JP2812461B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a multi-function printer capable of obtaining high-quality image output, for example.
Full-color inkjet printer using a head
While moving the recording head relative to the recording material.
And an image forming apparatus for forming an image. [Prior Art] Conventionally, a recording head equipped with a multi-nozzle is used as a recording material.
Form full-color image while moving relative to
In such a device, the dot position accuracy is
Determined by the resolution of the encoder
The resolution was about one pulse at several dots. [Problems to be Solved by the Invention] However, especially in the case of a full-color image, the resolution is low.
Color dots that must overlap each other in order to
This is the quality of the image, especially the color
It was a cause to lower the position. An object of the present invention is to eliminate the disadvantages of the conventional example as described above,
Without improving the resolution of the encoder of the main scanning motor
Gives accurate dot ejection timing to produce high-quality images
An object of the present invention is to provide an obtained image forming apparatus. [Means for Solving the Problems] The present invention has a plurality of recording heads, and forms an image on a recording material.
In the image forming apparatus for forming an image, the plurality of recording
Scanning of the recording medium in the main scanning direction with respect to the recording material
Means and data of an image to be recorded by the plurality of recording heads
Means for storing the information, and a timing for driving the head
Timing signal generation that generates a timing signal according to the
Generating means, and dots at intervals according to the timing signal.
So that the storage according to the timing signal
Means for reading the data from the
Head driving means, and a frequency higher than the timing signal.
Delay signal generating means for generating a number of signals;
According to the amount of deviation of the recording head in the main scanning direction,
From the storage means for deviations greater than
Data read is delayed based on the timing signal
Delay for a shift smaller than the dot interval.
The recording head based on the signal generated by the extension signal generating means.
Head drive timing to delay drive timing
Correction means. [Operation] According to the present invention, the plurality of recording heads are shifted in the main scanning direction.
On the other hand, for deviations larger than the dot spacing,
Reading data from the storage means
Delay based on the number
Based on a signal with a higher frequency than the timing signal
Delaying the print head drive timing
Then, the deviation is corrected. [Embodiment] (Outline of Apparatus Mechanism) FIG. 1 shows a digital color image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of the apparatus 100, and FIG.
FIG. 1 and 2, the configuration of the present invention will be described.
explain. The platen glass 1 holds the original 20 on a flat surface
I have. The original surface of the original 20 faces the surface of the platen glass 1
The document 20 is pressed by the pressure plate 1a. Read manuscript 20
The read head (hereinafter referred to as the reader) 3 is red,
Green, blue (hereinafter R, G, B) three rows each for three colors
A read sensor consisting of a CCD array of read elements
(Hereinafter referred to as CCD unit) 17 and exposure lamp 19
Driven by being connected to main scanning motor 6a by main scanning wire 8a
Is done. The sub-scanning table 5a supports one end of the main scanning wire 8a,
The sub-scanning motor 10a is connected to the sub-scanning motor 9a by the sub-scanning wire 10a.
Be moved. The recording paper 21 is placed on the recording table 2 and a recording head (hereinafter referred to as
The copy image is recorded by the printer 4. Printer 4
Yellow, magenta, cyan, black (hereinafter Y, M, C,
B _K ) A multi-inkjet head for four colors (in the present invention,
From the following BJ head)
A recording element (hereinafter referred to as a BJ head unit) 18
Driven by being coupled to main scanning motor 6b by scanning wire 8b
It is. The sub-scanning table 5b supports one end of the main scanning wire 8b,
Driven by being connected to sub-scanning motor 9b by scanning wire 10b
Is done. When trying to obtain a copied image in the above configuration,
3 is connected to the main scanning motor 6a via the main scanning wire 8a.
And is reciprocated in the main scanning direction. At this time,
The lamp 19 lights up and the original 20 is read from below by the read sensor 17.
And output the image information as an electric signal. This electricity
Based on the signal, the printer 4 runs through the main scanning wire 8b
The recording paper 21 is driven by the inspection motor 6b and reciprocates.
