JP4585262B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to image formation using a drum, such as a copying machine or a facsimile machine that transfers a toner image onto a printing sheet by a photosensitive drum, and a stencil printing apparatus that performs stencil printing using a drum around which a stencil sheet has been made. In particular, the present invention relates to an image forming apparatus that conveys printing paper so that an image is formed at a desired position on the printing paper.

  Conventionally, as an image forming apparatus using a drum, for example, a stencil printing apparatus using a printing drum with a pre-made stencil sheet attached and a copying machine using a photosensitive drum such as a PPC have been proposed. And, for example, as the stencil printing apparatus, a printing paper is inserted between a printing drum that rotates with a pre-made stencil sheet wound around an outer peripheral surface, and a press roller that rotates while being pressed against the printing drum. There has been proposed a stencil printing apparatus that performs printing by extruding ink in a drum from a hole in a stencil sheet that has been made, and transferring the ink to printing paper.

  In the stencil printing apparatus as described above, the printing paper fed out from the paper feed table is conveyed toward the printing drum by the conveying roller, and printing is started when it reaches the contact point between the printing drum and the press roller. Therefore, in order to align the printing range of the printing paper and the printing surface range of the stencil stencil sheet, when the printing start position of the printing paper reaches the contact point, the printing surface start position of the printing drum comes to the contact point. There is a need to. Therefore, for example, the rotation angle information of the printing drum when the printing paper reaches the conveyance roller may be obtained, and the rotation speed of the conveyance roller may be controlled based on the rotation angle information. The amount of printing paper held by the conveying roller when it reaches the position varies, and the printing roller slips when the printing paper is conveyed by the conveying roller. It is difficult to always match the printing surface start position with the printing start position.

  Therefore, a sensor for detecting the leading edge of the printing paper in the middle of conveyance is provided between the conveying roller and the contact point, and the printing start position of the printing paper is determined based on the point in time when the leading edge of the printing paper is detected by the sensor. There has been proposed a method of controlling the rotation speed of the conveying roller so that the time until the printing roller reaches the contact point and the time until the printing surface start position of the printing drum reaches the contact point are matched.

  For example, in Patent Document 1, the printing paper is waited in a state where the printing paper is in contact with the conveyance roller, and when the printing drum rotates to a predetermined position, rotation of the conveyance path roller is started, and rotation of the conveyance roller is started. To obtain a time interval until the leading edge of the printing paper is detected, compare the obtained time interval with a preset reference time interval, and control the rotation speed of the conveying roller according to the difference Has been proposed.

  In Patent Document 2 and Patent Document 3, when an encoder for detecting rotation angle information of a printing drum is provided to measure a pulse signal corresponding to the rotation angle information of the printing drum, and the leading edge of the printing paper is detected A method of controlling the rotation speed of the conveying roller based on the number of the pulse signals of is proposed.

Japanese Examined Patent Publication No. 63-30256 JP-A-62-88748 Japanese Unexamined Patent Publication No. 63-97549

  However, in the method described in Patent Document 1, since the reference value is calculated based on a preset printing drum speed, if there is a variation in the rotation speed of the printing drum, only the variation is included. An error occurs between the actual rotation speed of the printing drum and the rotation speed of the printing drum used when setting the reference value, and the rotation speed of the transport roller cannot be set appropriately, and the printing position is adjusted. Cannot be done properly. Further, when the rotation speed of the printing drum is changed to change the printing speed, it is necessary to change the value of the reference value.

  Further, in recent years, stencil printing has become highly precise and multi-colored, and a technique for aligning the printing position with higher accuracy is required. However, in the methods described in Patent Document 2 and Patent Document 3, printing paper is used. The accuracy of the rotation angle information of the printing drum at the time of detecting the leading edge of the printing drum depends on the resolution of the mechanism for detecting the rotation angle information (the number of pulse signals of encoder pulses per rotation of the printing drum). When the diameter is 173 mm (the circumference of the printing drum is 543 mm) and the resolution of the rotary encoder that detects the rotation angle information of the printing drum is 300 (300 pulse signals are generated while the printing drum rotates once). Since 543/300 = 1.81 mm, it is difficult to align the printing position with an accuracy finer than 1.81 mm. In addition, if the rotary encoder slit is made finer, the printing position can be adjusted with finer precision. However, making the rotary encoder slit finer may cause malfunction due to paper dust mixing into the slit, resulting in high assembly accuracy. It becomes necessary. Further, when a cover for preventing paper dust from being mixed as described above is provided, the cost increases. Further, when the slit of the rotary encoder is made fine, a highly accurate optical sensor corresponding to the pitch of the slit is required, resulting in an increase in cost. If the pitch of the slits is not changed, it is conceivable to increase the diameter of the rotary encoder, but the apparatus main body is enlarged. In addition, it is possible to reduce the size of the machine body by installing a rotary encoder via a gear or pulley speed reducer, but there is a phase difference between the printing drum and the rotary encoder slit due to gear backlash or belt expansion / contraction. Therefore, it is not preferable.

  Further, when detecting the rotation angle information of the printing drum based on the pulse signal of the rotary encoder as described above, the protrusion provided at a predetermined position of the printing drum is detected by the optical sensor provided in the apparatus main body. Thus, the rotation reference position of the rotation angle information is detected. However, the phase of the slit of the rotary encoder provided on the printing drum is shifted for each printing drum, so the rotation reference position is detected with respect to the phase of the pulse signal of the rotary encoder. The timing is different for each printing drum. Therefore, even if the number of pulse signals of the rotary encoder detected as the rotation angle information is the same, the angle at which the printing drum is actually rotated is shifted by a maximum of one pulse signal for each printing drum. Cannot perform proper printing alignment. Further, the detection timing of the rotation reference position with respect to the phase of the pulse signal of the rotary encoder may be made the same for all the printing drums, but an assembly positioning jig is required, and the number of assembly steps increases. Further, although it can be improved by using a high-resolution disk slit as a rotary encoder, as described above, such a high-resolution disk slit is not practically desirable.

  Further, as described above, the rotation reference position is detected by the optical sensor, and the pulse signal of the rotary encoder is measured from 0 by a control processing device such as a CPU, DSP or ASIC based on the signal detected by the optical sensor. The response speed of the optical sensor as described above and the processing speed of the control processing device have a delay of several ns to several tens of μs and a variation of several percent. Therefore, even in the same printing drum, the pulse signal of the rotary encoder Variations occur in the signal detection timing of the rotation reference position with respect to the phase. Therefore, for example, if the rotary encoder is installed so that the edge of the pulse signal detected by the optical sensor is close to the edge of the pulse signal of the rotary encoder, the pulse signal measured as the rotation angle information Variation in the number of one pulse occurs, and proper print alignment cannot always be performed.

  In addition, when printing position alignment is performed by controlling the rotation speed of the conveyance roller as described above, it is necessary to control the rotation speed of the conveyance roller with higher precision in order to perform higher-precision printing alignment. There is.

  When the rotation speed of the conveyance roller is controlled based on the rotation angle information of the printing drum as described above, the target rotation of the conveyance roller is based on the rotation angle information of the printing drum when the leading edge of the printing paper is detected. The speed is calculated and controlled so that the rotation speed of the transport roller becomes the target rotation speed. When performing the control as described above, for example, the actual rotational speed of the transport roller is measured by a rotary encoder provided on the transport roller, and the difference between the measured rotational speed and the target rotational speed is used. However, when the rotational speed is measured by the rotary encoder as described above, the measurement accuracy depends on the resolution of the rotary encoder, so it is difficult to measure the rotational speed with higher accuracy. It is difficult to accurately control the rotation speed of the transport roller.

