JPH10235930A - Optical writing printer head and color printer employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the color overlapping accuracy. SOLUTION: The optical writing head of a tandem color printer comprises an Y1 displacement setting circuit 22, a delay circuit 23, a displacement clock signal generation circuit 28 and a detection signal, generation circuit 29 and a sheet detector 11 is disposed at a specified position on the sheet carrying path. When the sheet detector 11 detects a sheet, the detection signal generation circuit 29 outputs a detection signal and a print data DATA is transferred to a shift register circuit 201. The delay circuit 23 begins to count displacement clocks clk and when the count matches a displacement value set in the Y1 displacement setting circuit 22, a load signal generation circuit 26 is reset and then a strobe signal generation circuit is reset by a load signal LOAD. When a strobe signal STB is delivered to a gate circuit 203, an LED array 21 emits light depending on the DATA.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing printer such as a laser printer or an LED printer, and more particularly to an optical writing printer head used for a tandem type color printer and a color printer using the same.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram showing an example of an engine unit of a conventional color printer. The color printer shown in FIG. 11 is a tandem type color printer, and has four transfer units 101-C, 101-M,
01-Y, 101-B, a fixing device 2 for fixing the toner transferred to the paper 10 to the paper 10, and a transport belt 3 for transporting the paper 10. Transfer units 101-C, 101-M, 1
01-Y, 101-B, and the fixing device 2 are arranged in this order.
−C to the fixing device 2 sequentially. Here, the subscripts “C” indicate cyan, “M” indicates magenta, “Y” indicates yellow, and “B” indicates black, respectively, and the four transfer units 101-C, 101-M, and 101-Y. , 10
1-B transfers each color to the paper 10. Each transfer unit 101 has a photosensitive drum 12, a charger 13, an optical writing head 100, a developing unit 15, a transfer unit 16, and a cleaner 17. In addition, when the subscript is not described as described above but simply described as “photosensitive drum 12”, the photosensitive drums 12 -C, 12 -M, and 12-
Any one of -Y and 12-B is indicated.

FIG. 12 is a circuit block diagram of the optical writing head 100. The optical writing head 100 includes n (n is a positive integer) driver ICs 20-1 to 20 having the same configuration.
20-n and n (n is a positive integer) LEDs having the same configuration
Arrays 21-1 to 21-n and clock signal generation circuit 2
4, a data buffer 25, and a load signal generation circuit 26
And a strobe signal generation circuit 27. Here, n = 40.

The clock signal generation circuit 24 is reset by a start signal st from a control unit (not shown) of the color printer, and generates a clock signal CLK. The data buffer 25 temporarily holds print data data from a control unit (not shown), and outputs the above print data data as a print data signal DATA when a clock signal CLK is input. Load signal generation circuit 26
Are reset by a start signal st and generate a load signal LOAD. Strobe signal generation circuit 27
Are reset by the load signal LOAD to generate a strobe signal STB.

[0005] The driver IC 20-k (k is any integer from 1 to n) includes a shift register circuit 201-k.
, A latch circuit 202-k, and a gate circuit 203-k
And a driver circuit 204-k. The shift register circuit 201-k includes a clock terminal to which the clock signal CLK is input, a data input terminal, m (m is a positive integer) stages of shift registers, and m output terminals of these shift registers. And performs a data shift operation at the rising edge of the clock signal CLK. The n shift register circuits 201-1 to 201-n are cascaded, and a print data signal DATA is input to a data input terminal of the first-stage shift register circuit 201-1. The latch circuit 202-k includes a clock terminal to which the load signal LOAD is input, m registers, and input terminals of these registers, and the m terminals connected to the corresponding output terminals of the shift register 201-k. , And m output terminals of the register, and the load signal LOAD
Latch operation at the rising edge of. Gate circuit 203-
k has m AND elements, a strobe signal STB is invertedly input to a first input terminal of each AND element, and a second input terminal of each AND element is connected to the latch circuit 202-k. Connected to the corresponding output terminal. The driver circuit 204-k has m drivers, and the input terminal of each driver is connected to the output terminal of the corresponding AND element of the gate circuit 203-k. Here, m = 64.

The LED array 21-k includes m LEDs 2
11-k to 21m-k. LED211-k ~ 2
1m-k anode terminals are connected to the driver circuit 20 respectively.
4-k is connected to the corresponding driver output terminal, and the cathode terminal is grounded. Here, on the plane of the paper 10 set on the transport belt 3, the transport direction of the paper 10 is referred to as a Y direction or a sub-scanning direction, and a direction orthogonal to the transport direction is referred to as an X direction or a sub-transport direction. Then, n × m LEDs 211-1 to 21m-n
Are arranged in a straight line in parallel with the main scanning direction.
The number n × m of D is equal to the number of printing dots for one line in the main scanning direction. For example, if the print dot density is 300 [dots /
Inches], the LEDs 211-1 to 21m-n are:
They are arranged at a pitch of 84.6 [μm], and when performing A4 size color printing, 2560 LEDs are arranged.

FIG. 13 is a driving timing chart of the optical writing head 100. FIG.
(B) shows the clock signal CLK, (c) shows the displacement clock signal CLK, (c) shows the print data signal DATA, (d) shows the load signal LOAD, and (e) shows the strobe signal STB.

In FIG. 13, a start signal st shown in FIG. 13A is a constant standby time T from the start of printing (time t0).
This is a signal input from the control unit after elapse of c, Tm, Ty, or Tb, and here, a positive polarity pulse (s1,
s2). The pulse interval of the start signal st is a fixed time T0. The above Tc indicates the standby time in the transfer unit 101-C.
m, Ty, and Tb are transfer units 101-M, 1
The standby time in 01-Y and 101-B is shown. FIG.
In the color printer, the transfer units 101-C, 101-M, 101-
Since Y and 101-B are arranged in this order, Tc <Tm <T
y <Tb.

The clock signal CLK shown in (b) is a signal having clock sections (C1, C2 in the figure) which rise in synchronization with the rise of the start signal st. One clock section has n × m, ie, It consists of 2560 clock pulses, and the interval between clock sections is a fixed time T0
It is. Also, the print data signal DATA shown in FIG.
Is a signal having a line data portion (D1, D2 in the figure) outputted in synchronization with the clock pulse of the clock signal CLK. One line data portion is one line of print data, that is, 2560 bits. Consists of data.

The load signal LOAD shown in (d) is a positive pulse (L1, L2 in the figure) which rises after a lapse of a predetermined time T1 from the rise of the start signal st.
And the pulse interval is a fixed time T0. The strobe signal STB shown in (e) is a signal having negative polarity pulses (S1 and S2 in the figure) falling in synchronization with the falling of the load signal LOAD, and the LEDs 211-k to 21m-. k is a signal for controlling the light emission time according to the print data. That is, while the strobe signal STB is at the “L” level, LE
D211-k to 21m-k emit light in accordance with the print data.

Next, an electrophotographic printing process by the color printer of FIG. 11 will be described with reference to FIGS. When a printing instruction is given to the printer device 1 from a personal computer (not shown), which is a higher-level device, the transport belt 3 rotates to start transporting the paper 10,
The photosensitive drum 1 is rotated at the same speed as the rotation speed of the transport belt 3.
2 starts to rotate. At this time, the surface of the photosensitive drum 12 is uniformly charged by the charger 13. Next, a certain time Tc
Is passed from the control unit, the optical writing head 100-C
Is input to the transfer unit 101-
The cyan transfer process in C is started.

