JPH0429255A - Image forming apparatus control method - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the quality of a recorded image by disposing a mode for detecting the standby state of a transfer material at a transfer material standby position and ejecting the transfer material outside an equipment regardless of an image forming operation. CONSTITUTION:The presence or absence or absence of the transfer material 13 in a standby state is discriminated by a sensor 16 for discriminating the presence or absence of the transfer material. And in the case that a time necessary for finishing to convert encoded character or graphic information received from an information processing equipment to picture element information after starting the paper feeding action is a fixed time >=Tf, the transfer material 13 which is sandwiched between resist rollers 11, that is, a transfer material standby position, is forcibly ejected. Thus, the transfer material 13 being retained at the transfer material standby position for a long time is forcibly ejected, and the occurrence of defective image is previously prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus that obtains character or graphic information as bitmap information and forms an image based on it.

[Conventional technology]

Electronic printers are capable of high-resolution and high-quality printing, so in recent years laser printers, LED printers, liquid crystal printers, etc.
Many printers have been developed and are in widespread use. Taking advantage of its high-quality features, it is being used to output complex figures and images.

A controller (for example, a postscript controller) that processes complex image data covering one page of printed surface requires at least one page of image memory (hereinafter referred to as page memory). For example, printing A4 size paper at a resolution of 300 dpi requires IM bytes of page memory.

The amount of image information processed in such high-quality printers is quite large. For this reason, the image data handled by the memory devices of computers and other information processing equipment/systems is often coded or programmed data rather than raw image data.

The performance of the P7 printer is determined by how quickly it converts and prints consistent encoded image information into consistent image information.

A conventional example of the control form of this page printer is shown below.

FIG. 9 shows a cross-sectional view of a laser beam printer, which is typical among P7 printers.

Further, FIG. 2 shows a simplified block diagram of a control circuit of a general laser printer. In FIG. 2, numeral 25 represents an information processing device (for example, a personal computer or a workstation) other than the laser printer. 27 is an external interface (for example, Centronics or R8232C), which sends coded image information (for example, ASCII I code, hereinafter referred to as code information) to the laser printer. Within the laser printer, the code information is received at an interface circuit 18. Microprocessor 17 receives the code information received by interface circuit 18 via internal bus 28. This internal bus 28 is a combination of a data bus, an address bus, and a control bus. Further, the microprocessor 17 operates according to a control program stored in the memory 21. Note that the memory 21 is a nonvolatile ROM.

The microprocessor 17 somewhat processes the code information obtained from the interface circuit 18 and stores it in the memory 19. The memory 19 is a RAM for storing code information. The microprocessor 17 sequentially stores the code information received from the outside in the RAM 19, and also converts the code information into image information of a dot image and stores it in the RAM 20. The RAM 20 is a memory for storing image data (bitmap memory). 22 is a DMA controller that reads data stored in the RAM 20 and sends it to the raster conversion circuit 24.

DMA controller 22 can monopolize internal bus 28 independently of microprocessor 17. When the microprocessor 17 detects that the image data stored in the RAM 20 has reached one page (that is, when it detects that -pages of code data have all been converted to image data), it activates the DMA controller 22. Make it swell. The DMA controller 22 and the microprocessor 17 alternately occupy the internal bus. Then, the DMA controller 22 responds to the request from the raster conversion circuit 24,
Image data is sequentially read from the RAM 20 and sent to the raster conversion circuit 24. The raster conversion circuit 24 converts the parallel image data received from the DMA controller 22 into serial image data. Then, serial image data is outputted to a laser driver (not shown) of the mechanical control section 26 in synchronization with the horizontal synchronization signal to modulate the laser beam.

The microprocessor 17 not only develops the code data into image data, but also instructs the mechanical control section 26 of the laser printer for various printing processes. I1
The 0 driver 23 is in charge of an interface between the microprocessor 17 and the mechanical control section 26.

Next, mechanical control of the laser printer will be explained with reference to FIG. 9. In FIG. 9, 1 indicates the main body of the laser printer. When the microprocessor 17 finishes developing one page of code data and storing the image data in the memory 20, it rotates a transport motor (not shown) via the I10 driver 23. At this time, the photosensitive tram 2, the secondary charging roller 5, the developing roller 7, the transfer roller 1
0, the fixing roller 15 and the ejection roller 16 start rotating.