Print on At this time, the main components of the read head 3 and the recording head 4
The scanning directions are set to be opposite to each other in this embodiment.
ing. One copy operation in the main scanning direction is completed, and the exposure
After turning off the lamp 19, the leader 3 and the printer 4 are running
The next main scan is performed in the direction perpendicular to the scan, that is, in the sub-scan direction.
Move to the position. At this time, the reader 3 is the main scanning wire
The sub-scanning wire 10a together with the sub-scanning table 5a supporting 8a
Driven by the sub-scanning motor 9a to a predetermined position.
Move with and stop. The printer 4 has a main scanning wire 8b.
Via the sub-scanning wire 10b together with the supporting sub-scanning table 5b
Driven by the sub-scanning motor 9b to move to a predetermined position
And stop. FIG. 3 is a block diagram of the control circuit of the above-described embodiment, and FIG.
FIG. 4 is a timing chart of the entire sequence,
FIG. 5 shows a flowchart of the program. Fig. 4,
First, an outline of the operation of the apparatus will be described with reference to FIGS.
Now. Note that on the timing chart and flowchart
Are the same. Sequence controller 23, Image controller 24
Both have a microcomputer unit in the center,
The sequence control of each device and the timing of image data formation
Is programmed and both microcomputers are
The computer communicates data via line 39. Power supply
The sequence from the start is explained.
According to the flowchart of FIG.
In step 1, the copying machine is initialized, and in step 2,
Home position of printer and printer
Go home. Then, in Step 3, the inkjet head
Recovery operation is performed. The head recovery operation takes a long time
Enhance the adhesion of ink at the tip of the inkjet nozzle after a pause
To remove the ink after the ink ejection operation.
To remove the liquid pool near the tip of the spill, use a porous member
A good water-absorbing material such as to the tip of the head, or
This is an operation performed by sliding in contact. In sequence
Rotate the linter main scanning motor 6b in the reverse direction to
It stops at the detection output of the position sensor 22. next
Driving device such as a solenoid that presses a porous member against the head
Turn on the mechanism and press it against the nozzle tip for a predetermined time. After finishing
Rotate the linter main scanning motor 7b in the forward direction and print
Stop at detection output of main scanning home position sensor 12
Let it. Next, proceed to step 4 while the apparatus is suspended until the copying operation
To prevent the viscosity of the ink at the nozzle tip from changing.
An operation of capping the node is performed. This is the printer
For example, a solenoid that caps at the home position
Achieved by turning on the drive mechanism. Then run in step 5
Waiting for operator input from the inspection unit 25,
Decrypt the data, set the copy mode, and
Judge whether the command is a copy start command or not.
If not, return to step 5 and start copying
In the case of, the process proceeds to step 7, where the copying operation is started.
Release the head cap drive. Then step 8
To perform idle discharge processing of the head before the copy operation.
U. The idle discharge process is performed to perform stable printing
Ink remaining in the inkjet nozzle during processing
At the start of ejection for image formation caused by viscosity changes
Copy pause time and temperature inside the machine to prevent ejection unevenness
(Temperature sensor not shown), Copy duration program
The ink in the inkjet nozzle is
This is an operation of discharging and eliminating. Next, proceed to step 9 and
After turning on the exposure lamp 19, perform shading correction processing.
U. Shading correction is performed on white data before scanning the original.
Read the reference standard white plate and adjust the optical lens
Data for correcting differences in the sensitivity of each bit of the CCD sensor.
Sampling the data. Next, go to step 10 to determine whether the copy has just started
Immediately after starting, that is, before starting the first main scan
If so, proceed to step 11;
Proceed to step 12. In step 11, anticipate after a long pause of the device
Then, a head recovery operation is performed. The recovery action in this case is
The operation is the same as that described in Step 3. Then step 12
Then, the main scanning is started. (Note that for each signal,
(Refer to Fig. 4.)
Speed data and data according to the magnification are input to the driver circuit 26a.
