JP3085991B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus which controls the amount of ink discharged by performing pulse width modulation of an applied pulse.

[0002]

2. Description of the Related Art Conventionally, in an ink jet printing apparatus, in order to minimize the occurrence of density fluctuations and density unevenness in a printed image or the like, in particular, the ejection direction (landing accuracy) and the ejection amount (hereinafter referred to as the ejection amount) of a recording head. The amount is Vd [Pl
/ Dot]) has been variously controlled.

[0003] The main methods employed in these controls are:
By adjusting the temperature of the ink (hereinafter, referred to as temperature control), the viscosity of the ink that affects the ejection amount is controlled, and bubbles are generated in the ink by thermal energy, and the ink is ejected by the growth of the bubbles. In the method, the conditions for generating bubbles are also controlled to stabilize the discharge amount. As a specific configuration for adjusting the ink temperature, a heater for heating the recording head holding the ink (also serving as a dedicated heater or a discharging heater), a temperature sensor for detecting the temperature related to the recording head, Using
There is a configuration in which a temperature detected by a temperature sensor is fed back to a heating amount by a heater. There is also a configuration in which heating by a heater is simply adjusted without feedback of temperature.

In the above-described configuration, the heater and the temperature sensor may be provided in the vicinity of the print head, for example, on a member constituting the print head, or may be provided outside the print head.

As another method for controlling the discharge amount or the like, or as a method used together with the above method, an electrothermal converter (hereinafter also referred to as a discharge heater) for generating thermal energy in the above-described discharge method generates heat energy. Pulse (hereinafter, referred to as heat pulse)
In some cases, the amount of generated heat is controlled to stabilize the discharge amount by changing the pulse width of the pulse.

The following four modes are mainly used as the control modes described above.
Are distinguished into two aspects.

1) Always perform head temperature control (external / nearby).

[0008] With temperature feedback.

2) The head temperature is adjusted as needed (external / nearby).

[0010] With temperature feedback.

3) Perform high-temperature head temperature control (higher than ambient temperature). With feedback.

4) Pulse width modulation of a single heat pulse.

[0013] However, in the method of the first aspect,
Since the temperature of the print head is constantly controlled, the evaporation of the ink moisture accompanying the heating of the heater is promoted, thereby causing the ink in the discharge port of the print head to thicken and stick, thereby resulting in a deflection of the discharge direction. This causes deterioration in recording image quality, for example, by causing an increase in deflection or non-ejection, or by a change in density or uneven density due to a relatively high dye density in the ink. In addition, as a result of the continuous heating by the heater, a change in the structure of the head and the deterioration of members constituting the head are promoted, and the reliability and durability of the recording head are reduced. In addition, this method is generally susceptible to changes in environmental temperature and self-heating (heating by printing), which may cause fluctuations in the ejection amount, causing density changes and density unevenness.

The second method is a method for adjusting the temperature as required, and is an improvement of the first method. For example, since the temperature is adjusted after a print command is input, the method can be performed in a relatively short time. , A predetermined temperature must be reached, and a large amount of energy [for example, the amount of heat generated by the heater (W)] must be given for heating. For this reason, in the temperature control, the width of the temperature ripple may increase and accurate temperature control may not be performed. In such a case, the discharge amount may fluctuate due to the temperature ripple, and density change or density unevenness may occur.
Conversely, if an accurate temperature control is to be performed, it is necessary to reduce the applied energy, the time required to reach the target temperature is increased, and the waiting time until the start of printing is increased.

In the third method, the temperature control temperature is set higher than the environmental temperature in order to reduce the influence of a change in the environmental temperature or a temperature change due to a self-heating (heating by printing).
This makes it possible to reduce fluctuations in the ejection amount during low-duty printing.
For example, when the temperature rise due to printing is large, as in all solid printing, the influence of this temperature rise cannot be avoided.

As a method of controlling the temperature, the temperature control outside the recording head can generally reduce the influence of the environmental temperature, but has a poor response to the self-heating, and is affected by the self-heating. It can be said that it is easy.

If the temperature is controlled in the vicinity of the recording head (for example, a heater or a temperature sensor is provided on an aluminum plate as a substrate supporting a heater board on which a discharge heater is provided), the response is improved, and printing is performed. Although effective for raising the temperature, a temperature ripple may occur due to a large heat capacity of the aluminum plate serving as the substrate, and the discharge amount may fluctuate due to the temperature ripple.

Further, a single pulse of the above method 4 (hereinafter referred to as a single pulse)
The pulse width modulation method (also called single pulse)
In particular, in the above-described bubble-forming ink-jet method, when the control range of the discharge amount is small enough to absorb the change in the discharge amount corresponding to the temperature change, and when it is difficult to obtain a linear increase in the discharge amount with an increase in the pulse width. The present inventors have recognized that it is necessary to improve the reproducibility and perform more accurate ejection amount control for higher image quality.

