JPH02235660A - Controller for driving light emitting element - Google Patents

Abstract

PURPOSE:To reduce the cost, which is achieved by decreasing the number of signal lines and obviating the need of a large scale buffer, and to prevent the occurrence of noise by permitting a common signal generating part to apply a select signal to each set of light emitting element integrated arrays via a low current output buffer. CONSTITUTION:An LED head 8 is provided with segment drivers 21-1 to 21-4, LED arrays D1 to D40, a common signal generating circuit 2, etc. The segment drivers 21-1 to 21-4 are composed of a shift register 25, a latch circuit 26, an AND gate 27, a constant current buffer 28 and a buffer 29. A control signal CTR is input to the constant current buffer 28 via a terminal I6, and the buffer 28 controls the current value thereof, and outputs input video data D to the corresponding LED arrays from outputs Y1 to Y64. Each of the LED arrays D1 to D40 is formed with 64 LEDL1 to L64. However, this controller does not require a large buffer which discentralizingly supplies common signals C1 to C10 lighting and driving the LEDL1 to L64.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an LED printer in which light emitting elements are arranged in a row;
The present invention relates to devices such as EL printers and facsimile machines, and particularly relates to a light emitting element drive control device that controls the driving of light emitting elements.

[Conventional technology]

As a device in which light emitting elements are arranged in a row, for example, L
2. Description of the Related Art LED printers equipped with ED (light emitting diode) light emitting elements are known. Such a printer device is a device that selectively emits light from light emitting elements arranged in a row based on print data, writes light onto a photoreceptor every line, and creates an image on paper by an electrophotographic process.

However, the number of light-emitting elements used in the above-mentioned device is large, and these light-emitting elements require a large current (for example, 10 to 15 yen per one light-emitting element) to drive. It drives the element. FIG. 9 is a diagram showing a conventional drive circuit for a light emitting element. Each light emitting element array D1 to D4. are each formed with 64 light emitting elements, and each of 4 light emitting element arrays D, ~D. , D.S.
~Da%...D3, ~D4. One end of the light emitting element inside is connected to the corresponding outputs Y, ~Y, 4 of the four segment drivers 1-1 to 1-4, and the other end is connected to the common driver C.
Connected to any one of OM1 to COMIO.

The light emitting elements are driven by common drivers COMI to CO.
A common signal C 1 '' C 10 is sequentially supplied to MIO via buffers 2-1 to 2-10, and sequentially to each light emitting element array D, to D4, D, to Da...D, 7 to D,. It outputs a common signal.It also inputs video data D to the cascade-connected segment drivers 1-1 to 1-4 in synchronization with the output of the clock signal CK, and further inputs this video data D latched by a latch signal LA. Strobe signals (STBI to STB) are output from Y1 to Y64.
By outputting to the light emitting element array according to the output of 4), the light emitting element array D. - Lighting control of each light emitting element in D4. This process is performed on the light emitting element arrays D, -D. -D,
~I) tz-...-Dhff~D4. The common signals C, .about.C, which are sequentially output up to . By repeating the following, one line of optical writing is performed in a time-division manner.

Further, FIG. 10 is a diagram showing a part of another conventional example of a light emitting element drive control circuit. In addition, segment driver 1-1~
1-4, LED array D, ~D4.

The configuration is the same as that shown in FIG. In this conventional example, each light emitting element array D l-D is similar to the conventional example shown in FIG.
a. is the common signal C. -C. . Controls the lighting of the built-in light emitting elements according to the input. However, in the case of the conventional example shown in FIG. 9, bumpers 2-1 to 2-10 and common drivers COMI to COMIO are used, but in this conventional example, the first
As shown in Figure 0, common signals C, ~C,. To generate the output, two shift registers 3-1 and 3-2 are connected in cascade and used. In this case, common data (COM-
High (H) signal (data '1') only at the initial time as D)
) is input to the A and B portions of the shift register 3-1 in synchronization with the clock signal (CLK), and thereafter the common data is sequentially shifted to the right in synchronization with the clock signal as shown in FIG. That is, in synchronization with the input of the clock signal, the output QA of the shift register 3-1 is
．． →H in the order of output QA-Qll of shift register 3-2
Common signals C, .about.CIO are output to the LED array via the corresponding buffer 4 and current limiting resistor 5. These common signals 01 to Cl6 cause the respective LED arrays D1 to D, as in the above conventional example. The light emitting elements inside are driven in a time division manner.

