 1 starts to rotate, and the ink pump 2 is driven n times by a predetermined number of times (n The ink supply control operation of stopping after the operation is repeated.

  By performing ink replenishment control as described above, it is not possible to prevent the viscosity of the ink 10 in the ink reservoir 10a even when printing at a low image ratio is continuously performed. Since the ink replenishment is not performed while the ink 10 is not consumed, the ink 10 does not flow down from the ink reservoir 10a, and as a result, it is possible to prevent the ink 10 from leaking out of the printing drum 31. .

  The stencil printing apparatus provided with the ink amount detection device 17 of the doctor roller detection type in the first embodiment shown in FIG. 1 and the stencil provided with the ink amount detection device 300 of the conventional ink detection needle type shown in FIG. Using a printing apparatus, a low image rate was continuously printed in large quantities, and the capacitance C corresponding to the ink amount was measured under the same conditions in which the dielectric constant ε of the ink 10 in the ink reservoir 10a was reduced. Example 1 will be described in comparison with a conventional example.

Apparatus used: Conventional example: A “Preport N800 / N850” stencil printing apparatus manufactured by Ricoh Co., Ltd., equipped with a conventional ink detection needle type ink amount detection apparatus 300 shown in FIG. The material specifications, dimensions, and the like of the doctor roller 4 and the ink roller 5 were the same as those described in the first embodiment.
The present invention is a stencil printing apparatus of the same model as the conventional example, and only the ink amount detection device is modified to the doctor roller detection type ink amount detection device 17 shown in FIG.
Ink: "Preport CM color ink" manufactured by Ricoh Co., Ltd.
Ink amount detection circuit: Both used the same ink amount detection circuit 21 shown in FIG.

Measurement result: Detection result output value of the ink amount detection circuit 21 shown in FIG. 19 Conventional ink detection needle method: 14 μsec
Doctor roller detection method of the present invention 496 μsec
Here, since charging resistors R having the same size are used, comparison can be made with a simple ratio. C1 below represents the capacitance detected by the ink detection needle method, and C2 represents the capacitance detected by the doctor roller detection method.
Conventional ink detection needle method: 14 μsec = C1 × R
Doctor roller detection method of the present invention 496 μsec = C2 × R
From the above, the present invention / conventional ... 496 / 14≈35.4, and the doctor roller detection method of the present invention is approximately 35 times the capacitance (under the same printing conditions as the conventional ink detection needle method). Ink amount). Therefore, it can be said that the detection and detection performance of the electrostatic capacity of the ink 10 by the doctor roller detection method of the present invention has a remarkable effect as compared with the conventional ink detection needle method.
In the above description of the principle of detecting capacitance by the doctor roller detection method of the present invention, a simple parallel plate model has been described. However, in reality, both the electrodes are opposed to each other (ink roller 5 and ink detection). The area S of the needle 20, the ink roller 5 and the doctor roller 4) is not the same, and the distance d between the two electrodes is cylindrical, so it is not uniform, and the values of the area S and the distance d described above are also approximate. Since it is an actual measurement value, it is considered that a deviation from the theoretical value (expected value) has occurred.

(Modification 1 of the first embodiment)
8 to 10 show a first modification of the first embodiment.
This modification 1 is different from the configuration of the stencil printing apparatus of the first embodiment in that it has an operation panel 40A instead of the operation panel 40, and an ink supply control device instead of the ink supply control device 50. The main difference is that 50A is used. Others are the same as in the first embodiment.

As shown in FIGS. 8 and 9, the operation panel 40 </ b> A has a normal print mode key 45 and a solid image print mode key 46 as image ratio setting means for setting an image ratio, as compared with the operation panel 40. The only difference is that When the normal print mode key 45 and the solid image print mode key 46 are respectively pressed, a lamp composed of an LED (light emitting diode) that lights and displays that the “normal print mode” or “solid image print mode” is set. Built in.
Compared with the ink supply control device 50 shown in FIG. 1, the ink supply control device 50A uses a CPU 51A in place of the CPU 51, as shown in FIG. 9, and a normal print mode key 45 and a solid image print mode key. The main difference is that an operation panel 40A provided with 46 is used. Others are the same as those of the ink supply control device 50.