Rotation control of the transport motor is performed by a mechanical control section 26.

3 is a laser scanning device, which includes a laser scanning mirror, a laser scanning motor, a laser light emitting element, and a laser drive circuit. The I10 driver 23 rotates the transport motor and also rotates the laser scanning motor inside the laser scanning device W3. Then, the I10 driver 23 sequentially applies a high voltage to the primary charging roller 5, the developing roller 7, and the transfer roller 10. Also, the I10 driver 23 is the paper feed roller 1
2 is turned on, and the transfer material 13 loaded in the paper cassette 14 is fed. The fed transfer material 13 is temporarily stopped by the registration rollers 11. Then, the mechanical control unit 26 notifies the I10 driver 23 that the fed transfer material 13 has reached the registration rollers 11. When the transfer material 13 stops on the registration rollers 11, the microprocessor 17 activates the DMA controller 22. Then, serial image data is sent out from the raster conversion circuit 24. The sent serial image data is sent to the laser scanning device 3.
The photosensitive drum 2 is irradiated with a laser beam modulated by the image data. A latent image is formed on the surface of the photoreceptor and visualized as a toner image by the developing unit 6.

The transfer material 13 stopped by the registration rollers 11 is conveyed again by the registration rollers 11, and the toner image is transferred onto the transfer material 13 by the transfer rollers 10. The transfer material 13 to which the toner has adhered is thermally fixed by a fixing roller 15, and then discharged to the outside of the machine by a discharge roller 16. Toner that has not been transferred to the transfer material 13 by the transfer roller 10 is collected by the cleaner 9.

As described above, the code information given from the external information processing device is printed on the sheet as image information.

When printing several pages of data, printing is performed at the timing shown in FIG. In Figure 10, (a
), the microprocessor 17 starts receiving code information. At the same time, the microprocessor 17 starts image development and stores the image data in the memory 20. When the reception of the first page code data is finished at the timing (b), reception of the second page code information is subsequently started at the timing (C). Assuming that the image development on the first page is completed at the timing (d), (
At the timing f), the conveyance motor is rotated to perform the paper feeding operation. Then, at the timing (g), the registration roller 11
DMA controller 2 at timing (h).
2 starts reading out the image data, and the same ((h
), serial image data is formed by the raster conversion circuit 24, and laser exposure is started. Then, the laser exposure for the first page ends at timing (1). Further, reception of the code information for the second page has already been completed at the timing (e), and image development for the second page starts at the timing (1) as well. Then, the second page is printed in the same sequence as the first page.

In Figure 10, periods (a) to (d) during which image development is performed
And (1) to (j) are completely independent of the image data readout period (h)=(i) (which is also the laser exposure period), and there is no overlapping period. This is because the image memory is only for one page.

In such a method, no access to the image memory 20 is made during the period (f) to (h) (or period (k) to (m)).

Therefore, in an LBP in which the distance from the paper feed roller 12 to the registration roller 11 is very long, the throughput (the number of sheets printed per unit time) decreases. If the image memory is provided for two pages, the image development period and the image data readout period can overlap, and throughput can be improved. However, in that case, the memory cost would double. In order to solve this drawback, the applicant proposed a recording device disclosed in Japanese Patent Application No. 1-195626.

In this proposal, when the microprocessor 17 receives one page of code information from an external information processing device 25 such as a host computer, it starts feeding the transfer material 13 such as paper, and when the transfer material 13 reaches a predetermined position, The transportation of the equipment is stopped and the equipment is kept on standby. Thereafter, when the microprocessor 17 has finished developing the code information into dot image image data, the dot image image data is sequentially sent as serial image data to the mechanical control section 26, which modulates the laser beam. The electrophotographic photosensitive drum 2 is exposed to light, and the transfer material 13 is restarted from a standby state in synchronization with the exposed image.

[Problem that the invention is trying to solve]

However, in this proposal, as shown in FIG. 11, the transfer material 13 is pressed against the registration rollers 11 and the transfer material 13 is kept on standby in a state where it forms a loop 31.

Alternatively, as shown in FIG. 12, the transfer material 13 is sandwiched between the registration rollers 11 and is on standby. Note that 30 is a photosensor for stopping the transfer material 13 at a standby position. In this way, in FIG. 11, the transfer material 13 receives the deformation force and forms a loop 31. Although no loop is formed at the position indicated by reference numeral 32 in FIG. 12, the transfer material 13 is subjected to a deforming force due to the nip of the registration roller 11 and the pressurized portion of the paper feed roller 12.

