JPH0516425A - Print head - Google Patents

Abstract

PURPOSE:To provide an inexpensive print head by simplifying an external wiring and an external control mechanism. CONSTITUTION:A latch signal sent from outside is input to a driving control circuit X1 on the substrate. As a result, a plurality of strobe signals are generated inside, which are output to a gate circuit 4. An array of light emitting elements of a luminescent body 8 is driven per every block by a signal from the gate circuit. Accordingly, it becomes unnecessary to control the strobe signal outside, thus eventually dispensing with a connecting wiring between the outside and the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printhead in which a plurality of light emitting element arrays are arranged in a row, and more particularly to an improved structure of a drive portion of the printhead for time-divisionally driving the light emitting elements of the plurality of light emitting element arrays. Pertain.

[0002]

2. Description of the Related Art A large number of light emitting elements such as LEDs (light emitting diodes) arranged in high density
An LED printer is known as a device that records an image by an electrophotographic method or the like using an ED array.

Such a printer device is a device that selectively emits light from LEDs arranged in a line based on print data to write light on a photoconductor line by line and creates an image on a sheet by an electrophotographic process. is there.

However, a large number of light emitting elements are used in the above device, and these light emitting elements are driven by a relatively large current (for example, 5 to 15 per LED).
mA is required, one line is usually divided into a plurality of blocks and sequentially driven, or a plurality of LEDs are time-divisionally driven by one driving element.

(Prior Art 1) FIG. 13 shows a conventional example in which one line is divided into a plurality of blocks and sequentially driven.

FIG. 13 is a functional block diagram of a conventional LED print head. In the figure, reference numeral 12 denotes an LED print head, which includes a self-focusing rod lens array 11, a light-emitting body 8 in which a plurality of LED arrays are arranged in a row, and a light-emitting body 8. A driving unit 1 for driving the LED array, and these are mounted on a substrate.

The drive unit 1 is composed of a plurality of drive elements (driver ICs) having a drive circuit 6, a constant current control circuit 5, a gate circuit 4, a latch circuit 3 and a shift register 2.

FIG. 14 shows an example of the basic circuit configuration of the driver IC. The current control circuit 5 includes resistors R1 to R64, and the drive voltage VDD and the resistors R1 to R64 determine the current of each bit. For this, a constant current control circuit using a current mirror circuit may be used. The drive circuit 6 is composed of a source output type transistor array, and the gate circuit 4 is composed of an AND circuit for switching each output of the latch circuit 3 with a strobe signal. Further, the latch circuit 3 and the shift register 2 have a 64-bit configuration.

FIG. 15 is a circuit diagram of an A4 size, 300 dot / inch (dpi) LED print head using the driver IC shown in FIG. The luminous body 8 is 6
LED array L consisting of a 4-bit LED array chip
A total of 2560 LEs using 40 A1 to LA40
It is composed of D1 to LED2560. In addition, the driving unit 1 includes the 64-bit driver IC 4 shown in FIG.
I use 0.

A method of driving the conventional LED printhead constructed as described above will be described below. FIG. 16 shows a conventional L
The drive timing in printing one line of the ED print head is shown.

First, the serial print data of one line is set to D
It is sent from the ATA IN terminal to the shift register 2 in synchronism with a clock (CLOCK) signal, and the latch (L)
The ATCH) signal is used to latch the print data in the latch circuit 3.

The strobe signal is, as shown in FIG.
It is divided into four strobes of STROBE1 to STROBE4, and IC1 to IC10, ..., IC31 to IC, respectively.
Although it is connected to 10 driver ICs of 40, time-division driving of 1 line 4 divisions can be performed by sequentially making these signals active as shown in FIG.

(Prior Art 2) The above-mentioned prior art 1 is LE
One driver IC is used to drive one D array, but one driver IC is used to reduce the price.
There is also one using a dynamic drive unit that drives a plurality of LED arrays in a time-division manner.
Shown in.

FIG. 17 is a circuit diagram of an LED print head using this dynamic drive system. As shown,
The output terminals O1 to O64 of the driver IC are L
A common select circuit 7 that is connected to each of the 64 light emitting elements of the ED arrays LA1 to LA40 and that switches the cathode common electrode by a common select signal from the outside is mounted.

The common select circuit 7 includes output transistors Tr1 to Tr40 and respective transistors Tr1 to Tr40.
A circuit that turns on 40 one by one, for example, 40
It consists of a bit shift register (not shown).