When the start signal st is input to the optical writing head 101-C, the clock generation circuit 24
And the load signal generation circuit 26 starts outputting the clock signal CLK and the load signal LOAD, respectively. Further, the strobe signal generation circuit 27 is reset by the load signal LOAD and starts outputting the strobe signal STB. The first line data portion D1 of the cyan print data signal DATA is shifted by the first clock C1 of the clock signal CLK to the shift register circuits 201-1 to 202.
-40, the first pulse s1 of the start signal st
From the first line data D1 by the first pulse L1 of the load signal LOAD output after a lapse of time T1 from
Are latched by the corresponding latch circuits 202-1 to 202-40, and during the first pulse S1 of the strobe signal STB, the drive current corresponding to the bit data of the first line data portion D1 is supplied to the driver circuits 204-1 to 204. -40 to L
The LEDs 211-1 to 2164-40 emit light in response to the ED arrays 21-1 to 21-40, and the light causes the electrostatic latent elements on the surface of the photosensitive drum 12-C to correspond to the first line print data. An image is formed. Similarly,
The electrostatic latent images after the second line data portion D2 are transferred to the photosensitive drum 1
2-C Form sequentially on the surface.

Next, a cyan toner is attached to the electrostatic latent image formed on the surface of the photosensitive drum 12-C by a developing unit 15-C, and the photosensitive drum 1 is transferred by a transfer unit 16-C.
The cyan toner on the 2-C surface is transferred to the paper 10. Through the above steps, transfer of the cyan toner from the first line to the last line, that is, one page of the paper 10 according to the print data data is completed. Also in the transfer units 101-M, 101-Y, and 101-B, the same transfer process as that of the transfer unit 101-C is repeated, and magenta, yellow, and black toners are sequentially transferred to the paper 10. Then, the four color toners transferred to the paper 10 are fixed on the paper 10 by the fixing device 2.

FIG. 14 is a diagram showing an example of color printing by the conventional color printer. In FIG. 14, C indicates a print dot of cyan, M indicates a magenta color, Y indicates a yellow color, and B indicates a black print dot. Here, ideal color printing means that four printing dots of C, M, Y, and B overlap each other. However, in the above-described conventional color printer, particularly, the optical writing head 100, the following problems occur. There is a point. (1) If the speed at which the paper 10 is conveyed does not match the light emission timing of the LED in each of the optical writing heads 100, a "writing position shift Y1" shown in FIG. 14 occurs. (2) When each optical writing head 100 is mounted on a color printer, an alignment error in the main scanning direction or a tilt with respect to the main scanning direction occurs, or the LED arrays 21-1 to 21 are attached to the optical writing head 100. −
When aligning n, the four optical writing heads 10
Due to the relative displacement of the corresponding LED array 21-k of "0", "the displacement in the main scanning direction # 1" and "the displacement in the sub-scanning direction Y2" shown in FIG. 14 occur.

[0015]

As described above, in the conventional color printer, a "write start position shift", a "main scan direction position shift" and a "sub-scan direction position shift" occur, so that four colors are superimposed. There was a problem that the accuracy was poor and the print quality was significantly reduced.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide an optical writing printer head capable of improving color registration accuracy.

[0017]

In order to achieve the above object, an optical writing printer head according to a first aspect of the present invention transports and moves toner adhered to an electrostatic latent image on the surface of a rotating photosensitive drum. The paper is transported to a predetermined position on a transport path in an optical writing printer head that is used for an optical writing printer that transfers to a paper to be formed and forms the electrostatic latent image according to print data on the surface of the photosensitive drum. Paper detecting means for outputting a detection signal when detecting that the print data has been input, light emitting means for holding input print data and emitting light in accordance with the print data when a strobe signal is input, and synchronizing with the detection signal. Transfer the print data to the light emitting means, generate the strobe signal delayed by a predetermined time with respect to the detection signal, and generate the strobe signal. And having a light emission control means for outputting to the device.

According to a second aspect of the present invention, in the optical writing printer head according to the first aspect, the sheet detecting means includes a sheet detector for detecting the sheet and a detection signal generating circuit for generating the detection signal. The paper detector is configured such that the time required from when the detection signal is output to when the sheet reaches the toner transfer position is such that an electrostatic latent image is formed on the surface of the photosensitive drum after outputting the detection signal. The electrostatic latent image is set so as to be equal to the time required for the electrostatic latent image to reach the toner transfer position or to be larger by a predetermined value.

According to a third aspect of the present invention, in the optical writing printer head according to the first or second aspect, the light emission control means includes:
A delay setting circuit for externally setting a delay time of the strobe signal with respect to the detection signal, and a delay circuit for outputting a reset signal delayed by a time corresponding to the setting of the delay setting circuit with respect to the detection signal; A strobe signal generation circuit for generating a strobe signal in synchronization with the reset signal.

According to a fourth aspect of the present invention, in the optical writing printer head according to the third aspect, the light-emitting means is divided into n (n is a positive integer) light-emitting blocks, and the light-emission control means includes the n light-emitting blocks. It has n number of the delay setting circuits, n number of the delay circuits, and n number of the strobe signal generation circuits respectively corresponding to the light-emitting blocks, and the k-th (k is 1 to 1)
n) and a k-th strobe signal generation circuit generates a k-th strobe signal delayed from the input of the detection signal by a time corresponding to the setting of the k-th delay setting circuit. , The k-th light-emitting block emits light according to the k-th block data of the print data when a strobe signal is input.

According to a fifth aspect of the present invention, in the optical writing printer head according to the first to third aspects, the print data is n.
× m (m is a positive integer) bits of serial data,
The light emitting means has an n × m (m is a positive integer) stage shift register circuit, and the light emission control means externally sets a correspondence between the register of the shift register circuit and the bit data of the print data. When the detection signal is input, according to the setting, the data from the i-th bit (i is 0 or a positive integer) to the (n × m) -th bit of the print data is stored in the shift register circuit. The print data is transferred to the (n × m) th to i-th registers, or the first to (n × m−i) -th bits of the print data are transferred to the (n × m−i) -th register of the shift register circuit. × m-
i) It has bit shift means for transferring data to the registers from the first stage to the first stage.

According to a sixth aspect of the present invention, there is provided a color printer according to any one of the first to fifth aspects, wherein each of the transfer units is a tandem type color printer having a plurality of transfer units. It is characterized by using a head.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment FIG. 1 is a configuration diagram of an engine unit of a color printer according to a first embodiment of the present invention. The color printer shown in FIG.
A tandem-type LED printer, having four transfer units 1-C, 1-M, 1-Y and 1-B having the same configuration, a fixing device 2 for fixing the toner transferred to the paper 10 to the paper 10, And a transport belt 3 for transporting the paper 10.
With respect to the traveling direction of the paper 10, the transfer unit 1-
C, 1-M, 1-Y, 1-B, and the fixing device 2 are arranged in this order, and the paper 10 is sequentially conveyed from the transfer unit 1-C to the fixing device 2 by the conveying belt 3.