Sends a rotation start signal in the leader forward direction
Turn ON the motor 6a. Next, the reader and pre-
After taking the synchronization delay time of the
Printer forward to printer motor driver circuit 26b
Direction rotation start signal and the printer main scanning motor 6b
Turn ON. Reader and printer main scanning motors 6a and 6b
The number of rotations is 7 for each rotary encoder
Pulses (FG signals) from a and 7b (hereinafter encoder)
Comparison with the rotation speed reference pulse by the data driver circuits 26a and 26b
Is locked to a predetermined speed by PLL control.
The rotation speed is constant. In addition, each encoder
Lus generates video data sync signal via lines 42 and 43
The circuit 28 is sent to the head data synchronization signal generation circuit 37. (Reader Side Process) Next, the process proceeds to step 13, where a copying operation is performed. The following
This will be described with reference to FIGS. 7 (E) and 7 (B). video
In the data synchronization signal generation circuit 28, the reader main scanning motor
-6a, synchronized with the encoder pulse, in the main scanning direction of the reader
Video data with resolution l in the sub-scanning direction.
Video line enable signal indicating the effective range of the
VLE) is made as shown in Fig. 6 (A) and Fig. 6 (B).
It is. Still further, the video data synchronization signal generation circuit 28
Video data start signal input from CCD drive circuit 29
Signal indicates the effective data width of all CCD pixels, and the encoder
Video data enable signal (VD
E) is output. Also generates video data synchronization signal at the same time
The circuit 28 includes a CCD driving circuit 29 and three rows of the CCD unit 17.
Blue (B), green (G), red (R) three colors respectively
CCD start signal to command image reading to CCD corresponding to
Signal synchronized with encoder pulse and supplied via line 57
I do. Analogue of three colors read in CCD unit 17
Video signals have the same sensor sensitivity for each color
Digital with 8bit depth after gain adjustment
Output via line 44 as value. That is, B, G,
R3 color digital video data (hereinafter video data)
It is input to the reader synchronization circuit 30. At this time, all CCD pixels
The video data start signal indicating the effective data range of
Input from the D drive circuit 29 to the video data synchronization signal generation circuit 28
Is forced. Here, the video synchronization signal generation circuit 58 will be described.
To the video sync signal generation circuit 58.
The signal PHREGP from the condition sensor 15 is on line 45, VLE
Signal copied from line 46 and image controller 24
The value of the VLE signal counted according to the magnification is indicated by line 47
Each entered through the
After the CCD unit passes the leader registration position,
Time delay until the document reaches the leading edge, that is, the reading start position
This is performed by counting the VLE signal. Also
The video synchronizing signal generation circuit 58 is a main scanning method according to the copy size.
Video enable signal (hereinafter VE
Signal) to the reader synchronization circuit 30 via the line 48.
You. In the reader synchronization circuit 30, as shown in FIG.
For reading the same part of the CCD original corresponding to each color G, R
Then, a positioning operation in the main scanning direction is performed. That is, B, G, R
Assuming that the interval between the CCDs corresponding to each color is L1, the document position S1
Is input to the CCD corresponding to each color because the speed of main scanning is
V, each has a time lag of L1 / V. Obedience
The image of the S1 point of the CCD of R that is input last in time
Video data from B and G CCDs until input
Are stored in the buffer memory in the reader synchronization circuit 30, respectively.
The image is temporarily stored and the S1 point image is B, G, and R color video data.
Then, it is output from the reader synchronization circuit 30. Also a reader
-The synchronization circuit 30 receives the VE signal,
B, G, R color video data
Output video data area (VDA) signal
I do. The vertical direction in FIG. 6 (C) is the time axis,
Not in the search direction. Video data that has been color-matched by the reader synchronization circuit 30
The data is then input to the scaling buffer memory 31 and scaled.
You. (Scaling Process) Here, the scaling process will be described with reference to FIG. main
In the scaling process in the scanning direction, the scanning speed V1 of the printer is kept constant.
By changing the scanning speed of the reader to V1 / n (n
Is the magnification). This is the ink that forms the image forming means of the printer.
The upper limit of the jet head drive frequency is the CCD drive frequency
Lower than the upper limit of the number. Therefore, when copying at the same size,
Maximum inkjet drive frequency at 1x for faster speed
It uses numbers. At this time, pass line 49 in FIG.
