JPH04189162A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To improve the throughput of printing process by a method wherein when it is detected that a storage medium that has been printed is discharged, image data recorded on the storage medium is erased from a memory. CONSTITUTION:A timing T6 shows a timing at which a signal (POSNS) of a paper discharge sensor is turned to false (low level). That is, it shows a timing at which a transferred toner image is fixed on a sheet of recording paper by a fixing unit and the recording paper is completely discharged outside an apparatus. At this timing, an engine controller 29 performs a control process so that a PROUT signal is turn to true (low level) and output to a video controller 19 for a second, for example. Thereby, the video controller 19 detects the fact that the recording paper is normally discharged. Thus, the video controller 19 erases code data and bit image data from a RAM 21.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an image forming apparatus that receives image code data from, for example, a host computer, and develops it into pixel data to form an image.

[Conventional technology]

Conventional image forming apparatuses include a video controller that converts video code data constituting an image signal into pixel data, and a printer engine that forms an image based on the pixel data from the video controller and transfers and fixes it onto recording paper or the like. It consists of. Such a video controller temporarily stores code data sent from a host computer or the like in a memory such as a RAM, and after the capacity of the stored code data reaches one page, analyzes the stored code data. It converts it into pixel data and sends a print start command to the printer engine. When the printer engine receives a command to start printing from the video controller, it makes preparations to enable image formation, such as raising the temperature of the fixing device, and when image formation becomes possible, it starts feeding the recording paper. ing. When the leading edge of the fed recording paper is detected by a sensor or the like, a synchronization signal in the sub-scanning direction is sent to the video controller at a predetermined timing. The video controller sends one page worth of pixel data to the printer engine in synchronization with this synchronization signal in the sub-scanning direction. After this, the video controller determines the maximum time ((
The code data stored in the memory is held until a period of time (hereinafter referred to as recovery time) has elapsed. As a result, if image formation is not completed normally due to a problem with the printer engine, such as a paper jam, the code data stored in the memory can be read out and the image recorded again. can. In this way, even if a problem occurs in the printer engine, the same image data can be printed without receiving code data from the host computer or the like again.

[Problems to be Solved by the Invention] However, in the conventional example described above, the recovery time set by the video controller is set as the time from the synchronization signal in the sub-scanning direction from the printer engine, so the following There was a problem. It is necessary to always keep the recovery time constant regardless of the recording paper size, or, if the recording paper size is unknown, to set the recovery time in accordance with the maximum recording paper size in the sub-scanning direction. Therefore, even if a short recording paper size is used in the sub-scanning direction, this recovery time is set according to the maximum length of recording paper, so the recording paper after image formation is removed from the machine. Code data stored in memory cannot be erased for a long time after being ejected. As described above, conventional image forming apparatuses have problems such as poor usage efficiency of the memory that stores code data for the page, and furthermore, a reduction in throughput. The present invention has been made in view of the above-mentioned conventional example, and when the ejection of a printed recording medium is detected, the image data recorded on the recording medium is erased from the memory, and the image data of the next page can be received. An object of the present invention is to provide an image forming apparatus that can increase the throughput of printing processing. Means for Solving the Problems In order to achieve the above object, an image forming apparatus of the present invention has the following configuration. That is, a storage means for storing image data, an image forming means for forming an image on a recording medium based on the image data stored by the storage means, and a recording medium on which an image has been formed by the image forming means is outside the apparatus. When the ejection detection means detects that the recorded recording medium has been ejected from the apparatus, the recorded image data stored in the storage means is stored. and erasing means for erasing.

[Effect]

In the above configuration, an image is formed on the recording medium based on the image data stored by the storage means. When it is detected that the recording medium on which the image has been formed in the image forming means is ejected from the apparatus, it operates to erase the recorded image data stored in the storage means.