The transfer unit 1 has a photosensitive drum 12, a charger 13, an optical writing head 14 having a paper detector 11, a developing unit 15, a transfer unit 16, and a cleaner 17. Around the photosensitive drum 12, a charger 13, an optical writing head 4, a developing unit 15, a transfer unit 16, and a cleaner 17 are arranged.

The photosensitive drum 12 rotates at the same constant speed as the conveyor belt 3 (rotates clockwise in FIG. 1). The charger 13 uniformly charges the surface of the photosensitive drum 12. The optical writing head 14 forms an electrostatic latent image on the charged surface of the charged photosensitive drum 12. The developing device 15 makes toner adhere to the electrostatic latent image formed on the surface of the photosensitive drum 12. Developing unit 15-C is a cyan toner, developing unit 15-M is a magenta toner, developing unit 1
5-Y adheres yellow toner, and the developing unit 15-B adheres black toner. The transfer unit 16 transfers the toner attached to the electrostatic latent image on the photosensitive drum 12 to the paper 10. The cleaner 17 removes the toner transferred to the paper 10 from the surface of the photosensitive drum 12.

FIG. 2 is a circuit block diagram of the optical writing head 14. In FIG. 2, the optical writing head 14 includes a remotely located paper detector 11, n driver ICs 20-1 to 20-n having the same configuration (n is a positive integer), and n LED arrays having the same configuration. 21-1 to 21-n and Y1
Displacement setting circuit 22, delay circuit 23, clock signal generation circuit 24, data buffer 25, load signal generation circuit 26, strobe signal generation circuit 27, displacement clock signal generation circuit 28, detection signal generation circuit 29 And Here, n = 40.

The paper detector 11 is disposed on a transport path before the transfer device 16 with respect to the transport direction of the paper 10, and
0 is detected. As the paper detector 11, for example, a photo sensor is used. Also, the detection signal generation circuit 29
When the paper detector 11 detects the paper 10, the detection signal DTC
Generate. The paper detector 11 includes a detection signal generation circuit 2
9 starts outputting the detection signal DTC and the time required for the paper 10 to reach the transfer unit 16 is the detection signal DTC.
Of the print data on the surface of the photosensitive drum 12
An electrostatic latent image of the line data portion is formed, and is set at a position where it is equal to the time required for the electrostatic latent image to reach the transfer unit 16 or is increased by a predetermined value. still,
The sheet detector 11 and the detection signal generation circuit 29 constitute a sheet detecting unit.

The clock signal generation circuit 24 outputs the detection signal D
It is reset by TC to generate a clock signal CLK. The data buffer 25 temporarily holds print data data from a control unit (not shown) of the color printer, and outputs the above print data data as a print data signal DATA when a clock signal CLK is input. The displacement clock signal generation circuit 28 detects the detection signal DTC.
To generate a displacement clock signal clk. Here, the clock pulse of the displacement clock signal clk may have any frequency, for example, the clock signal CLk.
It may be the same as the K clock pulse.

The Y1 displacement setting circuit 22 is provided for the sheet detector 11
A Y1 displacement value for further finely correcting the “write start position deviation” coarsely corrected by the detection signal generation circuit 29 is set from the outside. As the Y1 displacement setting circuit 22, for example, a circuit having a dip switch or a circuit for storing an external input signal or generating a signal corresponding to the input signal is used. The Y1 displacement setting circuit 22 corresponds to a delay setting circuit. The delay circuit 23 includes a counter circuit 231 and a comparison circuit 232. The counter circuit 231 is reset by the detection signal DTC, starts counting clock pulses of the displacement clock signal clk, and outputs a count value. The comparison circuit 232 outputs a reset signal RST when the Y1 displacement value from the Y1 displacement setting circuit 22 matches the count value from the counter circuit 231.

The load signal generation circuit 26 is reset by the reset signal RST, and the load signal LOAD (Y
1) is generated. The STB generation circuit 27 is reset by the load signal LOAD and outputs the strobe signal STB
(Y1) is generated. Incidentally, the Y1 displacement setting circuit 22,
Delay circuit 23, clock signal generation circuit 24, data buffer 25, load signal generation circuit 26, strobe signal generation circuit 27, displacement clock signal generation circuit 28
Constitute light emission control means.

The driver IC 20-k (k is any integer from 1 to 40) includes a shift register circuit 201-k
, A latch circuit 202-k, and a gate circuit 203-k
And a driver circuit 204-k. The n shift register circuits 201-1 to 201-n are cascaded, and the print data signal DATA is input to the data input terminal D of the first-stage shift register circuit 201-1.
The shift register circuit 201-k includes m stages of shift registers, and m output terminals Q1,
Qm, and performs a data shift operation at the rising edge of the clock signal CLK input to the clock terminal.
The latch circuit 202-k includes m registers, input terminals of these registers, m data input terminals connected to corresponding output terminals of the shift register 201-k, and m output terminals of the register. A clock signal CLK having terminals Q1, Q2,.
Latch operation at the rising edge of. Gate circuit 203-
k has m AND elements, a strobe signal STB is invertedly input to a first input terminal of each AND element, and a second input terminal of each AND element is connected to a corresponding one of the latch circuits 202-k. Output terminal. The driver circuit 204-k has m drivers, and each driver has an input terminal connected to the gate circuit 20-k.
3-k is connected to the output terminal of the corresponding AND element.

The LED array 21-k includes m LEDs 2
11-k to 21m-k. LED211-k ~ 2
1m-k anode terminals are connected to the driver circuit 20 respectively.
4-k is connected to the corresponding driver output terminal, and the cathode terminal is grounded. nxm LEDs 211-
1 to 21 m-n are arranged in a straight line parallel to the main scanning direction. The driver ICs 20-1 to 20-n and L
The ED arrays 21-1 to 21-n constitute light emitting means.

FIG. 3 is a driving timing chart of the optical writing head 14, wherein (a) shows the detection signal DTC and (b)
Is a clock signal CLK, and (c) is a displacement clock signal cl.
k, (d) are the print data signal DATA, (e) is the load signal LOAD (Y1), (f) is the strobe signal STB
(Y1) is shown.

In FIG. 3, the detection signal DT shown in FIG.
C is a standby time TC, TM, from the start of printing (time t0).
This signal is generated when the paper detector 11 detects the paper 10 after passing TY or TB, and here is a signal having positive polarity pulses (d1, d2 in the figure). The pulse interval of the detection signal DTC is a fixed time T0, and the number of pulses is equal to the number of print lines. The above TC indicates the standby time in the transfer unit 1-C, and similarly, TM, TY,
TB indicates the standby time in the transfer units 1-M, 1-Y, and 1-B, respectively. This waiting time TC, TM, T
Since Y and TB are times from the time t0 to the time when the sheet detector 11 detects the sheet 10, the sheet detector 1 starts moving from the conveyance start position of the sheet 10 (the position where the sheet 10 exists at the time t0).
It changes according to the fluctuation of the transport time of the sheet 10 up to 1.
That is, a transport error from the transport start position to the paper detector 11 is absorbed.

The clock signal CLK shown in (b) is a signal having a clock section (C1, C2 in the figure) which rises in synchronization with the rise of the detection signal DTC, and one clock section has n × m, ie, It consists of 2560 clock pulses, and the interval between the clock sections is a fixed time T0. The print data signal DATA shown in FIG.
This is a signal having line data portions (D1 and D2 in the drawing) output in synchronization with the clock pulse of the clock signal CLK. One line data portion is obtained by converting one line of print data, that is, 2560 bit data. Become. Further, the displacement clock signal clk shown in FIG.
It is a signal having a displacement clock section (c1, c2 in the figure) that rises with a certain delay time from the rise of C. The delay time is equal to the width of the clock portion of the clock signal CLK and the width of the line data portion of the print data signal DATA.