In order to solve the problem of each of the discharge amount control modes described above, as a relatively effective configuration, in the method of generating thermal energy and discharging ink, a pulse applied to a discharge heater is divided into a plurality of pulses. There is a configuration in which the discharge amount control is performed by modulating the pulse width of the first pulse of these pulses.

[0020]

One of the advantages of the ink jet recording apparatus is that recording can be performed on various recording media. For example, in addition to ordinary recording paper, thick paper such as an envelope, and an overhead projector (OHP) are relatively frequently used.
Transparent paper (hereinafter, referred to as OHP paper).

Of these, characters, images, and the like printed on OHP paper need to be printed at a high density because the projected image must be clear when projected.

Therefore, as described above, simply controlling the discharge amount by performing pulse width modulation in accordance with the temperature of the recording head cannot perform printing of a desired relatively high density especially on OHP paper. .

The present invention has been made based on the above-described viewpoint, and an object of the present invention is to provide an ink-jet recording apparatus for controlling an ejection amount by pulse width modulation.
An object of the present invention is to provide an ink jet recording apparatus capable of increasing a recording density by changing a pulse width to a predetermined width and increasing a discharge amount when recording on an OHP sheet.

[0024]

SUMMARY OF THE INVENTION To achieve this, the present invention relates to an ink jet recording apparatus which uses a recording head for discharging ink based on the energy generated by an energy generating element and discharges ink from the recording head to perform recording. A printhead driving means for generating the energy by applying a drive signal to the energy generating element, and a drive for changing the waveform of the drive signal applied by the printhead drive means in accordance with the result of detecting the temperature of the printhead A signal modulation unit, and when the recording medium used for recording is instructed to be a recording medium having optical transparency, the drive signal modulation unit can change the drive signal to the drive signal modulation unit. A drive control unit for limiting the drive signal to a drive signal having a waveform that generates larger energy among the waveforms; And characterized in that it comprises. Also,
In an ink jet recording apparatus that performs recording by discharging ink from the recording head using a recording head that discharges ink based on thermal energy generated by the electrothermal transducer, a drive signal is supplied to the electrothermal transducer of the recording head. A recording head driving unit that generates the thermal energy by applying the electric power, and a changing unit that changes a driving signal supplied to the electrothermal transducer according to a temperature detection result regarding the recording head, wherein the changing unit The range of the driving signal changed by the first recording mode corresponding to the recording medium having the optical transparency and the second recording mode corresponding to the recording paper which is normally used is changed.
Wherein the range of the change of the drive signal in the recording mode is a range including the drive signal for generating the maximum heat energy in the electrothermal transducer among the drive signals changed in the second recording mode. I do. Further, in an ink jet recording apparatus that performs recording by discharging ink from the recording head using a recording head that discharges ink based on thermal energy generated by the electrothermal conversion element, the recording head is driven by the electrothermal conversion element. A recording head driving unit that generates the thermal energy by applying a signal, and a changing unit that changes a driving signal supplied to the electrothermal transducer in accordance with a temperature detection result regarding the recording head, The range of the drive signal changed by the changing means is set to a first recording mode corresponding to a recording medium having optical transparency and a second recording mode corresponding to a recording sheet normally used.
And a drive signal that generates a larger amount of thermal energy than the drive signal in the range changed in the second recording mode. It is characterized by a range.

[0025]

According to the above arrangement, in the ink jet recording apparatus for changing the waveform of the driving signal applied in response to each ejection operation in accordance with the result of detecting the temperature of the recording head, the recording medium used for recording is When the recording medium has a light transmitting property, the waveform of the drive signal can be a waveform that generates a larger amount of energy and generates a larger amount of ink ejection. High density recording becomes possible.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, an outline of pulse width modulation of divided (plural) pulses and discharge amount control by the pulse width modulation according to an embodiment of the present invention will be described.

FIG. 1 is a diagram for explaining a divided pulse according to one embodiment of the present invention.

In FIG. 1, V _OP is a drive voltage, P ₁ is a pulse width of a first pulse (hereinafter, referred to as a pre-heat pulse) of a plurality of divided heat pulses, P ₂ is an interval time, and P ₃ is a second pulse. It is a pulse width of a pulse (hereinafter, referred to as a main heat pulse). T ₁ , T ₂ , and T ₃ indicate times for determining P ₁ , P ₂ , and P ₃ . The drive voltage V _OP is one of the values indicating electric energy required for the electric heat conversion element to which the voltage is applied to generate heat energy in the ink in the ink liquid path formed by the heater board and the top plate. The value is determined by the area, resistance value, film structure, and liquid path structure of the recording head of the electrothermal transducer. The divided pulse width modulation driving method includes P ₁ , P ₂ ,
And is to be given sequentially pulse width of P _3, the pre-heat pulse is mainly a pulse for controlling the ink temperature in the liquid path, have an important role in the discharge amount control of this embodiment I load . The preheat pulse width is set to a value that does not cause a bubbling phenomenon in the ink due to the thermal energy generated by the electrothermal converter when applied.

