JPH02225064A - Driving controller of light emission device - Google Patents

Abstract

PURPOSE:To prevent noise from occurring and besides, to enable a light emission device to be driven for a short time without requiring an additional circuit by a method wherein frequency of a clock signal for transfer of a data is lowered. CONSTITUTION:An output Y1 of a segment driver 22 is connected to a terminal L1 of an LED array 24-1 to 24-n and an output Y2 is connected to a terminal L3 of the LED array 24-1 to 24-n. Hereinafter an output Yk is connected to a terminal L2k-1 of the LED array 24-1 to 24-n in the same way. Besides, an output Y1 of a segment driver 23 is connected to a terminal L2 of the LED array 24-1 to 24-n and an output Y2 is connected to a terminal L4 of the LED array 24-1 to 24-n. Hereinafter at the same time, an output Yk is connected to a terminal L2k of the LED array 24-1 to 24-n. Video data D are outputted to the segment drivers 22, 23 with two low frequency clock signals CK1, CK2 without generating noise in transfer of a clock, and the LED array 24-1 to 24-n are driven to be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an LED printer, an EL printer, which prints by an electrophotographic process by arranging light emitting elements in an array.
The present invention relates to a device such as a facsimile, and particularly to a light emitting element drive control device that controls the driving of a light emitting element.

[Conventional technology]

2. Description of the Related Art As a device in which light emitting elements are arranged in an array, for example, an LED printer in which LED (light emitting diode) light emitting elements are arranged is 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 line by line, and creates an image on paper by an electrophotographic process.

However, a large number of light emitting elements are used in the above-mentioned device, and these light emitting elements require a large current (for example, 10 to 15 mA per one light emitting element) to drive, so the light emitting elements are operated in a time-sharing manner. It's driving.

FIG. 1O is a diagram showing a driving circuit diagram of such a light emitting element. Each of the light emitting element arrays 1-1 to 1-n is formed of two light emitting elements, and each light emitting element array 1-1 to 1-n is formed of two light emitting elements.
Two of the light emitting elements have one end connected to the corresponding terminal Ll""L
2k, and the other end is connected to the common electrode COMI~C0Mn
connected to one of the The light emitting elements are driven by sequentially supplying selection signals to the common electrodes COMI to C0Mn, and while one of the light emitting element arrays 1-1 to 1-n is selected, the clock signal CK rises as shown in FIG. In synchronization with , print data D is input to segment drivers 2 and 3 connected in cascade. Thereafter, the outputs V, -vk of the segment drivers 2 and 3 are outputted to the light emitting element arrays 1-1 to 1-n in synchronization with the latch signal LA. Outputs T and -yh of the segment driver 2 are connected to terminals L1 to Lk of each light emitting element array 1-1 to 1-n,
Outputs 'y, -yk of the segment driver 3 are connected to terminals Lh++ to Lzk of each LED array 1-1 to 1-n. Therefore, the video data D outputted from the outputs TI-Vh of the segment drivers 2 and 3 is outputted to one of the light emitting element arrays 1-1 to 1-n selected by the selection signal. Lighting of the light emitting element is controlled.

By repeating this process according to the selection signals sequentially output to the common electrodes COMI to C0Mn, one line of optical writing is performed in a time-division manner.

Further, FIG. 12 shows another conventional example of a light emitting element drive control circuit. In this conventional example, as in the conventional example shown in FIG.
Each light emitting element is selected by a selection signal inputted from ~C0Mn, and lighting control is performed according to video data inputted to terminals L1~L2. However, in the case of the conventional example shown in FIG. 12, in order to lengthen the period of the clock signal input to the segment drivers 4 and 5, the segment drivers 4 and 5 are not connected in cascade, but are made independent, and are separated as shown in FIG. Video data D is input to segment drivers 4 and 5 using clock signals CK+ and CKz.

However, since the video data D is serially output from a control circuit (not shown), in this case, the output order of the video data D has been changed in advance. That is, the first
As shown in Figure 3, "1st data" → "k+1st data" → "2nd data" → "k+2nd data"
Video data D is output from the control circuit in the order of →..., and among this video data D, "1st data", "2nd data"
. . , is input to the segment driver 4 in synchronization with the rising edge of the clock signal C'Kt, and rk+1
'th data', 'k+2nd data', etc. are input to the segment driver 5 in synchronization with the rise of the clock signal CK2. In this way, the input state of the video data D after being input to each segment driver 4 and 5 is the same as that shown in FIG. 10, and the input state is the same as that shown in FIG. By outputting video data D, lighting of each light emitting element is controlled.