The load signal LOAD shown in (e) is a positive pulse (Ly1, Ly2 in the figure) which rises when a time T2 according to the setting of the Y1 displacement setting circuit 22 elapses from the rise of the detection signal DTC. And the pulse interval is a fixed time T0. Also,
The strobe signal STB (Y1) shown in (f) is a signal having negative pulses (Sy1, Sy2 in the figure) falling in synchronization with the falling of the load signal LOAD, and the LEDs 211-k to 21m. -K is a signal for controlling the light emission time according to the print data. That is, while the strobe signal STB (Y1) is at the “L” level, the LEDs 211-k to 21m-k emit light according to the print data. (E) and (f) show the load signal LO in the conventional optical writing head 100 shown in FIG.
The timing of AD and strobe signal STB is shown by a dotted line.

Next, an electrophotographic printing process in the color printer of FIG. 1 will be described. When an instruction to start printing is given to the color printer of FIG.
Rotates to start conveying the sheet 10 and the conveying belt 3
The photosensitive drum 12 starts rotating at the same speed as the rotation speed. At this time, a high voltage of 300 to 500 [V] is applied to the charger 13, whereby the surface of the photosensitive drum 12 is uniformly charged to a positive potential.

Next, the leading end of the sheet 10 is connected to the sheet detector 11-.
After passing through C, the paper detector 11-C detects this, and the detection signal generation circuit 29 starts outputting the detection signal DTC (FIG. 3A). This detection signal DTC is input to the counter circuit 231, the clock signal generation circuit 24, and the displacement clock signal generation circuit 28 of the optical writing head 14-C. Thereby, the cyan transfer process in the transfer unit 1-C is started.

In the optical writing head 14-C, the clock signal generation circuit 24 and the displacement clock signal generation circuit 28 are reset by the detection signal DTC, and the clock signal CLK (FIG. 3B) and the displacement clock signal c
The output of lk (FIG. 3C) is started. The control unit (not shown) of the color printer has previously transferred the cyan print data data to the data buffer 25, and the data buffer 25 stores the print data data in synchronization with the clock pulse of the clock signal CLK. The output of the print data signal DATA is started by sequentially outputting the bit data. The counter 231 is reset by the detection signal DTC (however, the displacement clock signal clk
Counting operation is not started until the first displacement clock section c1 is input). The first line data section D1 of the cyan print data signal DATA is shifted by the first clock section C1 of the clock signal CLK to the shift register circuit 201-1.
~ 202-40. When the storage of the first line data portion D1 is completed, the first displacement clock portion c1 of the displacement clock signal clk from the displacement clock generation circuit 28 is output.
Is input to the counter circuit 231, and the counter circuit 231
Starts the counting operation.

When the count value of the counter circuit 231 matches the Y1 displacement value set in the Y1 displacement setting circuit 22, the reset signal RST is output from the comparing circuit 232.
Is output, and the load signal generation circuit 24 is reset by the reset signal RST.
The output of (Y1) (FIG. 3E) is started. Also, the strobe signal generation circuit 25 is reset by the load signal LOAD (Y1), and the strobe signal STB (Y1)
The output shown in FIG. 3F is started.

When the first pulse Ly1 of the load signal LOAD (Y1) is input to the latch circuits 202-1 to 202-40, the shift register circuits 201-1 to 201-40.
Are latched by the corresponding latch circuits 202-1 to 202-40. Next, when the first pulse Sy1 of the strobe signal STB is input to the gate circuits 203-1 to 203-40, the gate circuits 203-1 to 203-40 output the first pulse Sy1 from the latch circuit.
The line data section D1 is connected to the driver circuits 204-1 to 204-4.
−40, and the driver circuits 204-1 to 204-4
0 is the first pulse Sy of the strobe signal STB (Y1).
During the period 1, the driving current (current of several mA) corresponding to the first line data section D1 is applied to the LED arrays 21-1 to 21-.
40, and the LEDs 211-1 to 2164-40 are
The light emitting operation or the light extinguishing operation is performed according to the bit value of the first line data section D1.

Light corresponding to the first line data portion D1 from the LED arrays 21-1 to 21-40 is irradiated onto the charged photosensitive drum 12-C, whereby light on the surface of the photosensitive drum 12-C is emitted. The charge in the irradiated area is attenuated,
Print data D1 of the first line on the surface of the photosensitive drum 12-C
An electrostatic latent image corresponding to the image is formed.

Next, the second line data section D2 of the print data signal DATA is shifted by the second clock section C2 of the clock signal CLK to the shift register circuits 201-1 to 202-4.
0, and the second line data portion D2 is latched by the corresponding latch circuits 202-1 to 202-40 by the second pulse Ly2 of the load signal LOAD (Y1).
During the period of the second pulse Sy2 of the strobe signal STB (Y1), the driving current (several [m]) corresponding to the second line data portion D2
A] of the driver circuits 204-1 to 204-40
Is supplied to the LED arrays 21-1 to 21-40, and an electrostatic latent image corresponding to the second line data portion D2 is formed on the surface of the photosensitive drum 12-C. In the same manner, the electrostatic latent images subsequent to the third line data portion are sequentially formed on the surface of the photosensitive drum 12-C.

Next, a cyan toner containing carbon as a main component is adhered to the electrostatic latent image formed on the surface of the photosensitive drum 12-C by the developing unit 15-C (development of the electrostatic latent image). Then, the cyan toner attached to the electrostatic latent image on the photosensitive drum 12-C is transferred to the sheet 10 transported by the transport belt 3 by the transfer unit 16-C. The cyan toner remaining on the surface of the photosensitive drum 12-C after the transfer is collected by the cleaner 17-C, and the surface of the photosensitive drum 12-C is charged uniformly, and an electrostatic latent image is formed, developed, The cycle of toner transfer is repeated. With the above steps, the transfer of the cyan toner from the first line to the last line, that is, according to the print data data of one sheet of paper 10 is completed.

Next, the leading end of the sheet 10 is connected to the sheet detector 11-.
After passing through M, the sheet detector 11-M detects this, and the detection signal generation circuit 29 starts outputting the detection signal DTC.
The detection signal DTC is transmitted to the counter circuit 231 of the optical writing head 14-M, the clock signal generation circuit 24,
This is input to the displacement clock signal generation circuit 28, and the cyan transfer process in the transfer unit 1-M is started.

In the optical writing head 14-M, the first line data portion D1 of the magenta print data DATA
Are stored in the shift register circuits 201-1 to 202-40. When the storage of the first line data section D1 is completed, the first displacement clock section c1 of the displacement clock signal clk is output.
Is input to the counter circuit 231, and the counter circuit 231
Starts the counting operation. And the counter circuit 23
When the count value of 1 and the displacement setting value from the Y1 displacement setting circuit 22 match, the reset signal R
ST is output, the load signal generation circuit 24 starts outputting the load signal LOAD (Y1), and the strobe signal generation circuit 25 starts outputting the strobe signal STB (Y1).