FIG. 18 is a timing chart showing a driving method of the LED print head shown in FIG. Figure 1
The driving method will be described with reference to FIGS.

First, the print data corresponding to the LED array chips LED1 to LED64 in the first LED array LA1 is sent from the DATA IN terminal to the shift register 2 in synchronization with the clock signal, and then this data is sent by the latch signal. The latch circuit 3 is latched. Then, a common select signal is output to the common select circuit 7 to turn on the first transistor Tr1 so that the LED array LA1 can emit light.

When the strobe signal is turned on, L
The LED array chips LED1 to LED64 corresponding to the printing in the ED array LA1 emit light. At the same time when this strobe signal is turned on, the second LED array L
The print data corresponding to the printing in A2 is output to the shift register 2 in synchronization with the clock signal and is latched by the latch circuit 3 by the latch signal. After the LED array chips LED1 to LED64 are made to emit light for a period t required for printing, the strobe signal is turned off to stop the light emission.

Subsequently, in the same manner as described above, the print data corresponding to the LED array LA3 is input and latched, and at the same time, the strobe signal is turned on to the transistor Tr2 to set L.
LED corresponding to print data in ED array LA2
The array chips LED65 to LED128 are caused to emit light.

As described above, the LED arrays LA1 to LA1
LA40 LED array chip LED1 to LED256
0 is sequentially emitted to print.

[0021]

However, the conventional LED
In the print head, in any method,
It is necessary to control the drive unit 1 with at least input signals such as print data, clock signal, latch signal, strobe signal, and the LED arrays LA1 to L1.
A common select signal for sequentially selecting the common electrode of A40 must be input. Therefore, there are many connections to connect to the outside, and considering that much connector,
Requires a lot of space. Further, the drive control is complicated and the load on the drive side becomes large, and in view of the external control circuit and the control program, the efficiency is not good in terms of price and dimensions.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a print head which has a relatively simple circuit, has a small number of wirings connected to the outside, is easy to control, and is inexpensive.

[0023]

1 to 4, a plurality of light emitting element arrays LA1 to LA40 having a plurality of light emitting elements LED1 to LED2560 corresponding to printing dots are provided. And a drive unit 1 for driving the light emitting element arrays LA1 to LA40, wherein the plurality of light emitting element arrays LA1 to LA40 are divided into a plurality of blocks, and each block is driven in a time division manner with different strobe signals. The light emitting elements LED1 to LED1
In the print head in which the light of the LED 2560 is projected on the photoconductor to form an electrostatic latent image, the drive unit 1
The gate circuit 4 has a shift register 2 for inputting print data, a latch circuit 3 for latching the print data input to the shift register 2, and a gate circuit 4 for switching the data of the latch circuit 3. A drive control circuit X1 for automatically generating a strobe signal to be output based on a latch signal from the outside is provided.

According to a second aspect of the present invention, the drive control circuit X1 according to the first aspect includes a pulse counter Ct1 for counting the clock signal transmitted from the outside for a period corresponding to the pulse width of the strobe signal. The decoder Dc1 comprises a block number counter Ct2 for counting the carry-out signal from the pulse counter Ct1 by the number of blocks of the light emitting element arrays LA1 to LA40 and a decoder Dc1 for decoding the output signal from the block number counter Ct2. Is configured to output the strobe signal according to claim 1.

A means for solving the problems according to claim 3 of the present invention is to provide a plurality of light emitting elements L corresponding to printing dots as shown in FIGS.
A plurality of light emitting element arrays LA1 to LA40 having ED1 to LED2560, and the light emitting element arrays LA1 to LA4
Drive unit 1 for driving the light emitting element array L
A1 to LA40 are driven in a time division manner, and the light emitting element LE is
In the print head in which the light of D1 to LED 2560 is projected onto the photoconductor to form an image to form an electrostatic latent image, the drive unit 1 shifts the print data into the shift register 2 and the print input to the shift register 2. A latch circuit 3 for latching data and a gate circuit 4 for switching the data of the latch circuit 3 are provided, and a latch signal for the latch circuit 3 and a strobe signal for the gate circuit 4 are generated based on a clock signal input from the outside. And a drive control circuit X2 for automatically generating

According to a fourth aspect of the present invention, in the drive control circuit X2 according to the third aspect, the light emitting elements LED1 to LED1 are provided.
The common select circuit section 22 for sequentially driving the common electrodes C1 to C40 of the LED 2560 is provided.

