JPH10181017A - Recording apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a stable recording operation regardless of the number of recording elements, by making it possible to control a driving power in accordance with a count of recording elements driven at the same time. SOLUTION: A block including a plurality of recording elements (nozzles) which can be driven at the same time is selected by a block signal 1 and a decoder 2. A counter 8 counts black pixels of input image data, thereby obtaining a count of nozzles to be driven to discharge among the plurality of nozzles in the block. A pulse width control circuit determines a width of driving pulses to be impressed to heat-generating elements 3 of the plurality of nozzles in the block on the basis of the number of nozzles to be driven which is obtained by the counter 8. The image data are input to a shift register 6 as well. Recording elements to be driven among the plurality of recording elements in the block are determined and driven with the pulse width determined by the pulse width control circuit, whereby the ink is discharged from each nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a printing apparatus for forming a visible image by driving a plurality of printing elements and a control method thereof.

[0002]

2. Description of the Related Art In a so-called ink jet printer in which a recording liquid (ink) is ejected as droplets from an orifice and adheres to a recording medium (recording paper) to form an image, the quality and speed have been remarkable in recent years. . As a method of increasing the speed of an ink jet printer, there is a method of increasing the number of nozzles as one of the methods generally used conventionally. By increasing the number of nozzles, the printing width for printing one line (the printing width of one printing scan) has been increased to achieve higher speed.

However, when the number of nozzles increases, an excessive voltage drop occurs when all the nozzles are driven at the same time, and if the nozzles are driven as they are, a printing failure due to insufficient voltage is caused. For this reason, a method called block driving is used in which all nozzles are divided into several blocks, and the drive timing is shifted for each block, thereby reducing the number of simultaneously driven elements and reducing the voltage drop.

[0004]

If the number of blocks to be divided is increased to reduce the amount of voltage drop, the voltage drop is certainly reduced. However, the increase in the number of blocks
This causes a problem that the time required to drive all the blocks is increased, the driving frequency is reduced, and the overall throughput is reduced. Therefore, the number of blocks to be divided cannot be increased for speeding up.

On the other hand, to increase the speed, it is only necessary to increase the number of nozzles. However, for the above reason, the number of blocks to be divided cannot be increased. Therefore, the number of nozzles driven simultaneously (the number of nozzles in one block) However, there is a problem that the voltage drop cannot be reduced even by performing the block driving.

Conventionally, in such block driving, all nozzles have been driven with a driving pulse width determined by the characteristics of the heater. For this reason, both the case where all nozzles are driven simultaneously and the case where only one nozzle is driven in the same block are driven with the same pulse width. Obviously, when all the nozzles in the same block are driven, the voltage drop is larger by the number of nozzles than when only one nozzle is driven. Therefore, in preparation for driving all the nozzles in the block, it is necessary to set the drive pulse to a longer pulse width in consideration of the voltage drop. That is, 1
It is possible to provide sufficient power even when all nozzles in a block are driven at the same time, and printing defects such as blurring caused by the lack of an appropriate amount of ink droplets from the heating element due to insufficient power due to insufficient voltage Need to be prevented. However, if only one nozzle in one block is driven under such a setting,
Since a large amount of power is applied to the heater of the nozzle, there is a problem that the life of the heater is shortened, and in the worst case, the heater is disconnected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and enables control of driving power in accordance with the number of printing elements driven simultaneously, thereby enabling stable printing operation regardless of the number of printing elements. It is an object of the present invention to provide a recording apparatus for realizing the above and a control method thereof.

[0008]

The recording apparatus according to the present invention for achieving the above object has the following arrangement. That is, a printing apparatus having a plurality of printing elements that can be driven simultaneously, wherein the counting means counts the number of printing elements to be driven among the plurality of printing elements based on input image data; Determining means for determining a driving mode of the plurality of printing elements based on a result of counting by means,
Recording means for determining a printing element to be driven from the plurality of printing elements based on the image data, and printing the visible image by driving the printing element to be driven in the drive mode determined by the determination means. Prepare.

Preferably, the apparatus further comprises a plurality of blocks comprising a plurality of printing elements which can be driven simultaneously, and further comprises a block driving means for executing image printing by the printing means in units of the blocks. In a printing apparatus that performs block driving, printing control that achieves the above object can be realized.

Preferably, the recording element has an electrothermal converter, and the determining means determines a pulse width of an electric signal applied to the electrothermal converter as the driving mode.

