JPH075789A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device capable of stably making a fixed image preventing the temp. inside the device from rising with a little power consumption. CONSTITUTION:Printing data (black data) are counted by the image decision circuit 21 for each line or each character based on the dot patterned image data, the counted data are stored in the line buffer 22 and the counted data are outputted from the output data control circuit 23, then a voltage is applied to the thermal head TH based on the output and the fixing is processed at the temp. in accordance with the number of the printing data (black data).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording device such as an electrophotographic printer or an electrophotographic copying machine, and more particularly to a fixing device for fixing an image formed on a paper to the paper.

[0002]

2. Description of the Related Art A recording device such as a printer or a copying machine using an electrophotographic system transfers a toner image (developer) formed on a photoconductor onto a sheet, and the image transferred onto the sheet is later peeled off, A fixing process is applied to prevent bleeding. Conventionally, the following methods have been proposed for this fixing process. (A) First, the heat fixing method using a heat roller. This heat fixing method is composed of a heat roller with a built-in heater and a pressure contact roller that is in pressure contact with the heat roller at a predetermined pressure, and allows the paper on which the unfixed toner is formed to pass between the heat roller and the pressure contact roller. The toner image (image) is fixed on the sheet by heat and pressure. (B) In addition to the heat fixing method described above, so-called flash fixing, in which the toner image on the surface of the paper is fixed by light (heat) radiation of the light emitting element, the toner is melted only by pressure using two pressure rollers. A pressurizing method for fixing the paper to the paper is also proposed.

[0003]

However, the above method has the following problems. That is, in the method (a), the heat is released from the heat roller, so that the temperature inside the device rises and a cooling device such as a cooling fan is required. In addition, a large amount of power is required and it is difficult to reduce the size of the device. Further, it takes a warm-up time to set the heat roller to a predetermined temperature, and the device cannot be driven immediately.

There is also a problem in the flash fixing and the pressure system shown in (B). In the case of flash fixing, it is necessary to consider the life and deterioration of the light emitting element, and a large amount of electric power is required. On the other hand, in the case of the pressure system, the stability of the fixed image is poor because the toner is fixed on the paper only by the pressure.

An object of the present invention is to provide a fixing device which can form a stable fixed image with a small amount of electric power without raising the temperature inside the device.

[0006]

The present invention is applied to a fixing device of a recording device which forms a toner image on a recording medium based on dot image data for line scanning recording, and is applied in the main scanning direction of the recording medium. A plurality of heating elements arranged side by side along with each other, heating control information generating means for generating heating control information for each heating element based on the dot image data, and driving each heating element based on the heating control information. Drive means for driving.

[0007]

According to the present invention, the heat generation control information generating means is based on the dot-patterned image data, line by line, or 1 line by line.
The print data (black data) is counted for each character, and a voltage based on this counted data is output to the driving means so as to correspond to the plurality of heating elements arranged side by side in the main scanning direction. Printing data for heating element (black data)
It is possible to perform the fixing process with a very high temperature efficiency and without waste of electric power.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing an example of a printer device as a recording device to which the fixing device of one embodiment is applied.
It is a principal part block diagram of a printer apparatus. In the figure, LE
The D printer 1 includes a photosensitive drum 2, and the photosensitive drum 2.
A charging device 3, a print head 4, which are sequentially arranged near the peripheral surface of the
An image forming unit including a developing device 5, a transfer device 6, and a cleaner 7, and a slip roll 10 for carrying the paper P carried out from a paper feed cassette 8 by a paper feed roller 9, a paper sensor 11, a standby roll 12 , Fixing unit 13, transport roll 14
It is composed of a paper transport mechanism.

[0009] The charger 3 is a photosensitive drum that rotates in the direction of the arrow.
It is a device that applies an initial charge to the photosensitive surface of
The character head 4 exposes the photosensitive surface on the basis of image data and stops the exposure.
The developing device 5 is a device for forming an electrostatic latent image,
Device that converts the electrostatic latent image formed on the photosensitive surface into a toner image
The transfer device 6 is a device that transfers the toner image onto the paper P.
is there. The cleaner 7 removes the toner remaining on the photosensitive surface.
The fixing unit 13 fixes the toner image on the paper P.
It is a device to wear. That is, the fixing unit 13 of this embodiment is
It is arranged here.