The first line data section D1 is latched by the corresponding latch circuits 202-1 to 202-40 by the first pulse Ly1 of the load signal LOAD (Y1).
During the period of the first pulse Sy1 of the strobe signal STB (Y1), the drive current (several [m]) corresponding to the first line data portion D1
A] of the driver circuits 204-1 to 204-40
To the LED arrays 21-1 to 21-40, and an electrostatic latent image corresponding to the first line data portion D1 is formed on the surface of the photosensitive drum 12-M. Similarly, the electrostatic latent images subsequent to the second line print data are sequentially formed on the surface of the photosensitive drum 12-M.

Next, a magenta toner is applied to the electrostatic latent image formed on the surface of the photosensitive drum 12-M by the developing unit 15-M (development of the electrostatic latent image). 1
The magenta toner adhered to the electrostatic latent image on the photosensitive drum 12-M by 6-C is transferred to the sheet 10 transported by the transport belt 3. The magenta toner remaining on the surface of the photosensitive drum 12-M after the transfer is collected by the cleaner 17-M, and the surface of the photosensitive drum 12-M is charged uniformly, the electrostatic latent image is formed, developed, The cycle of transferring the magenta toner is repeated. Through the above steps, the transfer of the magenta color toner from the first line to the last line, that is, one page of the paper 10 according to the print data data is completed.

Thereafter, the transfer units 1-C, 1-M
Transfer unit 1-Y,
In 1-B, the transfer process of yellow and black is repeated. Paper 10 on which the above four color toners are transferred
Is transported to the fixing device 2 by the transport belt 3, and the four color toners transferred to the paper 10 are fixed to the paper 10 by the fixing device 2, thereby completing the electrophotographic printing process.

Here, the displacement value Y of the Y1 displacement setting circuit 22
1 is the respective optical writing heads 14-C, 14-
It is set for each of M, 14-Y, and 14-B, and is set in the following procedure. First, as a procedure before setting, four optical writing heads 14-C, 14-M, 14-Y, 14
Displacement values y1 (C), y1 of the Y1 displacement setting circuit 22 of −B
(M), y1 (Y), and y1 (B) are all set to the reference value yr, and color printing is performed. The displacement value y1 is a positive integer. Based on the printing result, the amount of shift in the Y direction (sub-scanning line direction) of the print dots of the other three colors (for example, magenta, yellow, and black) with respect to the print dot of a certain reference color (for example, cyan) (“write start position shift Amount)
Is measured. The shift amounts of the other three colors are converted into time based on the shift amounts and the speeds of the photosensitive drum 12 and the conveyor belt 3.
The correction values ym, yy, and yb are calculated from the shift time and the clock cycle of the displacement clock signal clk. The correction value is a positive or negative integer or 0. And y1
(C) = yr, y1 (M) = yr + ym, y1 (Y) =
Displacement values y1 (C), y1 (M), y1 (Y), y1 (B) calculated by yr + yy, y1 (B) = yr + yb
Is set in each Y1 displacement setting circuit 22. As a result, the optical writing heads 14-M, 14-Y, 14-
B, detection signal D of strobe signal STB (Y1)
The delay time with respect to the TC changes, and the print start position shift Y of the print dots of the other three colors (for example, magenta, yellow, and black) with respect to the print dot of the reference color (cyan)
1 "can be corrected.

FIG. 4 is a diagram showing an example of printing by the color printer according to the first embodiment of the present invention. When FIG. 4 is compared with FIG. 14, in FIG. 4, the write positions of the magenta (M), yellow (Y), and black (B) print dots in the Y direction are corrected and overlap the cyan (C) write positions. , It can be seen that “write start position shift Y1” has disappeared.

As described above, according to the first embodiment of the present invention, the toner transfer is started after the sheet 10 is detected by the sheet detector 11, and the LED 211-1 is set by the Y1 displacement setting circuit 22 and the delay circuit 23. 2164-40 can be adjusted, so that 4
Since the “write position shift Y1” of the color print dots can be corrected, the color overlay accuracy of the four colors is improved, and the print quality can be improved.

Second Embodiment A color printer according to a second embodiment has a function of correcting a displacement X1 in the main scanning direction. The printer according to the first embodiment shown in FIG. At
The optical writing head 31 is provided at the position where the optical writing head 14 is arranged. FIG. 5 is a circuit block diagram of the optical writing head 31 in the color printer according to the second embodiment. The optical writing head 31 includes n driver ICs 20-1 to 20-n and n LED arrays 2
1-1 to 21-n, a sub shift register circuit 40 including p (p is an integer) registers, an X1 displacement setting circuit 41, and a clock signal generation circuit 42. Here, n = 40 and p = 7. The driver IC 20-
1 to 20-n and the LED arrays 21-1 to 21-n,
The configuration is the same as that shown in FIG. The optical writing head 31 is not shown, but the paper detector 11 is not shown.
, A detection signal generation circuit 29 and a Y1 displacement setting circuit 22
, A delay circuit 23, a data buffer 25, a load signal generation circuit 26, and a strobe signal generation circuit 27. The above-described paper detector 11 and detection signal generation circuit 29
The Y1, displacement setting circuit 22, delay circuit 23, data buffer 25, load signal generation circuit 26, and strobe signal generation circuit 27 have the same configuration as that shown in FIG.

The clock signal generation circuit 42 outputs the detection signal D
The clock signal CLK (X1) is reset by TC.
And a clock signal CLK. Clock signal C
The number of clock pulses in one clock section of LK (X1) is 2560 + p, and the number of clock pulses in one clock section of clock signal CLK is 256
There are zero.

The sub-shift register circuit 40 comprises p registers 40-1 to 40-p connected in cascade, and a print data signal DATA is inputted to an input terminal of the register 40-1 at the first stage. The registers 40-1 to 40-
The clock signal CLK (X1) is input to the clock terminal of p. The sub shift register circuit 40 performs a data shift operation at the rising edge of the clock signal CLK (X1).

The X1 displacement setting circuit 41 has p + 1 input terminals I0 connected to the input terminal and output terminal of the register 40-1 and the output terminals of the registers 40-2 to 40-p of the sub shift register circuit 40, respectively. To Ip and an output terminal OUT connected to the input terminal of the shift register circuit 201-1 of the driver IC 20-1. One of the input terminals I0 to Ip and the output terminal OUT are externally set. According to the print data signal DATA
(X1) is output. Optical writing head 31-C, 31
In each of the X1 displacement setting circuits 41 of -M, 31-Y, and 31-B, variables indicating which input terminal is connected to the output terminal OUT are x1 (C), x1 (M), x1
(Y), x1 (B), and will be referred to as X1 displacement value. Here, when the variable x1 = h (h is any integer from 0 to p) is set, the input terminal Ih and the output terminal OUT are connected. The sub shift register circuit 40, the X1 displacement setting circuit 41, and the clock signal generation circuit 42 constitute a bit shift unit.