  In view of the above circumstances, the present invention detects rotation information of a printing drum such as a rotary encoder in an image forming apparatus using a drum without being affected by variations in the rotation speed of the drum or changes in the rotation speed. An object of the present invention is to provide an image forming apparatus that can perform high-precision printing alignment without increasing the resolution of the mechanism.

The image forming apparatus of the present invention includes:
A printing drum;
Drum rotation information detecting means for detecting drum rotation angle information from a predetermined reference position of the printing drum as a pulse signal;
A transport roller for transporting printing paper to the printing drum;
A transport motor for driving the transport roller;
A paper leading edge detecting means for detecting that the leading edge of the printing paper being conveyed by the conveying roller has reached a predetermined position;
Based on the drum rotation angle information detected by the drum rotation information detecting means and the leading edge detection information detected by the paper leading edge detecting means, the printing start position of the printing paper conveyed by the conveying roller and the printing face start position of the printing drum are determined. In an image forming apparatus provided with a motor control unit that controls the rotation speed of the transport motor so as to match,
A drum counter means for generating a drum counter pulse signal having a cycle shorter than the cycle of the pulse signal detected by the drum rotation information detecting means, and measuring the number of the generated drum counter pulse signals;
Roller rotation information detecting means for detecting roller rotation angle information of the conveying roller as a pulse signal;
A roller counter means for generating a roller counter pulse signal having a cycle shorter than the cycle of the pulse signal detected by the roller rotation information detecting means, and measuring the number of the generated roller counter pulse signals;
For drums from the time of detection of the pulse signal last detected by the drum rotation information detection means to the time of detection of the front edge of the printing paper by the paper front edge detection means before the front edge of the printing paper is detected by the paper front edge detection means The number of counter pulse signals or the number of counter pulse signals for the drum from the time when the leading edge of the printing paper is detected by the paper leading edge detection means to the detection time of the pulse signal first detected by the drum rotation information detecting means after the leading edge detection. And acquiring the number of drum counter pulse signals corresponding to one cycle of the pulse signal detected by the drum rotation information detection means,
The number of counter pulse signals for rollers from the detection time of the pulse signal last detected by the roller rotation information detection means to the predetermined time before the predetermined time after the detection of the front edge of the printing paper by the paper front edge detection means or the paper While acquiring the number of counter pulse signals for the roller from the predetermined time after the detection of the leading edge of the printing paper by the front edge detection means until the detection time of the pulse signal first detected by the roller rotation information detection means after the predetermined time, Counter information acquisition means for further acquiring the number of roller counter pulse signals corresponding to one cycle of the pulse signal detected by the roller rotation information detection means,
The counter pulse for drum from the time when the pulse signal detected by the drum rotation information detecting means is detected last by the motor control means to the time when the paper leading edge is detected by the paper leading edge detecting means before the leading edge of the printing paper is detected. The number of signals or the number of counter pulse signals for the drum and the drum from the time when the leading edge of the printing paper is detected by the paper leading edge detection means to the detection time of the pulse signal first detected by the drum rotation information detecting means after the leading edge detection The ratio of the counter pulse signal for the drum corresponding to one cycle of the pulse signal detected by the rotation information detecting means, and the drum rotation information detecting means until the leading edge of the printing paper is detected by the paper leading edge detecting means. From the number of detected pulse signals or the time when the leading edge of the printing paper is detected by the leading edge detection means, Based on the number of detected pulse signal to the detection time of the detected pulse signal by drum rotation information detection means, calculates a target rotational angle at a given point in the conveying motor with a,
The number of roller counter pulse signals from the detection time of the pulse signal last detected by the roller rotation information detection means before the predetermined time to the predetermined time, or the roller rotation information detection means first after the predetermined time from the predetermined time A ratio of the number of roller counter pulse signals up to the detection point of the pulse signal detected by the number of roller counter pulse signals corresponding to one cycle of the pulse signal detected by the roller rotation information detecting means, and a predetermined value Based on the number of pulse signals detected by the roller rotation information detecting means up to the point of time or the number of pulse signals detected by the roller rotation information detecting means lastly after the predetermined time and detected by the roller rotation information detecting means. Calculate the measured rotation angle at a given point in time,
The rotational speed of the transport motor after a predetermined time is controlled so that the actually measured rotational angle approaches the target rotational angle.

In the image forming apparatus of the present invention,
Drum rotation information detection means detects drum rotation angle information based on a pulse signal detected first after the printing drum rotates to a predetermined reference position or a pulse signal detected immediately before the printing drum rotates to a predetermined reference position. Shall be
The counter information acquisition means determines the number of counter pulse signals for the drum from the time when the printing drum rotates to the predetermined reference position to the time when the first pulse signal is detected by the drum rotation information detection means or the printing drum reaches the predetermined reference position. The number of counter pulse signals for the drum from the time when the pulse signal was last detected by the drum rotation information detecting means to the time when the printing drum was rotated to a predetermined reference position before the rotation to
The motor control means changes the number of counter pulse signals for the drum from when the printing drum rotates to the predetermined reference position to the time when the first pulse signal is detected by the drum rotation information detection means or until the printing drum reaches the predetermined reference position. Before the rotation, the number of drum counter pulse signals from the time when the pulse signal is detected by the drum rotation information detection means to the time when the printing drum rotates to a predetermined reference position and the drum rotation information detection means are detected. The ratio of the counter pulse signal for the drum according to one cycle of the pulse signal,
The number of drum counter pulse signals from the time when the last pulse signal detected by the drum rotation information detecting means to the time when the paper leading edge is detected by the paper leading edge detecting means before the leading edge of the printing paper is detected or the paper The number of counter pulse signals for the drum and the drum rotation information detection means from the time when the leading edge of the printing paper is detected by the leading edge detection means to the detection time of the first pulse signal detected by the drum rotation information detection means after the leading edge detection. The ratio with the number of counter pulse signals for drums corresponding to one cycle of the detected pulse signal,
And the number of pulse signals detected by the drum rotation information detecting means until the time when the leading edge of the printing paper is detected by the paper leading edge detecting means, or the first time after detecting the leading edge from the time when the leading edge of the printing paper is detected by the paper leading edge detecting means. Based on the number of pulse signals detected up to the point of detection of the pulse signal detected by the drum rotation information detecting means, the target rotation angle of the carry motor at a predetermined time can be calculated.

  Here, the “printing drum” means a drum for printing, and includes, for example, a stencil drum on which a pre-made stencil sheet is attached in a stencil printing apparatus, a PPC photosensitive drum, and the like.

  Further, it is desirable to use the same counter means as the “drum counter means” and the “roller counter means”.

  According to the image forming apparatus of the present invention, the rotation angle information of the printing drum can be obtained with higher accuracy by using the pulse signal detected by the drum rotation information detection unit and the drum counter pulse signal having a shorter cycle than the pulse signal. Since it is detected, the rotation speed of the carry motor can be set with high accuracy, and high-precision printing alignment can be performed.

  In the image forming apparatus, when the rotation reference position of the printing drum is detected using the drum counter pulse signal, the rotation reference position can be detected with high accuracy. Since the actual rotation angle of the printing drum can be calculated in consideration of the relationship between the drum rotation angle information and the phase of the pulse signal, a more appropriate rotation speed of the transport roller can be set and more appropriate printing can be performed. Alignment can be performed.

  In addition, the target rotation angle of the conveyance motor at a predetermined time is calculated using the pulse signal detected by the drum rotation information detection unit and the drum counter pulse signal, and the pulse signal detected by the roller rotation information detection unit The actual rotation angle of the conveyance motor is calculated using the number of roller counter pulse signals having a shorter cycle than the cycle of the pulse signal, and the conveyance motor after the predetermined time is set so that the actual rotation angle approaches the target rotation angle. When the rotational speed is controlled, the actually measured rotational angle of the transport roller can be calculated with higher accuracy, and the rotational speed of the transport motor after the predetermined time can be set with higher accuracy. Therefore, it is possible to perform printing alignment with higher accuracy.