In recent years, as recorded images have become more complex, the time required to develop an image has tended to become longer. Moreover, as the transfer material 13,
In addition to plain paper, second original drawing paper, OHP film, artificial paper,
Envelopes and the like are used, but since they are all thin sheets, if the transfer material 13 is left in such a state for a long time, the transfer material 13 will bend locally.

Then, when the portion comes into contact with the photosensitive drum 2 and an image is transferred, the adhesion becomes poor, resulting in a transfer failure. That is, the quality of the recorded image deteriorates because the toner is not transferred partially, causing a white image to disappear, or because the image is transferred without close contact, the image appears blurred.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that can solve the above technical problems and improve throughput without increasing costs or deteriorating the quality of recorded images.

[Means and operations for solving the problems] In order to achieve the above object, an image forming apparatus according to the present invention includes a data receiving means for receiving coded character or graphic information from another information processing device, and a data receiving means for receiving coded character or graphic information from another information processing device, In an image forming apparatus that has a pixel conversion means that converts character or graphic information into pixel information, and operates a paper feed means and feeds paper independently of the operation of the pixel conversion means, the paper feed means and the transfer means are It is characterized by having a transfer material standby position in between, and having a mode in which the standby state of the transfer material at the transfer material standby position is detected and the transfer material is discharged outside the machine regardless of the image forming operation. By performing such control, when the transfer material remains in the transfer material standby position for a long time, the transfer material is forcibly ejected, making it possible to prevent the occurrence of defective images.

〔Example〕

FIG. 1 is a main body configuration diagram showing an image forming apparatus (laser printer) 1 according to a first embodiment of the present invention. The configuration of the control unit that generates image signals and controls the printer is the same as the configuration shown in the second figure described in the related art, and detailed explanation thereof will be omitted here.

The feature of the first embodiment of the image forming apparatus of the present invention is that from the start of paper feeding operation until the end of converting coded character or graphic information received from an information processing device into pixel information. If the required time is longer than the predetermined time Tf, the transfer material 11 held at the transfer material standby position, that is, the registration rollers 11, is forcibly discharged.

In FIG. 1, the surface of an electrophotographic photosensitive member (photosensitive drum) 2 is uniformly charged by a charger 5a, and then a laser beam from a laser scanning device 3 is irradiated onto the photosensitive drum 2 via a reflecting mirror 4. The image is exposed to light to form a latent image. Next, the toner 8 in the developing device 6 is developed by a developing roller.

On the other hand, the transfer material 13 loaded in the paper cassette 14 is fed by the paper feed roller 12 and is fed by the registration roller 11.
The transfer charger 34 is on standby with its tip held between the
The image is transferred to the printer. The image transferred to the transfer material 13 is fixed by the fixing device 15 and discharged outside the machine.

Furthermore, the toner remaining on the photosensitive drum 2 after transfer is cleaned by a cleaner 9, and the image forming process after charging is repeated.

The presence or absence of the transfer material 13 in a standby state is determined by the transfer material presence/absence sensor 16. Also, the transfer material presence sensor 16
is also used as a sensor for detecting the trailing edge of the transfer material. The time required from the start of paper feeding operation to the end of converting the coded character or graphic information received from the information processing device into pixel information increases, and the transfer material presence sensor 16 causes the transfer material 13 to be placed in the transfer material standby position. If the time period during which it is determined that the transfer material 13 remains at Tf is longer than Tf, the registration rollers 11 and other conveyance systems are driven and the transfer material 13 is discharged outside the machine.

FIG. 3 shows a sequence of an embodiment of the present invention.

In this example, periods (a) to (b), (i) to (j), (
Assume that three pages of code information are received in steps p) to (q).