According to a fifth aspect of the present invention, the drive control circuit X2 according to the fourth aspect includes a bit number counter Ct3 for counting the clock signal by the number of light emitting elements in each of the light emitting element arrays LA1 to LA40. The carry-out signal of the bit number counter Ct3 is sent to the light emitting element array LA.
1 to LA40, which is composed of an array number counter Ct4 that counts a number corresponding to the number of 1 to LA40, and a decoder Dc2 that decodes the output from the array number counter Ct4. It is configured to switch C1 to C40.

The means for solving problems according to claim 6 of the present invention is, as shown in FIGS. 9 to 12, a plurality of light emitting element arrays LA1 to LA40 having a plurality of light emitting elements LED1 to LED2560 corresponding to printing dots, and the light emitting element array LA1. ~ LA
And a drive unit 1 for driving the light emitting element array LA1 to LA40 driven in a time division manner.
In the print head in which the light of ED1 to LED 2560 is projected and imaged on a photoconductor to form an electrostatic latent image, the drive unit 1 is input to the shift register 2 for inputting print data and the shift register 2 for inputting print data. A latch circuit 3 for latching print data and a gate circuit 4 for switching the data of the latch circuit 3 are provided, and a latch signal for the latch circuit 3 and a strobe signal for the gate circuit 4 are generated based on a clock signal from the outside. A drive control circuit X3 that is automatically generated and light-emitting elements LED1 to LED25
A common select circuit 31 for sequentially driving the common electrodes C1 to C40 of 60 is provided. The common select circuit 31 forms a select signal from a carry-out signal generated by the drive control circuit X3. And a shift register section 36 controlled by the select signal from the select signal generating section 35, and the light emitting element array LA according to the output of the shift register section 36.
1 to LA 40 and a driver section 37 for turning on / off the common electrodes C1 to C40.

[0029]

In the means for solving the problems according to claims 1 and 2, the drive control circuit X1 outputs the latch signal transmitted from the outside.
Input to the pulse counter Ct1. Pulse counter C
At t1, the number of blocks is counted based on the latch signal, and a carry-out signal is output to the block number counter Ct2. The block number counter Ct2 counts the number of blocks of the light emitting element arrays LA1 to LA40 based on the carry-out signal and outputs a count signal to the decoder Dc1. Then, the decoder Dc1 decodes and internally generates a plurality of strobe signals, and outputs the strobe signals to the gate circuit 4. The strobe signals drive the light emitting element arrays LA1 to LA40 for each block. This eliminates the need for external strobe signal control and the connection wiring necessary for this.

In the first aspect, only the strobe signal is internally generated. However, in the problem solving means according to the third aspect, in addition to the strobe signal, the latch signal is internally generated in the drive control circuit X2. Therefore, external control of the latch signal and strobe signal and the connection wiring necessary for this are unnecessary.

In the means for solving the problems according to claims 4 and 5, the clock signal is input to the bit number counter Ct3 of the drive control circuit X2. The bit number counter Ct3 is LE
The number of light emitting elements in the D arrays LA1 to LA40 is counted, and a carry-out signal is output to the array number counter Ct4. The array number counter Ct4 counts the number corresponding to the number of the light emitting element arrays LA1 to LA40 based on the carry-out signal, and outputs the count result to the decoder Dc2. The decoder Dc2 decodes the common electrodes C1 to C40 of the light emitting elements LED1 to LED2560.
Are sequentially driven using only the clock signal. This makes it possible to omit the common electrode control from the outside and the connection wiring necessary for this.

In the problem solving means according to the sixth aspect, when a clock signal is input to the drive control circuit X3, the drive control circuit X3 sends a carry-out signal to the select signal generating section 35 of the common select circuit 31 based on this clock signal.
Output to. The select signal generator 35 controls the shift register 36 based on the carry-out signal to turn on / off the common electrodes C1 to C40 of the light emitting elements LED1 to LED2560. Thus, only by using the clock signal, the light emitting element arrays LA1 to LA1 are similar to the fourth and fifth aspects.
A40 can be time-division driven.

[0033]

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

(First Embodiment) FIG. 1 is a schematic circuit block diagram of a print head according to a first embodiment of the present invention, FIG. 2 is the same circuit diagram, and FIG. 3 is a similar internal circuit block diagram of a drive control circuit. FIG. 4 is a timing chart showing a driving method for printing the one line. Note that FIG.
Throughout the drawings, the same functional parts as those of the conventional technique shown in FIG.

