JP3133841B2 - Image forming 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 image forming apparatus for forming an image using an ink jet recording system.

[0002]

2. Description of the Related Art Various products have been announced as printers for performing recording by a so-called ink jet recording method in which recording is performed by discharging ink from nozzles (recording elements) provided in a recording head. Among them, several heaters are mounted in a nozzle in which ink is immersed, and a pulse signal is applied to these heaters to heat the heater to boil the ink, and to generate ink from the nozzle by a bubble pressure generated by the heater. A method of discharging is also known. When an image forming apparatus such as an ink jet printer is configured using a recording head employing such a method, a plurality of nozzles are arranged on the recording head, and the recording head scans to form an image. .

FIGS. 10A and 10B show an example of a conventional control circuit for driving such a recording head. FIG. 10 (A)
, The image data VD is transferred as serial binary data, and
After being converted from a serial signal to a parallel signal by 901-n, data is latched corresponding to each nozzle by a latch (LAT) signal. Further, a plurality of nozzles of the print head are divided into a plurality of blocks, and pulse signals BE0 to BE for driving the heater are applied to each block (the pulse signals are at a high level for a certain period of time as shown in FIG. 10B). Signal). Accordingly, only the heater corresponding to the nozzle whose image data is latched at the high level is turned on, and the control is performed so that ink is ejected from the corresponding nozzle. In this case, the heater driving pulse signals BE0 to BE are applied to the head only during recording.

[0004]

When an image is formed by the above-described ink-jet method, the recording head is scanned once in the main scanning direction, and after the scanning, the recording head is returned to the original position, and the recording medium is sub-scanned. A method has been adopted in which the next scanning is performed after the recording head is moved in the scanning direction by the recording width of the recording head. For this reason, especially when printing on a large-size sheet and enlarging continuous shooting, the temperature of the heater of the print head decreases during the print time interval from the first scan to the next scan.
As a result, the amount of ink ejected from the ink head at the start of the next scan decreases, and there is a problem that density unevenness occurs.

Further, as in the case of half-end feeding or recording of a reduced image, only the nozzles of a part of the print head are used in the first scan, and the nozzles not used in the first scan are used in the second scan. Also in the case of performing printing by using the same, there has been a problem that, similarly to the above, the ink ejection amount changes due to a decrease in the temperature of the heater, and density unevenness occurs. A similar problem also occurs when printing an image that is printed using a specific nozzle of the print head at high frequency.

The present invention has been made in view of the above conventional example, and provides an image forming apparatus capable of generating many types of drive signals for driving a recording head by merely changing stored pattern data. The purpose is to do.

[0007]

[0008]

In order to achieve the above object, an image forming apparatus according to the present invention has the following arrangement.
That is, in an image forming apparatus that forms an image using an inkjet recording type recording head,
Reference signal generation that generates a reference signal that defines timing
Means, storage means for storing pulse pattern data,
According to the pattern data stored in the storage means
Pulse generating means for generating a drive signal for driving each nozzle of the recording head by dividing the reference signal ;
It is characterized by having.

[0009]

[0010]

According to the above arrangement, in the above arrangement, a driving signal for driving each nozzle is generated in accordance with the pattern data stored in the storage means, the reference signal defining the driving timing of the recording head.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of the ink jet printer of this embodiment. As shown in FIG. 1, the ink jet printer of this embodiment is roughly composed of two components. That is, the head control unit 10 that generates signals necessary for controlling the interface with the external device 19 and driving the head, and the head control unit 10
The recording paper 17 as a recording medium is
And a recording head unit 11 for forming an image.

The head control unit 10 includes a CPU 12, a head control signal generation unit 13, a heater drive signal division unit 14, another load unit 18, and the like. The CPU 12 controls the interface with the external device 19 to which the serial image data VD is transferred, and controls the operation of the entire head control unit 10. When the serial image data VD is transferred from an external device 19 such as a host computer, the head control signal generator 1
At 3, a drive signal required to drive the recording head unit 11 is generated. The head control signal generator 13 performs a process such as a mirror process on the image data VD. Among the drive signals output from the head control signal generator 13, the reference signal BE for driving the heater 16 is provided.
0 to 3 (in the present embodiment, the print head unit 11 has 256 nozzles, these nozzles are divided into four blocks, and the heater drive signal BE (BE
0 to BE3) are output, the waveform is divided (generation of a pulse pattern) by the heater drive signal dividing unit 14, and the divided signals are output to the heater 16 of the recording head unit 11.