【Example】

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Description of Laser Beam Printer (FIGS. 1 and 2)> FIG. 1 is a sectional view for explaining the configuration of a laser beam printer according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a paper feed tray on which recording paper P serving as a set recording medium is placed. 2 is a paper feed row, which is a paper feed tray I by driving a paper feed solenoid (not shown).
The recording paper P placed on top is fed into the machine. 3 is a paper feed pad that presses the fed recording paper P against the paper feed roller 32; Reference numeral 5 denotes a paper feed sensor serving as a paper detection means, which detects whether or not, for example, the leading edge of the fed paper has passed. Reference numeral 6 denotes a photoreceptor, which is scanned by a polygon mirror 8 with a laser beam modulated according to image information, and an electrostatic latent image is formed on the surface of the photoreceptor. A charging roller 7 uniformly charges the surface of the photoreceptor 6. A developing roller 9 develops the electrostatic latent image on the photoreceptor 6 into a toner image. A transfer roller 10 transfers the toner image developed on the photoreceptor 6 onto the recording paper P being fed. Reference numeral 11 denotes a paper ejection roller that ejects the recording paper P onto the paper feed tray 12. 1
3 is the front door. A fixing unit 17 includes a fixing heater 14, a heating roller 16, and a pressure roller 15-, and fixes the toner image transferred to the recording paper P onto the recording paper by heat and pressure. Reference numeral 18 denotes a paper ejection sensor, and when a paper ejection sensor lever disposed at a paper ejection port (not shown) is pushed up by the recording paper P ejected by the paper ejection roller 11,
The presence of recording paper in the paper output slot is detected. C0NT
is a controller section, which has a configuration as shown in FIG. FIG. 2 is a block diagram showing a schematic configuration of the controller section. A video controller 19 converts code data received from a host computer or the like into video data. To explain this configuration, character font data and -CP
A ROM 20 that stores the control program etc. of the U 22, a RAM 21 that stores image code data received from a host computer etc. via the host I/F, and video data obtained by analyzing the code data, and data between the host computer and the like. Sending/receiving, video I/ to printer engine 23
The CPU 22 generally controls image data processing, such as receiving and passing data through F and converting code data into video data. 23 is an engine controller, based on a control program of the CPU 24 stored in a ROM (not shown), etc.
Image formation is performed by comprehensively controlling each section shown in FIG. FIG. 3 is a diagram showing a signal list of the video I/F between the video controller 19 and the engine controller 23 in this embodiment, and the functions of each interface signal will be explained with reference to FIG. In FIG. 3, "output" indicates an output from the engine controller 23 to the video controller 19, and "input" indicates an input from the video controller 19 to the engine controller 23. The /BD signal is a horizontal synchronization signal of the printer engine in the main scanning direction, and the video controller 19 outputs video data for one main scanning line /VD in synchronization with the falling edge of the /BD signal.
Send O signal. /PPRDY signal indicates that power is being supplied to the printer engine and the engine controller 2
After the initialization of 3 is completed, video controller 1
This is a signal indicating that command/status communication is now possible with 9. The /RDY signal is a signal indicating that the printer engine is enabled to perform a printing operation in response to a print start command (/PRNT signal is true) from the video controller 19. The conditions for this /RDY signal to become true are that the temperature of the heating roller 16 in the fixing unit 17 is appropriate (temperature sufficient to fix the toner image on the paper), the recording paper P is not in a jam state, and the polygon mirror 8 is not in a jammed state. It may be rotating normally at the specified rotation speed, or the /BD signal may be normally output at the specified cycle. The /TOP signal is a print synchronization signal in the sub-scanning direction in the printer engine, and the video controller 19 sets the image writing position in the sub-scanning direction in synchronization with the fall of this /TOP signal. In this embodiment, the time from when the paper feed sensor 5 detects the leading edge of the recording paper P until the recording paper reaches the transfer roller lO and the latent image formed on the photoreceptor 6 by the laser beam are The paper feed sensor 5 is arranged so that the time taken by the rotation of the photosensitive drum 6 to reach the transfer roller 10 is equal. Therefore, when the engine controller 23 detects that the paper feed sensor signal (PFSNS) from the paper feed sensor 5 becomes true, it immediately makes the /TOP signal true for one second. The /5BSY signal is a level signal indicating that the printer engine is sending status (printer status) to the video controller 19. The /STS signal is serial information in 8-bit units that the engine controller 23 transmits to the video controller 19, and this signal is called a status. The /PCLK signal is a synchronization clock when transmitting the /STS signal serially. The /PP0UT signal is a signal indicating to the video controller 19 that the recording paper on which printing has been completed has been ejected at a timing to be described later. The /CBSY signal is a signal indicating that the video controller 19 is sending a command (instruction to the engine controller). The /PRNT signal is a signal from which the video controller 19 instructs the printer engine to start a print operation. However, in the case of continuous printing, this means that the printing operation continues. The /CPRDY signal is a signal indicating that power has been supplied to the video controller 19, initialization of the video controller 19 has been completed, and communication of command status with the printer controller 23 is now possible. . The /VDO signal indicates the image signal to be printed by the printer engine. This image signal is sent by converting the image coat data received from the host computer into dot data by the video controller 19. The /CMD signal is serial information in 8-bit units sent from the video controller 19 to the engine controller 23, and is called a command. /CCLK signal is /C