As shown in FIGS. 1 and 2, the print head P of this embodiment is applied to, for example, an image forming apparatus of A4 size and 300 dpi, and includes 40 light emitting element arrays (LED arrays) LA1 to LA1. LA40 has 64 light emitting elements LED1 to LED64, LED65 to LED12, respectively.
.., LED2496 to LED2560, and a drive unit 1 for driving these in a time division manner is provided. The drive unit 1 is provided for each of the LED arrays LA1 to LA40.
A total of 40 drive elements I arranged so as to correspond to each other
A drive control circuit X1 including C1 to IC40 (driver IC) and automatically generating a strobe signal to be transmitted to the drive unit 1 is provided.

The LEDs 1 to 2560 have their cathode terminals commonly connected and grounded to the GND 2, and are mounted in a line on the substrate to form the light-emitting body 8. Then, the LED arrays LA1 to LA40 are 10
Each block is divided into four blocks, and each block is driven by four different strobe signals from the drive control circuit X1 as described later.

IC1 to IC40 of the driving unit 1 are as shown in FIG.
The same as the conventional one shown in 0, a 64-bit shift register 2, a 64-bit latch circuit 3, a gate circuit 4,
A current control circuit 5 and a drive circuit 6 are built in.

The shift register 2 is, as shown in FIG.
The latch circuit 3 is connected to the COLCK terminal and the DATA IN terminal, and the latch circuit 3 is connected to the LATCH terminal.

The gate circuit 4 is an AND circuit for switching each output of the latch circuit 3 with a strobe signal.
It is composed of circuits G1 to G64, and is connected to the STROBE terminal through an inverter 20.

The current control circuit 5 is composed of resistors R1 to R64 and is the same as the conventional one in which the current of each bit is determined by the drive voltage VDD and the resistors R1 to R64.

The drive circuit 6 includes a transistor Tr.
1 to Tr64, and as shown in FIG. 2, 64 bit outputs O1 to O64 of the circuit 6 are LE of 64 dots, respectively.
It is connected in parallel to the anode terminals of the D arrays LA1 to LA40. That is, the output O1 is LED1, LED65,
..., LED2496, O2 is LED2, LED66,
2497, output O64 is LED64, LED12
, ..., LED 2560, respectively.

As shown in FIG. 3, the drive control circuit X1 is mounted on the substrate by forming a chip in a gate array. The drive control circuit X1 uses a clock signal for synchronously sending print data to the shift register 2. Pulse counter Ct1 for outputting a carry-out signal having a constant width, and a block number counter Ct2 for counting the number corresponding to the block number of the light emitting element arrays LA1 to LA40 based on the carry-out signal from the pulse counter Ct1.
And a decoder Dc1 for decoding the output signal from the block number counter Ct2 and outputting a strobe signal to the gate circuit 4.

The pulse counter Ct1 is a counter for determining the pulse width of the strobe signal. For example, when a clock signal with a period t = 1 μs is input and the pulse width is 100 μs, it becomes a 100-base counter. A carry-out signal is generated each time 100 clock signals are counted.

The block number counter Ct2 counts the carry-out signal from the pulse counter Ct1 and outputs a binary output signal for switching the strobe signal according to the count number to the decoder Dc1.

The decoder Dc1 decodes the binary signal from the block number counter Ct2 to obtain four L signals.
Different strobe signal STR for each ED array block
Outputs OBE1 to STROBE4.

Incidentally, as shown in FIG. 3, when a latch signal is input, both the counters Ct1 and Ct2 are reset and the latch signal is transmitted to the latch circuit 3.

In FIG. 1, Re is the light emitting element array LA1.
Is a self-focusing rod lens array for forming an electrostatic latent image by projecting light from the LA 40 on a photoconductor and forming an image.

Next, the drive timing of the LED print head of this embodiment will be described with reference to FIG. First, the clock signal is transmitted to the shift register 2 and the pulse counter Ct1 of the drive control circuit X1, and serial print data for one line is input to the shift register 2 in synchronization with the clock signal. Next, the latch signal is sent to the drive control circuit X1.
To both counters Ct1 and Ct2. in this way,
Only the above three signals are input from the outside. Here, both counters Ct1 and Ct2 are reset based on the latch signal.