[Problems with conventional technology]

The following problems occur in the conventional drive control device for a light emitting element as described above.

(b) In the drive control device shown in FIG. 9, the number corresponding to the number of time divisions (for example, in the above example, the common signal C, ~
For example, in an LED printer, the controller that outputs the common signals C, ~CIO and the LED array D. ~D4. The number of wires between the LED array boards on which LED array boards are arranged increases.

(Explanation) In the drive control device shown in FIG. 10, each of the four corresponding LED arrays D, ~Da + is controlled by one common signal.
D5 = Ds + ”・D3?”' Since it is necessary to supply a common current to the 64×4 light emitting elements formed in D40, it is necessary to flow a large common current, and the buffer 4 is used for large current supply. Need a sofa.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a light emitting element drive control device that reduces the number of signal lines and does not require a large current buffer.

[Key points of the invention]

According to the present invention, the above-mentioned object includes a light-emitting element accumulation part formed by arranging a light-emitting element accumulation array in which a plurality of light-emitting elements are integrated in a predetermined number of rows; a segment signal generation section that supplies a drive signal based on the above, and a common signal generation section that applies a selection signal in a time-sharing manner to a set of a predetermined number of the light emitting element integrated arrays, the common signal generation section This is achieved by providing a light emitting device drive control device characterized in that a selection signal is applied to each set of light emitting device integrated arrays through a low current output buffer.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

This example describes an LED drive control device using an LED as a light emitting element, and FIG.
1 is an overall configuration diagram of an ED printer to which an ED drive control device is applied. In the figure, the LED printer P includes a photoconductor drum 6, a charger 7, an LED head 8, a developer 9, and a transfer device 10, which are sequentially arranged near the circumferential surface of the photoconductor drum 6.
, the cleaner l1, and the feed roller 13 from the paper feed cassette 12.
The sheet conveying mechanism includes a slip roll 14, a resist plate 15, a fixing roll 16, a wandering roll 17, and guide plates 18a to 18c for conveying the sheet T-t conveyed by the printer. Furthermore, an interface controller board Fil9 provided with an interface controller circuit and a printer controller board 20 provided with a printer controller circuit are disposed below the LED printer P. The interface controller circuit is a circuit that receives print data output from a host device (not shown) and converts it into video data, and the printer controller circuit controls each part including the LED elements in the LED head 8 according to the video data. It is also a circuit that controls the application of high voltage to the charger 7, the transfer device 10, etc., and controls the driving of other parts of the electrophotographic process. The charger 7 is a device that applies an initial charging voltage to the photoconductive surface of the photoconductive drum 6 rotating in the direction of arrow A, and the LED head 8 is a device that exposes the photosensitive surface based on video data, which will be described in detail later. The developing device 9 is a device that converts the electrostatic latent image formed on the photosensitive surface by the above-mentioned exposure into a toner image, and the transfer device 10 is a device that transfers this toner image onto the paper T. Further, the cleaner l1 is a device for removing toner remaining on the light-separating surface, and the fixing roll 16 is a device for conveying the paper onto which the toner image has been transferred and thermally fixing the toner image on the paper.

FIG. 1 is a diagram showing a detailed configuration of the LED head 8, which includes segment drivers 21-1 to 21-2.
1-4, LED array DI"' D a., common signal generation circuit 22, bias resistor R.-R,.

and low current transistors Q, ~Q,. It consists of
Bias resistance R, ~R1. and transistor Q, ~Q,.

These constitute transistor circuits 23-1 to 23-10. Each LED array DI~D.