Compared with the CPU 51, the CPU 51A, in addition to the function as the first control means of the CPU 51, outputs the output signal from the normal print mode key 45 or the solid image print mode key 46 and the pumping frequency signal from the pumping frequency sensor 7. Based on the second control means for changing the amount of ink supplied to the ink reservoir 10a by using the ink supply device 35 shown in FIG. 18, in other words, the ink pump 2 shown in FIG. 18 supplies the ink 10 to the ink reservoir 10a. It has a function as a second control means for controlling the ink replenishing motor 1 so as to operate a predetermined number of pumping times by changing the amount of replenishing the ink.
The control may be such that the number of pumping times of the ink pump 2 is changed by changing the rotational speed of the ink replenishing motor 1 (the same applies hereinafter).
In the ROM, related data for exhibiting the control function of the CPU 51A, a program relating to an ink replenishment operation described later, and the like are stored in advance.

Next, only the characteristic ink supply operation of Modification 1 will be described. In the first modification, for example, the user looks at image information of a document or image information transmitted from a personal computer or the like to determine the image rate, and selects either the normal print mode key 45 or the solid image print mode key 46. By pressing the button, an image ratio corresponding to the print image ratio can be selected. By selecting one of them, an ink supply operation suitable for the print image and printing conditions is performed.
For example, when printing at a high image ratio (solid image), the solid image printing mode key 46 is pressed to select “solid image printing mode”, whereby the ink replenishment operation is a normal case “normal printing mode”. Since it is stored and set in advance in the ROM so as to operate more (for example, the number of pumping times is n + α) compared to (for example, the number of pumping times is n), the amount of ink in the ink reservoir 10a is increased. It becomes control. In this case, as shown in FIG. 10B, the ink amount / size of the ink reservoir 10a is about 1.5 to 2.0 times that in the “normal printing mode” when the “solid image printing mode”. The ink reservoir 10a is set. Α is a natural number.
Accordingly, the margin for occurrence of image blur is improved as compared with the case of the ink replenishment control in the first embodiment.

  On the other hand, when printing a non-solid image, pressing the normal print mode key 45 and selecting “normal print mode” completes the ink replenishment operation in a smaller number of times than in the former case, and the ink storage amount. It will be controlled to reduce. FIG. 10A shows the ink amount and size of the ink reservoir 10a when the “normal printing mode” is selected, and it is possible to reduce the amount of ink remaining in the ink reservoir 10a after printing is completed. Degradation of the ink 10 due to the ink 10 being left (the printing drum 31 and the stencil printing apparatus are stopped and left for a long time) can be minimized.

Modification 1 is not limited to the above-described configuration and operation, and may be as follows. That is, the image ratio setting means is not limited to the normal print mode key 45 and the solid image print mode key 46, but one mode switching key for selecting the normal print mode key 45 or the solid image print mode key 46 and switching to each mode. It is also possible to do this. As the image ratio setting means, the normal print mode key 45 and the solid image print mode key 46 are used to simplify the explanation. However, for example, the image ratio is set finely in a dial or touch panel type in three or more stages. Such means may be used. The notification / display means for displaying that each mode setting state is lit is not limited to the LED, but may be, for example, an LED, a voice notification, or a combination notification / display means thereof.
Further, for example, the normal print mode key 45 may be set in an initial setting state so that the built-in LED of the key is turned on so that the user does not particularly need to operate the operation panel 40A.

(Modification 2 of the first embodiment)
FIG. 11 shows a second modification of the first embodiment.
This modification 2 is mainly different from the configuration of the stencil printing apparatus of the first embodiment in that an ink supply control device 50B is used instead of the ink supply control device 50 shown in FIG. Others are the same as in the first embodiment.
Compared with the ink supply control device 50 shown in FIG. 1, the ink supply control device 50B uses a CPU 51B instead of the CPU 51 as shown in FIG. 11, and an image memory 98 as a storage means for storing image data. The main difference is that it has an image signal processing device 97 that is connected to the CPU 51B via the input port and the output port and transmits and receives image signals. Others are the same as those of the ink supply control device 50.