The interval time is provided to provide a predetermined time interval so that the preheat pulse and the main heat pulse do not interfere with each other, and to make the temperature distribution of the ink in the ink liquid passage uniform. The main heat pulse is caused to foam in the ink in the liquid passage is for discharging ink from the discharge port, the area of the width P ₃ is an electrothermal transducer, resistance, film structure and the recording head It is determined by the structure of the ink liquid path.

FIG. 2 is a diagram showing the dependence of the ejection amount on the preheat pulse. In the figure, V ₀ is P ₁ = 0 [μsec
c], and this value is determined by the head structure. Incidentally, V ₀ in this embodiment is the environmental temperature T _R = 25.
In the case of ° C., V ₀ = 18.0 [ng / dot].

[0032] As shown in curve a of Figure 2, in accordance with an increase in the pulse width P ₁ of the pre-heat pulse, the ejection amount V _d is increased with a linearity from Pasuru width P ₁ is 0 to P _1LMT In the range where the pulse width P ₁ is larger than P _1LMT , the change loses linearity and saturates and becomes maximum at the pulse width P _1MAX .

[0033] Thus, the range of variation of the ejection amount V _d relative to the change in the pulse width P ₁ until the pulse width P _1LMT showing the linearity is easily control the discharge amount by changing the pulse width P ₁ It is effective as a range that can be performed. _Incidentally , in this embodiment shown by the curve a, P _1LMT = 1.87 (μs), and the discharge amount at this time is V _LMT = 24.0 [ng / do].
t]. The pulse width P _1MAX when the discharge amount V _d is saturated is P _1MAX = 2.1 [μs],
The discharge amount V _{MAX at} this time was 25.5 [ng / dot].

[0034] When the pulse width is greater than P _1MAX, the ejection amount V _d is smaller than V _MAX. This phenomenon is that when a preheat pulse having a pulse width in the above range is applied, fine bubbling (a state immediately before film boiling) occurs on the electrothermal transducer, and the next main heat pulse is generated before the bubble disappears. The ejection rate is reduced by the applied micro bubbles, which disturb the bubbling by the main heat pulse. This region is called a pre-foaming region, and in this region, it becomes difficult to control the discharge amount via a preheat pulse.

If the slope of a straight line indicating the relationship between the discharge amount and the pulse width in the range of P ₁ = 0 to P _1LMT [μs] shown in FIG. 2 is defined as the preheat pulse dependence coefficient, the preheat pulse dependence coefficient is:

[0036]

(Equation 1)

Is as follows. This coefficient K _P is determined by the head structure, driving conditions, physical properties of the ink, and the like irrespective of the temperature. That is, curves b and c in FIG. 2 show the case of another print head, and it can be seen that the ejection characteristics change when the print head is different. As described above, since the upper limit value _P1LMT of the preheat pulse P1 is different when the printheads are different, the discharge amount control is performed by setting the upper limit value _P1LMT for each printhead as described later. Incidentally, in the recording head and the ink indicated by the curve a in the present embodiment, K _P = 3.209 [ng / ng].
μsec · dot].

That is, another factor that determines the ejection amount of the ink jet recording head is the recording head temperature (ink temperature).

FIG. 3 is a diagram showing the temperature dependence of the discharge amount. As shown in curve a of Figure 3, the discharge amount V _d relative to the increase in environmental temperature T _R of the recording head (= head temperature T _H) increases linearly. If the slope of this line is defined as a temperature-dependent coefficient, the temperature-dependent coefficient:

[0040]

(Equation 2)

## EQU1 ## This coefficient K _T does not depend on the driving conditions, but is determined by the structure of the head, the physical properties of the ink, and the like. FIG.
Also, curves b and c show the cases of other recording heads.
Incidentally, in the recording head of this embodiment, K _T = 0.3 [n]
g / ° C. · dot].

Next, the ink jet recording apparatus according to this embodiment will be described below.

FIG. 4 shows an ink jet recording apparatus to which the present invention can be applied. This apparatus is a full-color serial type printer having conversion type recording heads corresponding to four color inks of black (Bk), cyan (C), magenta (M), and yellow (Y). The head used in this printer has a resolution of 400 dpi, a driving frequency of 4 KHz, and
It has 28 discharge ports.