For example, Zn is selectively diffused into an n-type GaAsP layer epitaxially grown on an n-type GaAs substrate through a photomask to form a p-type CaAsP, and a large number of LED elements are created by wiring this. ing. The above-mentioned photosensitive surface is exposed to light by these LED arrays D, to D4. Each LED in
Due to light emission from the element.

LED head 8 and the aforementioned printer controller board 20
are connected by a signal line (not shown). For example, the segment drivers 21-1 to 21-4 include printer controllers,
R base Fi. 20 to Kurofuku signal CK, lunch signal LA
, and signal lines for supplying the strobe signals STB 1 to 4 are connected to the printer control board 20 and the common signal generation circuit 22.
A signal line for supplying LK is connected.

FIG. 3 is a diagram showing the circuit configuration of the segment drivers 21-1 to 21-4. Segment driver 21-1
~2l-4 are both shift registers 25,
It is composed of a latch circuit 26, an AND gate 27, a constant current buffer 28, and a buffer 29. The video data D is input from the terminal I1 to the segment driver 25, and is serially input into the shift register 25 from the terminal 2 in synchronization with the manually inputted clock signal CK. The shift register 25 has a 64-bit data area, and the input video data D of 64 bits or more is output to the adjacent shift register 25 connected in cascade via the buffer 29 and the terminal I. When all the video data D is input to the shift registers 25 in the segment drivers 21-1 to 21-4, the launch signal LA is output to the terminal I4, and the video data D in the shift registers 25 is latched by the latch circuit 26. The video data D latched by the latch circuit 26 is ANDed via the terminal I.
The strobe signal (STBI~4) to the gate 27 is outputted to the constant current buffer 28 at the timing of manual input. A control signal (CTR) is connected to the constant current buffer 28 at terminal ■. controls the current value flowing through the constant current buffer 28, and outputs the input video data D through the constant current buffer 28.
Output from Y1 to the corresponding LED array.

LED array-DI””D4. By the above manufacturing method, 64 LEDLs shown in FIG. 4 were manufactured. It is formed by 〜■,,4. One end (anode side) of LED LI to L1+4 shown in the same figure A I" A 64 is the corresponding output Y, to Y of the segment drivers 21-1 to 21-4.
ba, and the other end (cathode side) K is connected to a common common electrode.

LED arrays D1 to D4. terminal A. ~A64 and the output terminals Y. of segment drivers 21-1 to 21-4. ~Y&
4 is connected as shown in FIG. That is, as shown in the figure, the outputs Y, ~Y64 of the segment driver 21-1 are the LED array D+ + Ds +
09 + ...Connected to terminals A, ~A64 of D21, output Y, = Y. of segment driver 21-2.
．． are LED arrays Dz, D&, D+. ,...D3
Similarly, the output of segment driver 21-3 Y.%Y...,
and output Y+”-Y6 of segment driver 21-4
4 is LED array D3, D?・・・I)++”I)
iq or LED array D4 + 011 + DI
! +...D4. are connected to terminals A, ~A64.

On the other hand, the common signal generation circuit 22 is configured as shown in FIG.
The driver 30 has the same circuit configuration as that of the driver 30, and the connecting portion 31 connects the outputs Y's to Y', 4 of the driver 30 to connections described later.

The driver 30 is the segment driver 21-1 to 21 mentioned above.
-4, it has a terminal 11"l6, and terminal 1 has 64 pieces of serial data "ooooooooooooo0100" as common data (COM-D).
000000010...1" is input, and 1 is entered thereafter.
Data “1” is input every 0 bits, and terminals I2 and I,
A clock signal CLK is input to. Furthermore, since terminal I is not used, nothing is connected to it, + voltage is applied to terminal I4 since there is no need to input a latch signal, and + voltage is applied to terminal 1h. Further, a pull-down resistor Rl1 is connected to the terminals It and Is, and a dividing resistor Rl! is connected between the terminals ■ and ground. +R12 is connected. Then, the voltage obtained by dividing the ten voltages applied to the terminal I by the dividing resistors RIZ and Rl at a predetermined ratio is the control signal (CTR).
is supplied to the driver 30 as each output Ys%Y. ．． Controls the current of the common signal output from the