The serial image data VD output from the head control signal generator 13 is converted from serial data to parallel data by a serial-parallel converter 15, and the parallel data is temporarily stored by a latch signal LAT. Will be retained. The heater of each nozzle of the print head is heated and driven by the image data VD thus held and the heater drive signals BEO0 to BEO3 generated by the heater drive signal dividing unit 14. In this way, the ink is ejected from the nozzles and the ink adheres to the recording paper 17 to form an image.

FIG. 2 is a diagram for explaining the state of waveform division (pulse generation) performed by the heater drive signal division section 14. As shown in FIG.

As shown in FIG. 2, with respect to the heater drive signals BE0 to BE3 output from the head control signal generator 13, the residual heat of the heater 16 is reduced only during the period when each of the heater drive signals BE0 to BE3 is at a high level. When the recording is performed, the signal is divided into signals having a pulse width that is short enough not to discharge the ink, and a signal for discharging the ink is applied to the heater 16 when the recording is actually performed. By this pre-heat treatment, the heater 16
Can be kept constant, and the fluctuation of the ink discharge amount from the nozzle can be suppressed. Also, the heater drive signal dividing unit 14
In this case, several types of pulse patterns can be generated, such as a heater drive signal (pulse pattern) for actually performing printing and a heater drive signal (pulse pattern) for preheating the heater. According to C
The pulse pattern to be output can be switched by the output signal from the sensor of the PU 12 or the other load unit 18 or the like.

Next, the heater driving pulse signal BE
The details of the heater drive signal dividing unit 14 that performs control for finely dividing O0 to O3 will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of the heater drive signal dividing unit 14.

The heater drive signal dividing section 14 comprises a heater drive signal data set section (for preheating) 30, a heater drive signal data set section (for recording) 31, and a heater drive signal select section 32. In the heater drive signal data setting unit (for preheating) 30, pattern data that generates a pattern signal obtained by dividing the heater drive signal so that ink is not ejected is set before printing is started. In the heater drive signal data setting section (for recording) 31, pulse pattern data for actually performing recording
When the heater 12 is set by the PU 12 and the printing operation is actually started and the heater driving signals BE0 to BE3 are input, the driving signal is output to the block of each nozzle to heat and drive the heater 16. I have.

[0019] FIG. 4 is a diagram for explaining the switching between the recording due to the scanning of the head 11, the region and the residual heat region for discharging ink.

As shown in FIG. 4, sensors 41 to 44 are arranged in the scanning path of the recording head 11, and ink is ejected from nozzles of the recording head 11 in an area 45 defined by the sensors 41 and 42. Pre-discharge), and the sensor 4
An area 46 for actually recording is set between the area 3 and the sensor 44. The signal PBVE is a switching signal that is generated based on detection signals from these sensors and switches between preheating of the recording head 11 and heating for performing ink ejection.
The switching signal PBVE has a high level in an area where the heater 16 is heated to eject ink, and has a low level in the areas 47 and 48 where ink is not ejected. That is, the sensor 4
After the detection of the recording head 11 by the sensor 1, it is determined that the area 45 is for preventing nozzle clogging or the like until the sensor 42 detects the recording head 11, and the signal PBV
The areas 47 and 48 where E is at the low level are determined to be the preheating areas, and the period from when the sensor 43 detects the recording head 11 to when the sensor 44 detects it is the actual recording area 46. The PBVE signal is input to the above-described heater drive signal selection unit 32, whereby the heater drive signal selection unit 32 switches the pulse width of the heater drive pulse signal between preheating and recording in a hardware manner. .