First, in the control section including the microprocessor 17, 1
Image development of the page code information (code information received during periods (a) to (b)) is started. When the reception of the code information for the first page is completed, the conveyance motor is driven at the timing (C), the photosensitive drum 2 is rotationally driven (drum drive), and the laser scanning motor is driven (
scanner rotation). Next, primary charging and transfer bias are sequentially applied, and a series of print preparation operations called pre-rotation are started, such as equalizing the charging state of the surface of the photosensitive drum 2 and adjusting the output of the laser beam. After this, the image on the photosensitive drum 2 and the transfer material 13 are synchronized (
At the timing d), an operation (sheet pickup operation) of driving the paper feed roller 12 and transporting the transfer material 13 to the position of the registration roller 11 is performed. If the image development on the first page ends at timing (e) but the previous rotation has not finished, the image data will not be read out and will be on standby, and when the previous rotation is finished, at the timing (f). Image data reading begins.

In this case, for the first page, the time required from the start time (d) of the paper feed pick-up operation to the time (e) when image development is completed is less than time Tf, so no forced paper ejection signal is issued.

As the image data is read, the image is written onto the photosensitive drum 2 by modulating the laser light from the laser scanning device 3. The transfer material 13 that has arrived at the registration roller 11 is arranged so that it can be synchronized with the photosensitive drum 13 (for example, the distance from the laser exposure position to the transfer roller 10 is 1).
1, the time T1 for the photosensitive drum 2 to move, and the distance f+ (<z
The registration rollers 11 are driven at a timing (g) delayed by a difference TT2 between the transfer material 13 and the time T2 during which the transfer material 13 moves.

When the electrostatic latent image written on the photosensitive drum 2 by laser exposure comes to the development position, a development bias is applied and development is performed.

Timing (h) When the reading of the image data of the first page is completed, image development of the code information of the second page received in periods (i) to (j) is started.

At this time, the microprocessor 17 has received the code information for the second page, so the paper feed pickup operation for the second page is performed at the timing (k) while the image data for the first page is being read. . Since the image development on the second page takes longer than the paper interval processing time of the printer, the leading edge of the transfer material is sandwiched between the registration rollers 11 and waits for the image development to be completed while forming a loop. At the timing l') when the image development ends, the elapsed time from the paper feed pickup operation start time (k) has not reached Tf, so the forced paper ejection signal is not issued (at the timing (n), the transfer material 13 is sent, and the image data is read out at timing (m).In this case, the time during which the transfer material 13 is sandwiched between the paper feed roller 12 and the registration roller 11 is less than Tf, so the transfer is not completed. The deformation of the material is slight and no transfer defects occur.

Since the microprocessor 17 has received the code information for the third page, it picks up the paper feed for the third page at the timing (r) while reading the image data for the second page, just as it did for the second page. An action is taken. When the reading of the image data for the second page is completed, image development for the third page is started. Regarding the third page, since the image development has not been completed even after the period Tf has elapsed since the paper feed pickup operation start time (r), the microprocessor 17 issues a forced paper ejection signal at the timing (S).

This signal drives the registration roller 11 at the same timing as (S), and forcibly discharges the transfer material 13 to the outside of the machine. When the image development for the third page ends at timing (1), there is no longer any transfer material 13 in the printer, so the paper feed pickup operation is performed again at timing (V), and the registration roller is moved at timing (X). 11, the transfer material 13 is sent, and image data is read out at timing (W).

The transfer material 13 is transferred to the paper feed roller 12 and the registration roller 11.
If the time for which the transfer material 13 is held between the transfer materials 13 and 13 exceeds Tf, the transfer material 13 is forcibly ejected, and the image data that took a long time to develop is printed on the newly fed transfer material 13, resulting in transfer failure. There isn't. Further, in this case, the throughput is reduced because the paper is re-feeded after being forcibly ejected, but since it has already taken enough time to develop the image, this degree of delay does not bother the user too much.

Since this image forming apparatus (laser printer) has not received the code information for the third and subsequent pages, the paper feeding operation for the fourth page is not performed, and when the image is transferred to the transfer material 13 of the third vane, the When the operation called rotation begins, the transfer bias is turned off, the surface of the photosensitive drum 2 is brought to a uniform potential by only primary charging, and the transfer material 13 is discharged outside the machine.
The drum drive and scanner rotation stop, and the printer stops.

Incidentally, the value of Tf varies depending on the pressing force of the paper feed roller 12, the loop amount of the transfer material formed between the paper feed roller 12 and the registration roller 11, the transfer conditions, and the like. For example, the pressing force per unit length of the paper feed roller 12 = 0.1 kg weight/cm, and the distance between the paper feed roller 12 and the registration roller = 70 mm.