The connection configuration of the connection part 31 is the output Y'h of the driver 30.
4+ Y's. , Y'44+ Y'34+ YZn
The six outputs of +Y'+4 are lines! 1 through the transistor Q.1. connected to the base (B) of the driver 3
0 output Y'631 Y'S3+ Y'=. ．． Y'
33+Y'! 6 outputs of $+Y'I3 are line l2
are connected to the base (B) of the transistor Q2, and the outputs Y, . ',
Y', t, ...Y'. is the line! , through
Output Y. ．． 'rY',,...Y'11 outputs Y', through line l4. ,Y′,. ．．・・・
Y'l. via line l, output Y' S%+
Y'd9+...Y'q passes through line 1h4, and outputs Y' 511, Y' 4B,...
Y', via line l7, output Y's. Y. ．． '
, ...Y'? through line 1ll, output Y
'Sol Y'461...Y'6 via line l, output Y 'SS+ Y'' 4S+
...Y' is line i. are connected to the bases (B) of corresponding transistors Q, -QIO, respectively. Therefore, each line! , ~ji'io, common signals 01~C, flowing. are each driven by six outputs in the driver 30.

In the LED printer P configured as described above, each L
ED array D1-D4. LEDL, -L formed in
．． ．． The drive control will be explained below using the time charts of FIGS. 6 and 7.

As described above, video data D is serially input to the shift registers 25 in the segment drivers 21-1 to 21-4 in synchronization with the clock signal CK output from the printer controller board 20. As described above, the video data D input to the shift register 25 is the print data from a host device (not shown) converted into video data D by the interface controller circuit, and then supplied to the printer controller board 20. .

First, the first 256 (64x4
) video data D is completed, the launch signal LA. The 256 pieces of video data D are raffled to the rasochi circuit 26 in synchronization with the output of the video data D.

Further, the common data (COM-D) is inputted in advance to the driver 30 of the common signal generation circuit 22, and the output Y'641Y'Si of the driver 30 is generated as shown in FIG.
...Y. ．． ' outputs a common signal C to the transistor circuit 23-1 via line l. This common signal C1 causes the LED array D. ~ If video data D is subsequently input to D4, each L in LED arrays D1 to D4
A state is reached in which EDLI to L64 can be driven to light up. Therefore, as the strobe signals ST8 1 to ST8 are sequentially outputted, the LEDs in the LED array D are adjusted based on the video data D outputted from the corresponding launch circuit 26.
L+ ~ L64 → LED LI ~ Lb in LED array D2
a → LED array D, LED LI-L64 → LED
LEDL in array D4. The lighting of LED Ll''L&4 in each LED array D, ~D4 is controlled in the order of ~L&4.

On the other hand, as mentioned above, the LED array D. ~LED in D4
When LI""L&4 is being driven and controlled as described above, the next 64 x 4 pieces of video data D are input to the shift register 25 in synchronization with the clock signal CK, and the latch signal LA
The output of z is latched into the launch circuit 26. Thereafter, as shown in FIG. 7, the common data in the driver 30 is shifted by one step by inputting the CLK signal (CLKI), and the next common signal C2 is the output Y'&l+ of the driver 30.
Y'ss+...Y'1, is outputted to the transistor circuit 23-2 via line 12. If video data D is subsequently input to the LED arrays D, .about.Dll by the output of this common signal C2, each LEDL in the LEE arrays D, .about.D8. ~ Is it possible to drive L&4 to light up? Ru.

Thereafter, as the strobe signals STB 1 to STB 4 are sequentially output, the LEDs in the LED array 10 are set based on the video data D output from the corresponding latch circuit 26.
L l= L b 4 → LEDL in LED array D6
．． ~Lh4→LED array D, LED L +~L&
4→LEDL, -L&4 in each LED array Ds''Di is controlled to turn on in the order of LEDLI to L, 4 in LED array Di.