  Compared with the CPU 51, the CPU 51B stores the image data read by the document reading unit 80 shown in FIG. 16 or the image data transmitted from the personal computer in addition to the function of the CPU 51 as the first control means. The image ratio (or the printing rate or the image area amount) is calculated from the image data stored in the image memory 98, and based on the image ratio obtained by this calculation and based on the pumping frequency signal from the pumping frequency sensor 7. The third control means for changing the amount of ink supplied to the ink reservoir 10a by the ink supply device 35 shown in FIG. 18, in other words, the ink pump 2 shown in FIG. 10 as a third control means for controlling the ink replenishing motor 1 so as to operate a predetermined number of pumping times by changing the amount of replenishing 10 Having.

The image memory 98 is composed of, for example, a buffer memory having a capacity for storing image data for one page or more of a document. In the ROM, related data for performing the control function of the CPU 51B (ink so that the ink pump 2 changes the amount of ink 10 supplied to the ink reservoir 10a in accordance with the image ratio and operates for a predetermined number of pumping operations. Data for controlling the replenishing motor 1) and a program relating to an ink replenishing operation described later are stored in advance.
Here, for simplification of explanation, it is assumed that image ratios corresponding to “normal print mode” and “solid image print mode” are stored in the ROM. Needless to say, the details may be set step by step. A computer such as a personal computer (hereinafter referred to as “personal computer”) or a host computer is connected to the image signal processing device 97 via an I / F (interface device) (not shown) and transmitted from the computer via the I / F. The digital image data to be processed may be taken into the image memory 98 via the image signal processing device 97 (the same applies hereinafter).

Here, the image ratio (image area amount) of the document is the print rate (print area amount) or perforated portion of the plate-making image when enlargement or reduction processing is not performed on image data sent from a personal computer or the like. It means the same as the aperture ratio (opening area amount). The ink consumption is such that the ink on the inner surface of the plate cylinder 6 of the printing drum 31 is filled to the extent that ink can be printed and there is no problem such as ink leakage, and the amount of ink passing through the plate-making master 61a. Since it can be regarded as the total amount, the total number of heating elements used for punching and plate making of the master 61 corresponding to the black data of the image data, that is, the punching rate of the plate making master 61a (regarding the original size and plate making size) It can be said that the total amount of perforated area).
Therefore, if the document size is fixed to the same size and the ratio of the image area amount to this is fixed (image ratio = ratio of black data), the image ratio of the document and the image area amount of the document are the same. Means. In other words, when compared with the same document size, the image ratio to the document size (some amount of image area) is synonymous with the print image ratio for the print image on the paper and the print rate (or aperture ratio) for the plate-making image. .

Next, only the characteristic ink supply operation of Modification 2 will be described. As described with reference to FIG. 16, an image of a document is read by the document reading unit 80, and optical information of the document for one page is sequentially photoelectrically converted by the image sensor 89. The analog image signal photoelectrically converted by the image sensor 89 is input to the A / D converter 96 and converted into a digital image signal. The digital image signal is temporarily stored and stored in the image memory 98 as image data via the image signal processing device 97.
Next, the CPU 51B calls the image data temporarily stored in the image memory 98 via the image signal processing device 97, calculates the image ratio, and according to the image ratio obtained by this calculation, that is, for example, the image ratio, for example. It is determined whether or not the black data corresponding to the “normal print mode” or “solid image print mode” when the original is fixed. Except for the above, the CPU 51B is the same as the ink replenishment control by the CPU 51A in the first modification, and the description thereof is omitted.

For example, when the CPU 51B determines that the image data has a high image ratio (solid image), the “solid image printing mode” is automatically set, and the “normal printing mode”, which is the normal case of the ink supply operation. Since it is stored and set in advance in the ROM so as to operate more (for example, the number of pumping times is n + α) compared to (for example, the number of pumping times is n), the amount of ink in the ink reservoir 10a is increased. It becomes control. At this time, the ink amount and size of the ink reservoir 10a are set so that about 1.5 to 2.0 times that in the “normal printing mode” is the ink reservoir 10a in the “solid image printing mode”. ing.
Accordingly, the margin for occurrence of image blur is improved as compared with the case of the ink replenishment control in the first embodiment.