  Hereinafter, a stencil printing apparatus using the first embodiment of the image forming apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of the stencil printing apparatus, and FIG. 2 is a block diagram showing a drive control system of the stencil printing apparatus.

  As shown in FIG. 1, the stencil printing apparatus includes a cylindrical printing drum 10, a press roller 11 that is pressed against an outer surface of the printing drum 10, and is rotatably arranged in parallel with the printing drum 10. A primary feed provided with a scraper roller 21, a pickup roller 22, a sucker plate 23, and a double feed detection switch 24 that feeds and feeds the printing paper S 1 placed on a paper board (not shown) one by one for each rotation of the printing drum. The paper unit 20 includes conveyance rollers (hereinafter referred to as registration rollers) 31 and 32 and guide plates 33 and 34 for inserting printing paper fed from the primary paper supply unit 20 between the printing drum 10 and the press roller 11. The secondary paper feed unit 30 and a paper discharge unit that discharges the printing paper S2 that is nipped and conveyed between the printing drum 10 and the press roller 11 onto a paper discharge tray (not shown). The suction roller 41 and the suction belt 43 is provided as a 0.

  The printing drum 10 is rotated by a drum motor (not shown) via a transmission means such as a belt. As shown in FIG. A drum rotation information detecting means 50 including a drum encoder 51 and an optical sensor 52 for detecting drum rotation angle information is provided. The drum rotation information detecting means 50 detects a pulse signal by the drum encoder 51 and the optical sensor 52 and detects the count number of the pulse signal as drum rotation angle information of the printing drum 10. Further, as shown in FIG. 2, a protrusion 12 is provided at a specific position on the outer peripheral surface of the printing drum 10, and an optical for detecting the rotation reference position of the printing drum by detecting the protrusion 12 on the apparatus body side. A sensor 13 is provided. By detecting the rotation reference position by the optical sensor 13 and the rotation information by the drum rotation information detecting means 50, the rotation angle information of the printing drum 10 can be obtained.

  The registration rollers 31 and 32 are configured to rotate in opposite directions by being engaged with each other at both ends of the respective shafts, and in the vicinity of the registration rollers 31 and 32, As shown in FIG. 2, a conveyance motor (hereinafter referred to as a registration motor) 35 for rotating them is installed. In the present embodiment, the registration rollers 31 and 32 having the above-described configuration are used. For example, one registration roller is driven and the other registration roller is pressurized by a bearing bearing. The registration roller may be driven to rotate.

  Further, on the outer circumference of the drive shaft of the registration motor 35, as shown in FIG. 2, a roller rotation information detection means 38 having a registration encoder 36 and an optical sensor 37 for detecting motor rotation angle information of the registration motor 35 is provided. The roller rotation angle information of the registration rollers 31 and 32 is equivalently detected by detecting the motor rotation angle information of the registration motor 35. Note that a servo motor is preferably used as the registration motor 35.

  As shown in FIGS. 1 and 2, a registration sensor 60 is provided between the registration rollers 31 and 32 and the press roller 11 to detect the leading edge of the printing paper conveyed by the registration rollers 31 and 32. Yes. As the resist sensor 60, a transmissive or reflective photosensor may be used.

  Further, as shown in FIG. 2, the stencil printing apparatus is configured to detect the tip detection information detected by the registration sensor 60, the drum rotation angle information detected by the drum rotation information detection means 50, and the roller rotation of the registration rollers 31 and 32. Drive control means 100 for driving and controlling the registration motor 35 based on the angle information, and drum counter means 101 for generating a drum counter pulse signal having a predetermined frequency and measuring the number of the generated drum counter pulse signals. And.

  The drive control means 100 is constituted by a CPU, DSP, ASIC, or the like, and is acquired by the counter information acquisition means 102 for acquiring the number of drum counter pulse signals measured by the drum counter means 101 and the counter information acquisition means 102. Based on the number of counter pulse signals for the drum, the motor controller 103 calculates the target rotational speed of the registration motor 35 and controls the rotational speed of the registration motor 35 so that the rotational speed of the registration motor 35 becomes the target rotational speed. And. A specific drive control method for the registration motor 35 will be described later.

  The drum counter unit 101 generates a pulse signal having a frequency higher than the pulse signal, which is the drum rotation angle information output from the drum rotation information detection unit 50, as a drum counter pulse signal, and measures the number thereof. .

  Next, the operation of the stencil printing apparatus of the first embodiment will be described.

  First, a stencil sheet is subjected to a stencil printing process in a stencil printing unit (not shown), and the stencil stencil sheet is wound around the printing drum 10.

  Then, the printing drum 10 around which the stencil stencil sheet has been wound rotates at a predetermined speed in the direction of the arrow A, and the pickup roller 22 and the scraper roller 21 from the uppermost surface of the printing paper S1 placed on the paper feed table. A sheet of printing paper is fed out by the sheet plate 23 and conveyed to the registration rollers 31 and 32 while being guided by the guide plate 33. If double feed is performed at this time, the double feed detection switch 24 detects the double feed. It is sandwiched between registration rollers 31 and 32 that rotate at a predetermined speed, and is further conveyed toward the contact point between the printing drum 10 and the press roller 11 by the rotation of the registration rollers 31 and 32.

  Here, in the stencil printing apparatus, when the printing surface start position of the printing drum 10 comes to the contact point between the printing drum 10 and the press roller 11, the printing start position of the printing paper is the contact point between the printing drum 10 and the press roller 11. The rotational speeds of the registration rollers 31 and 32 are controlled so as to come to the right. In the present embodiment, the printing surface start position of the printing drum 10 may be a position set in advance in the printing drum 10 or may be the front end of a predetermined printing surface range in the stencil sheet. Further, the printing start position may be the leading end of a predetermined printing range in the printing paper.

  Specifically, when the count Dfg of the pulse signal detected by the drum rotation information detecting means 50 reaches Dfg = 56, the printing surface start position of the printing drum 10 comes to the contact point between the printing drum 10 and the press roller 11. Is set to Note that Dfg is a count number of pulse signals measured with reference to the time when the projection 12 provided on the printing drum 10 is detected by the optical sensor 13.

  The registration rollers 31 and 32 start rotating when Dfg = 0, and when the printing surface start position of the printing drum 10 comes to the contact point between the printing drum 10 and the press roller 11, that is, when Dfg = 56. The rotation speed is controlled so that the printing start position of the printing paper comes to the contact point. A specific control method will be described below. Since the control of the rotation speed of the registration motor 35 and the control of the rotation speed of the registration rollers 31 and 32 are equivalent, the control of the rotation speed of the registration motor 35 is hereinafter referred to as the rotation speed of the registration rollers 31 and 32. This will be described as control.

  In the stencil printing apparatus, the rotation speed of the registration rollers 31 and 32 is controlled by the motor control means 103 as shown in FIG. FIG. 3 shows the ratio between the rotational speed (linear speed) of the registration rollers 31 and 32 and the rotational speed (linear speed) of the printing drum 10 and the count Dfg of the pulse signal detected by the drum rotation information detecting means 50. It is a figure which shows a relationship. The speed ratio “1” means that the linear speed of the registration rollers 31 and 32 and the linear speed of the printing drum 10 are the same.

  As shown in FIG. 3, first, the registration rollers 31 and 32 are accelerated at a constant acceleration such that the rotation speed of the printing drum 10 and the rotation speed of the registration rollers 31 and 32 are the same at Dfg = 30 (region I ) When the leading edge of the printing paper is detected by the registration sensor 60, the acceleration is temporarily stopped and rotated at a constant speed (region II), and thereafter, until the rotational speed becomes the same as the rotational speed of the printing drum 10. It is controlled to accelerate again with the above-mentioned constant acceleration (region III) and then rotate at the same rotational speed as the printing drum 10 (region IV). The rotation speed of the printing drum 10 is a constant rotation speed set in advance.