If the pulse counter Ct1 is an n-ary counter, the pulse counter Ct1 counts n clock signals and then the block number counter C
The carry-out signal is output to t2, and the block number counter Ct2 counts the carry-out signal. When the decoder 13 decodes the binary output signal of the block number counter Ct2, strobe signals ST1 to ST4 are sequentially output in synchronization with the carry-out signal, as shown in FIG. Here, when the cycle of the clock signal is t, the pulse width Tp of the strobe signal is Tp = n × t. Since the present embodiment is of A4, 300 dpi, the number of serial print data for one line is 25.
There are 60, and assuming that one line period is T1, T1> 2560 × t> 5 × Tp. Therefore, the decoder Dc1 receives four strobe signals ST at the time when 2560 clock signals are input.
It suffices to configure so that ROBE1 to STOROBE4 are completely output and five or more strobe signals are not output.

After the print data for one line is input,
When the latch signal is input again, both counters Ct are input again.
1 and Ct2 are reset to prepare a strobe signal for the next line printing, and the print data is latched by the latch circuit 3. The printing of this print data is
The strobe signal is generated when the print data of the next line is input.

As described above, in the LED print head which is driven in a time division manner by a plurality of strobe signals, by configuring the drive control circuit by a relatively simple circuit,
Printing can be performed without applying a strobe signal from the outside, and the strobe signal input terminal can be omitted as compared with the prior art 1 shown in FIG. Therefore, it is possible to provide the LED print head which is simple and can reduce the space for the connector and the like.

(Second Embodiment) FIG. 5 is a schematic circuit block diagram of a print head according to a second embodiment of the present invention, FIG. 6 is the same circuit diagram, and FIG. 7 is a diagram showing the number of internal circuit blocks of the drive control circuit. FIG. 8 is a timing chart showing a driving method for printing one line.

As shown in FIGS. 5 and 6, the LED print head of this embodiment has the same A4 size and 300 dp as the first embodiment.
i driver, one driver I mounted on the board
A plurality of LED arrays LA1 to L are provided in the driving unit 1 including C.
When the A40 is time-divisionally driven dynamically, only the print data and the clock signal are used in relation to the outside.

LED arrays LA1 to LA40 of this embodiment
6, the cathode terminals are commonly connected to each LED array to form common electrodes C1 to C40, which are arranged in rows.

The drive control circuit X2 of this embodiment is
A micro computer chip having a CPU, a ROM, and a RAM is mounted on a substrate, and a latch signal for a latch circuit 3 and a strobe signal for a gate circuit 4 are automatically generated based on only the clock signal. Let

The internal structure of the drive control circuit X2 is as follows.
As shown in FIG. 7, the clock signal is sent to each of the LED arrays LA1 to LA1.
A bit number counter Ct3 that counts only the number of light emitting elements (64-ary) that A40 has, and the bit number counter Ct3
Internal gate circuit Ga1 for outputting a latch signal and a strobe signal based on a carry-out signal generated by
And a common select circuit section 22 for sequentially switching the common electrodes C1 to C40 of the LED array in synchronization with the carry-out signal.

The common select circuit section 22 outputs a carry-out signal L generated by the bit number counter Ct3.
Number corresponding to the number of ED arrays LA1 to LA40 (40 + 1
An array number counter Ct4 that counts only the number of steps), output transistors Tr1 to Tr40 for sequentially switching the common electrodes of the LED arrays LA1 to LA40,
It is composed of a decoder Dc2 for decoding the output of the array number counter Ct4 and sequentially turning on the output transistors Tr1 to Tr40.

The LED arrays LA1 to LA of this embodiment are
Since the internal configuration of the A40 and the driver IC that constitutes one drive unit 1 are the same as those in the first embodiment, their description will be omitted.

Next, the operation of the LED print head of this embodiment will be described with reference to FIG.

First, 64-bit print data corresponding to the first LED array LA1 is transmitted from the DATA IN terminal to the shift register 2 in synchronism with the clock signal, and a 64-bit bit counter of the drive control circuit X2. The clock signal is transmitted to Ct3. The bit number counter Ct3 sends a carry-out signal to the internal gate circuit Gt1.
The internal gate circuit Gt1 outputs the latch signal to the latch circuit 3 in synchronization with the carry-out signal.
After the above process, the 64-bit print data is latched by the latch circuit 3.

On the other hand, the 40-ary array number counter Ct4 which received the carry-out signal from the bit number counter Ct3 counts up by one. Then, when this counter output is output to the decoder Dc2, the decoder Dc2 first turns on the first transistor Tr1 to make the corresponding first LED array LA1 ready for light emission. At this time, at the same time, the strobe signal is output from the internal gate circuit Ga1, the gate circuit 4 of the driving unit 1 turns on the output bit based on the print data corresponding to the LED array LA1, and only the LED array LA1 outputs the print data. It will emit light correspondingly.