Preferably, the recording means has a conversion unit for serially inputting pixel data and converting the data into a parallel form for each of the number of pixels recordable by the plurality of recording elements. And the counting means counts the number of pixel data indicating the driving of the recording element from the serial pixel data input to the conversion unit. Since the number of printing elements to be driven is counted from input data to a serial-parallel conversion mechanism provided in a general printing apparatus, the present invention can be implemented easily and at low cost.

Preferably, the recording element is a recording element for ink jet recording that performs recording by discharging ink.

Preferably, the recording element is a recording head that discharges ink using thermal energy, and includes a thermal energy converter for generating thermal energy applied to the ink.

Preferably, the recording element causes a state change in the ink by the thermal energy applied by the thermal energy converter, and discharges the ink from the discharge port based on the state change.

According to another aspect of the present invention, there is provided a method of controlling a printing apparatus having a plurality of print elements which can be driven simultaneously, wherein the method is based on input image data. A counting step of counting the number of printing elements to be driven among the plurality of printing elements; a determining step of determining a driving mode of the plurality of printing elements based on a result of the counting in the counting step; and And determining a printing element to be driven from the plurality of printing elements, and driving the printing element to be driven in the drive mode determined in the determining step to print a visible image.

[0016]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

First Embodiment <Schematic Description of Apparatus Main Body> FIG. 1 is a schematic view of an ink jet recording apparatus to which the present invention can be applied. In the figure,
The lead screw 5005 rotates via driving force transmission gears 5011 and 5009 in conjunction with forward / reverse rotation of the drive motor 5013. The carriage HC has a pin (not shown) that engages with the spiral groove 5005 of the lead screw 5004, and reciprocates in the directions of arrows a and b with the rotation of the lead screw 5004. This carriage HC
Is equipped with an ink jet cartridge IJC.

Reference numeral 5002 denotes a paper pressing plate, which presses the paper against the platen 5000 in the moving direction of the carriage. Reference numerals 5007 and 5008 denote home position detecting means for confirming the presence of the lever 5006 of the carriage in this area and switching the rotation direction of the motor 5013. A member 5016 supports a cap member 5022 for capping the front surface of the recording head. Reference numeral 5015 denotes a suction unit that suctions the inside of the cap, and performs suction recovery of the recording head through the opening 5023 in the cap. 5017 is a cleaning blade.
Reference numeral 019 denotes a member which allows the blade to move in the front-rear direction, and these members are supported by the main body support plate 5018. It goes without saying that the blade is not limited to this form and a known cleaning blade can be applied to this example. or,
Reference numeral 5021 denotes a lever for starting suction for suction recovery. The lever 5021 moves with the movement of the cam 5020 that engages with the carriage, and the driving force from the driving motor is controlled by a known transmission means such as clutch switching. .

The capping, cleaning, and suction recovery are configured so that desired processing can be performed at the corresponding positions by the action of the lead screw 5004 when the carriage comes to the area on the home position side. If a desired operation is performed at a timing, any of the examples can be applied.

<Description of Control Structure> Next, a control structure for executing the recording control of the above-described apparatus will be described with reference to a block diagram shown in FIG. In the figure showing a control circuit, 1700 is an interface for inputting a recording signal, 1701 is an MPU, 1702 is a program ROM for storing a control program executed by the MPU 1701,
Reference numeral 1703 denotes a dynamic R for storing various data (such as the recording signal and recording data supplied to the head).
AM (hereinafter, DRAM). A gate array 1704 controls supply of print data to the print head 1708.
1. Data transfer control between the RAMs 1703 is also performed. 171
Reference numeral 0 denotes a carrier motor for transporting the recording head 1708, and reference numeral 1709 denotes a transport motor for transporting the recording paper.
1705, a head driver for driving the head, 170
Reference numerals 6 and 1707 denote motor drivers for driving the transport motor 1709 and the carrier motor 1710, respectively. Reference numeral 1711 denotes a control unit.
ROM 1702, RAM 1703, and gate array 17
04.

The operation of the above control configuration will be described. When a recording signal enters the interface 1700, the gate array 1
The recording signal is converted into recording data for printing between the 704 and the MPU 1701. And the motor driver 1
The printheads 706 and 1707 are driven, and the printhead is driven according to the print data sent to the head driver 1705 to perform printing.