This is the synchronization clock for the serial data when transmitting the MD signal. Next, the structure of commands sent and received from the video controller 19 to the engine controller 23 and status signals sent from the engine controller 23 to the video controller 19, which are transmitted and received through serial communication, will be explained. As mentioned above, command and status information are 8-bit serial signals. When 1 byte of command information is given from video controller 19 to engine controller 23 in synchronization with the /CCLK signal, engine controller 23 returns 1 byte of status to video controller 19. This command includes two commands: a status request command for checking the status of the printer engine, and an execution command for instructing the printer engine to perform some operation. Both command information and status information use the 8th bit as a parity pit, and odd parity is added at the time of transmission. The status information returned by the engine controller 23 further has the first bit as a command error bit, and if the command from the video controller 19 is undefined data or a parity error occurs, the first bit is a command error bit. The bit is set to "1" and sent back (see Figure 4). Also, if it is not a command error (
An example of status information (first bit is "0") is shown in FIG. FIG. 4 shows status information when an error occurs. Here, the first bit becomes "1", and the type of error is specified by the subsequent second to seventh bits. FIG. 5 shows status information when no error occurs. These status information are returned when the video controller 19 sends 01M'' as a status request command, and in the case of FIG. In other words, when the second bit becomes "1", it indicates that the printer engine is ready to receive the PRNT signal.When the third bit becomes "1", it indicates that the printer engine is ready to receive the PRNT signal. indicates that the recording paper is being conveyed.When the fourth bit becomes "1", a jam or misprint of the recording paper has occurred in the printer engine, and the print data needs to be resent to the engine controller 23. When the 5th bit becomes "l", it indicates that the temperature of the heating roller 16 in the fixing bit of the printer engine is not at the appropriate temperature, so the printer is waiting. When it becomes “1”, the video controller 19
Indicates that the printer engine is paused by a pause command from. When the 7th bit becomes 1, it indicates that the printer engine is in a defective state that requires a serviceman or operator to be called and corrected. 23 can notify the video controller 19 of conditions such as a recording paper jam, no paper, oven in the front door 13, fixing failure, motor failure, etc. The figure shows the signal timing of the video controller 19 and the printer controller 23 when the laser beam printer of this embodiment prints, and FIG. 7 is a flowchart showing the control operation of the CPU 24 by the engine controller 23. FIG. 8 is a flowchart showing the operation of the CPU 22 of the video controller 19. Using these diagrams, the print sequence and code data release timing of the video controller 19 will be explained. In FIG. 19 receives image code data from a host computer (not shown) through the host I/F, and stores the code data in the RAM 21.
When one page is received, the stored code data is analyzed, and if necessary, font data is read out from the built-in font information stored in the ROM 20 or external font information from a font cartridge (not shown) and converted into a dot pattern. (step 513). This converted image data is stored in the RAM 21 as video data. In this way, when all the code data for one page is converted into video data and stored in the RAM 21, step S14
Proceeding to step S15, the video controller 19 sends a print start command to the engine controller 23 (
Make /PRNT signal true Timing TI in Figure 6)
. As a result, the operation shown in the flowchart of FIG. 7 is started, and in step S2, the engine controller 23:
Fixing unit 1 is heated to a temperature that can sufficiently fix the toner image.
The temperature of the heating roller 16 in the optical unit 7 is increased, and the number of rotations of the polygon mirror 8 in the optical unit is adjusted to a specified number of rotations, thereby making the printer engine ready for printing. In this way, when the state is ready for printing, in step S3, the solenoid signal (PFDRV) that drives the paper feed solenoid (not shown) is set to a high level for, for example, 1 second, and feeding of the recording paper P on the paper feed tray 1 is started ( At timing T2) in FIG. 6, a high voltage is applied to the charging roller 7, the developing roller 9, and the transfer roller 10, and the amount of light of a laser (not shown) is adjusted. After this, in step S4, when the paper feed sensor signal (PFSNS) from the paper feed sensor 5 becomes true (high level) and the leading edge of the fed recording paper is detected (timing T)
Proceeding to step S5, for the video controller 19,