In addition, when the recording head 11
When printing is performed using only some of the nozzles, the nozzles of the print head 11 are freely divided into four blocks by the setting of the CPU 12 in order to keep unused nozzles in a preheated state. The driving mode of the heater 16 can be switched to another.

Next, the control method of the heater drive signal data setting units 30 and 31 will be described in detail with reference to FIG.
Although FIG. 5 shows a control circuit for generating pulse data of only heater BE0 of heater drive signals BE0 to BE3 for simplicity of description, other heater drive signals BE1 and BE1
Since the same applies to 2 and 3, description thereof will be omitted.

In FIG. 5, each of 500 to 505 is an 8-bit latch circuit, and each of 510 to 515 is an 8-bit shift register circuit. Prior to the start of recording, pulse data (for example, data for determining the BEO0 signal as shown in FIG. 2) is latched from the CPU 12 to the 8-bit latch circuits 500 to 505 via the data bus. After that, when the recording operation is started and the BE0 signal is input and becomes high level, the pulse pattern data is loaded in parallel into the corresponding 8-bit shift register circuits 510 to 515 from each latch circuit. Thereafter, in synchronization with the clock signal 520, the shift register 515 →
In each shift register, pulse pattern data is sequentially shifted in the order of 514 → 513 → 512 → 511 → 510 and output as a serial signal.

In this embodiment, the period during which the heater drive signal BE0 is at the high level is 16 μsec, which is 3 MHz.
, And is divided into a maximum of 48 clock signals. For this purpose, six 8-bit latch circuits 500 are set so that 48 pulse pattern data can be set.
To 505, six 8-bit shift register circuits 510
To 515. Since the serial input terminal of the last 8-bit shift register 515 is grounded, the serial output of the shift register 510 automatically goes low after the output of the 48 pulse pattern data is completed. By performing the above control, as shown in FIG. 2, while the BE0 signal is at a high level, a BEO0 signal obtained by dividing the heater drive signal BE0 into a plurality of pulse signals can be output.

The clock signal 52 used in this embodiment is
Since the frequency of 0 is 3 MHz, the number of divided pulses is set to a maximum of 48, but the present invention is not limited to this. That is, by setting the frequency of the clock signal 520 higher and increasing the number of latch circuits and shift register circuits, more pulses can be generated. This enables more accurate preheating.

Next, the control method of the heater drive signal selection section 32 will be described in detail with reference to FIG.

The heater drive signal selection section 32 includes selectors 60 to 64, 66 and latch circuits 65, 67. The selector 60 uses the recording-preheat switching signal PBVE based on the signals from the sensors 41 to 44 in FIG.
EA0-3 (for preheating), BEB0-3 (for actual recording)
Is selected and output. That is, the selector 6
1 to 64 indicate the signal B according to the set value of the latch circuit 65.
One of EA0 to 3 and BEB0 to 3 is selected and output. Here, since the nozzles of the recording head 11 are divided into four blocks, the selection is made in block units using four selectors 61 to 64. This is to enable the other nozzles to be preheated when printing is performed using only one nozzle of the print head 11.

Then, the CPU 12 sets which heater drive signal is used for which block in the latch circuit 65 through the data bus, and selects the selector 6 according to the set value.
1 to 64 select the BEA signal or BEB. In the final stage selector 66, of the signals output from the two types of selectors 60 and selectors 61 to 64,
Which is output to the recording head 11 is selected based on the data set in the latch circuit 67 by the CPU 12. That is, a heater driving signal corresponding to the recording-preheating is output from the selector 60, and a heater driving signal corresponding to each nozzle block of the recording head 11 is output from the selectors 61 to 64. The signals are appropriately switched in accordance with the contents and output to the heater 16.

FIG. 7 is a flowchart showing the control of the CPU 12 of the ink jet printer of this embodiment. A control program for executing this processing is stored in the ROM in the CPU 12. The processing shown in the flowchart of FIG.
The recording head 11 is activated at the timing of recording, and at this time, the next data to be recorded is the recording head 1.
1 is set in the serial-parallel converter 15.