Here, the procedure for selecting the connection input terminal of the X1 displacement setting circuit 41 (the procedure for setting the X1 displacement value x1 will be described. The four optical writing heads 31-C, 31-M,
The X1 displacement values x1 (C), x1 (M), x1 (Y), and x1 (B) of the X-position setting circuits 41 of 31-Y and 31-B are:
It is determined by the following procedure. First, as a procedure before setting, displacement values x1 (C), x1 (M), x1 (Y), x1 (B)
Are set to the reference value “0”, and color printing is performed. That is, color printing is performed by connecting the input terminal I0 and the output terminal OUT. From this printing result, it is measured how many writing start positions of the printing dots of the four colors are shifted to the left in the X direction (main scanning direction) with respect to the reference position. Here, in a print dot row for one line of a certain color, the print dot on the leftmost side (writing position) of the paper 10 corresponds to the LED 21m-n, and the print dot on the rightmost side corresponds to the LED 211-1. I do. Then, displacement values x1 (C), x1 (M), x1
(Y) and x1 (B) are set. For example, if there is a shift of 2 dots, x1 = 2, that is, the input terminal I2 is connected to the output terminal OUT (this case is shown in the X displacement setting circuit 41 of FIG. 5).

FIGS. 6A and 6B are timing charts for driving the optical writing head 31. FIG. 6A shows the detection signal DTC, and FIG.
Is a clock signal CLK (X1), (c) is a clock signal CLK, (d) is a print data signal DATA, (e) is a print data signal DATA (X1), and (f) is a load signal L.
OAD (Y1) and (g) indicate strobe signal STB (Y
1) are shown. The detection signal DTC shown in (a) and the load signal LOAD (Y1) shown in (f)
And the strobe signal STB (Y1) shown in FIG.
This is the same as that shown in FIG.

In FIG. 4, Cx1 is composed of 2560 + p clock pulses, and the first line print data D1 is 25
It consists of 60 bits. Strobe signal STB (Y1)
Is a signal for controlling the time during which the LED 211 emits light.

In FIG. 6, a clock signal CLK (X1) shown in (b) is a signal having clock sections (Cx1 and Cx2 in the figure) which rise in synchronization with the rise of the detection signal DTC, and one clock section Is composed of n × m + p clock pulses, that is, 2560 + p clock pulses, and the interval between clock sections is a fixed time T0. The clock signal CLK is a signal having clock sections (C1, C2 in the figure) that rise in synchronization with the (p + 1) th clock pulse of the clock section of the clock signal CLK (X1), and one clock section is n × m, that is, 2560 clock pulses.

The print data signal DATA shown in FIG.
This is a signal having line data portions (D1 and D2 in the drawing) output in synchronization with the clock pulse of the clock signal CLK. One line data portion is obtained by converting one line of print data, that is, 2560 bit data. Become. The print data signal DATA (X1) shown in FIG.
According to the setting of the displacement setting circuit 41, that is, the displacement value x1
= H, h + of the clock portion of the clock signal CLK
A signal having a line data portion (Dx1, Dx2 in the figure) output in synchronization with the first clock pulse;
One line data portion includes bit data from the first bit to the (2560-h) th bit of the line data portion of the data signal DATA.

Next, an electrophotographic printing process in the color printer according to the second embodiment will be described. The operation of the components other than the optical writing head 31 is described below.
Since it is the same as the first embodiment, the description of the operation is omitted.

In the optical writing head 31, the clock signal generation circuit 42 is reset by the detection signal DTC, and outputs the clock signal CLK (X1) (FIG. 6B) and the output of the clock signal CLK (FIG. 6C). Start.
The data buffer 25 not shown in FIG.
The output of the data signal DATA (FIG. 6D) is started in synchronization with the clock signal CLK. Therefore, the clock signal C
The data “0” is written into the shift registers 40-1 to 40-p of the sub-shift register circuit 40 by the first to p-th clock pulses of the first clock unit Cx1 of LK (X1), and the first clock unit (P +
1) The first and subsequent clock pulses cause the shift registers 40-1 to 40-p to send the first print data signal DATA to the shift registers 40-1 to 40-p.
The bit data of the line data section D1 is sequentially transferred.
The first line data section D1 is provided with an X1 displacement setting circuit 41.
And output from the output terminal OUT of the X1 displacement setting circuit 41 as the first line data portion Dx1 of the print data signal DATA (X1) (FIG. 6 (e)).
20-1 to 20-40 shift register circuit 201-1
２０１201-40.

Here, if the X1 displacement setting circuit 41 is set to connect the input terminal I2 and the output terminal OUT, that is, if the displacement value x1 is set to 2, the first The line data part Dx1 becomes a signal delayed by two clock pulses with respect to the first line data part D1, and the shift register circuits 201-1 to 201-4
0 when the storage of print data is completed.
LEDs 2164-40 and 216 of array 21-40
Data “0” is stored in the shift register of the shift register circuit 20-40 corresponding to the LED 3-21.
The first bit data of the first line data portion D1 is stored in the shift register corresponding to 62-40.
In the shift register corresponding to 2161-40, the second bit data of the first line data D1 is stored.
At this time, the last 2-bit data of the first line data D1 is not stored in the shift register circuit 201.

When the storage of the first line print data D1 is completed, the first of the load signals LOAD (Y1) (FIG. 6 (f)) generated in the same manner as in the first embodiment.
The pulse Ly1 and the first pulse Sy1 of the strobe signal STB (Y1) (FIG. 6 (g)) generate the driver IC2
0-1 to 20-40 latch circuits 202-1 to 202-
40 and the gate circuits 203-1 to 203-40 operate, and the print data DATA (X
An electrostatic latent image corresponding to the first line data portion Dx1 of 1) is formed. Similarly, the print data signal DATA
An electrostatic latent image after the second line data portion Dx2 of (X1) is sequentially formed on the surface of the photosensitive drum 12, and an electrostatic latent image for one page of the paper 10 is formed on the surface of the photosensitive drum 12.

FIG. 7 is a diagram showing an example of printing by the color printer according to the second embodiment. A in the figure indicates a writing reference position in the X direction. When FIG. 7 is compared with FIG. 4, in FIG. 7, the writing positions of the printing dots of the four colors in the X direction (main scanning direction) are corrected and overlapped at the reference position A,
It can be seen that "main scanning direction displacement X1" has disappeared.

As described above, according to the second embodiment, the sub shift register circuit 40, the X1 position setting circuit 41, and the clock signal generation circuit 42 are provided, and the bit data of the print data for one line and the shift register circuit 201-1
Since the correspondence with the register 201-n can be shifted, the “position shift X1 in the main scanning direction” of the print dots of four colors can be corrected.
The color overlay accuracy of the colors is further improved, and the print quality can be improved.

In the clock signal generation circuit 42,
(I +) of the clock portion of the clock signal CLK (X1)
1) In the period from the clock (i is any integer from 0 to p) to the (2560-i) th clock, the timing of outputting the clock portion of the clock signal CLK is as follows.
In accordance with the setting of the X1 displacement setting circuit 41, the i-th bit to the 2560th bit of the line data portion of the print data signal DATA
The data up to the bit is transferred to the shift register circuit 201-1.
Of a 2560-stage shift register according to 201-n
The data is transferred to the registers from the 560th stage to the i-th stage, or from the first bit to the (256th
Data up to 0-i) bits can be transferred to the (2560-i) th to first registers of the shift register, and the print dot position in the main scanning direction can be set not only on the right side but also on the left side. Can also be moved.

The second embodiment can improve the print quality as described above even when applied to a conventional color printer. In this case, the above-described bit shift means may be provided in the conventional optical writing head 100 shown in FIG. 12, and the start signal st may be used instead of the detection signal DTC.