On the other hand, when the CPU 51B determines that the image data has a low image ratio that is not a solid image, for example, the “normal print mode” is automatically set. The ink replenishment operation is completed in a smaller number of times than in the former case, and control is performed to reduce the amount of ink reservoir (see FIG. 10A). 31, the deterioration of the ink 10 due to prolonged stop-standing state) of the stencil printing device is also Ru can be minimized.

  In addition to the functions of the CPUs 51A and 51B of the first and second modified examples, in order to perform finer ink replenishment control, control is performed to change the ink amount in consideration of the number of printed sheets 62 corresponding to the image data. You may make it perform. In this case, the ROM stores in advance data related to the solid image printing mode, the normal printing mode, the number of printed sheets, and α. The CPU 51A or the CPU 51B recognizes the number of printed sheets based on a signal relating to the number of printed sheets set / input by the ten key 43 of the operation panel 40A or 40, and counts the number of discharged sheets from the sheet discharge sensor 119 shown in FIG. Check and collate by the printed sheet counter.

(Second Embodiment)
12 to 14 show a second embodiment. Compared with the configuration of the stencil printing apparatus of the first embodiment, the second embodiment is an ink based on the doctor roller detection system of the first embodiment shown in FIG. 1, as shown in FIGS. A point having an ink supply control device 50C capable of detecting the ink amount of the reservoir 10a and detecting the ink amount of the ink reservoir 10a by the conventional ink detection needle method shown in FIG. 19, and an operation panel 40A are used. The point is mainly different. Others are the same as in the first embodiment.

  Compared with the ink supply control device 50 shown in FIG. 1, the ink supply control device 50C uses a combination of the conventional ink amount detection device 300 and the ink amount detection device 17, as shown in FIG. The point which uses panel 40A and the point which uses CPU51C replaced with CPU51 mainly differ. Others are the same as those of the ink supply control device 50.

The CPU 51C performs either one of the case where the ink amount is detected by the ink detection needle 20 and the case where the ink amount is detected by the doctor roller 4 based on the output signal from the normal printing mode key 45 or the solid image printing mode key 46. It has a function as a 4th control means to switch to. In other words, the CPU 51C detects the ink amount by the doctor roller 4 based on the output signal from the normal print mode key 45, and based on the output signal from the solid image print mode key 46, the ink detection needle 20 In order to detect the amount of ink, the fourth control means functions to enable or disable the output signal from the doctor roller 4 or the ink detection needle 20.
Further, the CPU 51C performs the ink supply device 35 shown in FIG. 18 on the basis of the no-ink signal from the ink detection needle 20 or the doctor roller 4 and the pumping frequency signal from the pumping frequency sensor 7, and supplies a predetermined amount to the ink reservoir 10a. The fifth control means for replenishing the ink 10, in other words, the ink replenishment so that the ink pump 2 shown in FIG. 18A operates for a predetermined number of pumping operations to replenish the ink reservoir 10 a with a predetermined amount of ink 10. It has a function as a fifth control means for controlling the motor 1.
In the ROM, related data for exhibiting the control function of the CPU 51C, a program relating to an ink replenishment operation described later, and the like are stored in advance.

Next, only the characteristic ink supply operation of the second embodiment will be described. In the second embodiment, for example, the user looks at image information of a document or image information transmitted from a personal computer or the like to determine the image rate, and either one of the normal print mode key 45 and the solid image print mode key 46 is used. By selecting and pressing, it is possible to select an image ratio corresponding to the print image ratio, and by selecting one of them, an ink supply operation suitable for the print image and printing conditions is performed.
For example, when printing at a high image ratio (solid image), when the user presses the solid image print mode key 46 and selects “solid image print mode”, as shown in FIG. This is executed based on the ink amount detection by the detection needle method. This figure shows the ink timing (ink presence / absence detection) and the operation timing of the ink replenishment motor 1 by the conventional ink detection needle method and doctor roller detection method. This is a case where ink presence / absence detection control is performed using only the needle 20.