In FIG. 4, C denotes four recording head cartridges corresponding to the respective inks of Y, M, C, and Bk. The recording head and an ink tank storing ink for supplying ink to the recording head are integrally formed. Is formed. Each recording head cartridge C is detachably mounted on the carriage by a configuration (not shown). The carriage 2 is slidably engaged along the guide shaft 11 and is connected to a part of a drive belt 52 that is moved by a main scanning motor (not shown). As a result, the recording head cartridge C can be moved for scanning along the guide shaft 11. 15,
Reference numerals 16, 17, and 18 denote conveying rollers extending substantially parallel to the guide shaft 11 on the inner side and the lower side in the drawing of the recording area by scanning of the recording head cartridge C. The transport rollers 15, 16 and 17, 18 are driven by a sub-scanning motor (not shown) to transport the recording medium P. The conveyed recording medium P faces the surface of the recording head cartridge C on which the ejection port surface is provided, and forms a recording surface.

A recovery unit is provided facing a movable area of the cartridge C adjacent to a recording area of the recording head cartridge C. In the recovery unit,
Reference numeral 300 denotes a cap unit provided for each of the plurality of cartridges C having a recording head. The cap unit 300 is slidable in the left-right direction in the figure as the carriage 2 moves, and is movable up and down in the figure. When the carriage 2 is at the home position, the carriage 2 is joined to the recording head and capped. Further, in the recovery system unit, 401 and 402 are a first and a second blade as a wiping member, and 403, respectively.
Is a blade cleaner made of, for example, an absorber for cleaning the first blade 401.

Further, 500 is a cap unit 300
And a pump unit for absorbing ink and the like from the ejection port of the recording head and the vicinity thereof through the recording head.

FIG. 5 is a block diagram showing a configuration example of a control system in the ink jet recording apparatus.

Here, reference numeral 800 denotes a controller constituting a main control unit, for example, a CPU 801 in the form of a microcomputer for executing processing described later, a table for program pulse width modulation corresponding to the procedure, a voltage value of a heat pulse. That stores fixed data such as pulse width and pulse width
M803 and a RAM 805 provided with an area for developing image data, a work area, and the like. Reference numeral 810 denotes a host device (which may be a reader unit for reading images) serving as a supply source of image data.
Status signals and the like are transmitted through an interface (I / F) 812.
Is transmitted to and received from the controller via

Reference numeral 820 denotes a power switch 822, a copy switch 824 for instructing the start of recording (copying), and a large recovery switch 826 for instructing the start of large recovery.
, Etc., are a group of switches for receiving a command input by an operator. Reference numeral 830 denotes a sensor group for detecting the state of the apparatus, such as a sensor 832 for detecting the position of the carriage 2 such as a home position and a start position, and a sensor 834 including a leaf switch 530 and used for detecting a pump position.

Reference numeral 840 denotes a head driver for driving the electrothermal transducer of the printhead according to print data and the like. Part of the head driver is a temperature heater 30A,
It is also used to drive 30B. Further, the temperature detection values from the temperature sensors 20A and 20B are transmitted to the controller 80.
Enter 0. 850, a main scanning motor for moving the carriage 2 in the main scanning direction (the horizontal direction in FIG. 10);
52 is the driver. A sub-scanning motor 860 is used to convey (sub-scan) a recording medium.

The records mounted on the apparatus shown in FIGS. 4 and 5 are shown below.

FIG. 6 shows an example of the configuration of a head cartridge mountable on the carriage of the ink jet recording apparatus shown in FIG. The cartridge according to the present embodiment has an ink tank unit IT and a head unit IJU integrally, and these are detachable from each other.
A wiring connector 102 for receiving a signal or the like for driving the ink ejection unit 101 of the head unit IJU and outputting a remaining ink amount detection signal is provided at a position aligned with the head unit IJU and the ink tank unit IT. . Therefore, in a posture which is taken when the cartridge is mounted on a carriage described later, the height H can be reduced and the thickness of the cartridge can be reduced. This makes it possible to make the carriage small when arranging the cartridges side by side as shown in FIG. When mounting the head cartridge on the carriage, the knob 20 provided on the ink tank unit IT with the ejection unit 101 facing down is provided.
1 can be gripped and placed on the carriage. The knob 201 is engaged with a lever provided on a carriage described later for performing a mounting operation of the cartridge. Then, at the time of mounting, the pins provided on the carriage side engage with the pin engaging portions 103 of the head unit IJU, and the head unit IJU is positioned.

In the head cartridge according to the present embodiment, an absorber 104 for wiping the surface of the ink discharge portion 101 and cleaning a member for cleaning the surface is arranged in parallel with the ink discharge portion 101. Further, an air communication port 203 for introducing air with ink consumption is provided substantially at the center of the ink tank unit IT.

FIG. 7 is an exploded perspective view of the head cartridge shown in FIG. The head cartridge according to the present example includes:
It is composed of a head unit IJU and an ink tank unit IT.
This will be described with reference to FIG.