In the above configuration, the head driver 17
In a step 05, the plurality of nozzles of the recording head 1708 are driven by being divided into a plurality of blocks. Hereinafter, configurations and operations of the head driver 1705 and the recording head 1708 in the first embodiment will be described.

FIG. 3 is a block diagram showing a circuit constituted by the head driver 1705 and the recording head 1708 according to the first embodiment. In the present embodiment, the total number of nozzles is 256, which is divided into 16 blocks for driving. The pitch between nozzles is 600 dpi.

Reference numeral 1 denotes a block signal, which is 4 bits (BE
0 to BE4), and designates a block number (0 to 15) of a block to be driven among the 16 blocks. Reference numeral 2 denotes a decoder which sets the logic level of the signal line corresponding to the block number designated by the block signal 1 to H
Set to igh. Reference numeral 3 denotes a heating element, which is provided one for each nozzle.

Reference numeral 6 denotes a shift register, and pixel data 9 input serially via a gate array 1704
To the pixel clock signal 7 synchronized with the output of the pixel data 9
, And sequentially stored in synchronization with, and output as a 16-bit parallel signal. Reference numeral 5 denotes a latch, which latches 16-bit output data from the shift register 6 in response to the input of the latch signal 4. The latch signal 4 is a signal that is output each time one block of pixel data is stored in the shift register 6 (ie, every 16 pixel clocks).

Reference numeral 8 denotes a counter, which counts the number of pixels for which ink is to be ejected (the number of black pixels in this example) from input pixel data 9. The count value of the counter 8 is cleared by the latch signal 4 and counting is again performed from 1. Therefore, immediately before the count value is cleared by the latch signal 4, the counter 8 holds the count value corresponding to the number of black pixels in one block, that is, the number of nozzles to be driven simultaneously. Therefore, the latch 1 that holds the count value of the counter 8 by the latch signal 4
0 holds the number of black pixels in one block to be recorded next.

A pulse width control circuit 12 outputs a heater drive pulse 13 in response to the input of a heat signal 11.
Here, the pulse width of the heater drive pulse 13 is
Control is performed based on the counter value held at 0, that is, the number of nozzles to be driven simultaneously. FIG. 4 is a diagram showing the relationship between the counter value held in the latch 10 and the pulse width of the heater drive pulse. As shown in the figure, the pulse width control circuit 12 increases the pulse width of the heater drive pulse output as the counter value increases, that is, as the number of simultaneously driven nozzles increases.

The block signal 1, the latch signal 4, the pixel clock signal 7, the pixel data 9, and the heat signal 11 are signals input from the control unit 1711 to the head driver 1705. Further, the AND circuit 14 is provided for each of the 256 heating elements 3, and obtains the logical product of the heater driving signal and the block selection signal to enable the block driving of the heating elements 3. The AND circuit 15 includes a latch 5
And a logical AND of each of the one block of pixel data to be output and the heater drive pulse 13 to generate a heater drive signal to be supplied to the AND circuit 14.

According to the above configuration, the decoder 2, the latch 5, and the AND circuits 14 and 15 realize block driving in which the 256 heating elements 3 are divided into 16 times. Here, one block (1
When the data of 6 pixels) is held, the number of black pixels (the number of nozzles to be driven) in the block is held in the latch 10. The pulse width control circuit 12 outputs the heater drive pulse 1 having a pulse width corresponding to the numerical value held in the latch 10.
3 is output and provided to the AND circuit 15.

As a result, the pulse width of the heater driving pulse 13 becomes a pulse width corresponding to the number of nozzles driven by the pixel data held in the latch 5, and the heating element 3 can be driven appropriately. The pulse width control circuit 12 has a table as shown in FIG. 4 for converting the count value to the pulse width, and outputs a pulse width determined by the value of the input counter. Each time the heat signal 11 is input in this way, the heater drive pulse signal 13 having a pulse width suitable for the number of recording pixels of the pixel data held in the latch 5 is output to the pulse width control circuit 1.
2 and the heating element 3 is appropriately driven. still,
The pulse width control circuit 12 controls the pulse width with the characteristics as shown in FIG. 5. For example, the pulse width control circuit 12 controls a clock signal faster than the pixel clock by using a numerical value (pulse width ), And a drive pulse is output until the count up.