Subsequently, the second LED array LA
When 64 bit print data corresponding to 2 is input together with the clock signal, a latch signal is generated in the same manner as the above-mentioned operation, so that the latch circuit 3 of the driver IC latches the 64 bit data. Further, since the array number counter Ct4 further performs another count-up, the decoder Dc2 turns on the second transistor Tr2 to make the second LED array LA2 ready to emit light. Then, similarly to the above, at this time, since the strobe signal is also input to the drive unit 1, the LED array LA2
Emits light corresponding to print data. By further inputting the data and the clock signal, the LED arrays LA3 to LA40 sequentially emit light according to the print data in the same manner as described above, and the printing operation for one line is completed.

In FIG. 8, after the print data corresponding to the last LED array LA40 is input, a further 6
Inputting 4 clocks is the strobe signal pulse width for the LED array LA40 and the transistor Tr4.
This is because the on time of 0 is determined. Therefore, the array number counter is 1 plus 1 to the number of LED arrays.
A counter for counting, that is, a 41-ary counter is used.

As described above, the LE of the dynamic drive system is used.
In the D print head, the print data latch, the LED array light emission by the strobe signal, and the switching of the common electrode of the LED array can be automatically performed only by inputting the print data and the clock signal.

Therefore, as shown in FIG. 6, it suffices to provide only the clock terminal except for the data in / out, and to provide an LED print head which has a small number of external connections, is easy to drive, and is relatively inexpensive. it can.

(Third Embodiment) FIG. 9 is a schematic circuit block diagram of a print head according to a third embodiment of the present invention, FIG.
11 is a circuit diagram of the same, FIG. 11 is a block diagram of internal circuits of a drive control circuit and a common select circuit, and FIG. 12 is a timing chart showing a driving method in printing of one line.

As shown in FIGS. 9 and 10, the print head of this embodiment automatically generates a latch signal for the latch circuit 3 of the drive unit 1 and a strobe signal for the gate circuit 4 based on the clock signal from the outside. Drive control circuit X3, a common select circuit 31 for sequentially driving the common electrodes C1 to C40 of the light emitting elements LED1 to LED2560, and a reset circuit 32 for resetting these.
And are provided.

The drive control circuit X3 counts the clock signal by the number of light emitting elements 64 of each light emitting element array (64-ary), and the latch signal based on a carry-out signal generated by the counter section 33. And a gate circuit 34 for forming a strobe signal.

The common select circuit 31 includes a select signal generator 35 that forms a select signal from the carry-out signal generated by the counter 33 of the drive control circuit X3 and the reset signal output from the reset circuit 10, and the select signal. A 40-bit shift register section 36 controlled by a select signal from the generating section 35, and the LED arrays LA1 to LA1 according to the output of the shift register section 36.
It is composed of a driver section 37 for turning on / off the common electrodes C1 to C40 of the LA 40. The driver unit 37 is composed of 40 transistors D1 to D40. Each bit output of the shift register section 36 is connected to the base electrodes of the transistors D1 to D40 of the driver section 37.

The other structural parts, for example, the driving part 1 and the light-emitting body 8 are the same as those in the second embodiment, and therefore their explanations are omitted.

The operation of the print head will be described with reference to FIG. First, the 64-bit serial print data corresponding to the first array LA1 is input to the drive unit 1 in synchronization with the clock signal, and the drive control circuit X
3 to the 64 base counter section 33. Counter unit 33
Outputs a carry-out signal to the gate unit 34. The gate unit 34 forms a latch signal from the carry-out signal and each bit output of the counter unit 33, and inputs the latch signal to the latch circuit 3 of the driving unit 1 so that the printing data of 64 bits is latched to the driving unit 1. To be done. On the other hand, in the common select circuit 31, the reset signal formed by the reset circuit 32 and the carry-out signal from the counter section 33 of the drive control circuit X3 are transmitted to the select signal generating section 35, which then sends them to the select signal generating section 35. A shift data signal and a shift clock signal are formed in accordance with the above, and the 40-bit shift register unit 36 of the driving unit 1 is controlled. Then, the shift register section 36 turns on the output bit based on the select signal, that is, C1 shown in FIG. 10, so that only the first light emitting element array LA1 emits light corresponding to the print data.