Send the sub-scanning synchronization signal /TOP (true for 1 second, for example). As a result, the video controller 19 proceeds from step S16 to step S17 in FIG. 8, and sends out a /VDO signal (digital video signal), which is image information, in synchronization with the falling edge of the /TOP signal. The laser of the printer engine is turned on/off based on the /VDO signal thus sent out, and this laser light is reflected by the polygon mirror 8 and scans on the photoreceptor 6, thereby forming an electrostatic latent image. The latent image formed in this manner is developed into a toner image by a developing roller 9, and transferred onto a recording paper P by a transfer roller 10. Timing T4 in FIG. 6 indicates the timing at which the paper discharge sensor signal (POSNS) from the paper discharge sensor 18 becomes true (high level), and indicates the timing at which the leading edge of the recording paper P reaches the paper discharge port. . Thereby, the process in FIG. 7 proceeds from step S6 to step S7. Timing T5 indicates the timing at which the paper feed sensor signal (PFSNS) becomes false (low level), and this indicates the timing at which the trailing edge of the recording paper P passes through the paper feed sensor 5. From now on, the engine controller 23 is /VD
Prohibits laser lighting based on O signal. This results in
Even if the video controller 19 mistakenly sends out the /VDO signal for a longer time than the length corresponding to the recording paper size, an electrostatic latent image will not be formed on the photoreceptor 6. A toner image is no longer formed. Timing T6 is the signal from the paper discharge sensor (POSSNS)
This indicates the timing at which the transferred toner image becomes false (low level), and this indicates the timing at which the transferred toner image is fixed onto the recording paper P by the fixing unit and the recording paper P is completely discharged from the machine. At this timing, the engine controller 230 control process proceeds from step S7 to step S8, and the video controller 19 is
The PROOUT signal is made true (low level) and output. As a result, the video controller 19 manually inputs this signal in step 318 of FIG. 8 to detect that the recording paper P has been normally ejected. In this way, the process advances to step S19, and the code data and bit image data printed on the recording paper can be released (erased) from the RAM 21. As described above, the engine controller 23 can notify the video controller 19 that the printed recording paper has been ejected from the machine. This results in
The video controller 19 can erase code data, etc. stored in the memory at the optimal timing of the end of printing, and prepare for receiving the next data. Embodiment (Figs. 9 to 11)> Fig. 9 is a diagram showing a signal list of the video I/F of another embodiment of the present invention. Since the signals are almost the same as those shown in FIG. This is a diagram showing an example of the status information of the video I/F. This is status information indicating the number of recording sheets in the aircraft, and the video controller 19 sends "08H" to the engine controller 23 as a status request command. This command information is sent back within the printer as a 6-bit binary number consisting of bits 5 to 0, excluding the command error bit (1st bit) and parity bit (8th bit). Hereinafter, the status indicating the number of recording sheets in the printer will be referred to as status 4 (SR4), and the command requesting status 4 will be referred to as the status 4 request command. is a timing chart showing the operation of another embodiment, and the status 4 and the timing of releasing code data will be explained using the same diagram. When code data is received, the code data is stored in the RAM 21, the code data is converted into a dot pattern, and the video data (bit image) is converted into a dot pattern.
It is stored in the RAM 21 as . When the conversion of one page's worth of code data is completed, the video controller 19 sends a print start command to the engine controller 23 (timing T1.). As a result, engine controller 2
3. When the printer engine is ready to print,
Make the solenoid signal (PFDRV) true (high level) for 1 second and start feeding the recording paper (timing T, 2)
. Timing Tax indicates the timing at which the fed recording paper reaches the paper binding sensor 5. At this time, the engine controller 23 sends a synchronization signal /TOP in the sub-scanning direction to the video controller 19, and also increments the number of recording sheets in status 4 by one. Also, video controller 1
9 is /VD in synchronization with the falling edge of the /TOP signal.
At the same time as sending an O signal, a status 4 request command is sent, and the number of recording sheets in the printer engine is stored. Timing T I4 indicates the timing when the paper reaches the paper discharge sensor 18, and timing T1. indicates the timing at which the paper feed sensor signal (PFSNS) becomes false (low level). After this timing, the engine controller 23 prohibits image formation using the /VDO signal. Note that the video controller 19 normally outputs /V before this timing.
Sending of the DO signal has ended. Timing T I6 is the paper discharge sensor signal (POSSNS)
It shows the timing when becomes false (low level). The engine controller 23 outputs a paper discharge sensor signal (POSN
When S) is detected to be false, the number of recording sheets in status 4 is decremented by 1. At this time, the video controller 19
sends a status 4 request command at regular intervals (for example, every 1 second) after the sending of the /VDO signal ends,
Detects the number of recording sheets in the printer engine. If the number of recording sheets detected in this way is one less than the number stored at timing TI3, the image code data for which the /VDO signal has been sent is erased from the RAM 21, and the next code data can be stored. do it like this. As described above, according to this embodiment, the video controller can detect the number of recording sheets in the printer without providing a signal line indicating recording sheet ejection on the video I/F. Thereby, the code data stored in the memory can be erased at optimal timing. As explained above, according to this embodiment, by notifying the video controller from the engine controller of the timing at which printed recording paper is ejected outside the printer, the video controller can record data without setting a recovery time of a predetermined time. The code data can be erased from memory at the optimal timing appropriate for the paper size, and the next printing process can proceed.