And the scaling mode signal from the image controller 24 is
Is sent to the data synchronization signal generation circuit 28, and the VLE signal is
The mode of the leader is set so that the same frequency is
The frequency division ratio of the encoder pulse is set (Fig. 7
(A), FIG. 7 (B)). That is, as shown in FIG.
Dapulse φ _M Is φ for 1 × _M1 Divide by 1/6 as shown in
Then, when reducing to 1/2 times, φ _M1 Divide by 1/12 as shown in / 2
And when expanding twice, φ _M2 Divide into 1/3 as shown in
If it is three times, it is divided by half. Motor encoder pulse φ
_M Is doubled when the frequency is 1/2 times the same size, 2 times
When it is double, it becomes 1/2, and when it is 3 times, it becomes 1/3, so φ _M1 , φ _M2 ,
φ _M3 , φ _M The half frequency is actually the same frequency. FIG. 7B shows the reading position on the document,
Indicates the CCD movement distance at time t (= VLE section)
ing. When reducing to 1/2, double the moving distance for 1: 1
There is a separation, and when expanding 2 times, move 1/2 of the same size
You. Also, the scaling process in the sub-scanning direction is performed by the video clock φ
R, which is sent from the reader synchronization circuit 30 in synchronization with (CLK8),
Each pixel of the G and B video signals is stored in the scaling buffer memory 31.
Controls the address advance of the variable magnification buffer memory 31 when storing
(FIG. 7 (C)). This is imaged via line 50 to the memory control circuit 32
A scaling mode signal is input from the controller 24 and
Clock of the address counter when writing to
By increasing or decreasing the number of
Achieved (FIG. 7 (D)). This allows the scaling buffer
Write mode of the double buffer memories 59a and 59b in the memory 31
Memory 59b in memory (W) has the same pixel
Is written to n addresses, and when 1 / n reduction, n
That one of the pixels is written to one address
When the mode is changed to the read mode, the video clock
When the address is incremented by φ-CLK8, pixel data is complemented.
A thinning will be achieved. In this embodiment
Indicates that the motor speed on the reading side has been changed, but the motor on the recording side has changed.
The speed may be changed. Here, referring to FIG.
Another function will be described. Variable buffer memory
The double buffer memories 59a and 59b in 31
At the start, the clock for address increment is switched
However, this is because the VLE signal is
Since it is made from encoder pulses, motor rotation
Occurs, the position information between each main scan in the entire sub-scan area and
However, the frequency is uneven. VLE signal
And keep the CCD accumulation time unchanged
In order to perform the
Of the minimum value of the cycle of
φ-CLK4 is more than twice the frequency of video clock φ-CLK8
1x copy of double buffer memory 59a, b
The address clock during writing is the shift clock of CCD17.
Use φ-CLK4 and read, read, printer
The video clock φ-
CLK8 is used. As described above, the scaling buffer memory 31 and the memory control circuit 3
2 is the interpolation and interpolation of pixel data in the sub-scanning direction
In addition to the pulling operation, make the CCD accumulation time constant, and
Synchronized with the encoder pulse of the reader main scanning motor 6a
Pixel reading operation. (Image signal processing) In the scaling buffer memory 31, B,
The G and R color video data is then sent to the image processing circuit 33.
Then, the processing shown in the block of FIG. 8-a is performed. Ma
Video data of R, G, B colors
In the standard white plate data read in step 9
Positive can be added. In this embodiment, the CCD exposure amount E and light
Image light is read in a range where output voltage V maintains linearity.
Therefore, the following equation is added. However, VsG ;: output after shading correction V; output from CCD Vmax; output when reading white board Vsmax; setting output The video data to which the shading correction has been applied is as follows:
From the light intensity value input to the logarithmic conversion unit 61 for the ink density value
At the same time as the conversion, the complementary colors are converted, and the B, G, and R video
Are converted to y, m, and c density data, respectively.
You. The conversion formula is D for the ink density and E for the standard white plate reflected light amount.