First, in step S1, it is determined whether the time is a preheating timing or a timing for actually performing recording. If it is a preheating timing (the signal PBPBVE is at a low level), the process proceeds to step S2, where a head control signal generating unit 13 of the heater drive signal data setting unit 30
The latch circuit (500 to 50) corresponding to each of E3
In 5), the pulse patterns of BEA0 to BEA3 are determined 48
Set bit data. On the other hand, at the time of recording, the process proceeds to step S3, where the latch circuits (500 to 505) corresponding to BE0 to BE3 of the heater drive signal data setting unit 31 of the head control signal generation unit 13
48-bit data that determines the pulse patterns of BEAs 0 to 3 is set.

Thus, the pulse pattern (BEO0 in FIG. 2)
When the pulse signals of (3) to (3) are determined, the process proceeds to step S4, and when recording next, it is determined whether or not the heater drive signal is switched for each block. This is, as described above, when printing is performed using only a part of the nozzles of the recording head, such as in the case of half-end feeding or reduced printing, or when the heater 16 corresponding to an unused nozzle is preheated. used. When switching is not performed for each block, the process proceeds to step S5, and information for the selector 66 to select the output of the selector 60 is set in the latch circuit 67. As a result, the output heater driving signals BEO0 to BEO3 are switched in accordance with the preheating timing or the recording timing (the signal level of the signal PBVE).

On the other hand, if switching is to be performed for each block in step S4, the process proceeds to step S6, where data is set in the latch circuit 67 by the selector 66 so as to select the outputs from the selectors 61 to 64, and the next data is stored in the latch circuit 65. (Selecting one of the selectors 61 to 64) is set. When recording in one block is completed in step S7 in this manner, the process returns to step S6, and the next selector (for example, if the selector 61 is selected before that,
This time, the latch circuit 65 is selected so as to select the selector 62).
Set the data in. Steps S6 to S8 are repeated until printing by the four blocks of nozzles of the print head is completed.

By performing the above-described processing, the change in the ink ejection amount caused by the cooling of the heater due to recording on a large-size sheet or the enlargement continuous shooting, and the cooling of the heater due to the recording of a half-end feed / reduced image. Density unevenness can be prevented. <Second Embodiment> Next, a second embodiment of the present invention will be described.

In the above-described first embodiment, the pulse pattern data is created using a plurality of 8-bit latch circuits and 8-bit shift register circuits. However, the pulse pattern data can be created using a RAM.

FIG. 8 shows a configuration of a pulse pattern data generation circuit when a RAM is used.

A circuit for generating pulse pattern data in the case of using a RAM includes a 256 counter 70, a RAM 71, a selector 73, a gate circuit 72, and latch circuits 74 and 75. When the registration signal 801 is set to a low level before the start of recording, the address bus (A
BUS) is selected, and the gate circuit 72 selects the contents of the data bus (DBUS). In this state, the CPU
Thus, the pulse pattern data is stored in the lower address 0000 to 00FF (hexadecimal) of the RAM 71 through the data bus and the address bus.

At this time, when two or more types of pulse pattern data are required for recording and preheating, only one part of several blocks of the recording head is used for recording, and other blocks are used. If the nozzles for preheating are used,
By making the upper address of the RAM 71 variable by the latch circuit 75, several types of pulse pattern data
M71 can be written.

When the setting of the pulse pattern data in the RAM 71 is completed and the recording operation is started, the register signal 801 is set to the high level, the selector 73 selects the output of the counter 70, and the gate circuit 72 is closed. Next, when the heater drive signal BE0 is input, the counter 70 is counted up. Thus R
By changing the lower bits of the address of the AM 71, the pulse pattern data stored in the RAM 71 before the start of recording is read out from the ROM 71 and output. Here, the counter 70 outputs a maximum of “256” different addresses corresponding to the number of nozzles of each block of the recording head 11.

The switching between recording and preheating is performed according to the above-mentioned FIG.
By changing the set value of the latch circuit 75, the upper address (read address) of the RAM 71 can be changed to change the pulse pattern data (BEO0 to BEO3) to be output.

By performing the above processing, it is possible to prevent the occurrence of density unevenness as in the above-described embodiment.