Here, when Dfg when the leading edge of the printing paper is detected by the registration sensor 60 is N, and Dfg during the conveyance of the printing paper at a constant speed (area II) is X, the registration in the above areas I to IV is set. The transport distance [mm] of the printing paper by the rollers 31 and 32 can be calculated by the following equation. In the stencil printing apparatus, when the count Dfg of the pulse signal detected by the drum rotation information detecting means 50 reaches 300, the printing drum 10 rotates once, and the printing drum 10 The diameter is 173 mm.

  In the stencil printing apparatus, the printing drum 10 and the registration sensor 60 are installed so that the distance Lp (see FIG. 1) between the registration sensor 60 and the contact point between the printing drum 10 and the press roller 11 is 54.35 mm. Therefore, the total of the transport distances of the printing paper calculated by the above formulas (2) to (4) may be set to Lp (54.35 mm).

Therefore,

From the above equation (5), X is

It becomes.

Therefore, when the leading edge of the printing paper is detected by the registration sensor 60, the value N of Dfg counted in the drum rotation information detecting means 50 is acquired, and X is calculated from the value N and the above equation (6). The rotational speeds of the registration rollers 31 and 32 are controlled based on these values. However, for example, when the registration sensor 60 detects the leading edge of the printing paper when Dfg = 23, N = 23 and X = 9.36 from the above equation (6), which is not an integer. Therefore, when the rotational speeds of the registration rollers 31 and 32 are controlled based on the values N and X as described above, the value of X is set to an integer 9, which is a distribution of the transport distance as shown in FIG. The rotational speed of the registration rollers 31 and 32 is controlled. When the transport distances in each of the regions II to IV are obtained by the above formulas (2) to (4) and added,
12.50 mm (region II) + 11.20 mm (region III) + 30.80 mm (region IV) = 54.50 mm
Thus, it becomes 0.15 mm longer than the target value of 54.35 mm.

  Further, when N = 23, the conveyance distance of the registration rollers 31 and 32 in the region I is 15.97 mm from the above equation (1), and when N = 24, the conveyance of the registration rollers 31 and 32 in the same region I is performed. The distance is 17.39 mm from the above equation (1), and the difference is 1.42 mm. Therefore, depending on the timing at which the registration sensor 60 detects the leading edge of the printing paper and the timing at which the drum rotation information detection means 50 counts the pulse signal, the deviation is further 1 mm or more from the target value.

  Therefore, in this stencil printing apparatus, the rotational speed of the registration rollers 31 and 32 is controlled using a drum counter pulse signal having a frequency higher than the frequency of the pulse signal detected by the drum rotation information detecting means 50. Specifically, for example, when the rotation speed of the printing drum 10 is 150 rpm and 300 pulses / revolution, the frequency of the pulse signal detected by the drum rotation information detection unit 50 is 150 × 300/60 [s]. = 750 Hz. Therefore, as the drum counter means 101, a drum counter pulse signal of 40 MHz, which is sufficiently high with respect to 750 Hz, is generated and measured.

  Then, the counter information acquisition unit 102 of the drive control unit 100 acquires the count number of the drum counter unit 101 at the rising edge of the pulse signal detected by the drum rotation information detection unit 50 and the registration sensor 60 detects the leading edge of the printing paper. The count number of the drum counter means 101 when it is detected is acquired. Then, for example, when the timing of the pulse signal detected by the drum rotation information detecting means 50 and the timing of detecting the leading edge of the printing paper by the registration sensor 60 are the timing shown in FIG. The number of counter pulse signals for the drum corresponding to one cycle of the cycle of the pulse signal immediately before the cycle of the pulse signal of the drum rotation information detecting means 50 when the leading edge of the printing paper is detected by the sensor 60, that is, the drum While calculating the number α1 of drum counter pulse signals counted by the drum counter means 101 from the rise of the 22nd pulse signal detected by the rotation information detection means 50 to the rise of the 23rd pulse signal, Drum counter means 10 from the rise of the 23rd pulse signal to the detection of the leading edge of the printing paper It calculates the number of counted drum counter pulse signal β1 by.

α1 = 1226706-1173363 = 53343
β1 = 1260029-1226706 = 33323
Then, new rotation angle information N of the printing drum 10 when the registration sensor 60 detects the leading edge of the printing paper is calculated as follows. In the present embodiment, the number β1 of counter pulse signals for the drum from the time when the pulse signal detected last before the leading edge of the printing paper is detected to the time when the leading edge of the printing paper is detected, N is calculated based on the number of pulse signals “23” detected up to the time when the leading edge of the printing paper is detected. However, the present invention is not limited to this. The number of counter pulse signals for drums (1280029-1260029 = 20000) until the detection time of the first pulse signal detected after the leading edge detection, and the first detection after the leading edge detection from the time when the leading edge of the printing paper is detected N may be calculated based on the number “24” of pulse signals detected up to the time of detection of the pulse signal. Alternatively, N may be calculated using the number of pulse signals “24” and β1, the number of pulse signals “23”, and the drum counter pulse signal 20000.

Substituting this N value into N in the above equation (6),

  It becomes.

Substituting N and X calculated as described above into equations (2) to (4) to calculate the transport distance in each region,

The sum of these values is 54.35 mm, which matches the value of Lp.

Therefore, the rotational speed of the registration rollers 31 and 32 may be controlled at the timing shown in FIG. In other words, when the leading edge of the printing paper is detected by the registration sensor 60, the acceleration is terminated and the registration rollers 31 and 32 are rotated at a constant rotation speed. When Dfg reaches 31.614, the acceleration is resumed. When the value reaches 37.989, the re-acceleration is terminated and the registration rollers 31 and 32 are rotated at the same rotation speed.

As a method for obtaining the timing when Dfg reaches 31.614, for example, as shown in FIG. 7, the 31st pulse signal from the rising edge of the 30th pulse signal detected by the drum rotation information detecting means 50 is used. The number α2 of drum counter pulse signals counted by the drum counter means 101 before the rise of the pulse signal is calculated as follows:
α2 = 1653377-1600029 = 53348
Based on this α2, the number β2 of drum counter pulse signals from the rise of the 31st pulse signal to the time when Dfg reaches 31.614 is calculated as follows,
β2 = α2 × (31.614-31) = 32756
Based on this β2, the count number of the drum counter means 101 when Dfg = 31.614 is calculated as follows,
1653377 + 32756 = 1686132
When the count number of the drum counter pulse signal by the drum counter means 101 reaches 1686132, it may be controlled to re-accelerate the rotation speed of the registration rollers 31 and 32 assuming that Dfg becomes 31.614.

As a method for acquiring the timing when Dfg reaches 37.989, for example, as shown in FIG. 8, the 37th pulse signal from the rise of the 36th pulse signal detected by the drum rotation information detecting means 50 is used. The number α3 of drum counter pulse signals counted by the drum counter means 101 until the rise of the pulse signal is calculated as follows:
α3 = 1973358-1920030 = 53328
Based on this α3, the number β3 of drum counter pulse signals from the rise of the 37th pulse signal to when Dfg becomes 37.989 is calculated as follows,
β3 = α3 × (37.989-37) = 52742
Based on this β3, the count number by the drum counter means 101 when Dfg = 37.989 is calculated as follows,
1973358 + 52742 = 2026100
When the count number of the drum counter pulse signal by the drum counter means 101 reaches 2026100, it is assumed that Dfg has reached 37.989, and the acceleration of the rotation speeds of the registration rollers 31 and 32 is terminated. Control may be performed.