Assuming that p and the amount of image light are E, it is expressed by the following equation. The three-color density data after the conversion is then extracted by the black extraction / UCR unit 62 and
And input to the edge extraction unit 63. Black extraction is for Y, M and C colors
By calculating the amount of black ink applied from the density data
is there. This is because black (hereinafter B) _K )
When trying to express, it is difficult to express perfect black,
The amount of ink applied increases, causing "bleeding" on copy paper
This is to prevent excessive expansion of paper and paper. UCR (under color removal
Last) is for each color of Y, M, C when black ink is used by black extraction
This is a method to reduce the amount of ink in relation to the amount of black ink.
In the embodiment, the following calculation is performed. B _K = ｛Min (Y, M, C) -a ₁ ｝ A _Two Yout = (Y-a _Three B _K A) _Four Mout = (M−a _Five B _K A) ₆ Cour = (Ca ₇ B _K A) ₈ Where a ₁ ~ A ₈ Is an arbitrary coefficient. Edge extraction is to extract green and lines in the image.
The extracted edge amount has a specific relationship with the original image data.
Try to strengthen the outline of the image by adding
It is. In the present embodiment, 5 in the main scanning and sub-scanning directions.
Edge extraction using a × 5 convolution mask
Was performed. The extracted edge amount excludes noise component contamination.
Choose an arbitrary threshold to remove
Lower level detection values should not be added to the image data.
Was. In the edge extraction section, the status of video enable
Where Laplacian mask can extract edges
Data valid signal indicating the area (hereinafter VDV signal)
Is output. This means a 5x5 Laplacian mask
If used, the third signal after the VE signal becomes active
Indicates that the VDV signal is output from the subsequent VLE signal.
You. The density data Y, M, and C after UCR are input to the masking section 64.
Is masked. Masking does not require ink
To correct turbidity during ink overlay due to
The following operation is performed in the matrix operation process. Where a ₁₁ ~ A ₃₃ Is an arbitrary coefficient. Next, the masked Y, M, and C3 colors and B _K Concentration data
Is input to the output gradation correction circuit 65, and is output by the subsequent binarization circuit.
The gradation in pseudo halftone expression by the dither method
You can make corrections for The correction formula is shown below.
It is. Yout = ｛a ₅₁ (Y-a ₅₂ ｝ A ₅₃ Mout = ｛a ₅₄ (M-a ₅₅ ｝ A ₅₆ Cout = ｛a ₅₇ (Ca ₅₈ ｝ A ₅₉ Where a ₅₁ ~ A ₅₉ Is an arbitrary coefficient. Next, the output gradation corrected density data, Y, M, C, B _K And
And the edge amount ED are input to the binarization unit 66 and binarized.
You. The binarization process uses an organized dither method in this embodiment.
After binarizing the image data uniformly, the pixel of interest
On the other hand, correction based on the edge data ED is performed. In other words,
The correction based on the truth table shown in Fig.
The image that was blurred at the edge by the method strengthens the outline
It becomes a simulated halftone expression image. The image is processed by the image processing circuit 33 as described above,
Y, M, C, B for heads _K Four color binary signals (hereinafter referred to as density data)
The video signal converted to
The period memory 34 is inputted through a line 51. (Printer-side processing) Here, the operation of the reader / printer synchronous memory 34 will be described.
Before describing this, the head data synchronization signal generation circuit 37 will be described.
Now. In the head data synchronization signal generation circuit 37, the sixth-d,
As shown in Fig. 6-e, the printer main scanning motor 6b
Synchronized with the coder pulse, position information in the main scanning direction of the reader
And the effective range of the head data of resolution l in the sub-scanning direction.
Nozzle line enable signal (hereinafter NLE)
Made. NLE signal is a head data synchronization signal generation circuit
37 to the head synchronization signal generation circuit 38 via line 52
Can be The printer synchronizing circuit 38
Signal from the position sensor 16
The BJ head unit 18 passes the registration position
After the delay, the time delay until the copy position is reached
Performed by counting, according to the copy paper size
A signal indicating the copy width in the main scanning direction, that is, the noise for each color
Control signal (hereinafter NE) through line 54
Output to the printer / printer synchronous memory 34. The reader / printer synchronous memory 34 is
Buffer the speed difference between the motor 6a and the printer main scanning motor 6b.