As described above, when the ink amount detection control is performed only with the ink detection needle 20, the state of the ink reservoir 10a is as shown in FIG. Since the amount of ink in the ink reservoir 10a is controlled so as to be always constant as in the conventional case, the margin for image blurring when printing a solid image is considerably improved.
When the user selects the “normal printing mode” and performs printing at a low image rate, the ink supply operation is performed as shown in FIG.

(Modification 3 of the second embodiment)
FIG. 12, FIG. 14 and FIG. 15 show a third modification of the second embodiment. As compared with the configuration of the stencil printing apparatus of the first embodiment, the third modification is based on the doctor roller detection method of the first embodiment shown in FIG. 1, as shown in FIGS. The main difference is that it has an ink supply control device 50D that can detect the ink amount of the ink reservoir 10a and the ink amount of the ink reservoir 10a by the conventional ink detection needle method shown in FIG. Others are the same as in the first embodiment.

  Compared with the ink supply control device 50 shown in FIG. 1, the ink supply control device 50D uses a combination of the conventional ink amount detection device 300 and the ink amount detection device 17, as shown in FIG. A point having an image memory 98 as a storage means for storing data, a point having an image signal processing device 97 connected to the CPU 51D via the input port and the output port, and transmitting and receiving an image signal. The main difference is that a replacement CPU 51D is used. Others are the same as those of the ink supply control device 50.

The CPU 51D calculates the image ratio from the image data read by the document reading unit 80 shown in FIG. 16 or the image data stored in the image memory 98 that stores the image data transmitted from the personal computer. According to the obtained image ratio, it has a function as a sixth control means for switching between the case where the ink amount is detected by the ink detection needle 20 and the case where the ink amount is detected by the doctor roller 4. In other words, the CPU 51D performs ink detection needles based on the high image ratio including the solid image obtained by the calculation so that the doctor roller 4 detects the ink amount based on the low image ratio obtained by the calculation. 20 has a function as sixth control means for enabling or disabling the output signal from the doctor roller 4 or the ink detection needle 20 so as to detect the ink amount.
Further, the CPU 51D performs the ink supply device 35 shown in FIG. 18 on the basis of the no-ink signal from the ink detection needle 20 or the doctor roller 4 and the pumping frequency signal from the pumping frequency sensor 7, and supplies a predetermined amount to the ink reservoir 10a. The seventh control means for replenishing the ink 10, in other words, the ink replenishment so that the ink pump 2 shown in FIG. 18A operates a predetermined number of pumping times to replenish the ink reservoir 10 a with a predetermined amount of ink 10. It has a function as a seventh control means for controlling the motor 1.
In the ROM, related data for exhibiting the control function of the CPU 51D, a program relating to an ink replenishing operation described later, and the like are stored in advance.

Next, only the characteristic ink supply operation of Modification 3 will be described. As described with reference to FIG. 16, an image of a document is read by the document reading unit 80, and optical information of the document for one page is sequentially photoelectrically converted by the image sensor 89. The analog image signal photoelectrically converted by the image sensor 89 is input to the A / D converter 96 and converted into a digital image signal. The digital image signal is temporarily stored and stored in the image memory 98 as image data via the image signal processing device 97.
Next, the CPU 51D calls the image data temporarily stored in the image memory 98 via the image signal processing device 97, calculates the image ratio, and according to the image ratio obtained by this calculation, that is, for example, the image ratio. It is determined whether or not the black data corresponds to either a low image rate or a high image rate (including a solid image) when the original is fixed.

For example, when the CPU 51D determines that the printing condition is to print a high image ratio (solid image), as shown in FIG. 14, the ink supply operation is executed based on the ink amount detection by the conventional ink detection needle method. Is done. As described above, when the ink amount detection control is performed only with the ink detection needle 20, the state of the ink reservoir 10a is as shown in FIG. Since the amount of ink in the ink reservoir 10a is controlled so as to be always constant as in the conventional case, the margin for image blurring when printing a solid image is considerably improved.
If the CPU 51D determines that printing with a low image rate is the printing condition, the ink supply operation is performed as shown in FIG.