The base for mounting the components of the head unit IJU is a base plate 111 made of Al or the like, on which an element group for generating energy used for ink ejection is formed. Substrate 1
12 and a printed circuit board (PCB) 115 having wiring and the like for supplying power to the element,
These are connected by wire bonding or the like. The substrate 112 is provided with an electrothermal conversion element that generates thermal energy that causes film boiling of the ink in response to energization. And in the following, this substrate 1
12 is called a heater board.

The above-described wiring connector 102 is connected to the PCB 11
5, a drive signal from a control circuit (not shown) is received by the wiring connector 102, and the PCB 115
Is supplied to the heater board 112 via the. PCB11
Reference numeral 5 denotes a double-sided wiring board in this example, and further includes information unique to the head, for example, appropriate driving conditions for the electrothermal transducer,
A ROM-type IC 128 storing a D number, ink color information, driving condition correction data (head shading (HS) data), PWM control conditions, and the like, and a capacitor 12
9 are provided.

As shown in the figure, the IC 128 and the capacitor 129 are provided on the bonding surface side of the PCB 115 with the base plate 111 and the notch 11 of the base plate 111.
It is arranged at a position corresponding to 1A. by this,
If the height at the time of mounting the IC or the like is equal to or less than the thickness of the base plate 111, the IC or the like does not protrude from the surface when the PCB 115 and the base plate 111 are joined. Therefore, it is not necessary to consider a storage mode corresponding to the protrusion in the manufacturing process.

On the heater board 112, a common liquid chamber for temporarily storing ink supplied from the ink tank unit IT side, and a concave portion for forming a liquid path group communicating the liquid chamber with the discharge port are provided. The top plate 113 is arranged. The top plate 113 is integrally formed with a discharge port forming member (orifice plate) 113A in which ink discharge ports are formed. 114 is the top plate 113 and the heater board 11
2 is a pressing spring for forming the discharge section 101 by bringing the discharge section 101 into close contact.

Reference numeral 116 denotes a head unit cover, which is an ink supply pipe 1 that enters the ink tank unit IT.
16A, an ink flow path 116B for communicating ink with the top plate-side ink introduction tube, and a base plate 111
Three pins 116C for three-point positioning or fixing to the
It is a member formed by integrally molding the pin engaging portion 103, the mounting portion of the absorber 104, and other necessary portions. A channel cover 117 is provided for the ink channel 116B. A filter 118 for removing bubbles and dust is provided at the tip of the ink supply pipe 116A, and an O-ring for preventing ink from leaking from the joint is provided.

When assembling the above head unit, the pins 111P projecting from the base plate are connected to the PCB.
Positioning is performed so as to be inserted into the through-hole 115P provided in 115, and both are fixed by bonding or the like. In fixing the two, precision is not so required. This is because the heater board 112 to be mounted on the base plate 111 with high accuracy is fixed separately from the PCB 115.

Next, the heater board 112 is precisely placed and fixed on the base plate 111, and necessary electrical connection with the PCB 115 is made. Then, the top plate 113 and the spring 114 are arranged, and after bonding and sealing are performed as necessary, positioning is performed by inserting three pins 116C protruding from the cover into the holes 111C of the base plate 111. Thereafter, the head unit is completed by thermally fusing these three pins 116C. Ink tank unit In FIG. 7, 211 is an ink container forming the main body of the ink tank unit, 215 is an ink absorber for impregnating ink, 216 is an ink tank lid, 212 is an electrode pin for detecting the remaining amount of ink, 213 and 214 is a contact member for the pin 212.

The ink container 211 generally includes pins 212,
A portion 220 for mounting the contact members 213 and 214 and mounting the above-described head unit IJU, a supply port 231 for receiving the ink supply tube 116A, and a knob 201 are integrally provided, and the bottom side in FIG. It has a hollow cylindrical portion 233 erected almost at the center. Such an ink container can be formed by integral molding of a resin.

The bottom side of the cylindrical portion 233 is opened in consideration of the ink filling step, and after filling, a cap 217 shown in FIG. 7 is attached and closed to the atmosphere. On the other hand, a spiral or meandering groove 235 is provided on the upper end surface in FIG. 7 (vortex in the illustrated example), and a cylindrical portion 233 is formed at one end 235A of the groove (center of the spiral groove in the illustrated example). There is an opening communicating with the internal space.
The other end 235 </ b> B of the groove is located at the position of the atmosphere communication port 203 provided in the tank lid 216.

A plurality of (four in the illustrated example) grooves 237 are provided on the side surface of the cylindrical portion 233 at an equal angle, and communicate with the internal space of the cylindrical portion 233. As a result, communication between the inside of the ink tank unit and the atmosphere is made through the atmosphere communication port 203, the spiral groove 233, the internal space of the cylindrical portion 231, and the groove 237. And the cylindrical part 2
The internal space of 31 functions as a buffer unit for preventing ink leakage due to vibration or swing. In addition, since there is the spiral groove 233 that lengthens the path to the atmosphere communication port 203, ink leakage is more effectively prevented.