In the above-described second embodiment, the pulse signal is generated by writing the pulse pattern data in the RAM 71 before the start of recording.
By writing several patterns of pulse pattern data in this ROM in advance using M, it is possible to realize the same as in the case of the RAM 71.

In the above-described embodiment, the nozzles of the print head having a plurality of nozzles are divided into a plurality of blocks, and the control for supplying the heater drive signal to each block is performed. However, as shown in FIG. The heater drive signal (BE
0-BE256) and further dividing the heater drive signal, it is possible to realize more accurate preheating.

As described above, according to this embodiment, when the recording head is not driven during the recording time interval, or when the nozzles to be used are limited even during the recording, the recording head is not used. By applying a heater drive signal that does not cause ink to be ejected to the heater of each nozzle, it is possible to prevent the temperature of the heater from lowering and to properly adjust the amount of ejected ink, thereby preventing the occurrence of density unevenness.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS.

In the third embodiment, while printing is performed by scanning the print head, the temperature gradient of the heater of the print head is changed between a place where the temperature rise of the print head is large and a place where the temperature rise is small according to the discharge condition of the print head. Changes, and fine adjustment of density is no longer possible. This solves the problem that density unevenness occurs in a recorded image.

FIG. 11 is a block diagram showing a schematic configuration of an ink jet printer according to a third embodiment of the present invention. Portions common to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

Reference numeral 10a denotes a head control unit, 11a denotes a recording head, and according to a control signal from the head control unit 10a,
The head unit 24 is driven to eject ink to form an image on recording paper. The CPU 21 controls the entire head controller 10a. Now, when the serial binary image data VD is sent from the external device 19, the head control signal generation unit 22 generates a drive signal necessary for the head unit 24 to eject ink. The image data VD output from the head control signal generation unit 22 is the main scanning AHS
The conversion is performed by the unit 23 so as to prevent the occurrence of density unevenness due to an increase in the amount of ink discharged due to a rise in the temperature of the heater in the nozzle of the head unit 24. That is, the main scanning AHS unit 2
3 is the number of image data corresponding to each nozzle in the main scanning direction at a high level (in this embodiment, ink ejection is performed when the image data is at a high level, and when the image data is at a low level, ink is ejected. When the counted value reaches a predetermined value, control is performed so that the image data of several dots is forcibly set to the low level, and the number of ejections is reduced at the point where the ink ejection amount increases. are doing.

The image data VD controlled as described above,
By supplying the head drive signal to the head unit 24, only the corresponding nozzles of which the image data VD is at the high level are driven in the head unit 24, and the ink is ejected. This ink adheres to the recording paper to form an image.

Next, the details of the main scanning AHS section 23 in which ink ejection control in the main scanning direction is performed will be described with reference to FIG.

The main scanning AHS section 23 is a main scanning AHS
Parts 2001 to 2256 (for 1 to 256 nozzles), 256
A latch circuit 2257 and a 256-bit parallel input-serial output shift register 2258 are provided.
Each of the main scanning AHS units 2001 to 2256 counts the number of high levels of image data corresponding to each nozzle with respect to image data input as serial binary data, and the counted value reaches a predetermined value. Then, the image data is forcibly set to the low level for several dots. After that, the 256 latch circuit latches the image data corresponding to each nozzle, which has been subjected to these processes, into 256 bits. The image data latched by the latch 2257 is sent to the 256 shift register 2258, converted into serial binary data again, and supplied to the head unit 24.

In this embodiment, the head section 24 has 256 heads.
256 main scans A
The HS section is constituted by a 256-bit latch circuit and a 256-bit shift register. However, if the HS section is constituted by a larger number of nozzles, it is necessary to increase the circuit constitution for that.

Next, referring to FIG. 13, the main scanning AHS unit 2
3 will be described in detail.