  For example, when the rotation speed of the printing drum 10 is increased and a pulse of Dfg = 38 is generated earlier than the count number by the drum counter means 101 reaches 2026100, the calculation is performed as described above. Before the count number is counted by the drum counter unit 101, the acceleration of the registration rollers 31 and 32 may be terminated and rotated at the same rotation speed. That is, the drive control is switched so that the rotational speed of the registration rollers 31 and 32 can be driven and controlled based on either the count number by the drum counter means 101 or the pulse signal count number of the drum rotation information detection means 50. It is desirable to be able to do so.

  Further, as in the first embodiment, the timing pulse signal is generated when the value of the drum counter pulse signal becomes a numerical value at the boundary of each region, and the motor control means 103 is based on the timing pulse signal. The rotational speed of the registration rollers 31 and 32 may be switched. However, if the circuit for generating the timing signal as described above is provided, the circuit scale becomes large. For example, a timer is provided in the motor control unit 103. The rotation speed may be controlled using this timer. Specifically, when the drum counter pulse signal is 40 MHz as in the above embodiment, the time interval of α2 shown in FIG. 7 is 53348 pulses = 1333.7 μs, and the time interval of β2 is 32756 pulses = 819 μs. Therefore, the time may be measured by a timer from the time when Dfg = 31 becomes 31, and the rotation speed may be switched when 819 μs has elapsed. Further, when Dfg reaches 31, the count number of 1686132 shown in FIG. 7 is obtained in the same manner as described above, and thereafter, the count number of the counter pulse signal for drum is measured every 100 μs using a timer, and the count is obtained. The count number may be compared with the count number 1686132, and the rotation speed may be switched when the measured count number becomes 1686132 or more.

  Further, it is desirable that the drive control means 100 includes a motor control means 103 as shown in FIG. The motor control means 103 determines each of the areas I to IV based on the number of drum counter pulse signals output from the counter information acquisition means 102, and calculates a target rotational speed in each area. Unit 103a, subtraction unit 103b for subtracting the actual rotation speed of registration rollers 31 and 32 detected by roller rotation information detection unit 38 from the target rotation speed calculated by target speed calculation unit 103a, and subtraction unit 103b. A PID control unit 103c that outputs a PID control signal based on the obtained value, a control voltage output unit 103d that outputs a PWM signal as a control voltage signal to the registration motor 35 based on the PID signal output from the PID control unit 103c, Based on the pulse signal detected by the roller rotation information detecting means 38, the resist And an actual speed measuring unit 103e that measures the actual rotation speed of the rollers 31 and 32. By controlling the rotation speed of the registration rollers 31 and 32 by the motor control means 103 as described above, it is possible to perform highly accurate rotation speed control.

  According to the stencil printing apparatus of the first embodiment, the drum counter pulse signal having a cycle shorter than the cycle of the pulse signal detected by the drum rotation information detecting means 50 is generated, and the generated drum counter pulse is generated. The number of signals is measured, the number of drum counter pulse signals corresponding to one cycle of the pulse signal detected by the drum rotation information detecting means 50 is acquired, and from the time when the printing drum 10 rotates to a predetermined reference position. The number of drum counter pulse signals up to the point in time when the leading edge of the sheet is detected by the registration sensor 60 is acquired, and the rotation speed of the registration rollers 31 and 32 is controlled based on the ratio to the number of these drum counter pulse signals. As a result, the rotation angle of the printing drum 10 is obtained by determining the ratio of the counter pulse signal for the drum. It is possible to detect the distribution more accurately, the rotational speed of the registration rollers 31 and 32 can be set with high accuracy, it is possible to perform high-precision printing position alignment.

  In the stencil printing apparatus of the first embodiment, the registration sensor 60 uses the registration sensor 60 to obtain the number of drum counter pulse signals corresponding to one cycle of the pulse signal of the drum rotation information detecting means 50. Although the cycle of the pulse signal immediately before the cycle of the pulse signal of the drum rotation information detecting means 50 when the tip is detected is used, the present invention is not limited to this, and the cycle of the previous pulse signal is used. Alternatively, the period of the pulse signal after the leading edge of the printing paper is detected may be used. Further, the period of the pulse signal when the leading edge of the printing paper is detected may be used.

  Next, a stencil printing apparatus using the second embodiment of the image forming apparatus of the present invention will be described.

  The stencil printing apparatus of the second embodiment is different from the stencil printing apparatus of the first embodiment in the method of detecting the rotation reference position of the printing drum 10. Other configurations are the same as those of the stencil printing apparatus of the first embodiment.

  In the stencil printing apparatus of the first embodiment, as described above, the rotation reference position of the printing drum 10 is detected by detecting the protrusion 12 provided on the printing drum 10 by the optical sensor 13, and the detection signal is used as the detection signal. Accordingly, Dfg is set to 0 and the pulse signal of the drum rotation information detecting means 50 is counted. Specifically, the drum rotation information detecting means 50 detects the edge of the drum encoder 51, generates a pulse signal as shown in FIG. 9, and counts the rising edge of the pulse signal to count the drum of the printing drum 10. The rotation angle information is detected. Then, as shown in FIG. 10, the rise of the pulse signal detected by the protrusion 12 and the optical sensor 13 is detected, and the pulse signal is detected by the rise of the pulse signal first detected by the rotation information detecting means 50 after the rise is detected. The count number is set to 0.

  However, strictly speaking, depending on the generation timing of the pulse signal detected by the drum rotation information detection unit 50 and the pulse signal detected by the protrusion 12 and the optical sensor 13, the pulse detected by the drum rotation information detection unit 50 at the maximum. Variations in time for one pulse of the signal occur. There are two types of the occurrence of the variation, that is, the variation for each printing drum and the variation within the same printing drum.

  First, the variation for each printing drum will be described.

  The clamping device provided on the printing drum 10 that holds the protrusions provided on the printing drum 10 and the stencil sheet that has been made is made at a predetermined position on the printing drum 10, so that printing can be performed from the rotation reference position of the printing drum 10. There is little variation for each printing drum with respect to the circumferential angle up to the printing surface start position of the drum 10. However, it is difficult to install the slits of the drum encoder 51 so that the phases of the slits are the same for each printing drum.

  Therefore, as shown in FIG. 11, if there is a printing drum 10 in which the pulse signal detected by the protrusion 12 and the optical sensor 13 is generated immediately after the rise of the pulse signal detected by the drum rotation information detecting means 50, the drum rotation There is also a printing drum 10 that occurs immediately before the rise of the pulse signal detected by the information detection means 50. Therefore, for example, the drum rotation information detection unit 50 in the stencil printing apparatus according to the first embodiment detects 300 pulse signals for one rotation of the printing drum 10. Thus, even if the same number of pulse signals are counted, a rotation angle variation of 1.2 degrees (360 degrees / 300) at the maximum occurs for each printing drum 10. Therefore, as in the stencil printing apparatus (diameter 173 mm of the printing drum 10) of the first embodiment, when Dfg = 56, the leading edge of the printing paper is placed at the contact point between the printing drum 10 and the press roller 11. However, the maximum print position variation of about 1.8 mm (173π / 300) occurs for each print drum.

  Next, variations in the same printing drum will be described.

  In the stencil printing apparatus according to the first embodiment, as described above, the rotation reference position is detected by the protrusion 12 and the optical sensor 13, and the drum rotation information detection means 50 is based on the signal detected by the optical sensor 13. The pulse signal is counted from 0 by a control processing device such as a CPU, DSP, or ASIC.

