JPH0352872B2 - - Google Patents

Description

Detailed Description of the Invention (A) Technical Field of the Invention The present invention relates to printing apparatuses such as electrophotographic printing apparatuses and electrostatic recording apparatuses, and particularly to periodic cleaning of a latent image forming medium, that is, cleaning of a latent image forming medium. The present invention relates to a printing apparatus that can drive a developer powder removing means for removing developer powder on the printer with as little influence as possible on print output.

(B) Technical Background In recent years, as electronic computers have become faster, output devices such as line printers are required to meet the following requirements.

(1) High-speed printing (2) Miniaturization of the device (3) Easy maintenance (4) No noise To meet these demands, research and development of non-impact line printers is progressing.

FIG. 1 is a diagram for explaining the outline of an electrophotographic printing apparatus generally used as a non-impact line printer. In the figure, 1 is a photosensitive drum on which a latent image is formed, 2 is an initial charger that charges the entire surface of the photosensitive drum 1, 3 is a laser beam that forms an electrostatic latent image on the photosensitive drum 1, and 4 is a laser beam that forms an electrostatic latent image on the photosensitive drum 1.
5 is a developing device that converts a desired information latent image on the photosensitive drum 1 into a toner image using a two-component developer consisting of toner and carrier; 5 is a transfer device that transfers the toner image on the photosensitive drum 1 onto recording paper 10; 6 is after transcription,
a cleaning device 7 for removing toner images remaining on the photosensitive drum 1 without being transferred to the recording paper 10;
8 is a heating fixing device for fixing the toner image on the recording paper 10 onto the recording paper 10; 8 is a folding machine for folding the recording paper 10 on which the toner image has been heat-fixed by the heating fixing device 7; 9 is a device for fixing the recording paper 10; A guide plate 10 guides the recording paper inside, 11 a paper conveyance roller, and 12 a hopper. Recording paper 10
is transported to the transfer device 5 via the guide plate 9 by the paper transport roller 11 at the same speed as the circumferential speed of the photosensitive drum 1, and the toner image on the photosensitive drum 1 is transferred.
The paper is sent to a heat fixing device 7, heated and fixed, and then folded by a folding machine 8.

Printing is performed by sequentially repeating the above steps.

As described above, in a printing apparatus using an electrophotographic process, a toner image formed on the photosensitive drum 1 by the developing device 4 is transferred onto the recording paper 10 by the transfer device 5. However, the toner image on the photosensitive drum 1 is not completely transferred to the recording paper 10 and remains on the photosensitive drum 1. For this reason, although the cleaning device 6 is constantly removing the toner image remaining on the photosensitive drum 1, it cannot be removed sufficiently. In particular, as the speed of the printing device increases, the cleaning efficiency decreases, and the entire surface of the photosensitive drum 1 is not uniformly charged in the next step, resulting in a decrease in print quality.

(C) Prior Art and Problems For this reason, in the past, when the predetermined cleaning cycle came, even if the printing device was printing, the printing was temporarily stopped, that is, the initial charger 2 , the laser beam 3, the developing device 4, the transfer device 5, etc. are stopped, and while the photosensitive drum 1 is rotated, only the cleaning device 6 is driven to perform cleaning. however,
In this case, once the predetermined cleaning cycle is reached, the printing device is temporarily stopped even if printing is in progress, so there is a drawback that it takes time to output the printed material currently being printed by the cleaning time. Ta. In particular, for printing devices that print 10,000 lines per second, the print output is
Using 2000 sheets (one box of regular recording paper) within 10 to 15 minutes and spending cleaning time during that time is a huge waste of time and has the disadvantage of impairing the high speed of the printing device. .

(D) Object of the Invention In view of the above-mentioned drawbacks, the object of the present invention is to enable the next job to be started at the end of printing, for example at the end of the job or at the end of paper, without having to temporarily stop printing for cleaning the photosensitive drum. To provide a printing device which allows cleaning to be performed within the time before starting or until the end of changing sheets, without impairing its high-speed performance.

(E) Structure of the Invention The object is to provide an endless image carrier, an image forming means for forming a developer powder image on the image carrier, and a method for recording the developer powder image on the image carrier. A printing device comprising a transfer means for transferring onto a medium and a cleaning means for removing developing powder remaining on the image carrier without being transferred, and the time from the start of operation of the device. a first means for timing and issuing a first cleaning instruction; a second means for issuing a second cleaning instruction after a predetermined time after the first cleaning instruction is issued; Until the second cleaning instruction is issued, a cleaning operation is performed in which the cleaning means is operated while the image forming means is stopped after the image forming operation is stopped, and after the second cleaning instruction is issued. This is achieved by providing a printing apparatus comprising a control means for stopping the image forming operation and performing the cleaning operation.

(F) Embodiments of the Invention Hereinafter, embodiments of the printing apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 2 is a diagram for explaining an embodiment of the printing apparatus according to the present invention, and is a circuit block diagram. FIG. 3 shows an operation timing chart of FIG. 2. In the figure, 13 is the first counter CTR
1, and the counter step signal PLS shown in FIG.
1, counts up to a certain count value N1, and outputs a carry signal indicating that it is the cleaning cycle of the printing device. Note that the counter step pulse PLS1 is a pulse generated depending on the amount of use of the photosensitive drum 1, for example, the rotation period. 14 is an AND circuit which outputs the logical product of the carry signal outputted when the first counter CTR1 finishes counting and the counter step pulse PLS1. 15 is the second
The counter CTR2 counts the output of the AND circuit 14, that is, the first counter CTR1 counts the count value N1 and then advances by the counter step pulse PLS1 to count the count value N2. .
In other words, as shown in FIG. 3a, the first counter
Even though the CTR1 has finished counting and is outputting a carry signal indicating that it is time for the cleaning cycle of the printing device, the printing device is continuously printing output, and for example, there is still enough recording paper. If the job is output for a long time, the cleaning efficiency may be reduced, and the print quality of the printed matter may be extremely degraded.