Further, by providing a plurality of grooves 237 at an equal angle on the side surface of the cylindrical portion 233 located substantially at the center of the ink tank as in the present embodiment, it is possible to prevent the absorber 215 located around the same from being provided. It is possible to secure a uniform state of balance with the atmosphere and prevent local concentration of ink in the absorber. This can also ensure smooth ink supply to the absorber compression area (around the supply port 231) described later.

The groove 237 extends below the center of the thickness W1 of the container, and the supply port 231 in FIG.
Is provided over a range that completely covers the range A in which In addition, it is formed in a range in which the position of the remaining amount detection pin 212 is also taken into consideration, thereby ensuring a uniform ink presence state or air communication state around the pin existing portion, and improving the accuracy of the remaining amount detection. be able to.

The ink impregnating absorber 215 according to this embodiment is provided with a hole 215A for receiving the insertion of the cylindrical portion 233. By arranging the tubular portion 233 in the hole 215A, the absorber 215 is not compressed by the tubular portion 233, and no ink remains in the compressed portion where the negative pressure is high. On the other hand, the absorber 21 according to the present example
Reference numeral 5 is a shape in which the portion located at the supply port 231 is slightly swelled with respect to the shape of the space formed by the ink tank lid 216 and the ink container 211 (indicated by a dashed line in FIG. 17). Thus, when the absorber 215 is stored in the ink tank unit, the expanded portion is in a compressed state, so that the absorber 215 has a high negative pressure at that portion, and thus supplies ink smoothly. Mouth 2
It can be introduced to the 31 side.

When printing on OHP paper, it is important to correct the variation in the discharge amount, but it is often necessary to print at a high density as described above. Therefore, when performing printing on OHP sheet, without performing the PWM control in accordance with the recording head temperature, to fix the pulse width P _1. By long as possible a pulse width of P ₁ at this time, to increase the discharge amount to achieve high density printing.

FIG. 8 is a block diagram for explaining the head drive control according to one embodiment of the present invention, and FIG. 9 is a timing chart of each signal in this configuration.

The pattern of the head drive signal waveform is R
It is stored in the OM 805. First, at the output timing of the head drive signal, a clock is given to a counter 800C included in the controller 800 shown in FIG.
Each time this clock is input, the output of the counter becomes "1".
Is only incremented. As a result, the contents of the ROM 803 are output using the counter output as an address and become a head drive signal.

This head drive signal is output depending on which one of the PWM control tables in which the pulse width of the pre-pulse P ₁ is stored corresponding to each temperature is selected. That is, as shown in FIG. 9, a head drive signal having a waveform corresponding to the selected table is output. Which head drive signal table is selected is determined by the PWM control table selection signal input to the ROM 803.
When the HP paper selection signal is “H”, the OR gate 800
By A, all the input signals of the PWM table selection signal to the ROM 803 become H, and the table AN + α-1 is selected regardless of the PWM table selection signal.
Width P ₁ of pre-pulses shown at the top is a fixed value at the maximum. Specifically, when P ₁ = 2.618 μsec, P ₃
= 4.114 μsec.

FIG. 9 shows a head drive signal when printing is performed when the print ON signal is "H". When the print ON signal is "L" (no printing), FIG.
Head driving signal shown in distinction pulse P ₃ becomes "L" level.

In this embodiment, the ejection amount is increased only in the state where the pre-pulse P ₁ is fixed at MAX. However, the ejection amount may be further increased by raising the temperature of the head to a controlled temperature. Specifically, the temperature control temperature is increased from the normal 25 ° C. to 40 ° C. If the temperature is higher than this, the temperature rise during printing may be about 15 ° C., so that the limit temperature T _LIMIT of the recording head approaches 60 ° C., which is not preferable.

The above-described drive control is performed, for example, by shifting to the OHP mode processing when it is determined that the OHP mode is set when a paper type is detected. Further, in the above embodiment, the case of the PWM control of the pre-pulse of the divided pulse has been described. However, in the PWM control of the single pulse, the discharge amount may be increased as a fixed pulse in the OHP mode, and the temperature may be further adjusted.

Next, another embodiment of the head drive control will be described with reference to FIGS.

In FIG. 10, an image signal as print data is stored in the RAM 805. Image signal is RAM8
At the time point when the image data is stored in the shift register 05, the CPU 800 sets the image data in the shift register 800R to generate a head drive signal. This will be described in detail with reference to the flowchart of FIG.

In FIG. 12, in step S1, the CPU
800 reads out image data for one pixel from the RAM 805, and proceeds to step S2. In step S2, it is determined whether the read data of one pixel is a value to be printed or whether or not ink ejection is to be performed. If printing is to be performed, the process proceeds to step S3. If not, to step S9.