  Here, the response speed of the optical sensor 13 and the processing speed of the control processing device have a delay of several ns to several tens of μs and a variation of several percent. Further, due to minute distortion of components such as the printing drum, even if the same printing drum and an optical sensor with a high response speed are used, the pulse rotation signal detecting means 50 detects the pulse signal detected by the drum rotation information detecting means 50 for each printing. Variation in the generation timing of the pulse signal at the rotation reference position with respect to the generation timing occurs.

  Therefore, as shown in FIG. 12, the drum encoder 51 so that the rise of the pulse signal detected by the drum rotation information detecting means 50 is relatively close to the rise of the pulse signal detected by the protrusion 12 and the optical sensor 13. Is provided, a variation of one pulse occurs in the count number of the pulse signal counted by the rotation information detecting means 50 for each rotation of the printing drum 10 due to the above-described variation. Therefore, similarly to the case where the variation occurs for each printing drum, the printing position variation of about 1.8 mm (173π / 300) occurs for each printing.

  The occurrence of the variation as described above can be solved if the rising edge of the pulse signal at the rotation reference position and the rising edge of the pulse signal detected by the rotation information detecting means 50 are shifted by the same amount for each printing drum. An assembly positioning jig is required, which increases the number of assembly steps. Further, although it can be improved by using a high-resolution disk slit as the drum encoder, as described above, such a high-resolution disk slit is not practically desirable.

  Therefore, in the stencil printing apparatus of the second embodiment, the drum counter pulse signal of the drum counter means 101 used in the stencil printing apparatus of the first embodiment is used and detected by the drum rotation information detecting means 50. The position of the pulse signal at the rotation reference position with respect to the phase of the pulse signal to be detected is detected with high resolution, and the rotation angle information of the printing drum 10 from the rotation reference position is detected with high accuracy.

  Specifically, for example, when a pulse signal at the rotation reference position and a pulse signal detected by the drum rotation information detecting means 50 are generated at the timing shown in FIG. 13, a pulse signal at the rotation reference position is generated. The drum counter means from the rise of the pulse signal detected by the drum rotation information detection means 50 immediately before the start to the rise of the pulse signal detected by the drum rotation information detection means 50 immediately after the generation of the pulse signal at the rotation reference position The drum counter pulse signal number α4 counted by 101 and the drum reference pulse signal from the time when the pulse signal at the rotation reference position is detected until the rise of the pulse signal detected by the drum rotation information detecting means 50 immediately thereafter are detected. The number β4 of drum counter pulse signals counted by the means 101 is set as follows. calculate.

α4 = 1230029-1176706 = 53323
β4 = 1230029-1210120 = 19909
Based on α4 and β4 calculated as described above, y is obtained as follows. In the present embodiment, y is calculated based on the number β4 and α4 of drum counter pulse signals from the time when the printing drum 10 is rotated to the rotation reference position to the time when the first pulse signal is detected. However, the present invention is not limited to this, and the counter pulse signal for the drum from the time when the pulse signal was last detected before the printing drum 10 was rotated to the rotation reference position to the time when the printing drum 10 was rotated to the rotation reference position. You may make it calculate y based on a number (1210120-1176706 = 33414) and (alpha) 4.

y = β4 / α4 = 19909/53323 = 0.373
When the rotational speeds of the registration rollers 31 and 32 in the regions I to IV are set and controlled as in the stencil printing apparatus of the first embodiment, when Dfg = 56−y, The conveyance distance of the printing paper may be set to Lp = 54.35.

The conveyance distance of the printing paper in the regions I to IV is calculated by the following formula.

Therefore, from the above formula,

From the above equation (5), X is

It becomes.

In the case of performing the drive control of the registration rollers 31 and 32 as in the stencil printing apparatus of the first embodiment, N = 23.625, y = 0.373, X = 6.234 from the above formula.
So,

Thus, 8.894 + 10.322 + 35.322 = 54.35.

  Therefore, as shown in FIG. 14, if the rotational speeds of the registration rollers 31 and 32 are controlled, appropriate printing alignment can be performed without being affected by the above-described variations among the printing drums or variations in the same printing drum. can do.

  In this embodiment, after the printing drum 10 has rotated to the rotation reference position, the pulse signal first detected by the drum rotation information detecting unit 50 is set to 0, and the pulse signal is counted. After the drum 10 has rotated to the rotation reference position, the pulse signal is first counted based on the pulse signal detected by the drum rotation information detecting means 50. However, the present invention is not limited to such a counting method. After the printing drum 10 has rotated to the rotation reference position, the count number of the pulse signal first detected by the drum rotation information detection unit 50 may be incremented from the next pulse signal without incrementing the count. That is, the pulse signal detected immediately before the printing drum 10 rotates to the rotation reference position may be used as a reference. Even in the latter case, the rotation reference position may be detected in the same manner as described above.

  Next, a stencil printing apparatus using the third embodiment of the image forming apparatus of the present invention will be described.

  The stencil printing apparatus of the third embodiment sets the target rotation angle of the registration rollers 31 and 32 using the drum counter pulse signal in the same manner as the stencil printing apparatus of the first embodiment. Further, the actual rotation angle of the registration rollers 31 and 32 rotating based on the target rotation angle set as described above is detected with high accuracy, and the target rotation angle and the actual rotation angle (actual rotation angle are measured). ), The rotation angle of the registration rollers 31 and 32 is controlled with high accuracy.

  Specifically, for example, in the stencil printing apparatus of the third embodiment, a pulse signal is detected in the drum rotation information detecting means 50 at the timing shown in FIG. 15 as in the case of the stencil printing apparatus of the first embodiment. And a pulse signal is detected by the registration sensor 60, the drum stencil printing apparatus of the third embodiment also has the drum counter means 101 drum in the same manner as the stencil printing apparatus of the first embodiment. Based on the counter pulse signal, the target rotation angle in the regions I to IV is set.

That is, the value N of Dfg when the leading edge of the printing paper is detected by the registration sensor 60 is N = 23 + β / α = 23.625.
X = (N2−660) / (2 × N−60) = 7.989, and the region III to be accelerated again starts at the timing of Dfg = N + X = 31.614.

  Then, the region IV where the re-acceleration is stopped starts at the timing of Dfg = 30 + X = 37.989.

  In the stencil printing apparatus of the third embodiment, first, the target rotation angle of the registration rollers 31 and 32 is calculated as follows using the value of Dfg obtained as described above. The target rotation angles of the registration rollers 31 and 32 are calculated as a target value Rfg ′ of the count number of pulse signals detected by the roller rotation information detecting means 38.

First, Rfg ′ in the region I can be calculated by the following equation.

  When Dfg = 23.625 calculated as described above is substituted, Rfg ′ = 83.817 is obtained.

Here, when the timing when the registration sensor 60 actually detects the leading edge of the printing paper is as shown in FIG. 15, the count number of the pulse signal actually detected by the roller rotation information detection means 38. When Rn is calculated,

It becomes.

  Therefore, compared with Rfg ′ = 83.817 calculated as described above, the value of Rn is smaller, so the registration roller control is delayed.

Rfg ′ for region II can be calculated by the following equation.

  When Dfg = 31.614 calculated as described above is substituted, Rfg ′ = 138.513.

Rfg ′ for region III can be calculated by the following equation.

  When Dfg = 37.989 calculated as described above is substituted, Rfg ′ = 189.852 is obtained.

  Further, Rfg ′ for the region IV may be such that the conveyance amount of the registration rollers 31 and 32 from Rn becomes 54.35 when Dfg = 56.

Since 54.35 × 500 / 32π = 270.315 [pulse],

It becomes.

  As described above, the target value Rfg ′ for each region is calculated.