Similarly, the clock signal CLK. →CLK41...
The output Y'6 of the driver 30 according to the output of . +Y'
,,, ... Common signal C3 from Y'+■ via line l, output Y'6H, Y'61, ...
Common signal C4+ via line 14 from Y'll
Each time ... is output, the corresponding LED array D, ~D
1,,LEDLI~L6 in DIff~D16,...
Controls the lighting of 4. And the last 4 LED array D
,,~D4. Each LED L+=Lin in the LED array D1 to D4 is driven and controlled. When driving is completed, the optical writing (TW) of one line on the light spectroscopic surface is completed.

Thereafter, by repeating the LED drive control process in the same manner, optical writing according to the video data D can be performed on the optical surface line by line.

In the embodiment described above, the LED arrays D, ~D4
. The common currents for lighting and driving each of LED Lt to L&4 are lines 1 to 11, respectively. The common signal CI""CIG at this time is a current supplied from the six outputs Y'bar Y'sa...Y', 4, etc. of the driver 30, respectively. Therefore, the common current can be distributed and supplied, and there is no need to use a large-capacity buffer to supply the common current as in the conventional case.

Further, the signal line from the printer controller board 20 to the common signal generation circuit 22 can also be configured with two signal lines for generating the common signals 01 to CIO. In this embodiment, the connection configuration of each terminal It to I of the driver 30 is configured as shown in FIG. 5, but as shown in FIG.
It is also possible to configure the clock signal (CLK) to be individually input to the terminals It and Is to which the clock signal (CLK) is input. With this configuration, the output time of the clock signal CLK output to the terminal (2) can be varied, and by this control, the application time of the strobe signal (STB) in the driver 30 can be controlled. The output time Tc can be adjusted.

In addition, although this example describes the case where an LED is used as a light emitting element, other light emitting elements such as an EL, a recording electrode of an electrostatic multi-needle recording head, a heating resistor element of a thermal recording head, etc. can be used. It is sufficient to have a configuration in which the light emitting elements are arranged in a row, and the device in which the light emitting element drive control device of the present invention is used is not limited to an LED printer, but can also be applied to a facsimile, an image reading device, and the like.

〔Effect of the invention〕

As described in detail above, according to the present invention, the number of signal lines between the control circuit and the print head is reduced, so that noise generation can be prevented.

Furthermore, since no buffer is required for passing a large current, space on the board and heat radiation measures are not required, and the device does not need to be enlarged.

Furthermore, the cost of the device can be reduced by reducing the number of signal lines and eliminating the need for a puffer for large currents.

[Brief explanation of drawings]