In step S3, the main pulse P
_The fact that the section ₃ is “H” is stored in the register 12 of the CPU 800, and the process proceeds to step S4. In step S4, reads the PWM selection signal, the process proceeds to step S5 stores the width of the "H" level of the pre-pulse P ₁ to the register 12 of the CPU 800. In step S5, O
The HP selection signal is read, and the process proceeds to step S6 if the printing mode is for OHP paper, and to step S7 if the printing mode is for printing other than OHP paper.

[0079] In step S6, most significantly changes that can set the width of the H level of the pre-pulse P ₁ which defines in step S4, then stored in a register of the CPU 800, the process proceeds to step S7. In step S7, CPU 800
Create a pre-pulse P ₁ and a head drive signal from the information of the main pulse P ₃ which is stored in the register, and stored in the shift register 800R, the process proceeds to step S8. The head drive signal stored in the shift register 800R is output from the shift register 800R in synchronization with a clock.

In step S8, it is determined whether all the image data stored in the RAM 805 has been output.
If all the data has been output, the process ends. If all the data has not been output, the process returns to step S1.

FIG. 13 is a waveform diagram showing drive pulses that can be selected in the aforementioned PWM control.

In the case of using a general recording paper other than the recording medium having a light transmitting portion, such as the OHP paper according to the embodiment of the present invention, in the PWM control, the waveforms shown in FIGS. Select according to.

On the other hand, in the above-described embodiment of the present invention, when recording on an OHP sheet, control is performed such that only the pulse shown at 1 in FIG. 13 is used.

As another embodiment of the present invention, instead of fixing the pulse to be used to one driving pulse as described above, some of the pre-pulses shown in FIG. 13 having a relatively large width are set. When OHP paper is used, PWM control may be performed within the set pulse range. According to this, especially when a full-color image is recorded, it is possible to improve the image quality while securing a high density.

[0085] As the pulse setting range, for example, pulses shown in 1-4 in FIG. 13, a pulse, or pulse further prepulse width P ₁ is represented by 1 in the drawing indicated by 1 and 2 in FIG. One example is a combination of one or more large pulses.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging ink, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body or the ink from the apparatus main body is attached to the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention, since the effects of the present invention can be further stabilized. . If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Further, the types and the number of recording heads to be mounted are not limited to those provided only for one color ink, for example, and for a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature, or an ink jet system In general, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Anything can be used. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies in a standing state to prevent evaporation of the ink can be used. In any case, the ink is liquefied by the application of the thermal energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used. In such a case, the ink is disclosed in JP-A-54-56847 or JP-A-60
As described in JP-A-71260, a configuration may be adopted in which a liquid or solid substance is held in a concave portion or through hole of a porous sheet and opposed to an electrothermal converter. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0095]

As is apparent from the above description, according to the present invention, the drive signal waveform of the recording medium (for example, OHP paper) having a translucent portion used for recording is higher than that of general recording paper. A signal indicating that the recording mode for performing the waveform modulation in a limited high range is selected is output, and while the signal is selected, the drive control unit performs, for example, the preheat pulse modulation in the divided pulse driving with the pulse width of the preheat pulse modulation. Try to do it in a large specific range. Further, a predetermined head drive signal in which the pulse width of the preheat pulse is fixed within this range may be output.

As a result, the ink discharge amount can be increased by fixing the pulse width in a high driving condition range where the width is relatively large or at one point in this range, and high density printing on OHP paper is realized. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pulse waveform of a pulse width modulation driving method of a divided pulse according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a discharge amount and a pulse width according to the present invention.

FIG. 3 is a diagram showing a relationship between a discharge amount and a head temperature according to the present invention.

FIG. 4 is a perspective view of a full-color printer according to one embodiment of the present invention.

FIG. 5 is a block diagram illustrating a control configuration of the printer.

6 is a perspective view of a recording head cartridge of the apparatus shown in FIG.

7 is an exploded perspective view of the recording head cartridge shown in FIG.

FIG. 8 is a block diagram illustrating a configuration of printhead drive control according to an embodiment of the present invention.

9 is a timing chart of each signal in the configuration shown in FIG.

FIG. 10 is a block diagram illustrating a configuration of printhead drive control according to another embodiment of the present invention.

11 is a timing chart of each signal in the configuration shown in FIG.

FIG. 12 is a flowchart of a processing procedure according to the configuration shown in FIG. 10;

FIG. 13 is a waveform diagram showing a pulse waveform that can be selected by pulse width modulation driving of a divided pulse according to the embodiment of the present invention.