  In the present embodiment, as shown in the above equation, the rollers from the detection time of the pulse signal last detected by the roller rotation information detection means 38 to the detection time of the leading edge of the printing paper before the leading edge of the printing paper is detected. Rn is calculated based on the number of counter pulse signals for use (1260029-1255129 = 4900) and the number of pulse signals “81” detected by the roller rotation information detecting means 38 up to the time when the leading edge of the printing paper is detected. However, the present invention is not limited to this, and the number of counter pulse signals for rollers (1261068−1260029 = 1039) from the time when the leading edge of the printing paper is detected to the time when the pulse signal detected by the roller rotation information detecting means 38 first is detected. The detection time point of the pulse signal detected by the roller rotation information detecting means 38 for the first time after detecting the leading edge of the printing paper It may be calculated to Rn on the basis of the detected pulse signal "82" to the in. Rn may be calculated based on the number of pulse signals “81” detected by the roller rotation information detection means 38 and the number of counter pulse signals for rollers “1039”, or the roller rotation information detection means 38. Rn may be calculated based on the number “82” of pulse signals detected by the above and the number “4900” of roller counter pulse signals.

Then, after calculating the target value Rfg ′ as described above, the actually measured rotation angles of the registration rollers 31 and 32 are calculated. For example, when the count number of the pulse signal detected by the drum rotation information detection means 50 and the count number of the pulse signal detected by the roller rotation information detection means 38 are as shown in FIG. 16, Dfg = 38. The actually measured rotation angle is calculated as follows based on the counter pulse signal for rollers. The roller counter pulse signal is a pulse signal having a cycle shorter than the cycle of the pulse signal detected by the roller rotation information detecting unit 38. In the stencil printing apparatus according to this embodiment, the roller counter pulse signal is generated in the drum counter unit 101. However, it is measured. Further, in the present embodiment, as shown in the following equation, the counter pulse for the roller from when the pulse signal detected last by the roller rotation information detecting means 38 before Dfg = 38 until Dfg = 38 is reached. The actually measured rotation angle is calculated based on the number of signals (2026682-2202193 = 4489) and the number 188 of pulse signals detected by the roller rotation information detection means 38 until Dfg = 38. The number of roller counter pulse signals (2028112-2026682 = 1430) from the time when Dfg = 38 to the time when the pulse signal detected by the roller rotation information detecting unit 38 first is detected, and Dfg = 38 is not limited thereto. Until the detection time of the pulse signal first detected by the roller rotation information detecting means 38 It may be calculated the actual rotational angle on the basis of the number "189" of the detected pulse signal. Further, the actually measured rotation angle may be calculated based on the number “188” of pulse signals detected by the roller rotation information detecting means 38 and the number “1430” of counter pulse signals for rollers, or the roller rotation information. The actually measured rotation angle may be calculated based on the number of pulse signals “189” detected by the detection means 38 and the number of roller counter pulse signals “4489”.

It becomes.

  When Dfg = 38, Rfg ′ = 1899.952 from the above equation, and the difference between the actually measured rotation angle and the target rotation angle at this time is Rfg′−Rfg = 189.952-1888.758 = It is 1.194 [pulses], and it may be controlled to increase the rotational speed of the registration rollers 21 and 32 by this difference.

  The drive control means 103 of the stencil printing apparatus of the third embodiment is configured as shown in FIG. 17, for example, and the actual rotation speed of the registration rollers 31 and 32 is calculated in the actual speed measuring unit 103e as described above. The

  According to the stencil printing apparatus of the third embodiment, the target rotational speed of the registration rollers 31 and 32 is set, the roller rotation angle information of the registration rollers 31 and 32 is detected as a pulse signal, and the cycle of the pulse signal A roller counter pulse signal having a shorter cycle, and the number of roller counter pulse signals generated is measured to obtain the number of roller counter pulse signals corresponding to one cycle of the pulse signal, Further acquiring the number of roller counter pulse signals up to a predetermined time after detection of the leading edge of the sheet, and based on the ratio of the roller counter pulse signals acquired as described above, the registration rollers 31 and 32 at the predetermined time. Calculate the measured rotation angle and reregister after the predetermined time so that the measured rotation angle approaches the target rotation angle. Since the rotation speeds of the rollers 31 and 32 are controlled, the measured rotation angles of the registration rollers 31 and 32 can be calculated with higher accuracy, and the rotation speeds of the registration rollers 31 and 32 after the predetermined time point can be calculated. Since it is possible to set with higher accuracy, it is possible to perform printing alignment with higher accuracy.

  In the stencil printing apparatus of the third embodiment, the rotation speed of the registration rollers 31 and 32 is controlled based on the difference between the target rotation angle of the registration rollers 31 and 32 and the actual rotation angle when Dfg = 38. Although the example to do was demonstrated, as a timing which controls a rotational speed, as long as the front-end | tip of printing paper is detected, you may carry out at any timing. For example, it may be performed at a preset sampling interval.

  Further, in the stencil printing apparatus of the third embodiment, a register counter is used to obtain the number of drum counter pulse signals corresponding to one cycle of the pulse signal of the roller rotation information detecting means 38 when calculating Rn. Although the cycle of the pulse signal of the roller rotation information detecting means 38 when the leading edge of the printing paper is detected by the sensor 60 is used, the present invention is not limited to this, and the cycle of the earlier pulse signal is used. Alternatively, the period of the pulse signal after the leading edge of the printing paper is detected may be used. When controlling the rotation speed of the registration roller when Dfg = 38, Dfg = 38 is detected in order to obtain the number of drum counter pulse signals corresponding to one cycle of the pulse signal of the roller rotation information detecting means 38. The period of the pulse signal of the roller rotation information detecting means 38 at this time is used. However, the present invention is not limited to this, and the period of the previous pulse signal may be used, or Dfg = 38 is detected. After that, the period of the pulse signal may be used. However, in order to obtain the accuracy, it is desirable to use the cycle of the pulse signal of the roller rotation information detecting means 38 when Dfg = 38.

  Further, in the stencil printing apparatus of the third embodiment, the target rotational speed of the registration rollers 31 and 32 is calculated based on the counter pulse signal for the drum in the same manner as the stencil printing apparatus of the first embodiment. As in the case of the stencil printing apparatus of the second embodiment, the rotation reference position is further detected on the printing drum 10 using the drum counter pulse signal, and the detected rotation reference position is also set. In consideration of this, the target rotation speed of the registration rollers 31 and 32 may be set. The calculation method of the target rotation speed is the same as that of the stencil printing apparatus of the second embodiment.

  In the stencil printing apparatuses of the first to third embodiments, the number of pulse signals in the drum rotation information detecting unit 50 and the roller rotation information detecting unit 38 is counted by detecting the rising edge of the pulse signal. However, it may be counted at both rising and falling. By counting as described above, the pulse signal can be detected with double the resolution. When both rising and falling are counted as described above, the ratio of the pulse signal between High and Low needs to be 50%, and sensor slit accuracy is required. Alternatively, it is possible to use both rising and falling edges by correcting the count numbers of the rising and falling drum counter pulse signals in accordance with the difference in the ratio between High and Low.

  The mathematical formula used in the stencil printing apparatus of the first to third embodiments is not limited to the above formula, and may be changed according to the machine dimensions of the apparatus, the acceleration of the registration rollers 31 and 32, and the like. Even when the printing start position of the printing paper is changed, appropriate printing position alignment can be performed by changing the above-described mathematical formula and changing the acceleration timing.