Subsequently, the second light emitting element array L
When 64 bit print data corresponding to A2 is input together with the clock signal, a latch signal is generated in the same manner as described above, so that the latch circuit 3 of the driving unit 1 latches the 64 bit data. In addition, the shift register unit 36 of the common select circuit 31 outputs 1 by the shift clock signal.
Bit shift is performed to turn on C2 shown in FIG. 10 to bring the light emitting element array LA2 into a state capable of emitting light. At this time, similarly to the above, since the strobe signal is also input to the drive unit 1, the light emitting element array LA2 emits light corresponding to the print data.

Further, by inputting the data and the clock signal, the light emitting element arrays LA3 to LA40 sequentially emit light according to the print data in the same manner as described above, and the printing operation for one line is completed.

When the print data and the clock signal of the second line are continuously input, the drive unit 1 is driven in the same manner as the previous period, but the common select circuit 31 is as follows from the second line. To drive. That is, the shift data for the shift register section 36 in the common select circuit 31 is not formed by the reset signal from the reset circuit 32, but a carry-out signal generated by the counter section 33 of the drive control circuit X3 is generated as a select signal. It is formed by counting 41 to the base 35. However, the shift clock is formed similarly to the first line.

As described above, the driving unit 1 is line by line.
And the common electrode C of the light emitting elements LED1 to LED2560
1 to C40 are controlled and sequentially printed, and similarly to the second embodiment, the LED print head of the dynamic drive system can be driven only by inputting the print data and the clock signal.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, in the above embodiment, the LED print head of A4 size and 300 dpi has been described, but it goes without saying that it may be compatible with other sizes.

In the first embodiment, the driver IC
It was provided to correspond to the LED array one by one,
A single driver IC may drive a plurality of LED arrays dynamically. In this case, for example, the gate circuits and the drive circuits may be provided in one driver IC by the number of blocks so that each block can be driven.

Further, in the first embodiment, as described in claim 3, only the clock signal is input to the drive control circuit, and the latch signal and the strobe signal are generated in the drive control circuit based on the clock signal. May be.

Furthermore, in the second and third embodiments,
It is also possible to divide the LED array into a plurality of blocks, provide driver ICs for the number of blocks, and drive the LED arrays for each block in a time division manner. In this case, in the block driven in each time division, the common select circuit may be driven in time division.

[0081]

As is apparent from the above description, according to the first aspect of the present invention, the drive control circuit for automatically generating a plurality of strobe signals based on the latch signal from the outside is provided. It is possible to omit the strobe signal control and the connection wiring to the outside such as a connector necessary for this.

According to claim 2 of the present invention, the drive control circuit includes a pulse counter for counting the clock signal from the outside, a block number counter for counting the carry-out signal from the pulse counter by the number of blocks, and a block number counter. Since it is composed of a decoder for decoding the output signal of, the plurality of strobe signals can be output with a simple structure.

According to the third aspect of the present invention, since the drive control circuit for generating the latch signal to the latch circuit and the strobe signal to the gate circuit based on the clock signal from the outside is provided, the latch signal to the outside is provided. Also, the wiring for connecting the strobe signal control mechanism to the outside, such as a connector, can be omitted.

According to claim 4 of the present invention, since the drive control circuit according to claim 3 is provided with the common select circuit portion for sequentially driving the common electrodes of the light emitting elements, a plurality of clock signals are utilized only. LED arrays LA1 to LA
40 can be driven in a time-division manner, and the common electrode control on the outside and the connection wiring with the outside such as the connector necessary for this can be omitted.

According to claim 5 of the present invention, the drive control circuit includes a bit number counter for counting the clock signal,
An array number counter that counts the carry-out signal of the bit number counter according to the number of light emitting element arrays,
Since it is composed of a decoder which decodes the output from the array number counter, it is possible to provide a print head which is compact and inexpensive in driving the light emitting elements in a time division manner and which is easy to drive in dynamics.

According to the sixth aspect of the present invention, the drive control circuit for automatically generating the latch signal and the strobe signal based on the clock signal from the outside, and the common of the light emitting elements based on the carry-out signal of the drive control circuit. Since the common select circuit for sequentially driving the electrodes is provided, the plurality of LED arrays LA1 to LA40 can be driven in a time division manner by using only the clock signal as in the third and fourth embodiments. It is very advantageous that the light emitting element can be easily driven in a dynamic manner while reducing the number of wirings to be connected to the outside such as a connector.

[Brief description of drawings]

FIG. 1 is a schematic circuit block diagram of a print head according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the same.

FIG. 3 is a block diagram of the internal circuit of the drive control circuit.

FIG. 4 is a timing chart showing a driving method for printing the one line.