Further, the above LED printer 1 has a control circuit built in a control box (not shown). FIG. 3 is a system block diagram of this control circuit. An image signal including a character code or the like is input to the interface controller 16 from a host device (not shown), and based on the image signal, the interface controller 16 outputs image data (dot pattern data) corresponding to the print image on the paper in a one-to-one correspondence. ) Is created. This image data is output to the printer controller 17 and used for the above-described exposure of the photosensitive drum 2 and the fixing process of the fixing device 6. That is, the exposure control unit 18 in the printer controller 17 outputs the print data to the print head 4 based on the above image data, and the fixing control unit 19 creates the below-described fix data based on the above image data. Then, the data is output to the fixing unit 13.

The engine control unit 20 in the printer controller 17 controls the drive of the photoconductor drum 2, the charger 3, the developing unit 5 and the like which form the above-mentioned image forming unit. Figure 1
Shows a circuit block of the above-mentioned fixing controller 19, and FIG. 4 shows a concrete circuit thereof. The fixing controller 19 is composed of an image discrimination circuit 21, a line buffer (memory) 22, an output data control circuit 23, and a timing control circuit 24.
The image discrimination circuit 21 is a circuit that discriminates the ratio of print dots (black dots) included in one line of the image data output from the interface controller 16. Also, the line buffer 22 is the above-mentioned image discrimination circuit 21.
The output data control circuit 23 is a circuit for storing data on the basis of the determination result output from the output data control circuit 23. The timing control circuit 24 is a circuit that outputs a timing signal to the image discrimination circuit 21, the line buffer 22, and the output data control circuit 23 described above.

As shown in FIG. 4, specifically, the image discrimination circuit 21 includes an AND gate 25, a counter 26, and an OR gate 2.
7, latch circuit 28, delay circuit 29, input / output circuit 3
It consists of zero. Counter 26 is AND gate 25
It is a counter for counting the number of print data (black data) included in the above-mentioned image data input in synchronization with the clock signal via. The counter 26 also outputs the upper 3 bits of data to the latch circuit 28 and the lower 9 bits of data to the latch circuit 28 via the OR gate 27. With this configuration, the latch circuit 28 includes the counter 2
As the number of print data (black data) counted in 6, the count data in which the upper 3 bits of data and the lower 9 bits of data are configured by 1 bit is input. The latch circuit 28 latches this data in synchronization with the latch signal output from the input / output circuit 30 at a predetermined timing, and outputs the data to the line buffer 22 in synchronization with the next latch signal.

The line buffer 22 is RAMs 31 and 32.
And the 4-bit count data (WRD0 to WRD3) output from the latch circuit 28 are stored in the RAMs 31 and 32.
Alternately memorize. The RAMs 31 and 32 have the same configuration and alternately store the above-mentioned 4-bit count data (WRD0 to WRD3) in synchronization with the write signal input to the input terminal WE. A pair of RAM as the line buffer 22
31 and 32 are arranged on one RAM 31 or 3
While writing the count data to 2, another RAM 32 or 3
The output data control circuit 23 outputs the count data stored from 1
This is for the purpose of improving the processing speed.

The output data control circuit 23 is composed of a shift register 23 ', and is configured to hold the above-mentioned count data in the shift register 23' for one time and then output it to the fixing section 13 described below.

The timing control circuit 24 comprises a timing control signal output section 34, a counter 35, and an address selector 36. The timing control signal output unit 34 includes address data (A6 to 15) for designating the address of the RAM 31, address data (A'6 to 15) for designating the address of the RAM 32, and the latch signal of the register 23 '. 1 signal, clock signal (FUCLK),

[0016]

[Outer 1]

Enable signals (OE) to the RAMs 31 and 32 and writing / writing of data to the RAMs 31 and 32
Read signal (CS / WE), address set signal (AD
R) and an address signal (ADA) are output.