[Problems with conventional technology]

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

(a) First, in the drive control device shown in FIG. 10, the frequency of the clock signal for writing the video data D to the cascade-connected segment drivers 2 and 3 becomes extremely high. For example, A3 size paper (paper width 297mm)
The resolution is 400dpi and the printing speed is 20PP.
In the case of M, an extremely high frequency clock signal of about 10 MHz is required. Therefore, since such an extremely high frequency clock signal is transferred, high frequency noise is generated.

The amount of high-frequency noise generated increases as the distance between the control circuit and the light emitting element increases because the signal line becomes longer.

(b) Furthermore, in the drive control device shown in FIG. 12, it is necessary to rearrange the order of the video data D supplied to the segment drivers 4 and 5 in advance.

Moreover, in order to rearrange the video data D, it is necessary to write at least 2 pieces of video data D into a buffer etc. in the control circuit and then rearrange it, which requires an extremely long processing time and additional circuits such as buffers. Is required.

[Purpose of the invention]

In view of the above conventional drawbacks, the present invention makes it possible to drive a light emitting element in a short time without generating noise and without requiring an additional circuit by lowering the frequency of the clock signal for data transfer. An object of the present invention is to provide a drive control device for a light emitting element.

[Key points of the invention]

According to the present invention, the above object includes a plurality of optical dot generating chips in which m·k light emitting elements are arranged in an array, a plurality of light emitting element driving means having k-bit output and driving the light emitting elements; a data input terminal provided on the light emitting element driving means for inputting serial print data sent from an external device; a clock input terminal provided on the light emitting element driving means for inputting clock signals having different phases; One of the drive signals output from the first light emitting element driving means in the element driving means is connected to the first light emitting element of each optical dot generating chip, and the driving signal is output from the second light emitting element driving means. This is achieved by providing a drive control device for a light emitting element, characterized in that one of the drive signals is connected to the second light emitting element of each optical dot generating chip.

〔Example〕

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

FIG. 2 is an overall configuration diagram of an LED printer to which an LED drive control device is applied. In the figure, the LED printer P includes a photoreceptor drum 6, a charger 7, an LED head 8, a developer 9, and
A transfer device 10, a cleaner 11, a slip roll 14 for conveying the paper T carried out by a paper feed roller 13 from a paper feed cassette 12, a resist plate 15, a fixing roll 16, a paper ejection roll 17, a guide plate 18ax18c, etc. It consists of a paper transport mechanism. Further, at the bottom of the LED printer P, there is an interface controller board 19 provided with an interface controller circuit, and a printer controller board 2 provided with a printer controller circuit.
0 is placed. 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, transfer device 10, etc., and controls other parts of the electrophotographic process.

The charger 7 is a device that applies an initial charging voltage to the photosensitive surface of the photosensitive drum 6 rotating in the direction of arrow A, the LED head 8 is a device that exposes the photosensitive surface based on the video data, and the developer 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 IO is a device that transfers this toner image onto paper T. Further, the cleaner 11 is a device for removing toner remaining on the photosensitive surface, and the fixing roll I6 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 the detailed configuration of the LED head 8, in which the LED head 8 includes segment drivers 22, 23,
It is composed of LED arrays 24-1 to 24-n. Exposure to the photosensitive surface is performed by these LED arrays 24-1 to 24-.
This is performed by emitting light from each LED element within n. The LED head 8 and the aforementioned printer controller board 20 are connected by a signal line (not shown). The LED head 8 receives a clock signal CK from the printer controller board 20.

CK z video data D and latch signal LA are supplied,
Further, a selection signal for selecting one of the LED arrays 24-1 to 24-n is supplied.

FIG. 3 shows a specific circuit diagram of the segment drivers 22 and 23. As shown in the figure, the segment drivers 22 and 23 include an edge trigger shift register (hereinafter simply referred to as a shift register) 25, a latch circuit 26, a constant It is composed of a current buffer 27. shift register 25
The above video data D is input to terminal ■2, and terminal 11
The shift register 25 is sequentially shifted in synchronization with the clock signal CK or CK2 inputted from the shift register 25. At the timing when all the video data D is input to the shift register 25, the latch signal LA is input to the terminal I3, and the video data D in the shift register 25 is output to the latch circuit 26. Latch circuit 26 latched video data D
are from the outputs V and -Vk of the corresponding segment drivers 22 and 23 through the constant current buffer 27, respectively.
It is output to ED arrays 24-1 to 24-n.

Each of the LED arrays 24-1 to 24-n is 2 shown in FIG.
It is formed by LEDL+' to L2'. LEDL+′ to L2. shown in the figure. The outputs Y, ~v of the segment drivers 22 and 23 are connected to one end Ll''L2 of the segment drivers 22 and 23.
k, and the other end is connected to a common selection electrode (COM).

Note that a common driver 28 having a circuit configuration shown in FIG. 5 is connected between each selection electrode COM1=COMn and the printer controller board 20 described above, and when the selection signal output from the printer controller 20 is a high signal, the inverter is activated. The transistor 28b is turned on via the transistor 28a and the selection signal (voltage +Vcc) is applied to the desired selection electrode COM1-CO.
M n .

The terminals of the LED arrays 24-1 to 24-n, ~L2, and the output terminals V, ~Yh of the segment drivers 22 and 23
The connection configuration is as follows. That is, as shown in FIG. 1, the output \1 of the segment driver 22 is connected to the terminals of the LED arrays 24-1 to 24-n, and the output Y
2 is connected to the terminal L3 of the LED array 24-1 to 24-n, and the output V is connected to the terminal L3 of the LED array 24-1 to 24-n.
is connected to the terminal RI, and the output V is connected to LE in the same way.
-1 is connected to the terminal L2 of the D arrays 241 to 24-n. On the other hand, the output V of the segment driver 23 is L
Connected to terminal L2 of ED arrays 24-1 to 24-n,
The output V2 is connected to the terminal L4 of the LED arrays 241 to 24-n, and the output ¥3 is connected to the terminal L4 of the LED arrays 24-1 to 24-n.
The output V is connected to the terminal L6 of LE.
It is connected to terminal L2k of D arrays 24-1 to 24-n.

Therefore, the output ¥1 to Y of the segment driver 22,
supplies video data D to the odd-numbered terminals L+, Lz, . :IL E D7 It is configured to supply video data D to even numbered terminals Lz, La, . . . of Rays 24-1 to 24n.

In the LED printer P having the above configuration, especially the LE
LEDL+ arranged in D arrays 24-1 to 24-n
The drive control for '~L2' is shown below in Figures 6 and 7.
This will be explained using the time chart shown in the figure.

Shift register 2 in segment drivers 22 and 23
5, the video data D is serially input in synchronization with the clock signal CKI or CK2 outputted from the printer controller board 20 as described above. 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 by the interface controller, and then supplied to the printer controller board 20. First, the first two pieces of video data D are outputted during the period (1) shown in FIG.
It is input to the shift register 25 in synchronization with . At this time, the video data D is input to the shift register 25 in synchronization with the rise of the clock signals CK, CK2, as shown in FIG.

That is, the shift register 25 in the segment driver 22 receives the clock signal CK as shown in the figure.

``First print data'' is synchronized with the rising edge of .

"3rd print data", "5th print data"...
are sequentially input, and the shift register 25 in the segment driver 23 receives "second print data", "fourth print data", and "fourth print data" in synchronization with the rise of the clock signal CK2.
"Sixth print data", etc. are input sequentially. after that,
Latch signal L to each segment driver 22 and 23
With the input of A + , the latch circuit 26 in the segment driver 22 latches the first, third, . Fourth, . . . the second print data is latched.

Thereafter, in synchronization with the fall of the latch signal LA, a selection signal is output from the printer controller board 20 to the selection electrode C0M1 via the common driver 28, and the LED array 2
4-1 is selected. For this reason, as mentioned above, the latch circuit 2
The video data D latched in the constant current buffer 27
→ LED array 24- via the corresponding output V, -Vk
The signal is output from terminal 1 to ~L2. At this time, since the segment drivers 22, 23 and the LED array 24-1 are connected as described above, the LEs in the LED array 24-1
DLI', L:l', .
EDL2', L4', . . . are driven and controlled according to video data D supplied from outputs V and -Vn of the segment driver 23.

On the other hand, as described above, the LEDs in the LED array 24-1
When I' to Lk' are being driven and controlled, the next two video data D are clock signals CK,
and input to the shift register 25 in synchronization with CK2. Then, by outputting the next latch signal LA2, the latch circuit 26 receives the next two signals input into the shift register 25.
video data D are latched. Then, when the next selection signal is output from the printer controller board 20 to the selection electrode 24-2 of the LED array 24-2, the video data D latched by the latch circuit 26 is output from the segment drivers 22 and 23 at ¥1 to V. .

The signal is supplied to the terminal Ll''L2 of the LED array 24-2, and controls lighting/non-lighting (driving) of the LEDs LI to Lk' in the LED array 24-2.

Thereafter, in the same manner, the LED arrays 24-3 to 24- are sequentially input to the selection electrodes GOMI to C0Mn.
n is selected sequentially, and each LED array 24-3 to 24-
Drive control of LEDLI' to Lzh in n. And LED LI'~L in the last LED array 24n
2 to drive and control all LED arrays 24-1 to 24.
-n driving is completed, the above-mentioned optical writing of one line on the photosensitive surface is completed. Thereafter, by repeating the LED drive control processing in the same manner, optical writing according to the video data D can be performed on the photosensitive surface every l line.

As described above, this embodiment uses segment drivers 22 and 23.
The connection configuration between the LED lights L/-24-1 to 24-n is changed from the conventional one, and two low-frequency clock signals CKI,
CK2 outputs video data to the segment driver 22.23 without generating noise during clock transfer, and drives and controls the LED arrays 24-1 to 24-n.

Next, another embodiment of the present invention will be described. This example uses an LED as a light emitting element like the above example, and this L
This relates to an ED drive control device and is applied to an LED printer P. FIG. 8 is a diagram showing the circuit configuration within the LED head of the LED printer P. In the case of this embodiment, it is composed of six segment drivers 31 to 36 and n LED arrays 30-1 to 30-n. and one LED array 30-1.30-2,
... are formed with three (for example, 192) LEDs, and adjacent LED arrays 30-1 and 302, 30-3 and 30-4, ... are formed with one selection electrode COM1-COM.
Connected to n/2. Therefore, two adjacent LEs
This is a configuration in which D arrays 30-1, 30-2, etc. are selected simultaneously. Further, the clock signal CK, video data D, and latch signal LA are supplied to the six segment drivers 31 to 36, but the video data D is alternately selected within the printer controller 20 and divided into video data D and D2. The clock signal CK also has three systems of clock signals C
It is divided into KI to CK3 and supplied. clock signal CK
, are output to the segment drivers 31 and 32, and in synchronization with the rising edge of the signal, the video data D1 is input to the segment driver 3I, and the video data D2 is input to the segment driver 32. Further, the clock signal CKz is output to the segment drivers 33 and 34, and in synchronization with the rising edge of the clock signal CKz, video data D+ is input to the segment driver 33, and video data D2 is input to the segment driver 34. Further, the clock signal CK2 is output to the segment drivers 35 and 36, and in synchronization with the rising edge of the clock signal CK2, the video data DI is inputted to the segment driver 35, and the video data D2 is inputted to the segment driver 36.

Note that the video data DI and D2 are obtained by alternating six (for example, 384) pieces of video data D by a printer controller, with odd-numbered video data being set as Dl and even-numbered video data being set as Dl. Each segment driver 3 uses the clock signals CK, ~CKff.
The input timing of video data D and Dl to 1 to 36 is performed as shown in FIG. That is, in synchronization with the rise of the clock signal CK, "first video data", "seventh video data", etc. are sequentially input to the segment driver 31, "second video data",
"Eighth video data" . . . are manually input to the segment driver 32 one after another. In addition, in synchronization with the rise of the clock signal CKz, "3rd video data", "9th video data", etc. are sequentially input to the segment driver 33, and "4th video data", "10th video data", etc. "Video data"... are sequentially input to the segment driver 34. Further, in synchronization with the rising edge of the clock signal CK2, "5th video data", "11th video data", etc. are sequentially input to the segment driver 35, and "
"6th video data", "12th video data"
... are sequentially input to the segment driver 36.

Therefore, "1st video data", "7th video data", etc. are sequentially input to the shift register in the segment driver 31, and "2nd video data" is input to the shift register in the segment driver 32. J
1 "8th video data" are input sequentially, and the video data according to the above input is also input to the shift registers in the segment drivers 33 to 36. Therefore, after that, for example, when a selection signal is input to the selection electrode COMI and the LED array 30-1. Video data is LED
According to this video data, each LE in the LED array 30-1.30-2
Drive and control D.

After that, according to the time chart shown in FIG. 9, the next 6 pieces of video data are input to the segment drivers 31 to 36, and when a selection signal is input to the selection electrode C0M2, the next LED
The array 30-3.30-4 is selected, and the LED array 30-3.30-4 is driven and controlled according to the video data at this time.

Thereafter, LED arrays 30-5 to 30-n are sequentially arranged in the same manner.
The LED is driven and controlled according to the video data until optical writing is performed on the photosensitive surface.

As described above, in this embodiment, video data is output to the segment drivers 31 to 36 using clock signals CK and CK3, which have lower frequencies that can further prevent the generation of noise than the clock signals CKI and CK2 of the previous embodiments. Moreover, at this time, the video data D can be simply divided into data alternately and outputted as video data D, D2. does not require.

In this embodiment, we will explain the case where an LED is used as a light emitting element, but any structure in which other light emitting elements such as ELs are arranged in a row is sufficient, and the drive control of the light emitting element of the present invention is not limited to EDs. The device in which the device is used is not limited to LED printers, but can also be applied to facsimiles, image reading devices, and the like.

〔Effect of the invention〕

As described in detail above, according to the present invention, since the frequency of the clock signal for transferring video data is lower than that of the conventional technology, it is possible to prevent the generation of noise and prevent adverse effects on peripheral devices.

Further, there is no need for complicated control processing or additional circuitry for rearranging video data in advance, so that the drive processing time for the light emitting elements can be shortened and the cost of the device can be reduced.

[Brief explanation of the drawing]

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.
Overall configuration diagram of the D printer, Figure 3 is the circuit diagram of the segment driver, Figure 4 is the LED
The circuit diagram of the array, Figure 5 is the circuit diagram of the common driver, Figures 6 and 7 are time charts explaining the operation of the light emitting element drive control device of one embodiment, and Figure 8 is the light emission diagram of another embodiment. FIG. 9 is a circuit diagram of a main part of the device drive control device; and FIG. 9 is a time chart illustrating the operation of the device drive control device of the light emitting device according to another embodiment. 10 and 12 are circuit diagrams of a conventional light emitting element drive control device, and FIGS. 11 and 13 are time charts explaining the operation of the conventional light emitting element drive control device. 8. . . LED head, 20... Printer controller it, 22.23.3
1 to 36...Segment driver, 24-1 to 24-n, 30-1''30-n...LED
Array 25...Shift register, 26...Latch circuit, 27...Constant current buffer, L1' to L, '2'...LED. Patent applicant Casio Electronics Industries Co., Ltd. Same as above
Casio Computer Co., Ltd. Figure Figure 24-+ (~24-n) Figure Figure Procedural Amendment 1゜2゜3゜4゜Representation of the case 1999 Patent side No. 45686 Name of the invention Drive of light emitting element Relationship with the case of a person making control device amendments 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 Title (1)
44) Casio Calculation Co., Ltd. Representative Kazuo Kashio Yuyo Rihito Postal code 102 Address 6-1 Kojimachi, Chiyoda-ku, Tokyo @18%6 Figures 1, 10 and 12 of the drawings subject to amendment 7. Contents of correction 1) Figures 1, 10, and 12 of the drawings will be corrected as shown in the attached sheet. spontaneous

Claims (1)

[Claims] a plurality of optical dot generation chips in which m·k light emitting elements are arranged in an array; a plurality of light emitting element driving means each having a k-bit output and driving the light emitting elements; and a plurality of light emitting element driving means provided in the light emitting element driving means. a data input terminal for inputting serial print data sent from an external device; a clock input terminal provided in the light emitting element driving means for inputting clock signals having different phases; and a first one of the plurality of light emitting element driving means. One of the drive signals output from the light emitting element driving means is connected to the first light emitting element of each optical dot generating chip, and one of the drive signals output from the second light emitting element driving means is connected to the first light emitting element of each optical dot generating chip.
A drive control device for a light emitting element, characterized in that one of the optical dot generating chips is connected to a second light emitting element of each of the optical dot generating chips.