Loop amount (length of transfer material 13 held between paper feed roller 12 and registration roller 11 - distance between paper feed roller 12 and registration roller 11) = 8 mm.

When the diameter of the photosensitive drum 2 is -30 mm and the corona transfer device 5a is used, the temperature is 32.5°C.
1. When the transfer material 13 was left in a looped state in an environment of 85% relative humidity, transfer omission occurred due to deformation of the transfer material 13 after being left for 10 minutes. When left for 7 minutes, the transfer omission was very slight and no problem occurred, and when left for 5 minutes, no transfer omission occurred. Similar results were obtained under other conditions as well. From now on, the value of Tf should be set to about 7 minutes, preferably about 5 minutes.

In this embodiment, the corona transfer charger 34 is used as the transfer means, but contact transfer means such as a transfer roller may also be used. Here, the transfer roller has an elastic layer formed by solid or foaming urethane rubber, EPDM, neoprene rubber, silicone rubber, etc. on the surface of a core metal made of iron or stainless steel, and the elastic layer is made of carbon or zinc oxide. It is made to have a volume resistivity of 10' to 1012 Ω·cm. This transfer roller is pressed against the photosensitive drum to form a nip. Further, an extremely high voltage is applied between the photosensitive drum and the transfer roller to attract the toner developed on the photosensitive drum to the transfer material, and the toner is transferred to the transfer material by the pressure applied by the transfer roller and the electric field.

(Second Embodiment) In this embodiment, it is determined whether or not to release the pressure on the paper feed roller 12 depending on the progress of image development, and as the pressure is released, the photosensitive drum 2 is , and the rotation of the photosensitive drum 2 is stopped, and if image development is not completed for a predetermined period of time or more, the transfer material 13 in the printer is forcibly ejected. In other words, if the progress of image development has not reached a certain level after a certain period of time from the start of image development (when the paper feed roller starts operating), it is determined that the image development for -pages will take a long time, and the image development is immediately started. At the same time, the pressure on the paper feed roller 12 is released, the charging of the photosensitive drum 2 and the rotation of the photosensitive drum 2 are stopped, and if the image development is completed within a predetermined time, printing is continued on the waiting transfer material 13. If the image development is not completed even after a predetermined period of time has elapsed, the transfer material that was waiting will be forcibly ejected, and once the image development is completed, a new transfer material will be fed and printing will be performed. .

In this embodiment, since the above-mentioned control becomes a load on the microprocessor 17, an example is shown in which another independent microcomputer 17a is in charge of mechanical control of the laser printer.

FIG. 4 shows a block diagram of the main body of the electrophotographic printer of this embodiment. FIG. 5 shows a configuration for controlling this embodiment.

The configuration shown in Figure 5 is divided into a controller section 100 that mainly handles image information such as receiving image code information from an external information processing device and image development of the code information, and a printer section 102 that controls the operation of the printer main body. .

In Figure 5, the mechanical control of the laser printer is 17a.
Performed by a single-chip microcomputer. The motor driver 4 serves as a load for the microcomputer 17a.
1. Laser scanning motor driver 43, paper feed clutch 45
, a registration roller clutch 46, a sensor 47, a high voltage output circuit 48, a laser modulation circuit 49, a beam detection circuit 51, and the like.

The microcomputer 17a controls these loads according to instructions from the I10 driver 23. Between the microcomputer 17a and the I10 driver 23, READY
The signals PRINT, VSREQ, VSYNC, and PRFD are received. In addition, a serial communication line is also provided for notifying the I10 driver 23 of the printer's load status and for notifying the microcomputer 17a of special commands from the I10 driver 23.

In addition, the image signal output from the raster conversion circuit 24 (
VIDEO signal) is input to the laser modulation circuit 49,
The light output from the semiconductor laser 50 is modulated according to the V I DEO signal. The laser beam is scanned by a laser scanning mirror, and the scanned laser beam is sent to a photodiode 52 arranged on the scanning path of the laser beam.
incident on . The laser beam is then converted into a pulse signal by the beam detection circuit 51.

The pulse signal output from 51 is the horizontal synchronization signal (H8Y
The signal is input to the raster conversion circuit 24 as an NC signal). Further, a signal for releasing the pressure on the transfer material 13 is transmitted from the microcomputer 17a to the eccentric cam 3 via the drive unit 36.
5 will be informed.