And the density input from the reader unit (image processing circuit 33).
Synchronize data to printer speed, i.e.
The signal is output from line 55 in synchronization with the signal. In addition, leader
The linter synchronization memory 34 receives the VDV signal from the image processing circuit 33.
Is input, only the valid part of the video data is VLE
Write sequentially in synchronization with the signal, head synchronization signal generation circuit
When the NE signal is input from 38, that is, when the ink
When there is a jet head, the written density data
Read sequentially as head data in synchronization with NLE signal
You. Each read from the reader / printer synchronization memory 34
The recording head data is sent to the printer synchronous circuit through line 55.
Output to the road 35. In the printer synchronizing circuit 35, the color separation of the image of one point of the original S '
4 colors Y, M, C, B _K Head data of 4 colors at the same time line 55
, But the head data of those four colors is
Only the distance in the main scanning direction between the heads for each color
Perform position shift processing. That is, as shown in FIG. 6 (F), Y, M, C, B _K For each color
Set the inkjet head spacing to L _Two Then x
Y, M, C, B _K Images with ink of each color are inkjet heads
In order to be shot at the same point in the main scanning direction of
Scanning speed is V and L is applied to each color head. _Two / V time delay
Just hit it. In other words, the image is
MCB up to Y head position where image is hit _K Color f
Data in the buffer memory in the printer synchronization circuit 35.
After temporary storage, output sequentially from the printer synchronization circuit 35,
This is achieved by inputting to the linter head drive circuit 36.
You. In FIG. 6 (F), the vertical direction is the time axis,
Not in the sub-scanning direction. The NE signal is input to the printer synchronization circuit 35,
Since the NE signal is a signal indicating the copy area of the head of Y,
From this NE signal, each color pair indicating the ejection section of each color head
Corresponding head drive enable signal (hereinafter HDE signal)
And the printer head drive circuit 36 through line 56
Enter The NE signal,
Printer head from NLE signal HDE signal and clock φ
The drive signal of the inkjet head in unit 18
Print head data for each color to printer head unit 18
Output. The original image is read from the reader 3 by the above flow.
And is imaged by the printer 4. And the image
Page controller 24 is generated from reader 3 and printer 4
When the end of the VE signal and NE signal
The end of one-line copying of scanning is determined (step 14).
Go to step 15. (Post-processing) In step 15, the sequence controller 23 first exposes
Turn off the lamp 19 and set the respective modes of the reader and printer.
Motor OFF signal input to motor driver circuits 26a and 26b
And then the reverse direction speed data and rotation start signal
And turn on the respective motors 6a and 6b to start reverse
At the main scanning home positions 11 and 12.
Step. At the same time, step 16
Motor 9a (hereinafter referred to as “leader sub-scanning motor”)
A predetermined number of pulses according to the magnification is
And the feed for one sub-scan of the reader is performed. Ma
Similarly, the stepping motor 9b (hereinafter referred to as
(Printer sub-scan motor) also feeds one sub-scan.
Now. Next, proceed to step 17 to set the sub-scanning counter
In step 18, scan in width in the sub-scanning direction for the copy width.
Determines whether the counter is advanced, and counts
If not, return to step 8 to perform main scanning and
Repeat until the timer is up. The sub-scan counter is
Then go to step 2 and check the leader and printer.
A predetermined number of pulses are applied to each sub-scanning motor in reverse scanning.
Return to home position in feed mode. So
Next, proceed to step 3 and execute the
Step 4 performs a head recovery operation for cleaning the spill head.
Go to step 5 and cap the head.
Wait for command input. The above is the outline of the operation of the apparatus. Using FIG. 9, FIG. 10, FIG. 11, FIG. 12, and FIG.
The operation of the present invention will be described. FIG. 9 is a block diagram of the BJ head drive circuit 36. As shown in FIG.