【Effect of the invention】

As explained above, according to the present invention, when the ejection of a printed recording medium is detected, the image data recorded on the recording medium is erased from the memory so that the image data of the next page can be received. This has the effect of increasing the throughput of printing processing.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional configuration diagram of the laser beam printer of this embodiment, Fig. 2 is a block diagram showing a schematic configuration of the control section of the laser beam printer of this embodiment, and Fig. 3 is a diagram of the laser beam printer of this embodiment. A diagram showing a list of video interface signals, FIGS. 4 and 5 are diagrams showing examples of data formats of command data, FIG. 6 is a timing diagram showing signal timing of the first embodiment, and FIG. 7 is a diagram showing the signal timing of the first embodiment. FIG. 8 is a flowchart showing the processing of the video controller of the laser beam printer of the first embodiment; FIG. 9 is a flowchart showing the processing of the video controller of the laser beam printer of the first embodiment; FIG. 9 is the laser beam printer of another embodiment. FIG. 10 is a diagram showing an example of the data format of the status request command, and FIG. 11 is a timing chart showing the operation timing of the laser beam printer of another embodiment. In the figure, 1... paper feed tray, 3... paper feed pad, 4...
...Roller pad, 5...Paper feed sensor, 6...Photoconductor, 7...Charging roller, 8...Polygon mirror, 9
...Developing roller, 10...Transfer roller, 11...
Paper ejection roller, 12... Paper ejection tray, 14... Fixing heater, 15... Pressure roller, 16... Heat roller,
17... Fixing unit, 18... Paper discharge sensor, 19
...Video controller, 20...ROM, 21.
...RAM, 22...CPU, 23...engine controller, 24...CPU. 1!3 Figure 4 Figure 5 Figure 7 Figure 9 Figure 10

Claims (1)

[Scope of Claims] A storage means for storing the image data, an image forming means for forming an image on a recording medium based on the image data stored by the storage means, and a record formed with an image in the image forming means. ejection detection means for detecting that the medium has been ejected out of the apparatus; and when the ejection detection means detects that the recorded recording medium has been ejected from the apparatus, the recorded information stored in the storage means; An image forming apparatus comprising: erasing means for erasing image data of.