FIG. 5 is a diagram showing the generation timing of the pixel clock signal 7, the latch signal 4, the block signal 1, the heat signal 11, and the heater drive pulse 13 in the first embodiment. As is clear from the above description and FIG.
A latch signal is input once every 16 pixel clocks. The block signal 1 is set in synchronization with the latch signal 4 to select a block, and the heater drive pulse 13 is generated and output based on the heat signal 11 and the number of black pixels in the block. . That is, the pulse widths t1 and t2 of the heater drive pulse 13 are determined as shown in FIG. 4 based on the number of black pixels in the corresponding block.

Now, the problems in the conventional heater driving will be summarized as follows. That is, when the number of the heating elements 3 to be driven at one time is 16, the current value is 16 times larger than that when only one heating element 3 is driven, and the voltage drop is also 16 times. Therefore, if 16 heating elements 3 are driven with the pulse width when only one heating element 3 is ejected without directly considering the voltage drop, the voltage becomes insufficient,
Ink cannot be ejected from the 16 nozzles, and the printing result is blurred. On the other hand, if the width of the drive pulse for driving the heating element 3 is set to be long in anticipation of the voltage drop when the 16 heating elements are driven, even if one heating element is driven, 16 Are driven with a pulse width that can drive the heating elements. For this reason,
Excessive thermal stress is applied to the heating element, and the life of the heating element is significantly impaired.

On the other hand, according to the above embodiment, the drive pulse width is appropriately set by the pulse width control circuit 12 according to the number of nozzles to be driven. For example, 1
The pulse width is 1 to be greater than the pulse width when all six heating elements are driven.
The pulse width at the time of driving the heating element is set shorter and driven (see FIG. 4). As described above, in the present embodiment, the number of driving lines is detected by counting the data of the black pixels in the shift register 6, and the pulse width is controlled each time according to the number of driving lines. For this reason, excessive heat stress is prevented from being applied to the heating element, and a situation where the life of the heating element is shortened is prevented.

[Second Embodiment] Next, a second embodiment will be described. FIG. 6 is a block diagram illustrating a configuration of a head driver and a print head of a printing apparatus according to the second embodiment. Note that the appearance and schematic control configuration of the printing apparatus according to the second embodiment are the same as those of the first embodiment (FIGS. 1 and 2).

In the second embodiment, the total number of nozzles is 64. The shift register 106 has 64 bits for all nozzles. Pixel data 109 is serially input to the shift register 106 in synchronization with the pixel clock 107,
When the pixel data for 64 pixels is completed, the latch 105
Latched by Note that the latch timing is determined by the latch signal 104. In the second embodiment, the number of time-division driving is 2, and the odd-numbered SEG nozzle 32
And 32 even numbered SEG nozzles, each of which is simultaneously ejected.

The pixel data 109 is supplied to a data separation circuit 123
Odd SE of SEG1, SEG3,... SEG63
G and even SEG of SEG2, SEG4,.
Are separated into two. Then, the counters 108a and 108b count the number of the actually driven heating elements 103 in each of the separated 32 bits. Note that the counter 108a is for an even SEG,
b is for odd SEG.

Pulse width control circuit 112a for even SEG
And the odd-numbered SEG pulse width control circuit 112b
This circuit outputs a heater drive pulse 113 having a pulse width as shown in FIG.

The latch signal 104 and the heat signal 111 are synchronized, and the heat signal 111 is
2a and 2b, the 64-bit data latched by the latches 110a and 110b outputs the output value corresponding to the count value in each pulse width control circuit 112 to an odd SE.
G, and is supplied to the even SEG to drive each heating element 103. In this way, the width of the heater drive pulse is controlled by the pulse width control circuits 112a and 112b according to the number of drives. By doing so, as shown in the first embodiment, it is possible to prevent an excessive thermal stress from being applied to the heater, and it is also possible to prevent blurring when a large number of nozzles are driven.

As described above, according to each of the above embodiments, the counter circuit is added to the data serially sent into the shift register, and the number of driving elements of the heating element is counted. Cost can be suppressed. Further, since the heating element does not receive more energy than necessary, the life of the heater is prolonged.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copying machine, a facsimile). Device).

In the above embodiment, the pulse width control based on the number of driving nozzles is performed by hardware such as a counter and a latch circuit. However, it goes without saying that part or all of the pulse width control described in the above embodiment may be realized by software. In this case, a storage medium storing a program code of software for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus stores the program stored in the storage medium. By reading and executing the code, the function of the above embodiment is achieved.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0046]

As described above, according to the above embodiment, it is possible to control the driving power in accordance with the number of printing elements driven simultaneously, and to achieve a stable printing operation regardless of the number of printing elements. Can be realized.