FIG. 5 is a schematic circuit block diagram of a print head according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram of the same.

FIG. 7 is a block diagram of the internal circuit of the drive control circuit.

FIG. 8 is a timing chart showing a driving method in the printing of one line.

FIG. 9 is a schematic circuit block diagram of a print head according to a third embodiment of the present invention.

FIG. 10 is a circuit diagram of the same.

FIG. 11 is a block diagram of internal circuits of a drive control circuit and a common select circuit, similarly.

FIG. 12 is also a timing chart showing a driving method in the printing of the one line.

FIG. 13 is a basic functional block diagram of a print head according to the related art 1.

FIG. 14 is a schematic circuit block diagram of the same.

FIG. 15 is a circuit diagram of the same.

FIG. 16 is a timing chart showing a driving method in the printing of the same line.

FIG. 17 is an example of a block circuit of a printhead according to the related art 2 in which a common select circuit is mounted.

FIG. 18 is a timing chart showing a driving method in the printing of one line.

[Explanation of symbols]

1 drive 2 shift registers 3 latch circuits 4 gate circuit 5 Constant current control circuit 6 Drive circuit 22 Common select circuit 31 Common Select Circuit 35 Select signal generator 36 Shift register section 37 Driver LA1 to LA40 light emitting element array X1 to X3 drive control circuit Ct1 to Ct4 counter Dc1, Dc2 decoder C1-C40 common electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Fujiwara             22-22 Nagaikecho, Abeno-ku, Osaka-shi             Within the corporation

Claims (6)

[Claims] 1. A plurality of light emitting element arrays having a plurality of light emitting elements corresponding to printing dots, and a drive section for driving the light emitting elements, wherein the plurality of light emitting element arrays are divided into a plurality of blocks, In the print head, which is driven in time division by different strobe signals for each block and projects the light of the light emitting element onto the photoconductor to form an electrostatic latent image, the drive section inputs print data. Shift register, a latch circuit that latches the print data input to the shift register, and a gate circuit that switches the data of the latch circuit. The strobe signal output to the gate circuit is a latch signal from the outside. A printhead, which is provided with a drive control circuit which is automatically generated based on the above. 2. The drive control circuit according to claim 1, wherein a pulse counter for counting a clock signal transmitted from the outside only for a period corresponding to the pulse width of the strobe signal, and a carry-out signal from the pulse counter for the light emitting element. A block number counter for counting the number of blocks in the array and a decoder for decoding an output signal from the block number counter, the decoder being configured to output the strobe signal according to claim 1. And print head. 3. A light emitting element array having a plurality of light emitting elements corresponding to printing dots, and a drive section for driving the light emitting element array, wherein the light emitting element array is driven in a time division manner, and the light emitting element is driven. In the printhead for projecting and forming an image of light on a photoconductor to form an electrostatic latent image, the drive unit includes a shift register for inputting print data and a latch for latching the print data input in the shift register. Drive control for automatically generating a latch signal for the latch circuit and a strobe signal for the gate circuit based on a clock signal input from the outside. A printed head provided with a circuit. 4. The print head according to claim 3, further comprising a common select circuit section for sequentially driving the common electrodes of the light emitting elements. 5. The drive control circuit according to claim 4, wherein a bit number counter for counting the clock signals by the number of light emitting elements in each light emitting element array, and a carry-out signal of the bit number counter for the number of light emitting element arrays. A print comprising an array number counter for counting a number corresponding to the number and a decoder for decoding the output from the array number counter, and the output of the decoder is configured to switch the common electrode of the light emitting element array. Head. 6. A plurality of light emitting element arrays having a plurality of light emitting elements corresponding to printing dots, and a drive unit for driving the light emitting element arrays, wherein the light emitting element array is driven in a time division manner, and the light emitting elements are driven. In the print head that projects and forms the light of the above onto a photoconductor to form an electrostatic latent image, the drive unit includes a shift register for inputting print data and a latch for latching the print data input in the shift register. A drive control circuit for automatically generating a latch signal for the latch circuit and a strobe signal for the gate circuit on the basis of an external clock signal, and a gate circuit for switching the data of the latch circuit. And a common select circuit for sequentially driving the common electrodes of the light emitting elements, the common select circuit comprising the drive control circuit. A select signal generating section for forming a select signal from a carry-out signal generated by a path, a shift register section controlled by the select signal from the select signal generating section, and an output of the shift register section according to the output of the shift register section. A printed head comprising a driver section for turning on and off a common electrode.