The 12-bit counter 35 is
When outputting the above-mentioned image data, it is a circuit that counts a clock signal that is a synchronizing signal, and the address selector 36 is an address selector that selects an address to write data to the RAMs 31 and 32 based on the output of the above-mentioned counter 35. .

On the other hand, FIG. 5 is a diagram showing the circuit configuration of the fixing unit 13 and the configuration of the head unit. The circuit of the fixing unit 13 is a shift register 40, a latch circuit 41, a digital / analog conversion circuit (hereinafter referred to as D / A conversion). 42) and a buffer 43, and the head portion is composed of a thermal head TH. The shift register 40 is a so-called serial in-
This is a parallel-out type shift register, and the count data output from the shift register 23 '(output data control circuit 23) described above is supplied. This shift register 4
The maximum count data of 160 bits is input to 0 in synchronization with the clock signal (FUCLK). The latch circuit 41 latches the above-mentioned count data (WRD0 to WRD3) input to the shift register 40 in synchronization with the latch signal, and outputs it to the D / A conversion circuit 42 in synchronization with the next latch signal. The D / A conversion circuit 42 creates analog data corresponding to the input 4-bit count data (WRD0 to WRD3) and outputs it to the corresponding buffer 43. This buffer 43 has 4-bit count data (WRD0 to WR).
The corresponding voltage value based on D3) is set to the thermal head TH
Apply to. The thermal head TH is composed of 40 thermal heads TH1 to TH40.

FIG. 6 shows the thermal heads TH1 to TH4.
It is a figure explaining the composition of 0, and one thermal head T
H is arranged corresponding to dots that form one character of 64 × 64 dot configuration (note that the V direction in the figure indicates the direction in which the paper moves (sub scanning direction), and the H direction indicates thermal The direction in which the head TH is disposed (main scanning direction) is shown). As described above, these thermal heads TH1 to TH40 are
Data of a constant voltage value is supplied, and accordingly, temperature is generated according to the output voltage value to heat the paper to thermally fix the unfixed toner on the paper.

The operation of the fixing device of this embodiment having the above structure will be described with reference to the time chart shown in FIG. First, when an image signal is input from, for example, a personal computer (host device) connected to the LED printer 1 incorporating the fixing device of this embodiment, the interface controller 16 outputs dot pattern data based on the image signal as described above. Create image data. Thereafter, the exposure control unit 18 creates exposure data according to this image data and outputs it to the print head 4 to form an electrostatic latent image on the photosensitive drum 2 as described above. This electrostatic latent image is wisely converted into a toner image by the developing device 5, transferred to the paper by the transfer device 6, and the paper on which the unfixed toner is formed is the fixing unit 13 described above.
Sent to. On the other hand, during this period, the fixing control unit 19 executes the process according to the time chart shown in FIG. As shown in the figure, the image data created by the interface controller 16 is input to the counter 26 which is an input of the fixing controller 19 in synchronization with the clock signal. As described above, the counter 26 counts the print data (black data) included in one line. In this counting process, as shown in the same figure, the clock signal outputs “2560” pulses for one line, for example, whereas only print data (black data) is input to the counter 26. Only black data) are counted. More specifically, the above counting process is performed for 64 dots corresponding to the first character in one line, and at this time, the number of print data (black data) included in the 64 dots is counted. (FIG. 7). The count data (WRD0 to WRD3) thus counted is output to the latch circuit 28, and further written in the RAM 31 first. At this time, the writing position of the count data written in the RAM 31 is the address designated by the address selector 36,
The above data is address data (WRA0 to WRA).
5, the address data at this time is "0" as shown in FIG.
Is written in the first storage area of the RAM 31, for example.