Reference numeral 51 denotes a main scanning direction image data detecting unit which detects the state of the image data VD corresponding to each nozzle. A counter 52 counts the number of times the image data corresponding to each nozzle becomes high level. A comparison unit 53 compares the count value of the counter 52 with a value set by the CPU 21, and when the count value becomes larger than the set value, sets the comparison output to a low level. One of the comparison output signals is input to the delay unit 54, where the signal is delayed by several dots. The delayed signal resets the counter 52 and clears its count value to “0”. Reference numeral 55 denotes an AND circuit which takes a logical product of the comparison output of the comparison unit 53 and the serial binary image data VD. Accordingly, when the count value of the counter 52 is smaller than the value set by the CPU 21, the input image data VD is directly input to the AND circuit 55.
When the value is larger than the set value, the AND circuit 55 is closed and the image data is forcibly set to the low level and output.

The value set by the CPU 21 at this time is as shown in FIG.
As shown in FIG. 4, it is set to be higher in a portion where the ink discharge amount is small, and to be lower in a portion where the ink discharge amount is large. In this manner, image data of several dots is thinned out according to the ink ejection state. Note that the delay unit 34 has a function of delaying the reset timing of the counter 52 in order to thin out the dots to be thinned out when the number of ink ejection data exceeds a predetermined value.

FIG. 15 is a circuit diagram showing a specific circuit example of the main scanning AHS section 23. Portions common to FIG. 12 are denoted by the same reference numerals.

In FIG. 15, reference numeral 2001 denotes a main scanning AHS circuit for the first nozzle, and reference numeral 2002 denotes a main scanning AHS circuit for the second nozzle. In the latch circuit 401, the enable signal P indicating the effective component of the image data VD
VE is latched in synchronization with a clock (CLK), and a timing signal for detecting image data of the first nozzle is generated. Further, using the timing signal, the latch circuit 450 of the processing circuit 2002 of the second nozzle adds a delay of one clock to generate the detection timing of the image data of the second nozzle. Similarly, the third nozzle,
Fourth nozzle: Image data of the 256th nozzle is detected.

In the AHS circuit 2001, the latch circuit 402 latches the image data VD using the image data detection timing signal of each nozzle. The AND gate 403 detects an edge. Using the edge signal of the image data VD, the counter 404 counts the number of high levels. Further, the CPU 21 sets the maximum value of the count in the latch circuit 405.

The output value of the counter 404 is compared with the set value set by the CPU 21 by the comparator 406. When the output value of the counter 404 is larger than the set value set by the CPU 21, the comparison output of the comparator 406 becomes low level. Is delayed by a high-level edge signal of image data.
Further, the AND gate 411 resets the counter 404 by a signal obtained by taking the logical product of the output signal of the latch circuit 402 and the comparison output latched by the latch circuit 410,
Clear that count. Also, an AND gate 40
7, the logical product of the low-level comparison output and the input image data VD is calculated, and the output image data is forcibly set to the low level.

In this embodiment, since only the latch circuit 410 delays the image data, only one dot of image data can be thinned out. However, when it is desired to thin out several dots, the number of latch circuits (delay amount) is increased. Can be realized.

On the contrary, the counter 4 is set based on the set value of the CPU 21.
When the output value of 04 is smaller, the output signal of the comparator 406 becomes high level, and the input image data VD is output as it is through the AND gate 407. The operation of the main scanning AHS circuit 2001 for the second nozzle is executed in the same manner.

Such control is performed for all the nozzles of the head unit 24, and the latch circuit 2257 latches the image data VD at the fall of the signal PVE. The latched image data VD (256 bits) is converted from parallel to serial by the shift register 2258 and output.

By the above processing, at the point where the temperature of each heater of the nozzle in the head section 24 rises and a change in the ink ejection amount is expected, the image data VD is set to several low levels and is not output. By doing so, it is possible to prevent the temperature of the heater from rising, and to prevent the occurrence of density unevenness due to fluctuations in the ink ejection amount.

In the above-described embodiment, the description has been given of the configuration in which the AHS circuit in the main scanning direction is employed only in the printer. However, a circuit for counting the number of high-level image data is provided, and the counted value is used by using the counted value. By changing the threshold level when binarizing multi-value data on the reader side,
realizable.

FIG. 16 is a block diagram showing a schematic configuration of a copying machine according to a fourth embodiment of the present invention.