Fig. 1 is a main circuit diagram of a light emitting element drive control device of one embodiment, and Fig. 2 is an LE using the light emitting element drive control device of one embodiment.
The overall configuration of the D printer, Figure 3 is the circuit diagram of the segment 1 driver, Figure 4 is the LE
FIG. 5 is a circuit diagram of the common signal generation circuit, FIG. 6 and FIG. 7 are time charts explaining the operation of the light emitting element drive control device of one embodiment, and FIG. FIG. 9 and FIG. 10 are circuit diagrams of a conventional light emitting device drive control device. FIG. 11 is an operation of a conventional light emitting device drive control device. It is a time chart explaining. 8. . . LED head, 20... Printer controller board, 21-1 to 21
-4... Segment driver, 22... Common signal generation circuit, 25... Shift register, 26... Latch circuit, D, -D. . ...Light emitting element array L1-L64...LED array patent applicant Casio Electronics Co., Ltd. Same as above
Casio Computer Co., Ltd. Figure 2 Procedural Amendment 1. Case Description 1999 Patent Application No. 57518 2. Name of the invention Drive control device for light emitting elements 3. Relationship with the case of the person making the amendment Patent applicant Address: 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Name: Casio Electronics Industries Co., Ltd. Representative: Kazuo Kashio Address: 2-6-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name (
144) Kazu Kashio, Representative of Casio Computer Co., Ltd.
Male 4. Agent Postal code 102 Address 6-1-18 Kojimachi, Chiyoda-ku, Tokyo, Column ``3. Detailed description of the invention'' of the specification subject to amendment and No. 7 of the drawings
Figure 7. Contents of amendment 1) Replaced "Qκ" on page 4, line 19 of the specification with 'Q'
Correct with HJ. 2) In the second line of page 9 of the specification, "low current" is corrected to "drive". 3) In the 16th line of page 12 of the specification, the statement ``Common data for terminal It'' is corrected to ``Common data for terminal ■1 during initial setting of the LED printer.'' 4) Part 1 of the specification
On page 2, lines 17 to 19, ``Please close the terminal I in advance.''
2 and IsJ are corrected as follows. 64 pieces of serial data are supplied in advance as "1". This serial data supply is such that, for example, data "1" is input every 10 bits, and data "0" is input for all other bits. , terminal ■2 and IsJ 5) On page 13, lines 2 to 3 of the specification, ",
Delete the line that says 10 voltages are applied to the 6) Delete the statement "applied to terminal I6" on page 13, line 7 of the specification. 7) On page 13, lines 8 to 9 of the specification, “Driver 3
Correct "supply to terminal 0" to "apply to terminal ■6". 8) On page 13, line 9 of the specification, "Y5-Y,4" is corrected to "Y', - Y'saJ." 9) On page 14, line 3 of specification, "lbaJ There is a certain ``
26”. 10) On page 15, lines 10 to 13 of the specification, the statement ``Also, common signal CI'' shall be corrected as follows. "In addition, the driver 30 of the common signal generation circuit 22 has
The common data (COM-D) is inputted in advance, and as shown in FIG. 7, the output of the driver 30 is Y'55+Y'4
5+...The common signal CI● is from Y'5 to line l
1. The initial state that is output to is set. (The LED is kept in a non-lit state until the initial state is set.) In this state, common data (COM-D) having the same pulse width as the clock signal CLK is transmitted from terminal 1 every cycle Tw. It is input in synchronization with the falling edge of the clock signal. The state of this common data is determined by the clock signal CLK.
The signal is loaded into the shift register 25 in the driver 30 in synchronization with the rising edge of the clock signal, and thereafter its state is sequentially shifted in synchronization with the clock signal. Here, the signal Y'64gY"6L...Y shown in FIG.
# is the output Y'h a + Y' 6 2,...
It shows a signal output from the shift register 25 in the driver 30 to create Y'5. Output Y' ha, Y' 541 of the shift register 25 loaded (shifted) by the clock CLKo.
・Y"14 is gated by the clock signal CLK inputted from the terminal 5 as a strobe signal to the AND gate 27 in the driver 30, and the output Y' bar Y'
sa, ...line as Y'14! , is output as a common signal CI. Therefore, as shown in the figure, only the pulse width of the clock signal CLK is output as the common signal CI. ? That is, by controlling as described above, a relaxation period of period Tc0 is provided from the completion of output of the common signal C+ until the output of the common signal C2 of the next stage, so as to avoid unexpected situations when switching the common signal. I have to. The common signal C+ formed in this way is 11) "Evening circuit 23-2" on page 16, line 17 of the specification.
Output to. " and "Insert the following sentence between this common signal Cz J. "At this time as well, the pulse width of the common signal C2 is the signal Y' 63+ Y'53+" from the shift register.
'Y' l! It is shorter by the period T'co, and there is no overlap with the next common signal C■. 12) Figure 7 of the drawings will be amended as shown in the attached sheet.

Claims (1)

[Claims] a light-emitting element integration section formed by arranging a light-emitting element integrated array in a predetermined number of rows in which a plurality of light-emitting elements are integrated; and a segment that supplies drive signals based on image data to the light-emitting elements in the light-emitting element integrated array. and a common signal generating section that applies a selection signal to a predetermined number of the light emitting element integrated arrays in a time-divisional manner, and the common signal generating section applies a selection signal to each of the light emitting element integrated arrays through a low current output buffer. 1. A light emitting element drive control device, characterized in that a selection signal is applied to a set of light emitting element integrated arrays.