As described above, in the second embodiment and the third modification, it can be said that the ink amount detection method according to claim 5 described in the means column for solving the problem is used.
In the second embodiment and the third modification, two identical ink amount detection circuits 21 are used. However, the present invention is not limited to this. For example, a semiconductor switch is provided between the wirings 19 of the ink detection needle 20 and the doctor roller 4. It is also possible to provide a relay or a relay, which is switched by the CPU 51C or the CPU 51D being turned on / off, and to share the ink amount detection circuit 21 into one.

  As described above, the present invention has been described with respect to specific embodiments, examples, or modifications. However, the technical scope disclosed by the present invention is not limited to that described above in the examples or modifications. It is not limited, and they may be combined as appropriate, and within the scope of the present invention, various embodiments, examples, or modifications may be configured according to the necessity and application. It will be apparent to those skilled in the art.

It is a perspective view of the principal part of the ink amount detection apparatus in the stencil printing apparatus which shows the 1st reference example of this invention. It is a block diagram of the ink supply control apparatus of the 1st reference example . (A) is a timing chart explaining the relationship between the presence / absence detection of ink by the doctor roller detection method of the first reference example and the operation timing of the ink replenishing motor, and (b) in the conventional ink detection needle method. It is a timing chart explaining the relationship. (A) is the state around the ink reservoir associated with the ink replenishment operation by the doctor roller detection method of the first reference example , and (b) is the state around the ink reservoir when no ink is detected by the doctor roller detection method. It is a partial cross section front view of the principal part which shows each. (A)-(e) is explanatory drawing using the parallel plate model for guide | inducing the ink amount detection principle by the doctor roller detection system of this invention. (A) is a simplified front view around the ink reservoir for explaining the principle of ink amount detection by the conventional ink detection needle method, and (b) contributes to the area and distance of the ink amount detection principle by the same method. It is a simplified top view for demonstrating an area | region. (A) is a simplified front view around the ink reservoir for explaining the principle of ink amount detection by the doctor roller detection method of the present invention, and (b) contributes to the area and distance of the ink amount detection principle by the method. It is a simplified top view for demonstrating the area | region to do. It is a top view of the operation panel used for the reference modification 1 . It is a block diagram of the ink supply control apparatus in the reference modification 1 . (A) is a partial cross section of the main part showing the ink amount of the ink reservoir when the normal printing mode is selected in Reference Modification 1 , and (b) is the ink amount of the ink reservoir when the solid image printing mode is selected. It is a front view. It is a block diagram of the ink supply control apparatus in the reference modification 2 . It is a partial cross section front view of the principal part around the ink amount detection apparatus which shows the structure which combined the conventional ink detection needle | hook system and doctor roller detection system in 1st Embodiment . It is a block diagram of the ink supply control device in the first embodiment . It is a timing chart explaining the relationship between the presence / absence detection of the ink by the conventional ink detection needle | hook system and doctor roller detection system in 1st Embodiment, and the operation timing of an ink replenishment motor. FIG. 10 is a block diagram of an ink supply control device in Modification 1 . It is a block diagram of the conventional stencil printing apparatus to which this invention is applied. It is a top view of the operation panel of the conventional stencil printing apparatus in FIG. (A) is a perspective view of the main part around the ink supply apparatus used in common with the conventional stencil printing apparatus and the present invention in FIG. 16, and (b) is a part of the main part around the ink supply apparatus. It is a cross-sectional front view. It is a figure which shows the ink detection needle circumference and ink amount detection circuit of the ink amount detection apparatus used for the conventional stencil printing apparatus in FIG. (A) shows the state of the ink detection needle and the ink reservoir in the case of the initial ink in the conventional ink detection needle method, and (b) continuously printed at a low image ratio by the conventional ink detection needle method. FIG. 6 is a partial cross-sectional front view of the main part showing a state where the presence of ink in the ink reservoir cannot be detected unless most of the ink detection needles are buried in the ink reservoir as the electrostatic capacity of the ink decreases. FIG. 10 is a partial cross-sectional front view of an essential part showing an ink reservoir state in a stopped state of a printing drum in a low ink viscosity state that occurs when printing at a low image ratio is continuously performed by a conventional ink detection needle method.