[Explanation of symbols]

 2 Carriage 20A, 20B Temperature sensor 30A, 30B Temperature control heater 801 CPU 803 ROM 805 RAM C Recording head cartridge

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroshi Taka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-58-187364 (JP, A) JP-A-2 JP-179497 (JP, A) JP-A-60-48367 (JP, A) JP-A-60-48366 (JP, A) JP-A-56-146770 (JP, A) JP-A-56-1476769 (JP, A) )

Claims (14)

(57) [Claims] 1. An ink jet recording apparatus that uses a recording head that discharges ink based on energy generated by an energy generating element and performs recording by discharging ink from the recording head, wherein the recording head is driven by the energy generating element. A recording head driving unit that generates the energy by applying a signal; a driving signal modulation unit that changes a waveform of a driving signal applied by the recording head driving unit according to a result of detecting a temperature of the recording head; when it recording medium used in it is a recording medium having a light transmitting property is instructed, the drive signal modulating means
On the other hand, the drive signal modulation means can change the drive signal.
Generate more energy from the waveform
An ink jet recording apparatus, comprising: a drive control means for limiting the drive signal to a waveform drive signal . 2. The driving signal comprises two pulses,
2. The ink jet recording apparatus according to claim 1, wherein the drive signal modulating means changes a width of a pulse applied earlier than the two pulses. 3. The energy generating element generates thermal energy, generates bubbles in the ink by the thermal energy, and discharges the ink, and the drive signal generates the thermal energy without discharging the ink. The driving signal modulation unit changes a width of the first pulse, comprising a first pulse for generating the first pulse and a second pulse for generating thermal energy for discharging ink. The ink jet recording apparatus according to claim 1 or 2, wherein 4. The ink jet recording apparatus further comprises a head heating means for heating the recording head, and the drive control means fixes the drive signal to a predetermined waveform after heating by the heating means. The inkjet recording apparatus according to any one of claims 1 to 3, wherein: 5. The energy generating element is an electrothermal converter that generates thermal energy, generates bubbles in the ink by the thermal energy, and discharges the ink from the recording head based on the generation of the bubbles. The ink jet recording apparatus according to any one of claims 1, 2, and 4, wherein: 6. An ink-jet recording apparatus which performs recording by discharging ink from a recording head using a recording head which discharges ink based on thermal energy generated by an electrothermal transducer, wherein: Recording head driving means for generating the thermal energy by applying a driving signal to a body; and changing means for changing a driving signal supplied to the electrothermal transducer according to a temperature detection result for the recording head. Then, the range of the drive signal changed by the changing means is made different between a first recording mode corresponding to a recording medium having optical transparency and a second recording mode corresponding to a recording sheet normally used. together, said first range of change of the drive signal in the recording mode, the electrical out of the drive signal changes in the second recording mode The range includes the drive signal that generates the maximum thermal energy to the heat converter .
An ink jet recording apparatus characterized by that. 7. A change range of the drive signal in the first recording mode is a range of a drive signal that generates relatively large thermal energy among a change range of the drive signal in the second recording mode. The ink jet recording apparatus according to claim 6, wherein: 8. The change range of the drive signal in the first recording mode includes a drive signal that generates a larger amount of heat energy than a drive signal that generates a maximum amount of heat energy in the second recording mode. The ink jet recording apparatus according to claim 6, wherein: 9. The driving signal includes a first pulse for generating thermal energy without discharging ink and a second pulse for generating thermal energy for discharging ink. 9. The apparatus according to claim 6, wherein the changing unit changes a width of the first pulse. 10. The recording head according to claim 6, wherein bubbles are generated in the ink by the electrothermal transducer, and the ink is discharged based on the generation of the bubbles.
The inkjet recording device according to any one of the above. 11. An ink jet recording apparatus which performs recording by discharging ink from a recording head using a recording head which discharges ink based on thermal energy generated by an electrothermal transducer. Recording head driving means for generating the thermal energy by applying a driving signal to a body; and changing means for changing a driving signal supplied to the electrothermal transducer according to a temperature detection result for the recording head. Then, the range of the drive signal changed by the changing means is made different between a first recording mode corresponding to a recording medium having optical transparency and a second recording mode corresponding to a recording sheet normally used. with a range of changes of the drive signal in the first recording mode than the driving signals in the range to be modified in said second recording mode An ink jet recording apparatus characterized in that the range includes a drive signal for generating large thermal energy. 12. The driving signal includes a first pulse for generating thermal energy without discharging ink and a second pulse for generating thermal energy for discharging ink. The ink jet recording apparatus according to claim 11, wherein the changing unit changes a width of the first pulse. 13. The ink jet recording apparatus according to claim 11, wherein the recording head generates bubbles in the ink by the electrothermal transducer, and discharges the ink based on the generation of the bubbles. 14. The ink jet recording apparatus according to claim 1, wherein the recording medium having optical transparency is a recording medium used for an overhead projector.