Third Embodiment A color printer according to a third embodiment of the present invention is characterized in that it has a function of correcting a positional deviation Y2 in the sub-scanning direction of a one-dot printing dot row. In the printer according to the first embodiment shown in FIG.
4, an optical writing head 51 is provided. FIG. 8 is a circuit block diagram of the optical writing head 51. The number of the optical writing heads 51 is n (n is an integer).
Driver ICs 20-1 to 20-n, n LED arrays 21-1 to 21-n, and n Y2 displacement setting circuits 6
0-1 to 60-n and n delay circuits 61-1 to 60-
n and n strobe signal generation circuits 62-1 to 62-
n and a displacement clock generation circuit 63. The driver ICs 20-1 to 20-n and the LED arrays 21-1 to 21-n
21-n has the same configuration as that shown in FIG. 2, and the displacement clock generation circuit 63 has almost the same configuration as the displacement clock generation circuit 28 shown in FIG. Are different in the number of clock pulses). Although not shown, the optical writing head 51 includes a sheet detector 11, a detection signal generation circuit 29,
It has a Y1 displacement setting circuit 22, a delay circuit 23, a clock generation circuit 24, a data buffer 25, and a load signal generation circuit 26. The sheet detector 11, the detection signal generation circuit 29, the Y1 displacement setting circuit 22, the delay circuit 23, the clock generation circuit 24, and the data buffer 25
And the load signal generation circuit 26 have the same configuration as that shown in FIG.

Here, the driver IC 20-
1 to 20-n and the LED arrays 21-1 to 21-n, the driver IC 20-k and the LED array 20
When −k is referred to as a k-th block of the light emitting unit, and m-bit data corresponding to the k-th block in the line data portion is referred to as k-th block data, a Y2 displacement setting circuit 60-k and a delay circuit 61 -K and the strobe signal generation circuit 62-k are circuits for controlling the k-th block of the light emitting means.

The Y2 displacement setting circuit 60-k (k is an integer from 1 to n) includes, for example, the Y1 displacement setting circuit 2 shown in FIG.
2 is a circuit for setting the Y2 displacement value y2k in the k-th block. The delay circuit 61-k
Has the same configuration as the delay circuit 23 shown in FIG. 2, for example, and the displacement clock signal clk is provided to the delay circuit 60-k.
, The load signal LOAD (Y1) and the displacement value y2k set in the Y2 displacement setting circuit 60-k are input, and the count of the displacement clock signal clk is started at the falling of the load signal LOAD (Y1). If the count value matches the displacement value y2k, the reset signal RST (Y2
-K) is output. Also, the strobe signal generation circuit 62
-K is reset by the reset signal RST (Y2-k) to generate the strobe signal STB (Y2-k). This strobe signal STB (Y2-k) is input to the gate circuit 203-k of the driver IC 20-k.

Here, the Y2 displacement setting circuits 60-1 to 60-60
The displacement values y21 to y2n of -n are set for each of the optical writing heads 51-C, 51-M, 51-Y, and 51-B, and are set in the following procedure. First, as a procedure before setting, four optical writing heads 51-
Displacement values y21 (C) to y2n of Y2 displacement setting circuits 60-1 to 60-n of C, 51-M, 51-Y, and 51-B
(C), y21 (M) -y2n (M), y21 (Y)-
y2n (Y), y21 (B) to y2n (B) are all "
Color printing is performed by setting to 0 ". From this print result, the k-th block of the other three colors (for example, magenta, yellow, and black) with respect to the printing dot of the k-th block of a certain reference color (for example, cyan) Is measured in the Y direction (sub-scanning line direction) of the print dots of the other colors, and the shift amounts of the other three colors are converted into time from the shift amounts and the speeds of the photosensitive drum 12 and the conveyor belt 3. From the clock cycle of the displacement clock signal clk, the correction values y2k (M), y2k (Y), and y2k (B) of the k-th block are calculated, and the correction value y21 (C) of cyan as the reference color at this time.
Ｙy2n (C) are all set to “0”. Correction value y2
k is a positive or negative integer or 0. Then, the correction values y2k (C), y2k (M), y2k (Y),
y2k (B) is assigned to each optical writing head 51-C,
51-M, 51-Y, 51-B Y2 displacement setting circuit 60
Set to -k.

FIG. 9 is a drive timing chart of the optical writing head 51. FIG. 9A shows the detection signal DTC, and FIG.
Is a clock signal CLK, and (c) is a displacement clock signal cl.
k, (d) are the print data signal DATA, (e) is the load signal LOAD (Y1), (f) to (i) are the strobe signals STB (Y2-1), STB (Y2-2), STB.
(Y2-2) and STB (Y2-40), respectively. The detection signal DTC, the displacement clock signal clk, the print data signal DATA, and
The load signal LOAD (Y1) is the same as that shown in FIG.

In FIG. 9, the strobe signals STB (Y2-k) shown in (f) to (i) correspond to the setting of the Y2 displacement setting circuit 60-k from the fall of the load signal LOAD (Y1). Time, ie, Y2 displacement value y2
This is a negative polarity pulse that falls with a time delay corresponding to k. The strobe signal STB (Y2-1) shown in (f)
Is a signal when the Y2 displacement value y21 = 0, and FIG.
The timing is the same as that of the strobe signal STB (Y1) shown in (f), and the delay time from the rise of the detection signal DTC is T3. The strobe signal STB (Y2-2) shown in (g) is a signal when the displacement value y22 is set to a positive value, and the delay time from the rise of the detection signal DTC is T3 + T4.

Next, an electrophotographic printing process in the color printer according to the third embodiment will be described. The operation of the components other than the optical writing head 51 is described below.
Since it is the same as the first embodiment, the description of the operation is omitted.

In the optical writing head 51, the displacement clock signal generation circuit 63 is reset by the detection signal DTC. Although not shown in FIG. 8, the clock signal generation circuit 24 is also reset by the detection signal DTC,
The output of the clock signal CLK is started, and the data buffer 25 further outputs the print data signal D by the clock signal CLK.
Start output of ATA. Thus, as in the first embodiment, the first line data portion D1 of the print data signal DATA is changed to the shift register circuits 201-1 to 20-1 in synchronization with the first clock portion C1 of the clock signal CLK.
2-40.

When the storage of the first line data section D1 is completed, the load signal LO is output based on the detection signal DTC and the displacement clock signal clk in the same manner as in the first embodiment.
AD (Y1) is generated. Shift register circuit 201
-1 to 202-40 first line data portion D
1 is latched by the latch circuits 202-1 to 202-40 by the first pulse L1 of the load signal LOAD (Y1), and the latch circuits 202-1 to 202-40 connect the first line data section D1 to the gate circuit 203. -1 to 202-40
Output to

The delay circuit 61-k outputs the load signal LO
It is reset by the first pulse L1 of AD (Y1) and starts counting the displacement clock signal clk. When this count value matches the displacement value y2k set in the Y2 displacement setting circuit 60-k, the load signal LOAD (Y
Positive reset pulse RST having the same pulse width as in 1)
(Y2-k) is output to the strobe signal generation circuit 64-k. The strobe signal generation circuit 64-k is reset at the fall of the reset pulse RST (Y2-k),
First pulse S1k of strobe signal STB (Y2-k)
Is output.