Clock signal φ ₁ , HDE signal
Shift clock (SHIFT CLK) based on NLE and NLE signals
Signal, data latch path (LATCH) signal, enable signal
Lock (E-CLK) signal, enable clear (▲
▼) signal, enable-in (E-in) signal and
Generate an enable signal, and
Y, M, C and B output from the linter synchronization circuit 35 _K Each
Printer data via cable 102
Input to the buffer 103 in the page 4. From buffer 103
The signal excluding the enable signal is directly input to the head 105.
The enable signal is accurately output by the waveform shaping circuit 104.
The pulse is shaped into a predetermined pulse width (10 μsec in this embodiment) and B
Input to J head 105. FIG. 10 shows one color of the BJ head in the BJ head unit 18.
Drive circuit diagram, Fig. 11 shows the timing of the input signal in Fig. 10.
3 shows an operating chart. In this embodiment, the heater of 128 nozzles in the BJ head
Is divided into 4 blocks of 32 and driven. In FIG. 10, reference numerals 106a to 106d denote 32-bit shift registers.
Data in these shift registers.
The video data input by the video clock φ (CLK
8) Shift clock (ShiFT CLK) with same frequency and same phase
Shifted by signal, 128 bits through 4 blocks
After being converted to a parallel signal,
Is touched. Also, the latches 107a to 107d are shift registers
106a to 106d for discharging the output data latched
D-type F / F that outputs timing signals,
The falling edge of the E-CLK signal that appears four times during the IN (128 dot ejection)
At the rising edge, the E-in signal is latched 107a, then the latch 107b,
Then, 107c and then 107d are latched, and the gate 108a is latched.
To 108d are enabled in order. ▲ ▼ signal
Are input to the clear terminals of the latches 107a to 107d, and ▲
▼ When the signal is at the low level, the latches 107a to 107
The output of 7d goes low, and gates 108a-108d
Is disabled and do not drive heater 110.
No. The ENABLE signal determines the time to actually turn on the heater.
The shift resists 106a-10
The output signal of 6d and the output signals of latches 107a to 107d are
When turning on the ENABLE signal to the heater when it is on
By turning on for a while, heater drivers 109a-109d
When turned on, the heater is energized and ink is ejected. this
In the case, the ON time T of the ENABLE signal _ON Is not kept correctly
May cause breakage of the heater, disconnection or non-discharge.
You. Also, from when the NLE signal turns on until the ENABLE signal turns on.
By controlling the time Td at
The discharge timing of the laser can be finely adjusted. This implementation
In the case of the example, the time Td is the number of times the head drive timing signal is generated.
When the ENABLE signal is output on
Pulse signal (clock
φ), one dot (of the discharge nozzle)
Fine tune at intervals smaller than the interval. Also more time
Td is changed, for example, to the interval of 0 at the minimum and 1N.LE at the maximum
To do. FIG. 12 (A) shows the ejection timing of ink from the nozzle.
FIG. 12 (B) is a circuit block diagram for fine adjustment of
The internal block of the write drive timing signal generation circuit 101
FIG. In FIG. 12 (A), reference numeral 111 denotes a distance between the respective color heads.
Synchronous RA that shifts the position by the distance in the main scanning direction
M and the timing of reading data from this RAM 111
Overlapping for each color head by changing the
The dots that must be shifted by one or more lines
(This deviation is recorded, for example, by a BJ head.
Once a test image is formed on paper, etc.,
Ask). In FIG. 12 (B), reference numeral 112 denotes a preset from outside.
This is a delay counter that can be
The clock φ having a higher frequency than the
The lock φ is four times the video clock CLK8 in this embodiment.
Frequency) is input. 113 is the heater of the head 105
There is a multi-vibrator for controlling the
The heater ON time is determined by the time constant of the external CR113A.
adjust. 114 is for controlling ▲ ▼ signal
This is a gate circuit that generates an interval signal.
I used a counter. FIG. 13 (A) is a conceptual diagram of the head, and FIG.