[0047]

[Brief description of the drawings]

FIG. 1 is a schematic view of an ink jet recording apparatus to which the present invention can be applied.

FIG. 2 is a block diagram illustrating a schematic control configuration in the inkjet recording apparatus of FIG. 1;

FIG. 3 is a block diagram illustrating a circuit including a head driver and a print head according to the first embodiment.

FIG. 4 illustrates a pulse width control circuit according to the first embodiment.
FIG. 3 is a diagram illustrating a relationship between a counter value and a pulse width of a heater drive pulse.

FIG. 5 is a diagram illustrating generation timings of a pixel clock signal, a latch signal, a block signal, a heat signal, and a heater drive pulse according to the first embodiment.

FIG. 6 is a block diagram illustrating a detailed configuration of a head driver and a print head of a printing apparatus according to a second embodiment.

FIG. 7 illustrates a pulse width control circuit according to a second embodiment.
FIG. 3 is a diagram illustrating a relationship between a counter value and a pulse width of a heater drive pulse.

[Explanation of symbols]

 1 Block signal 2 Decoder 3, 103 Heating element 4, 104 Latch signal 5, 10, 105, 110a, 110b Latch 6, 106 Shift register 7, 107 Pixel clock signal 8, 108a, 108b Counter 9, 109 Pixel data 11, 111 Heat signal 12, 112a, 112b Pulse width control circuit 13, 113 Heater drive pulse

Claims (11)

[Claims] 1. A printing apparatus having a plurality of printing elements that can be driven simultaneously, comprising: a counting unit that counts the number of printing elements to be driven among the plurality of printing elements based on input image data; Determining means for determining a driving mode of the plurality of printing elements based on a result of counting by the counting means; determining a printing element to be driven by the plurality of printing elements based on the image data; Recording means for driving a recording element to be driven in the drive mode determined by the determination means to record a visible image. 2. The image processing apparatus according to claim 1, further comprising a plurality of blocks each including a plurality of printing elements that can be driven simultaneously, and further comprising a block driving unit that executes image recording by the recording unit in units of the blocks. Item 2. The recording device according to Item 1. 3. The recording element according to claim 1, wherein the recording element has an electrothermal converter, and the determining unit determines a pulse width of an electric signal applied to the electrothermal converter as the driving mode. The recording device according to any one of the preceding claims. 4. The recording means has a conversion unit for serially inputting pixel data and converting the pixel data into a parallel form for each number of pixels recordable by the plurality of recording elements. A printing element to be driven is determined based on the pixel data, and the counting means counts the number of pixel data indicating drive of the printing element from serial pixel data input to the conversion unit. 2. The recording device according to 1. 5. The recording apparatus according to claim 1, wherein the recording element is a recording element for inkjet recording that performs recording by discharging ink. 6. The recording element according to claim 1, wherein the recording element is a recording head that discharges ink using thermal energy, and includes a thermal energy converter for generating thermal energy to be applied to the ink. Item 6. The recording device according to Item 5. 7. The printing device according to claim 1, wherein the recording element causes a state change in the ink by thermal energy applied by the thermal energy converter, and discharges the ink from an ejection port based on the state change. The recording device according to claim 6, wherein 8. A method for controlling a printing apparatus having a plurality of printing elements that can be driven simultaneously, wherein the number of printing elements to be driven among the plurality of printing elements is counted based on input image data. A counting step, a determining step of determining a driving mode of the plurality of printing elements based on a result of the counting in the counting step, and determining a printing element to be driven from the plurality of printing elements based on the image data; A recording step of driving the recording element to be driven in the driving mode determined in the determining step to record a visible image. 9. The printing of a visible image in the printing step is performed by dividing a plurality of printing elements included in the printing apparatus into blocks each including a plurality of printing elements that can be driven simultaneously, and using the blocks as a unit. The method according to claim 8, wherein the control is performed. 10. The recording element having an electrothermal converter, wherein the determining step determines a pulse width of an electric signal applied to the electrothermal converter as the driving mode. 9. The method for controlling a recording device according to item 8. 11. The recording step includes serially inputting pixel data, converting the pixel data into a parallel form for each number of pixels recordable by the plurality of recording elements, and determining a recording element to be driven based on the conversion result. 9. The method according to claim 8, wherein the counting step counts the number of pixel data indicating the driving of the printing element from the pixel data serially input to the printing step. .