The above strobe signal STB (Y2-k)
By the first pulse S1k, the gate circuit 203-k of the driver IC 20-k outputs the k-th block data of the first line data section D1 to the driver circuit 204-k. Accordingly, the LED arrays 21-1 to 21-40 irradiate the light corresponding to the first line data portion D1 to the surface of the photosensitive drum 12 at different timings for each block data (see FIGS. 9F to 9I). Then, an electrostatic latent image is formed on the surface of the photosensitive drum 12. Similarly, the print data signal DATA
Are formed sequentially on the surface of the photosensitive drum 12, and an electrostatic latent image for one page of the paper 10 is formed on the surface of the photosensitive drum 12.

FIG. 10 is a view showing an example of printing by the color printer of the third embodiment, in which the second embodiment is applied at the same time. When FIG. 10 is compared with FIG. 7, in FIG. 10, the misregistration in the Y direction (main scanning direction) of the printing dot rows of four colors is corrected, and the printing dots for one line overlap, and the “misalignment in the sub scanning direction” It can be seen that "Y2" has disappeared.

As described above, according to the third embodiment of the present invention, L corresponding to each block in one line
For each ED array 21-k, a Y2 displacement setting circuit 60-k
, A delay circuit 61-k, and a strobe signal generation circuit 62
By providing -k and adjusting the light emission timing of the LEDs 211-1 to 2164-40 for each block, it is possible to correct the "Y2 sub-scanning direction displacement" of the four color print dots. The color overlay accuracy of the four colors is improved, and the print quality can be improved.

[0083]

As described above, according to the optical writing printer head of the present invention, the operation starts on the basis of the time when the paper is detected by the paper detecting means, and the light emission timing of the light emitting means is further controlled by the light emission control means. By making the adjustment possible, there is an effect that the writing position of the print dot can be corrected from outside.

Further, according to the optical writing printer head of the present invention, the light emission timing of the light emitting means can be adjusted for each block, so that the position of the print dot in the sub-scanning direction can be externally corrected. There is an effect that can be.

According to the optical writing printer head of the present invention, the correspondence between the bit data of the print data for one line and the register of the shift register circuit can be shifted by the bit shift means. Thus, there is an effect that the position of the print dot in the main scanning direction can be externally corrected.

Further, according to the color printer of the present invention which is a tandem type color printer using a plurality of the above-described optical writing printer heads, it is possible to correct the displacement of the printing dots of a plurality of colors. There is an effect that the color overlay accuracy is improved and the print quality can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a color printer according to a first embodiment of the present invention.

FIG. 2 is a circuit block diagram of an optical writing head according to the first embodiment of the present invention.

FIG. 3 is a drive timing chart of an optical writing head according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a printing example by the color printer according to the first embodiment of the present invention.

FIG. 5 is a circuit block diagram of an optical writing head according to a second embodiment of the present invention.

FIG. 6 is a drive timing chart of an optical writing head according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of printing by a color printer according to a second embodiment of the present invention.

FIG. 8 is a circuit block diagram of an optical writing head according to a third embodiment of the present invention.

FIG. 9 is a drive timing chart of an optical writing head according to a third embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of printing by a color printer according to a third embodiment of the present invention.

FIG. 11 is a configuration diagram of a conventional color printer.

FIG. 12 is a circuit block diagram of a conventional optical writing head.

FIG. 13 is a driving timing chart of a conventional optical writing head.

FIG. 14 is a diagram illustrating a printing example using a conventional color printer.

[Explanation of symbols]

1 transfer unit, 2 fixing device, 3 transport belt,
Reference Signs List 10 paper, 11 paper detector, 12 photosensitive drum, 13 charging device, 14 optical writing head, 15 developing device, 16 transfer device, 17 cleaner, 20 driver IC, 21 LED array, 22 Y1 displacement setting circuit, 23, 61 delay Circuit, 24, 42 clock signal generation circuit, 25 data buffer, 26 load signal generation circuit, 27, 62 strobe signal generation circuit, 28, 63 displacement clock signal generation circuit, 2
9 detection signal generation circuit, 40 sub-register circuit,
41 X1 displacement setting circuit, 60 Y2 displacement setting circuit, 201 shift register circuit, 202 latch circuit, 203 gate circuit, 204 driver circuit, 211-21 m LED, 231 counter circuit, 232 comparison circuit

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hiroshi Toyama 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (6)

[Claims] 1. An optical writing printer for transferring toner adhered to an electrostatic latent image on the surface of a rotating photosensitive drum onto a paper sheet to be conveyed and moved, wherein the electrostatic latent image corresponding to print data is provided on the surface of the photosensitive drum. In an optical writing printer head for forming a latent image, a paper detecting means for outputting a detection signal when detecting that the paper has been transported to a predetermined position on a transport path, and a strobe for holding input print data. A light emitting unit that emits light in accordance with the print data when a signal is input; and the strobe that transfers the print data to the light emitting unit in synchronization with the detection signal and that is delayed by a predetermined time with respect to the detection signal. A light emission control unit for generating a signal and outputting the strobe signal to the light emission unit. 2. The sheet detection means has a sheet detector for detecting the sheet, and a detection signal generation circuit for generating the detection signal, and the sheet detector outputs the detection signal. The time required for the sheet to reach the toner transfer position is the time required from the output of the detection signal to the formation of an electrostatic latent image on the surface of the photosensitive drum and the time required for the electrostatic latent image to reach the toner transfer position. 2. The optical writing printer head according to claim 1, wherein the optical writing printer head is provided so as to be equal to the time or to be larger by a predetermined value. 3. The light emission control means includes: a delay setting circuit for externally setting a delay time of the strobe signal with respect to the detection signal; and a time corresponding to the setting of the delay setting circuit with respect to the detection signal. 3. The optical writing printer head according to claim 1, further comprising: a delay circuit that outputs a delayed reset signal; and a strobe signal generation circuit that generates a strobe signal in synchronization with the reset signal. 4. The light-emitting means is divided into n (n is a positive integer) light-emitting blocks, and the light-emitting control means is n delay setting circuits respectively corresponding to the n light-emitting blocks. And n number of the delay circuits and n number of the strobe signal generation circuits, and a k-th (k is any integer from 1 to n) delay circuit and a k-th strobe signal generation circuit Generating a k-th strobe signal delayed by a time corresponding to the setting of the k-th delay setting circuit from the input of the detection signal, and the k-th light-emitting block, when a strobe signal is input, generates a k-th strobe signal. 4. The optical writing printer head according to claim 3, wherein the light is emitted according to k block data. 5. The print data is n × m (m is a positive integer) bit serial data, and the light emitting means has an n × m (m is a positive integer) stage shift register circuit. The light emission control unit can externally set the correspondence between the register of the shift register circuit and the bit data of the print data. When the detection signal is input, the light emission control unit outputs the i-th print data according to the setting. (I is 0 or a positive integer) bit to (n ×
m) bits of data are transferred to the (n × m) -th to i-th registers of the shift register circuit, or the first bit to (n × m)
5. A bit shift means for transferring data up to (mi) bits to registers (n.times.mi) to (1) to (1) in the shift register circuit. The optical writing printer head according to any one of the above. 6. A tandem type color printer having a plurality of transfer units, wherein the optical writing printer head according to claim 1 is used for each transfer unit.