The reader unit 601 converts the original image into the CCD 6
03, the read signal is amplified by an amplifier, and then converted into a digital signal by an A / D converter 605. After that, the image processing unit 606 performs various image processing such as shading, input masking, output masking, and sharpness processing. The image data subjected to such various types of image processing is converted into binary data by the binarizing unit 607. In the printer unit 602, similarly to the above-described embodiment, the head control signal generation unit 608 generates a control signal necessary for driving the head 610, and the head 610 discharges ink. The main scanning AHS unit 609 is
The number of times that the image data output from the head control signal generation unit 608 is continuously turned on is counted. According to the count value, the threshold level for binarization is changed as shown in FIG. Thus, the control is performed so that the image data is turned off when the ink is continuously ejected.

Referring to FIG. 18, main scanning AHS section 609
Will be described in detail. 800 is the AHS for the first nozzle
Circuits, 801 are second nozzles, 802 are third nozzles, and so on are provided with circuits corresponding in number to the number of nozzles of the head 610.

The latch circuit 81 latches a PVE signal indicating an effective area of image data in synchronization with a clock signal (CLK), and generates a timing signal 85 for detecting image data of the first nozzle. Using this timing signal,
The image data corresponding to the nozzle is latched by the latch circuit 82. Next, the AND gate 83 calculates the logical product of the latched image data and the timing signal 85.
The output of the AND circuit 83 obtained by taking this logical product becomes high level when the image data becomes high level, and the counter 74 is counted up by this signal. The counter 84 is reset when the output of the latch circuit 82 goes low. Thus, when the image data is continuously turned on, the counter 84 performs counting.

As described above, the occurrence of density unevenness can be prevented in the same manner as described above.

In the above-described embodiment, when the image data continuously goes to the high level, the threshold value for binarization is controlled to be changed. On the other hand, it is also possible to provide a subtraction circuit to perform level conversion when the image data continuously goes to a high level.

Further, the printer is provided with a means for counting the number of high-level image data, but the number of high-level image data after binarization on the reader side is counted and binarized. Level conversion or 2 for previous multi-valued data
This can be realized by changing the threshold value for value conversion.

As described above, according to this embodiment, when ink is continuously ejected in the main scanning direction, several dots of image data are thinned out to prevent a rise in the temperature of the heater and to reduce the amount of ink ejected. Can be properly adjusted.

The present invention particularly provides an excellent effect in an ink jet recording head and a recording apparatus in which a flying liquid droplet is formed by utilizing thermal energy and recording is performed.

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 can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or the liquid path holding the Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubbles are performed immediately and appropriately, so that the ejection of 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. When the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600 which discloses a configuration in which the heat acting surface is arranged in a bent region may be used. In addition, Japanese Patent Laid-Open Publication No. Sho 5 discloses a configuration in which a common slit is used as a discharge section of an electrothermal converter for a plurality of electrothermal converters.
Japanese Patent Application Laid-Open No. 9-123670 discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge portion.
A configuration based on JP-A-9-138461 can also be adopted.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition, the print head is exchangeable with a print head of an interchangeable chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus, or is integrated with the print head itself. Alternatively, a cartridge type recording head provided with an ink tank may be used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like provided as components of the printing apparatus of 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, and printing Performing a preliminary ejection mode for performing another ejection is also effective for performing stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a recording head integrally formed or a combination of a plurality of recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture.

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 below and which softens at room temperature, or which is liquid, In general, in the ink jet system, 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. It is sufficient if the ink is in a liquid state.

In addition, the temperature rise due to thermal energy is positively prevented by using it as energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in a standing state for the purpose of preventing evaporation of the ink. Either ink may be used, or in any case, the ink may be liquefied by application of heat energy according to the recording signal and ejected as a liquid ink, or may already start to solidify when reaching the recording medium. The use of ink having a property of being liquefied for the first time by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or Japanese Patent Application Laid-Open No. 60-71260, in which the porous sheet is opposed to the electrothermal converter while being held in a liquid or solid state in the concave portions or through holes of the porous sheet. It may be. 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 to the above, the recording apparatus according to the present invention may be combined with a reader or the like in addition to the one provided as an image output terminal of an information processing device such as a word processor or a computer as described above. It may take the form of a copier, or a facsimile machine having a transmission / reception function.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the present invention can also be applied to a case where the present invention is achieved by supplying a program for implementing the present invention to a system or an apparatus.

