JPH03236669A - Picture forming device - Google Patents

Abstract

PURPOSE:To make paper supply efficient by indicating a count when it is detected that a picture copied medium is in shortage. CONSTITUTION:When a paper shortage detection signal of a paper supply cassette 22 is fed from an engine control section 300 to a CPU 401, a liquid crystal display section of an operation panel 100 displays the shortage of paper in the paper supply cassette by a CPU 401. In this case, the CP 401 reads the content of an unprinted sheet number storage area 403a in a RAM 403 and displays a guide of 'no paper available' on the liquid crystal display section when the content is (0) and displays a guide of 'only one print paper is available' on the liquid crystal display section when the content is (1) displays a guide of alphaonly two print paper sheets are available' on the liquid crystal display section when the content is (2) and displays a guide of 'only two print paper sheets or over are available' on the liquid crystal display section when the content is (3) or over. The user confirms the available sheet number and supplies the required sheets.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention is applicable to, for example, a laser printer that receives image data from an external device and prints a recorded image on paper from the received data. The present invention relates to an image forming apparatus.

(Prior Art) Conventionally, image formation in an image forming apparatus such as a laser printer is performed through various steps such as charging, exposure, development, transfer, peeling, cleaning, and fixing. In such an image forming apparatus, a charging device, an exposure device, a developing device, a transfer device, a peeling device, a cleaning device, etc. are sequentially arranged around the photosensitive drum, and a fixing device is further provided to receive paper from the peeling device. By driving each of the above-mentioned devices according to the rotational movement of the photosensitive drum, each of the above-mentioned image forming steps is executed, and an image is formed on the paper.

In such a laser printer, the control system includes an engine control section that controls the above-mentioned devices and controls operations for completing each of the above-mentioned image forming steps, and a printer control section that controls the operations of the engine control section. The engine control section and the printer control section are connected by sending and receiving commands and statuses. Also,
The printer control section develops page-by-page image information sequentially supplied from an external device into bit image data, generates the generated image information, and then outputs the generated image information to the engine control section.

In such laser printers, when the paper cassette becomes empty while receiving multiple pages of image data and printing the recorded images continuously on the paper, the paper out display appears. to inform the user of the need to replenish paper. At this time, even if the laser printer stores unprinted image data for several sheets, the user cannot check the number of sheets, so even if the stored image data is, for example, one sheet, the user cannot use it. The operator stores a large amount of paper in the paper feed cassette to continue and finish printing.

As a result, when the laser printer receives multiple pages of image data and prints recorded images continuously on paper, when the paper in the paper cassette becomes empty, an out-of-paper display is displayed. However, the disadvantage is that it is not possible to know the number of unprinted image data.

(Problems to be Solved by the Invention) The present invention provides a method for storing images in a storage means while continuously forming images on a plurality of image forming media by receiving image data from an external device. This eliminates the disadvantage that it is not possible to know the number of unimaged image data when the image forming medium is empty.
When the image forming medium stored in the storage means becomes empty while continuous image formation is being performed on multiple image forming media by receiving image data from an external device, An object of the present invention is to provide an image forming apparatus capable of knowing the number of image data that has not yet been formed.

[Structure of the Invention] (Means for Solving the Problems) An image forming apparatus of the present invention includes a receiving unit that sequentially receives image data in units of pages from an external device, and a receiving unit that records the number of pages received as image data by the receiving unit. A counting means for counting, a storage means in which the image forming medium is stored, a conveying means for taking out and conveying the image forming medium stored in the storing means, and the above-mentioned image forming medium conveyed by this conveying means. An image forming means for forming an image using the image data received by the receiving means, a processing means for subtracting the counted contents of the counting means each time the image forming means performs image formation, and a processing means stored in the storing means. a detection means for detecting that the image forming medium in the storing means is empty; and a display for displaying the count value of the counting means when the detecting means detects that the image forming medium in the storage means is empty. It consists of means.

(Function) The present invention is capable of continuously forming images on a plurality of image forming media by receiving image data from an external device. When the medium becomes empty, the number of unformed image data is displayed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2 show the structure of an image forming apparatus of the present invention, such as a laser printer.

That is, the laser printer 1 includes a laser optical system 12.
, photosensitive drum 17, charging device 18, developing device 19, transfer device 20, static eliminator 21, peeling device 35, fixing device 3
7. In addition to process systems such as the cleaning device 45, a paper feed cassette 22, a delivery roller 23, a pair of aligning rollers 25, a conveyance belt 3B, a gate 38, a pair of paper discharge rollers 89
．． 42 etc. are arranged. The laser optical system 12 includes a semiconductor laser oscillator (not shown) that generates laser light, a collimator lens (not shown) that corrects the laser light from this oscillator into parallel light, and a collimator lens (not shown) that converts the laser light from this lens into one scanning line. Polygon mirror (rotating mirror) as a rotating body with a part of octahedral mirror that reflects each
13, an f/θ lens 14, a mirror 15.1B, and a mirror motor 60 that rotates (drives) the polygon mirror 13.