Here, the paper feed roller 12 is fixed at one end by a fixed shaft 39, and is pressed against the transfer material 13 near the other end by a crank 37 which is pressed by a pressure spring 38 having a fixed end 40. .

On the other hand, on the opposite side of the crank 37 from the pressure spring 38, an eccentric cam 35 is provided for pressing the paper feed roller 12 against or releasing the transfer material 13. It is controlled by a signal from 17a.

Next, a method of determining whether or not to release the pressure on the paper feed roller 12 according to this embodiment will be explained with reference to FIG. In the figure, the horizontal axis represents the elapsed time t [minutes] since the microprocessor 17 started image development, and the vertical axis represents the -purchased image data volume of data that has been converted from code information to pixel information. represents the ratio R [%] to The solid line in the figure represents a predetermined threshold value Rth(t) for determining whether or not the pressure on the paper feed roller 12 can be released. In this embodiment, the microprocessor 17 monitors the amount of data stored in the image data storage memory 20 from the start of image development, and thereby the amount of data that has been converted from code information to pixel information.
- Calculate the ratio R [%] of the purchased image data capacity, compare this R with Rth, and if R is less than Rth, it is determined that the image development will take a long time, and the paper feed roller 12 to release the pressurization. - As an example, R (t) in actual image development is shown by a dotted line in FIG. In this example, it takes 23.5 minutes to develop the image, but the pressure is released in the third minute. This action greatly reduces the deformation force on the transfer material 13, but if the transfer material is left for a long time, it will partially deform. If it is determined that the machine will be in the machine for more than 20 minutes, a forced ejection signal will be issued.

Next, for the case where the first page receives code information that takes relatively little time to develop the image, and the second page receives code information that takes time to develop the image as shown by the dotted line in FIG. This will be explained using the timing chart shown in the figure.

First, when the printer unit 101 is powered on and can receive the print signal PRINT at any time, the ready signal RDY is true. In this state, when the controller unit 100 finishes receiving one page of code information during periods (a) to (b), it sends a print signal PRINT to the printer unit 101 at timing (C). In response to this, the printer unit 101 starts drum driving, performs primary charging, paper feed pickup, etc. in sequence, and prepares to receive an image signal. Further, at timing (d), the paper feed pickup is performed, and at timing (e) when the leading edge of the transfer material 13 hits the registration roller 11 and forms a loop, the controller unit 100 indicates that it is ready to receive an image signal. VSRE to tell
Set Q to true. In this state, the printer unit 101 waits for an image signal to be sent.

On the other hand, in the controller unit 100, the code information is expanded into an image, the image expansion is completed, and VSREQ becomes true.
At timing (f), which is e, the controller unit 100 issues VSYNC to signal the start of image data transmission, and then the image data is read out and sent to the printer unit 101 as a video signal (VDO) during periods (g) to (h). sent to.

When the printer unit 101 receives the VSYNC signal, the transfer material 13 that has been waiting is moved to the photosensitive drum 2 by driving the registration rollers 11 at the timing (i) so that the leading edge of the image and the leading edge of the transfer material 13 are synchronized. The image is sent toward the image forming apparatus and is transferred by the transfer charger 34.

The controller unit 100 receives the code information for the second page during the period (j) to (k), and sends a prefeed signal (PRFD) to start the paper feeding operation regardless of the operation of the image developing means. ) is issued at the timing of When the printer unit 101 receives the prefeed signal, the paper feed pickup is performed at a timing (m) that allows the maximum throughput of this laser printer to be obtained, and the leading edge of the transfer material 13 hits the registration roller 11, forming a loop. VS to notify the controller that it is ready to accept image signals at timing (n).
Set the REQ signal to true. In this state, the printer unit 101 waits for an image signal to be sent.

On the other hand, in the controller section 100, image development of code information is performed. As shown by the dotted line in Figure 6, 1 minute and 2 minutes after the start of image development, R>Rth, so no pressure release signal is issued, but 3 minutes later, R>Rth, so the image development stops. It is determined that the period is long, and a pressurization release signal is issued at timing (0).

When the printer unit 101 receives the pressure release signal, the single-chip microcomputer 17a reverses the eccentric cam 35 by 180 degrees, and releases the pressure on the transfer material 13 from the paper feed roller 12. Further, the printer unit 101 stops primary charging at timing (p), and stops driving the drum at timing (q).