[0084]

As described above, according to the present invention, it is possible to generate many types of drive signals for driving the recording head only by changing the stored pattern data.

[0085]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an ink jet printer according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a state of waveform division (pulse generation) performed by a heater drive signal division unit of the first embodiment.

FIG. 3 is a block diagram illustrating a configuration of a heater drive signal dividing unit according to the first embodiment.

FIG. 4 is a diagram for explaining switching between an ink ejection area and a preheating area in accordance with scanning of the print head according to the embodiment.

FIG. 5 is a block diagram illustrating a circuit configuration of a heater drive signal data setting unit according to the first embodiment.

FIG. 6 is a block diagram illustrating a circuit configuration of a heater drive pulse selection unit according to the first embodiment.

FIG. 7 is a flowchart illustrating control of the CPU of the inkjet printer according to the present embodiment.

FIG. 8 is a block diagram showing a configuration of a pulse pattern data generation circuit when a RAM according to a second embodiment of the present invention is used.

FIG. 9 is a diagram showing an energizing circuit and energizing timing to each nozzle heater of the print head.

FIG. 10 is a diagram showing a conventional heater drive circuit and its timing.

FIG. 11 is a block diagram illustrating a schematic configuration of an ink jet printer according to a third embodiment of the present invention.

FIG. 12 is a block diagram illustrating details of a main scanning AHS unit in FIG. 11;

FIG. 13 is a block diagram showing details of a main scanning AHS corresponding to each nozzle of FIG.

FIG. 14 is a diagram illustrating a relationship between an ink ejection amount and a value set by a CPU according to a third embodiment.

FIG. 15 is a circuit diagram showing a specific circuit example of a main scanning AHS unit in FIG. 11;

FIG. 16 is a block diagram showing a schematic configuration of a copying machine according to a fourth embodiment of the present invention.

FIG. 17 is a diagram showing a relationship between a count value and a threshold value in the fourth embodiment.

FIG. 18 is a block diagram illustrating details of a main scanning AHS unit according to a fourth embodiment.

[Explanation of symbols]

 12, 21 CPU 13, 22 Head control signal generation unit 14 Heater drive signal division unit 16 Heater 23 Main scanning AHS unit 24 Head unit 30, 31 Heater drive signal data set unit 32 Heater drive pulse select unit 51 Main scan direction image data detection Unit 52 counter unit 53 comparison unit

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/045

Claims (5)

(57) [Claims] An image forming apparatus for forming an image using a recording head of an ink jet recording system generates a reference signal for defining a driving timing of the recording head.
Reference signal generating means for storing , pulse signal data storing means, and the pattern data stored in the storing means
An image forming apparatus, comprising: pulse generating means for generating a drive signal for driving each nozzle of the recording head by dividing the reference signal . 2. The storage unit stores first pulse pattern data for ink ejection and second pulse pattern data for preheating without ejecting ink, and stores a driving state of the recording head. The image forming apparatus according to claim 1, further comprising a selection unit that selects one of the first and second pulse pattern data according to the first and second pulse pattern data. 3. A print head comprising a plurality of nozzles.
Drive means for driving the motor in a divided manner, and the plurality of blocks
Means for storing the pattern data for each of
The pulse generating means further includes a pulse generator stored in the storage means.
The reference signal for each block according to the pattern data.
By dividing the signal, the drive signal corresponding to each block
The image forming apparatus according to claim 1, characterized in that occur. 4. Using a driving signal corresponding to the block,
Means to switch between using and not using
The image forming apparatus according to claim 3, wherein: 5. The recording head according to claim 1, wherein the recording head is a recording head that discharges ink using thermal energy, and is an inkjet recording head that includes a thermal energy converter for generating thermal energy to be applied to the ink. The image forming apparatus according to any one of claims 1 to 4, wherein: