JPH081990A - Printer - Google Patents

Abstract

PURPOSE:To provide a printer in which the efficiency of a transfer process can be enhanced. CONSTITUTION:The printer comprises an array having a plurality of elements, a driver 36 arranged corresponding to the array, a latch circuit 35 arranged corresponding to the driver 36 to hold dot line data, and a shift register 33 arranged corresponding to the circuit 35 to output the data. The printer also comprises means for holding only the data of the one line in the circuit 35 by transferring only the data of the one line when the plurality of the data are compared at the respective lines, if the data of at least two dot lines are the same and printing the line according to the held data. In this case, only the data of the one line is transferred to a print head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer.

[0002]

2. Description of the Related Art Conventionally, in a printer such as an electrophotographic printer which uses a light emitting element array as an exposure source, electronic data processing is performed as follows. First, a character, code or the like transmitted from an external host device is received and interpreted by a program of a microprocessor, a control circuit, etc., and then converted into bitmap image data of a divided portion, which is expanded and written in a buffer memory. Next, the bitmap image data is transferred to the exposure head as dot line data in units of one dot line at every predetermined timing. The exposure heads are each 1
It has a shift register for dot lines, a latch circuit, a driver, and a light emitting element array.

The dot line data for one dot line transferred to the exposure head and held in the latch circuit is
The light is output to the driver at a predetermined timing to blink the light emitting elements of the light emitting element array to expose the photosensitive drum. Hereinafter, the above-described processing is repeated for the number of dot lines per page to form an electrostatic latent image, and based on the electrostatic latent image, printing is performed on paper by an electrophotographic process.

[0004]

However, in the conventional printer described above, it is necessary to transfer the dot line data from the buffer memory to the exposure head for all the dot lines in the printing area. Therefore, even if the dot line data of a certain dot line and the dot line data of the previous dot line are exactly the same, it is necessary to transfer the same dot line data as the previous dot line to the exposure head again. The transfer process becomes less efficient.

It is an object of the present invention to provide a printer which solves the problems of the conventional printer and can improve the efficiency of transfer processing.

[0006]

Therefore, in the printer of the present invention, an array of a plurality of elements, a driver arranged corresponding to the array, and a driver arranged corresponding to the driver, It has a latch circuit for holding the dot line data, and a shift register arranged corresponding to the latch circuit and outputting the dot line data.

Then, a plurality of dot line data are compared for each dot line, and when the dot line data for at least two dot lines are the same, only the dot line data for one dot line is transferred to the latch circuit. It has means for holding and printing for each dot line according to the held dot line data.

[0008]

According to the present invention, as described above, in the printer, the array consisting of a plurality of elements, the driver arranged corresponding to the array, and the dot line arranged corresponding to the driver. A latch circuit for holding data,
And a shift register arranged corresponding to the latch circuit and outputting dot line data.

In this case, the dot line data output from the shift register is held in the latch circuit, and the element is selectively blinked depending on whether the dot line data is at the high level or the low level. Then, a plurality of dot line data is compared for each dot line, and when the dot line data for at least two dot lines is the same, only the dot line data for one dot line is transferred and held in the latch circuit, It has means for printing for each dot line according to the held dot line data.

In this case, only dot line data for one dot line is transferred to the print head, and dot line data for other dot lines is not transferred to the print head.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a block diagram of the printer according to the embodiment of the present invention. Although the electrophotographic printer has been described in the present embodiment, it can be applied to other printers such as a thermal printer.
In this case, a heating element is used instead of the light emitting element.

As shown in the figure, the address terminal t1 and the data terminal t2 of the buffer memory 11 are connected to a microprocessor (not shown) and the transfer control circuit 1
2, the serial data output terminal t5, the shift clock output terminal t6, the latch signal output terminal t7, and the strobe signal output terminal t8 of the transfer control circuit 12 are connected to the corresponding address terminal t3 and data terminal t4, The corresponding serial data input terminal t9 and shift clock input terminal t1 of the exposure head 13
0, the latch signal input terminal t11, and the strobe signal input terminal t12.

FIG. 3 is a circuit diagram of a main part of the transfer control circuit according to the embodiment of the present invention. As shown in the figure, the transfer control circuit 12 includes line memories 210a and 210b for storing dot line data for two dot lines, and n exclusive OR elements (hereinafter referred to as "XOR elements") 201 and 2 respectively.
, ..., 20n, n-input logical sum elements (hereinafter referred to as “OR elements”) 220, D flip-flops 260, logical product elements (hereinafter referred to as “AND elements”) 270 and 28.
0, a shift clock generation circuit 230, a latch signal generation circuit 240, and a strobe signal generation circuit 250.

The bit output terminals of the line memories 210a and 210b have the respective XOR elements 20 for each corresponding bit.
XOR connected to input terminals 1, 202, ..., 20n
The output terminals of the elements 201, 202, ..., 20n are connected to the input terminals of the OR element 220. The output terminal of the OR element is connected to the data input terminal D of the D flip-flop 260, and the output terminal of the strobe signal generating circuit 250 is the clock input terminal CN of the D flip-flop 260 and the strobe signal of the transfer control circuit 12. Output terminal t
8 is connected to the output terminal Q of the D flip-flop 260.
Are connected to the input terminals of the AND elements 270 and 280.

The output terminal of the shift clock generating circuit 230 is connected to the input terminal of the AND element 270, and the output terminal of the latch signal generating circuit 240 is connected to the input terminal of the AND element 280. Further, the output terminal of the AND element 270 is connected to the shift clock output terminal t6, and the output terminal of the AND element 280 is connected to the latch signal output terminal t7. SG1 is a gate signal, SG2 is a shift permission signal, and RS is a reset signal.

FIG. 1 is an internal circuit diagram of an exposure head of a printer according to an embodiment of the present invention. As shown in the figure, the exposure head 13 has n D flip-flops 331, 33.
, 33n, and a latch circuit 3 including n latches 351, 352, ..., 35n.
, 36n, and n light emitting elements 371, 372,
.., 37n.

The serial data input terminal t9 is connected to the input terminal D of the D flip-flop 331, and the output terminal Q of the D flip-flop 331 is the input terminal D of the D flip-flop 332 at the next stage and the latch 351 of the same stage. , 33n connected to the input terminal D. Similarly, the output terminal Q of each D flip-flop 332, 333, ..., 33n is the input terminal D of each D flip-flop 333, 334 ,. 352, 353, ..., 35
n input terminals D, respectively. However, the output terminal Q of the D flip-flop 33n at the last stage is connected only to the input terminal D of the latch 35n at the same stage. Further, the clock input terminal C of each D flip-flop 331, 332, ..., 33n is connected to the shift clock input terminal t10.

The output terminal Q of the latch 351 is connected to the data input terminal A of the driving element 361. Similarly, the output terminals Q of the latches 352, 353, ..., 35n are the driving elements 362, 363 of the same stage. ..., 36n connected to the data input terminal A. In addition, each latch 351, 35
The gate input G of 2, ..., 35n is the latch signal input terminal t
11 is connected.

Further, the output terminal Z of the drive element 361 is connected to the input terminal A of the light emitting element 371, and similarly, the output terminal Z of each drive element 362, 363, ...
, 37n connected to the input terminals A of the light emitting elements 372, 373, ... In addition, each drive element 361, 362,
, 36n are connected to the strobe signal input terminal t12. Then, each light emitting element 37
The output terminals of 1, 372, ..., 37n are grounded.

Next, the operation of the transfer control circuit 12 (FIG. 2) when transferring the dot line data to the exposure head 13 will be described. FIG. 4 is a first time chart of the transfer control circuit in the embodiment of the present invention, and FIG. 5 is a second time chart of the transfer control circuit in the embodiment of the present invention. Note that FIG. 4 shows a case where the dot line data of the first line and the dot line data of the second line are different from each other.
The case where the dot line data of the first line and the dot line data of the second line are the same will be described.

First, bit image data is written in the buffer memory 11 (FIG. 2) in dot line units by a microprocessor (not shown). Next, the transfer control circuit 12 reads out the bitmap image data for 2 dot lines from the buffer memory 11, and outputs the reset signal RS to the reset terminal R of the D flip-flop 260 (FIG. 3).
To clear the output terminal Q of the D flip-flop 260 to "0".

Subsequently, as shown in FIG. 4, the dot line data of the first dot line is transferred to the exposure head 13 via the serial data output terminal t5. In this case, a clock is sent to the exposure head 13 via the shift clock output terminal t6, and the dot line data is transferred in synchronization with the clock. The exposure head 13 includes D flip-flops 331, 332, ..., 33.
The dot line data is sequentially received by n (FIG. 1). When the exposure head 13 receives the dot line data for one line, the transfer control circuit 12 outputs a latch signal to the exposure head 13 via the latch signal output terminal t7 and the latch signal input terminal t11.

When the latch signal is input, the latch 3
, 35n are D flip-flops 33.
, 33n are read and held. Next, the transfer control circuit 12
Outputs a strobe signal to the exposure head 13 via a strobe output terminal t8 and a strobe input terminal t12. Driving elements 361, 36 of the exposure head 13
When the strobe signal is input to the light emitting elements 37, ..., 36n, according to the dot line data held in the latches 351, 352 ,.
Flashes 1, 372, ..., 37n. Then, the light emitting element 37 corresponding to the high level dot line data
, 372, ..., 37n are caused to emit light. In this way, exposure for one dot line can be performed.

By the way, the XOR elements 201 and 20
.., 20n and the OR element 220 compare the dot line data of the first transferred dot line with the dot line data of the next transferred dot line for each bit. And if more than one bit is different,
The gate signal SG1 becomes "1", the D flip-flop 260 is set to "1" by the falling edge of the strobe signal of the first dot line, and the shift enable signal SG2 is set to the high level.

In this case, the dot line data of one dot line is transferred to the exposure head 13 via the serial data output terminal t5, and the clock is transferred via the shift clock output terminal t6 via the latch signal output terminal t7. The latch signal is output to the exposure head 13.
Therefore, the transfer, latching, and exposure of the dot line data of the next dot line can be continuously performed.

On the other hand, as a result of comparing the dot line data of the first transferred dot line and the dot line data of the next transferred dot line for each bit, if all the bits are the same, the gate signal SG1 becomes "0". In this case, the D flip-flop 260 is reset to "0" by the falling edge of the strobe signal of the first dot line, and the shift enable signal SG2
To low level.

Therefore, the shift clock output terminal t6
The clock and latch signals are not output from the latch signal output terminal t7, and the dot line data is neither transferred nor latched. However, since the dot line data of the previously transferred dot line is still held in the latches 351, 352, ..., 35n of the exposure head 13, as shown in FIG. 5, the strobe signal output terminal t
When the strobe signal is output from 8, the exposure is performed on the same dot line data as the dot line data of the first 1 dot line.

When the exposure for two dot lines is completed in this way, new dot line data is read into the line memories 210a and 210b, and the above procedure is repeated. Further, in the present embodiment, in order to simplify the structure, two line memories 210a and 210b are provided and the dot line data is compared every two dot lines, but three line memories are used. As described above, it is also possible to sequentially move the dot line data for which comparison has been completed to the next line memory and sequentially read new dot line data into the vacant line memory for comparison. In this case, when the same dot line data continues for an arbitrary number of dot lines, only the dot line data of the first dot line can be transferred to the exposure head 13.

Although a printer has been described in this embodiment, it can be applied to a facsimile apparatus. It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0030]

As described in detail above, according to the present invention, in a printer, an array of a plurality of elements, a driver arranged corresponding to the array, and a driver corresponding to the array are provided. The latch circuit is provided and holds the dot line data, and the shift register is provided corresponding to the latch circuit and outputs the dot line data.

Then, a plurality of dot line data are compared for each dot line, and when the dot line data for at least two dot lines are the same, only the dot line data for one dot line is transferred to the latch circuit. It has means for holding and printing for each dot line according to the held dot line data. in this case,
Only dot line data for one dot line is transferred to the print head, and dot line data for other dot lines is not transferred to the print head. Therefore, the efficiency of transfer processing can be increased.

[Brief description of drawings]

FIG. 1 is an internal circuit diagram of an exposure head of a printer according to an embodiment of the present invention.

FIG. 2 is a block diagram of a printer according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of a main part of a transfer control circuit according to an embodiment of the present invention.

FIG. 4 is a first time chart of the transfer control circuit according to the embodiment of the present invention.

FIG. 5 is a second time chart of the transfer control circuit according to the embodiment of the present invention.

[Explanation of symbols]

 371, 372, ..., 37n Light emitting element 33 Shift register 35 Latch circuit 36 Driver 37 Light emitting element array

Claims (1)

[Claims] 1. An array comprising: (a) a plurality of elements;
(B) a driver arranged corresponding to the array,
(C) a latch circuit arranged corresponding to the driver and holding the dot line data; (d) a shift register arranged corresponding to the latch circuit and outputting the dot line data; (e) A plurality of dot line data are compared for each dot line, and when the dot line data for at least 2 dot lines are the same, only the dot line data for 1 dot line is transferred and held in the latch circuit, and is held. A printer for printing each dot line according to the dot line data.