Image development ends after 235 minutes at timing (S), but since the printer determines that the transfer material 13 has been in the standby position for more than 20 minutes, it has already sent the forced ejection signal at timing (r). It's emitting. After the timing (S) at the end of image development, the pressure release signal stops at the timing (1), and the single-chip microcomputer 17a of the printer unit 101 reverses the eccentric cam 35 to the original position again and resumes feeding. The paper roller 12 presses the transfer material 13.

As a result, the printer unit 101 starts driving the drum again at the timing (U), and turns the primary charging to (V).
It restarts at the timing (W), performs the paper feeding and pickup operation at the timing (W), and drives the registration rollers at the timing (X) to forcibly discharge the transfer material 13 to the outside of the machine. (y
After the transfer material 13 has formed a sufficient loop in the registration roller section after refeeding the paper at the timing (2), the VSREQ signal is generated at the timing (2).

The controller unit 100 sends the VSYNC signal to the printer unit 1.
01, the printer section 101 drives the registration roller 11, and reads the image data from the controller section.
The image DO) is transferred onto the transfer material 13. After reading the image data, the printer unit 101 enters backward rotation.
The primary charging and drum drive stop sequentially, and the operation ends.

According to this embodiment, even with code information that takes time to develop, the pressure on the paper feed roller 12 can be released depending on the progress status at the initial stage of image development.
Since deformation of the transfer material 13 can be minimized,
It is possible to take a sufficiently long time until the transfer material 13 is forcibly ejected.This not only makes it possible to prevent transfer defects more reliably, but also reduces the number of unnecessary outputs due to forced ejection.

In addition, in this embodiment, even if code information that takes time to develop is processed by the printer unit 100 at the initial stage of image development,
Since the photosensitive drum 2 enters post-rotation and stops and waits for the image development to finish, the photosensitive drum 2 may deteriorate due to being charged for a long period of time, and the surface of the photosensitive drum 2 may be scraped by the cleaner 9 due to the long period of rotation of the photosensitive drum 2. It is possible to effectively prevent damage to the surface of the photosensitive drum 2, wear of the cleaner 9, etc.

The threshold value Rth for determining whether or not to release the pressure on the paper feed roller 12 depends on the pressure on the paper feed roller 12, the loop amount of the transfer material 13 formed between the paper feed roller 12 and the registration roller 11, the transfer conditions, etc. You can set it to an appropriate value.

In this embodiment, a controller section 100 and a printer section 10
1 is separated, it is highly scalable to hosts with various page description languages.

Furthermore, since the controller unit 100 can operate without considering the paper feeding timing of the printer unit 101, control becomes simple.

Further, in this embodiment, the ratio R of the amount of data stored in the image data storage memory 20 to the image data capacity of one purchase is used to determine whether to release the pressure on the paper feed roller 12.
- The ratio of the code information that has been expanded into an image to the buyer's coat information may be used for the determination.

(Third Embodiment) In this embodiment, the time required for image development is predicted according to the number of commands (or operators) of code information sent from the host computer using a page description language,
Controls the time until the pressure on the paper feed roller 12 is released;
Furthermore, if the transfer material 13 remains in the standby position for a predetermined period of time or more, it is forcibly ejected from the machine.

The main body structure and control structure of this embodiment are the same as those shown in FIGS. 4 and 2, so their explanation will be omitted. In this embodiment, the external information processing device 25 sends code information written in, for example, the PostScript language, which is a Vane description language, to the laser printer via the external interface 27. The microprocessor 17 operates according to the control program in the control program built-in memory 21. The control program in the memory 21 includes a preprocessing program that counts the number of operators included in code information written in the PostScript language, and a PostScript language interpreter. The microprocessor 17 converts the code information received from the outside into dot image image information using a Postscript language interpreter while counting the number of operators included in the code information using a Blibro session song program, and stores the code information in a memory for storing image data. 20.

When the microprocessor 17 receives the total number of operators in the buyer's code information, the microprocessor 17 calculates the following according to the number of operators:
Time Tf until the pressure release signal of the paper feed roller 12 is issued
is determined by the regulations shown in Figure 8. In FIG. 8, the horizontal axis shows the number of operators, and the vertical axis shows the image development time. The solid line in the figure indicates Tf, and when the number of operators is less than 100, T
f=7 (minutes), and Tf=1 (minutes) for 100 or more.