Similarly, for the data to be input to the counter 26 next, the print data (black data) contained in the next 64 dots is counted (in FIG. 7), and the counted data (WRD0 to WRD3) is obtained. The data is output to the latch circuit 28 and written in the RAM 32 in synchronization with the latch signal.
At this time, the write position of the count data written in the RAM 32 is the address designated by the address data as described above, and the above data is the address data (WRA0
~ WRA5, the address data at this time is written in the first storage area of the RAM 32, for example, based on "1" as shown in FIG. Further, while writing the data of 1 to the RAM 32, the count data written to the RAM 31 is output to the shift register 23 '. In this manner, the print data (black data) included in the 64-bit data is sequentially counted (counted up to ◯ in FIG. 7), and the RAM 3 is stored as 4-bit count data (WRD0 to WRD3).
1 and 32 are stored alternately, and the count data (W
RD0 to WRD3) are sequentially output to the shift register 23 '.

The 4-bit count data (WRD0 to WRD3) output as described above are sequentially input to the shift register 40 shown in FIG. 5 as described above. When the input of the count data for one line is completed, the latch circuit 4
1, 4-bit count data (WRD0 to WRD3) is output to the buffer 43 via the D / A conversion circuit 42, and the buffer 43 supplies the count data (WRD0 to WR).
Voltages having values according to D3) are applied to the corresponding thermal heads TH1 to TH40. That is, the voltage applied at this time is the print data (black data) contained in 64 dots in one line which each thermal head TH is in charge of.
Is a value corresponding to the number of. Therefore, the more the print data (black data) included in the assigned 64 dots, the higher the voltage applied to the corresponding thermal head TH, and the fixing process can be performed at a sufficient temperature. On the other hand, the corresponding 6
When the print data (black data) contained in 4 dots is small, the voltage applied to the thermal head TH is low,
Since there is little print data (black data) for fixing the character by the thermal head TH, the necessary fixing temperature can be secured even in this case. That is, in this way, when the position of the sheet on which the toner image based on the corresponding print data is formed reaches the fixing unit 13, a voltage according to the number of print dots (black data) should be applied to the thermal head TH. Thus, the fixing process of the toner image can be performed at a temperature according to the number of print dots (black data).

Next, FIG. 8 is a diagram for explaining another embodiment, and this embodiment is the V direction (sub scanning direction) shown in FIG. 6 described above.
The same voltage is applied to the corresponding thermal head TH while the paper for 64 lines (for one character) moves. For this reason, 64 lines (1
It is necessary to count the print data (black data) during the movement of the paper (characters), and FIG. 8 is a diagram showing the circuit configuration thereof. Specifically, in this embodiment, 40 counters having the same configuration as the counter 26 shown in FIG. 4 are arranged (counters 26-1 to 26-40), and each counter 26-1
To 26-40 are connected to the decoder 46 via AND gates 47-1 to 47-40. The output of the decoder 46 is created based on the output of the 12-bit binary counter 54. In addition, the AND gates 47-1 to 4-4 described above.
Image data synchronized with the clock signal is supplied to the other input of 7-40 through the AND gate 48.
Therefore, for example, in the case of the counter 26-1, the print data (black data) included in the first 64 dots of the print dots of the first one line is counted according to the timing signal (Y0) output from the decoder 46. Then, the count data counted by the counter 26-1 is stored in the RAM 49 via the latch circuit 28-1. At this time, the storage position of the count data stored in the RAM 49 is
Address designated by the address selector 52 (A0 to A1
1). This address is created based on the output of the 6-bit binary counter 53 or the like.

Next, in the counter 26-2, the decoder 46
The print data (black data) contained in the second 64 dots in the image data of the first one line is counted by the timing signal output from the first line, and the counted data is written in the RAM 49 via the latch circuit 28-2. . Similarly, the counters 26-3, 26-4, 26-5, ... According to the timing signal output from the decoder 46,
・ 64 of 3rd, 4th, ...
The print data (black data) included in the dots is counted, and the print data (black data) included in the first one line is counted in the RAM 49 via the corresponding latch circuits 28-3, 28-4 ,. Data is stored every 64 dots.