In (A), when the printer advances in the arrow (main scanning) direction,
As shown in FIG. 13 (B), the overlap between the color heads
Dots to be matched are shifted more than the distance equivalent to 1N.LE period
The reading of the RAM 11 when Δl ≧ d
By changing the output timing for each color head
Correct the dot displacement (where d is the dot diameter,
Δl represents the shift amount of dots to be overlapped, and is shown in FIG.
(B) shows that the dots are shifted by Δl.
). Next, when 0 <Δl <d, the deviation amount
The preset data value of the delay counter 112 according to
Allows fine adjustment of misalignment correction with 1/4 dot accuracy
It works. FIG. 13 (C) shows that Δl = 0 as a result of the fine adjustment.
This indicates that the gap between dots of the pad has disappeared. The present invention is not particularly limited to a copying machine,
It can also be applied to a printer having the above configuration. Also,
Digital adjustment of discharge timing using pulses
Was performed in the same way, but it would not hinder any
No. [Effect of the Invention] As described above, according to the present invention, a plurality of recording
For the shift in the main scanning direction of the
Discharge timing by using high frequency clock
Can be fine-tuned and larger than the dot spacing
Increasing the number of stages of the delay counter circuit even for the amount
Recording positions of multiple recording heads
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the apparatus of the embodiment of the present invention, FIG. 2 is a schematic perspective view of the apparatus of the embodiment of the present invention, and FIG. 3 is a block diagram of a control circuit of the embodiment of the present invention. FIG. 4 is a timing chart of the sequence, FIG. 5 is a flowchart of the sequence, FIG. 6 (A) is a diagram showing the relationship between the original and the reading synchronization signal of the reader, and FIG. 6 (B) is FIG. FIG. 6 (C) is an enlarged view of a portion A of FIG. 6, FIG. 6 (C) is an explanatory diagram accompanying a positional shift of a reading CCD of each color, FIG. 6 (D) is a diagram showing a relationship between copy paper and a recording synchronization signal, FIG. (E) is an enlarged view of a portion B in FIG. 6 (D), FIG. 6 (F) is an explanatory diagram accompanying displacement of the ink jet head of each color, and FIG. 7 (A) is a change in a reader main scanning motor encoder pulse. FIG. 7B is a diagram showing the frequency division timing according to the ratio, and FIG. FIG. 7 (C) is a diagram illustrating the interpolation and thinning-out operations according to the scaling factor, FIG. 7 (D) is a detailed circuit diagram of the scaling buffer memory 31 in FIG. 3, and FIG. (E) is a video data synchronizing signal generating circuit 28 in FIG.
7 (F) is a timing chart of the video data synchronization signal, FIG. 8 (A) is a detailed circuit diagram of the image processing circuit 33, and FIG. 8 (B) is FIG. 8 (A). FIG. 9 is a block diagram of a BJ head drive circuit, FIG. 10 is a drive circuit diagram for one color in the BJ head, and FIG. 11 is a diagram relating to BJ head drive. FIG. 12 (A) is a block diagram of a discharge timing fine adjustment circuit, FIG. 12 (B) is a block diagram of a head drive timing signal generation circuit, and FIG. 13 (A) is a concept of a head. FIGS. 13 (B) and 13 (C) are diagrams showing the relationship between the ejection timing from the nozzles and the printing dots.

Claims (1)

(57) [Claims] In an image forming apparatus having a plurality of recording heads and forming an image on a recording material, a scanning unit configured to scan the recording material in a main scanning direction with respect to the recording material; Storage means for storing data of an image to be recorded by a head; timing signal generation means for generating a timing signal according to a timing for driving the head; and recording the dots at intervals according to the timing signal. A head driving unit that reads data from the storage unit in response to a timing signal and drives the recording head; a delay signal generation unit that generates a signal having a higher frequency than the timing signal; According to the shift amount in the main scanning direction, the reading of data from the storage unit is performed for the shift larger than the interval between the dots. And a head drive timing correction means for delaying the print head based on a signal generated by the delay signal generation means for a shift smaller than the dot interval based on an imaging signal. Characteristic image forming apparatus.