In the figure, the dotted lines Tmax, Tmod, and Tmin are the approximate maximum values required for image development of a general purchase, respectively;
Indicates average value and minimum value.

According to this embodiment, the time for which the paper feed roller 12 holds pressure does not exceed the deformation limit time of the transfer material 13,
- If the number of operators included in the purchaser's code information is large and the time required for image development becomes obvious, the pressure on the paper feed roller 12 is released early, so that no deformation of the transfer material 13 occurs. Furthermore, in this embodiment, when the printer section is brought to a halt state in synchronization with the release of pressure on the paper feed roller 12, deterioration of the photosensitive drum 1 due to abrasion can be effectively prevented.

Furthermore, as in the embodiment described above, when the transfer material 13 is in the transfer material standby position for a certain period of time (20 minutes) or more, it is forcibly ejected to the outside of the machine, so that transfer defects can be reliably prevented. Since the number of times that is performed is also reduced, unnecessary output can be reduced.

In addition, in this embodiment, the pressure release time of the paper feed roller 12 is determined by simply counting the number of operators in the -page code information, so the determination time can be brought forward, and the image data storage memory 20 can be monitored. Since there is no need to do this, the load on the microprocessor 17 is reduced.

Furthermore, in the case of using a vane description language that can be overwritten within one page of the image data storage memory 20, even if the image data storage memory 20 is monitored, image expansion is not completed. This embodiment is effective because it is impossible to predict the time it will take.

In this embodiment, the total number of operators in the page description language is used as a variable for determining whether to release the paper feed roller 12, but the contribution to the determining variable may be changed depending on the type of operator. That is, the number of operators for graphics, calculation, etc. may be multiplied by a constant, and the summed value may be used as the determination variable.

By doing so, it becomes possible to make highly accurate judgments that take into consideration the fact that a graphic operator takes more time to develop an image than a calculation operator.

〔Effect of the invention〕

As explained above, according to the present invention, the transfer material 13 is fed regardless of the operation of the pixel conversion means, and is made to stand by at a predetermined standby position, and when the standby time is long, the transfer material 13 at the standby position Because it has a mode for forcibly ejecting images, high throughput can be ensured if code information that allows the image development to be completed quickly is received, and conversely, if the image development is complex and the development time is long, it is possible to ensure high throughput. If the information is received, it is possible to prevent transfer defects due to deformation of the transfer material.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main body configuration of a laser printer which is an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a control section in a general laser printer, and FIG. A timing chart showing an example of the operation of the laser printer, FIG. 4 is a main body configuration diagram of a laser printer according to a second embodiment of the present invention, and FIG. 5 is a block diagram showing the configuration of a control section of the laser printer shown in FIG. 4. FIG. 6 is a graph for explaining the criterion for performing a pressure release operation in the laser printer shown in FIG. 4, FIG. 7 is a timing chart showing an example of the operation of the laser printer shown in FIG. 9 is a diagram illustrating the main body configuration of a prior art laser printer, and FIG. 10 is a timing chart showing an example of the operation of the laser printer shown in FIG. 9. , FIG. 11, and FIG. 12 are diagrams for explaining the problems of the prior art. DESCRIPTION OF SYMBOLS 1... Laser printer, 2... Photosensitive drum, 3... Laser scanning device, 6... Developing device, 9... Cleaner 11... Registration roller 12... Paper feed roller, 13... - Transfer material, 15... Fixing device, 17... Microprocessor, 18... Interface circuit, 19-21... Memory, 22... DMA controller, 23... I10 driver, 24... - Raster conversion circuit, 34... Transfer charger, 35... Eccentric cam 36... Drive unit, 37... Crank, 38... Pressure spring, 39... Fixed shaft, 40...・Fixed end. ♀ Figure

Claims (1)

[Claims] (1) The pixel conversion means has a data receiving means for receiving encoded character or graphic information from another information processing device, and a pixel converting means for converting the encoded character or graphic information into pixel information. In an image forming apparatus that operates a paper feeding means and feeds paper independently of the operation of An image forming apparatus characterized by having a mode in which a transfer material is detected and the transfer material is discharged outside the apparatus regardless of image forming operation.