When the counting process of the print data (black data) for the first dot data of the first line is completed in this way, the reset signal (R) output from the timing controller 55 resets the count data, and In the same manner, the print data (black data) counting process is executed for the second line. In this case, the same process is performed, and the counters 26-1, 26-2, 26-3, ... Are sequentially included in the first line, the second line, the third line ,. The print data (black data) is counted, and the count data of the print data (black data) included in two lines is stored in the RAM 49 for every 64 dots. The above processing is executed for 64 lines of one character, and each line 6
The count data of print data (black data) for every 4 dots is stored. After that, the print data (black data) stored in the RAM 49 is transferred to the above-mentioned FIG.
Is output to the shift register 40 shown in FIG. At this time, the count data output to the shift register 50 is the count data for every 64 dots. That is, H direction (main scanning direction)
This is count data obtained by counting print data (black data) for 64 lines (for one character) for every 64 dots. Therefore, the total of the number of print data (black data) included in the image data forming one character is each count data. Therefore, the voltage value to each of the thermal heads TH0 to TH40 output from the buffer 43 based on this count data depends on the number of print data (black data) included in one corresponding character. Therefore, at this time, the latch circuit 4
The output timing of the latch signal output to 1 is every 64 lines.

As described above, when the position of the sheet on which the toner image based on the corresponding print data is formed reaches the fixing unit 13, one character (64 × 6) in charge of each thermal head TH is taken.
A voltage corresponding to the number of print data (black data) included in 4 dots is applied, and the fixing process of the toner image can be performed at a temperature according to the number of print dots (black data) included in one character. . Therefore, in this embodiment, the more the print data (black data) included in one character, the higher the voltage value applied to the corresponding thermal head TH, and the less the print data (black data) included in one character, The voltage value applied to the corresponding thermal head TH is low, and the temperature according to the number of print data (black data) is supplied,
It is possible to efficiently perform the heat fixing process on the sheet on which the unfixed toner is formed.

In the above embodiment, the print head 4 is LE
Although the example using the D head is shown, the present invention is not limited to this, and the invention can be similarly applied to any electrophotographic printer using a print head for forming a dot image.

[0029]

According to the present invention, the fixing process can be performed by applying the minimum necessary heat to the portion requiring fixing, so that the heat generation is not wasted and the temperature inside the apparatus is raised. Nor.

Further, since the minimum necessary heat is applied, the voltage applied is small, and the waste of power can be prevented.

[Brief description of drawings]

FIG. 1 is a system block diagram of a fixing device according to an embodiment.

FIG. 2 is a configuration diagram of an LED printer to which the fixing device according to the embodiment is applied.

FIG. 3 is a system configuration diagram of an LED printer to which the fixing device according to the embodiment is applied.

FIG. 4 is a specific circuit diagram of FIG.

FIG. 5 is a circuit diagram of a thermal head.

FIG. 6 is a comparison diagram of a thermal head and dots forming one character.

FIG. 7 is a time chart illustrating the operation of the fixing device according to the embodiment.

FIG. 8 is a specific circuit diagram of a fixing device according to another embodiment.

[Explanation of symbols]

13 Fixing Head 19 Fixing Control Unit 21 Image Discriminating Circuit 22 Line Buffer 23 Output Data Control Circuit 24 Timing Control Circuit 26, 26-1, 26-2, 26-3, 26-4 Counter 27 OR Gate 28, 28-1, 28 -2, 28-3, 28-4, 41
Latch circuit 29 Delay circuit 31, 32 RAM 40 Shift register 42 D / A conversion circuit 43 Buffer TH Thermal head

Claims (1)

[Claims] 1. A fixing device of a recording device for forming a toner image on a recording medium based on dot image data for line scanning recording, wherein a plurality of the fixing devices are arranged side by side along a main scanning direction of the recording medium. A heat generating element, heat generating control information generating means for generating heat generating control information for each heat generating element based on the dot image data, and drive means for driving each heat generating element based on the heat generating control information. And fixing device.