Schematic configuration diagram of the first embodiment of the stencil printing apparatus of the present invention Block diagram showing a drive control system of the stencil printing apparatus shown in FIG. The figure for demonstrating the control method of the rotational speed of the registration roller of the stencil printing apparatus shown in FIG. The figure for demonstrating the control method of the rotational speed of the conventional registration roller The figure for demonstrating the concrete calculation method in the control method of the rotational speed of the registration roller of the stencil printing apparatus shown in FIG. The figure which shows the specific example of the control method of the rotational speed of the registration roller of the stencil printing apparatus shown in FIG. The figure for demonstrating the specific calculation method in the control method of the rotational speed of the registration roller shown in FIG. The figure for demonstrating the specific calculation method in the control method of the rotational speed of the registration roller shown in FIG. Block diagram of drive control means in the stencil printing apparatus shown in FIG. The figure for demonstrating the relationship between the phase of the pulse signal of a drum encoder, and the pulse signal which shows a rotation reference position The figure for demonstrating the dispersion | variation for every printing drum of the pulse signal which shows a rotation reference position. The figure for demonstrating the dispersion | variation in the same printing drum of the pulse signal which shows a rotation reference position The figure for demonstrating the specific calculation method in the control method of the rotational speed of the registration roller of 2nd Embodiment of the stencil printing apparatus of this invention. The figure which shows the specific example of the control method of the rotational speed of the registration roller of 2nd Embodiment of the stencil printing apparatus of this invention. The figure for demonstrating the specific calculation method in the control method of the rotational speed of the registration roller of 3rd Embodiment of the stencil printing apparatus of this invention. The figure for demonstrating the specific calculation method of the measurement rotational speed of the registration roller of 3rd Embodiment of the stencil printing apparatus of this invention. The block diagram of the drive control means of 3rd Embodiment of the stencil printing apparatus of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printing drum 11 Press roller 12 Protrusion 13 Optical sensor 20 Primary paper feed part 21 Scraper roller 22 Pickup roller 23 Bucket board 30 Secondary paper feed part 31, 32 Registration roller 33, 34 Guide plate 35 Registration motor 38 Roller rotation information detection Means 40 Paper discharge section 41, 42 Suction roller 43 Suction belt 50 Drum rotation information detection means 102 Counter information acquisition means 103 Motor control means

Claims (2)

A printing drum;
Drum rotation information detecting means for detecting drum rotation angle information from a predetermined reference position of the printing drum as a pulse signal;
A conveying roller for conveying printing paper to the printing drum;
A transport motor for driving the transport roller;
A paper leading edge detecting means for detecting that the leading edge of the printing paper being conveyed by the conveying roller has reached a predetermined position;
The printing start position of the printing paper conveyed by the conveyance roller based on the drum rotation angle information detected by the drum rotation information detection means and the front edge detection information detected by the paper front edge detection means, and the printing surface of the printing drum In an image forming apparatus comprising: a motor control unit that controls a rotation speed of the transport motor so that a start position matches the start position;
A drum counter means for generating a drum counter pulse signal having a cycle shorter than the cycle of the pulse signal detected by the drum rotation information detecting means, and measuring the number of the generated drum counter pulse signals;
Roller rotation information detecting means for detecting roller rotation angle information of the conveying roller as a pulse signal;
Roller counter means for generating a roller counter pulse signal having a cycle shorter than the cycle of the pulse signal detected by the roller rotation information detecting means, and measuring the number of the generated roller counter pulse signals;
The leading edge of the printing paper is detected by the leading edge detection means from the time of detection of the pulse signal last detected by the drum rotation information detecting means before the leading edge of the printing paper is detected by the paper leading edge detection means. The number of counter pulse signals for the drum up to the time point or the detection of the pulse signal detected by the drum rotation information detecting means for the first time after the leading edge is detected from the time when the leading edge of the printing paper is detected by the paper leading edge detecting means While obtaining the number of drum counter pulse signals up to the point of time, obtaining the number of drum counter pulse signals according to one cycle of the pulse signal detected by the drum rotation information detection means ,
The counter pulse for the roller from the detection time of the pulse signal last detected by the roller rotation information detection means to the predetermined time before the predetermined time after the detection of the front edge of the printing paper by the paper front edge detection means For the roller from the predetermined time after the detection of the number of signals or the front end of the printing paper by the paper front end detection means to the detection time of the pulse signal first detected by the roller rotation information detection means after the predetermined time Counter information acquisition means for obtaining the number of counter pulse signals, and further obtaining the number of counter pulse signals for the roller corresponding to one cycle of the pulse signal detected by the roller rotation information detection means ,
From the time of detection of the pulse signal last detected by the drum rotation information detecting means until the time of detecting the leading edge of the paper before the leading edge of the printing paper is detected by the motor control means. The number of counter pulse signals for the drum or the time point when the leading edge of the printing paper is detected by the paper leading edge detection means until the detection time point of the pulse signal detected by the drum rotation information detection means first after the leading edge detection. The ratio between the number of drum counter pulse signals and the number of drum counter pulse signals corresponding to one cycle of the pulse signal detected by the drum rotation information detecting means, and the leading edge of the printing paper by the paper leading edge detecting means The number of pulse signals detected by the drum rotation information detecting means up to the time when Based on the number of detected pulse signal to the detection time of the detected pulse signal by the drum rotation information detection means first after tip detection from the point at which the tip is detected in the printing paper by the detecting means, the conveying motor And calculating a target rotation angle at the predetermined point of time,
The number of the counter pulse signals for the roller from the detection time of the pulse signal last detected by the roller rotation information detection means before the predetermined time to the predetermined time or the first after the predetermined time from the predetermined time The roller counter pulse corresponding to the number of the counter pulse signals for the roller up to the detection time of the pulse signal detected by the roller rotation information detecting means and one cycle of the pulse signal detected by the roller rotation information detecting means The ratio to the number of signals, and the number of pulse signals detected by the roller rotation information detection means up to the predetermined time point, or the detection of the pulse signals detected by the roller rotation information detection means last after the predetermined time point Calculate the measured rotation angle at the predetermined time based on the number of pulse signals detected up to the time,
An image forming apparatus , wherein the rotation speed of the transport motor after the predetermined time is controlled so that the measured rotation angle approaches the target rotation angle . The drum rotation information detecting means uses the pulse signal detected first after the printing drum rotates to the predetermined reference position or the pulse signal detected immediately before the printing drum rotates to the predetermined reference position as a reference. Drum rotation angle information is detected,
The counter information acquisition means counts the number of counter pulse signals for the drum from the time when the printing drum rotates to the predetermined reference position to the time when the first pulse signal is detected by the drum rotation information detection means or the printing The drum counter pulse from the time when the pulse signal is finally detected by the drum rotation information detecting means before the drum rotates to the predetermined reference position to the time when the printing drum rotates to the predetermined reference position. To get the number of signals further,
The motor control means counts the number of counter pulse signals for the drum from the time when the printing drum rotates to the predetermined reference position to the time when the first pulse signal is detected by the drum rotation information detection means, or the printing drum The number of counter pulse signals for the drum from when the pulse signal was last detected by the drum rotation information detecting means before the print drum was rotated to the predetermined reference position before rotating to the predetermined reference position. And the number of counter pulse signals for the drum corresponding to one cycle of the pulse signal detected by the drum rotation information detecting means,
The drum counter pulse from the time of detection of a pulse signal last detected by the drum rotation information detection means before the time of detection of the paper front edge by the paper front edge detection means before the front edge of the printing paper is detected. The number of signals or the counter pulse signal for the drum from the time when the leading edge of the printing paper is detected by the paper leading edge detection means to the detection time of the pulse signal first detected by the drum rotation information detecting means after the leading edge detection. The ratio of the number of counter pulse signals for the drum according to one period of the pulse signal detected by the drum rotation information detecting means,
And the number of pulse signals detected by the drum rotation information detecting means until the time when the leading edge of the printing paper is detected by the paper leading edge detection means, or from the time when the leading edge of the printing paper is detected by the paper leading edge detection means. Based on the number of pulse signals detected up to the point of detection of the pulse signal detected by the drum rotation information detection means for the first time after detecting the leading edge, the target rotation angle at the predetermined time of the transport motor is calculated. the image forming apparatus according to claim 1, characterized in that it is.

Images