To prevent this, the counter 15 sends a print output stop signal (a second counter CTR2 shown in FIG.
It is provided to output a carry signal (carry signal) to a host device that controls each process member as shown in FIG. 1 for performing a printing operation, and also to an OR circuit 18.

16 is an OR circuit into which, for example, a paper end signal (PEND signal), job output end signal, print output stop signal, etc. from a host device (not shown) are input. 17 is an AND circuit, and a first counter
The logical product of the carry signal of the CTR 1 and the output signal from the OR circuit 16 is outputted and inputted to the OR circuit 18. That is, when the first counter CTR1 outputs an output indicating that the cleaning cycle of the printing device has come, for example, when the paper end signal PEND shown in FIG. 3b is input, the output signal is sent to the OR circuit 18. to perform cleaning of the photosensitive drum 1. 18 is an OR circuit which outputs the logical sum of the output signal of the second counter CTR2 and the output signal of the AND circuit 17. In other words, if one of the conditions (when the cleaning cycle of the printing device is reached and an output signal from a host device such as a paper end signal is input, or if a predetermined period of time has elapsed after the cleaning cycle of the printing device has been reached) if you did this)
When this happens, an output signal is input to the timer circuit 19 to cause the photosensitive drum 1 to be cleaned. Reference numeral 19 denotes a timer circuit. For example, when the output of the OR circuit 18 is triggered by a print stop signal from the second counter CTR2, the printing device is still in contact with the photosensitive drum by the laser beam 3 at the time when the print stop signal is output. Since a latent image may be formed on the recording paper 10, the laser beam 3 is output for the amount of data stored in a data buffer (not shown), and after all the printing is performed on the recording paper 10, the photosensitive drum 1 is cleaned. Drum cleaning signal DRMCL after adjusting the time to
This is a circuit for outputting. Here, the first counter CTR1 and the second counter CTR2 are the drum cleaning signals output from the timer circuit 19.
It is reset by DRMCL and ready for the next count.

As explained above, according to this embodiment, the above-described circuit configuration prevents printing from being temporarily stopped for cleaning the photosensitive drum, and allows the next job to be started based on conditions such as job end or paper end. It is possible to obtain a printing device in which cleaning is performed within the time until the start of the printing or the time until the end of paper replacement, and thereby the printing device does not lose its high-speed performance. In other words, in this embodiment, even if the cleaning cycle of the printing device is reached, there is some margin before the print quality deteriorates to an extreme level, and during this period, the end of the paper, the end of the job, or the print output stop signal is sent. By cleaning the printing device when it has been damaged, the high-speed print output of the printing device can be further improved.

Note that in this embodiment, the first counter
CTR1 uses a counter that can retain its value even after the printing device is powered off.
Even if the printing device is turned on and off frequently, it can be counted cumulatively.
Cleaning can be performed at accurate cleaning intervals. Further, even when the power is turned on and off, this can be easily implemented by providing battery support for the circuit of this embodiment.

(G) Effects of the Invention As explained above, according to the present invention, in order to remove developer powder from the latent image forming medium, the printing operation of the printing device is not stopped as much as possible, and the next job after the end of the job is stopped as much as possible. By removing developer powder while the printing operation of the printing device is stopped, such as during printing breaks such as the time until the start of printing, the time until the end of replacing paper at the end of printing, etc., the high speed performance is not impaired. A printing device can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the outline of an electrophotographic printing apparatus, FIG. 2 is a circuit block diagram for explaining an embodiment of the printing apparatus according to the present invention, and FIG.
FIG. 2 is a diagram showing an operation time chart of the circuit block diagram shown in the figure. In the figure, 1 is a photosensitive drum, 2 is an initial charger, 3 is a laser beam, 4 is a developing device, 5 is a transfer device, 6 is a cleaning device, 7 is a heat fixing device, 8 is a folding machine, 9 is a guide plate, 10 is a recording paper, 11 is a paper conveyance roller, 12 is a hopper,
13 is the first counter CTR1, 14 and 17 are AND circuits, and 15 is the second counter CTR2, 16,
18 is an OR circuit, and 19 is a timer circuit.

Claims (1)

[Scope of Claims] 1. An endless image carrier, an image forming means for forming a developer powder image on the image carrier, and transferring the developer powder image on the image carrier onto a recording medium. A printing apparatus comprising: a transfer means; a cleaning means for removing developer powder remaining on the image carrier without being transferred to the recording medium; a first means for issuing a first cleaning instruction; a second means for issuing a second cleaning instruction a predetermined time after the first cleaning instruction is issued; and a second means for issuing a second cleaning instruction after the first cleaning instruction is issued; Until the second cleaning instruction is issued, the cleaning operation is performed by operating the cleaning means while the image forming means is stopped after the image forming operation is stopped, and after the second cleaning instruction is issued, the image forming means is stopped. A printing device comprising: control means for stopping the forming operation and causing the cleaning operation to be performed.