Explanation of symbols

1 Ink supply motor (component of ink supply means, ink supply drive means)
2 Ink pump (component of ink replenishment means)
4 Doctor roller (detection electrode, ink amount regulating member)
5 Ink roller (ink supply member, counter electrode)
6 Plate cylinder 7 Pumping frequency sensor (ink replenishment amount detection means)
9 Leaf spring (component of ink level detector)
10 Ink (emulsion ink)
10a Ink reservoir 20 Ink detection needle (detection electrode, needle-shaped member)
21 Ink amount detection circuit 31 Printing drum 35 Ink supply device 40, 40A Operation panel 45 Normal printing mode key (image ratio setting means)
46 Solid image printing mode key (image ratio setting means)
50, 50A to 50D Ink supply control device 51 CPU (first control means)
51A CPU (second control means)
51B CPU (third control means)
51C CPU (fourth and fifth control means)
51D CPU (sixth and seventh control means)
98 Image memory as storage means

Claims (5)

An ink supply member that supplies ink, an ink amount restriction member that is disposed with a predetermined gap from the ink supply member and restricts the amount of ink on the ink supply member, the ink supply member, and the ink amount restriction member; A detection electrode that detects a capacitance corresponding to the amount of ink in the ink reservoir formed between the two, and the detection electrode is constituted by a needle-like member and the ink amount regulating member. In a printing apparatus comprising an ink amount detection device having a printing drum and
Image ratio setting means for setting the image ratio;
Based on a signal from the image ratio setting means, a fourth control means for switching to one of the case where the ink amount is detected by the needle-shaped member and the case where the ink amount is detected by the ink amount regulating member;
A printing apparatus comprising: The printing apparatus according to claim 1 .
An ink supply means for supplying ink to the ink reservoir;
An ink replenishment amount detecting means for detecting an ink replenishment amount by the operation of the ink replenishing means;
Based on the no-ink signal from the needle-shaped member or the ink amount regulating member and the ink replenishment amount signal from the ink replenishment amount detecting means, the ink replenishing means is used to replenish a predetermined amount of ink to the ink reservoir. Fifth control means;
Printing apparatus characterized by having a. An ink supply member that supplies ink, an ink amount restriction member that is disposed with a predetermined gap from the ink supply member and restricts the amount of ink on the ink supply member, the ink supply member, and the ink amount restriction member; A detection electrode that detects a capacitance corresponding to the amount of ink in the ink reservoir formed between the two, and the detection electrode is constituted by a needle-like member and the ink amount regulating member. In a printing apparatus comprising an ink amount detection device having a printing drum and
Storage means for storing image data;
The image ratio is calculated from the image data stored in the storage means and switched to one of the case where the ink amount is detected by the needle member and the case where the ink amount is detected by the ink amount regulating member. Control means,
A printing apparatus comprising: The printing apparatus according to claim 3.
An ink supply means for supplying ink to the ink reservoir;
An ink replenishment amount detecting means for detecting an ink replenishment amount by the operation of the ink replenishing means;
Based on the no-ink signal from the needle-like member or the ink amount regulating member and the ink replenishment amount signal from the ink replenishing unit, the seventh ink supply unit replenishes the ink reservoir with a predetermined amount of ink. Control means,
A printing apparatus comprising: Ink reservoir ink amount formed between an ink supply member that supplies ink and an ink amount regulating member that is disposed with a predetermined gap from the ink supply member and regulates the amount of ink on the ink supply member In the ink amount detection method for detecting the electrostatic capacity corresponding to
In addition to the acicular member, the ink amount regulating member is used as the detection electrode, so that the detection of the ink amount by the acicular member and the detection of the ink amount by the ink amount regulating member are switched. An ink amount detection method characterized in that

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