During the image forming operation, the laser beam from the laser optical system 12 corresponding to an image signal from an external device (not shown) or the operation panel 100 is transmitted to the photoreceptor drum 10.
imaged on the surface of The photosensitive drum 17 rotates in the direction of the arrow shown in the figure, and the surface thereof is first charged by the charging device 18, and then exposed by the laser optical system 12 in accordance with an image signal. That is, the laser beam generated from the semiconductor laser oscillator is scanned at a constant speed from the left to the right of the photosensitive drum 17 as the polygon mirror 13 is rotated by the mirror motor 60, thereby creating an electrostatic charge on the surface of the photosensitive drum 17. A latent image is formed. This electrostatic latent image is made visible by applying toner by the developing device 19.

On the other hand, the paper P serving as the image forming medium from the paper feed cassette 22 is taken out one by one by the delivery roller 23, and
4, and is guided to a pair of aligning rollers 25, and sent to a transfer section by this pair of rollers 25.

Also, to the transfer section, the paper P or the paper feed that is taken out one by one by the feed roller 32 from the paper feed cassette 30 in the multi-cassette feeder 2 and guided to the aligning roller pair 25 through the paper guide path 34.29. paper cassette 3
The paper P1 is taken out one by one by the delivery roller 33 from 1 and guided to the aligning roller pair 25 through the paper guide path 34.29, or the paper P1 is taken out one by one from the stacker 26 in the envelope feeder 3 by the delivery roller 27. The aligning roller pair 2 passes through the paper guide path 28 and 29.
The paper A1 guided to the aligning roller pair 25 and the paper P fed from the manual paper feed section 44 and guided to the aligning roller pair 25 through the paper guide path 29 are It is designed to be sent by

Then, the paper P or paper A sent to the transfer section is brought into close contact with the surface of the photoreceptor drum 17 at the transfer device 20, and the toner image on the photoreceptor drum 17 is transferred by the action of the transfer device 20. . This transferred paper P is removed by a peeling device 3.
The heat roller 37.5 is separated from the photosensitive drum 17 by the action of the photosensitive drum 17, and is sent to the fixing device 37 by the conveyor belt 36, and generates heat for fixing by passing through here. The transferred image is thermally fixed. This heat roller 37. A heater lamp 37a for heating is built inside.

After fixing, the paper P passes through a gate 38 to a pair of paper ejection rollers 3.
9 onto the paper output tray 40 or the gate 38
The sheet is sent to the upper conveyance path 41 by a pair of discharge rollers 42.
The paper is ejected onto a paper ejection tray 43.

Further, the photosensitive drum 17 after the transfer is cleaned by a cleaning device 4.
After the residual toner is removed in step 5, the residual image is erased by the static eliminator 21, thereby making it possible to perform the next image forming operation.

Note that the fixing device 37 is formed into a unit (user unit), and is configured to be able to be attached to and detached from the printer 1 independently. Further, in front of the pair of aligning rollers 25, there is an aligning switch 48 for detecting a paper feeding error to the transfer section by the pair of aligning rollers 25, etc., and in front of the pair of paper ejecting rollers 39, 42, an aligning switch 48 is provided. , are provided with paper ejection switches 49a and 149b for detecting paper ejection errors by the paper ejection roller pairs 39 and 42, respectively.

Further, a paper detector 50 for detecting paper P is disposed in the paper feed cassette 22, and detects the presence or absence of paper P in the paper feed cassette 22.

Further, above the laser optical system 12, there is an engine control board equipped with an engine control circuit 70 that controls each electrical device provided in the apparatus main body 1 to control operations for completing the electrophotographic process. A board mounted with a printer control circuit 71 that controls the operation of the engine control circuit 70 is arranged.

Up to three boards for the printer control circuit 71 can be installed depending on the degree of function addition (for example, adding more types of fonts, kanji, etc.). 3t! arranged on the front edge of the board of 71! Further functions can be added by inserting a function-adding IC card 517 into the IC card connector 72 at the i location. Further, a connector (not shown) for connecting to a host device 409 (described later), which is an external device such as a computer or a word processor, is provided on the left end surface of the board of the printer control circuit 71 located at the bottom. .

As shown in FIG. 3, the operation panel 100 has a number of panels,
Liquid crystal display 100 that displays the mode, guidance messages, etc.
a. LED display that lights up and displays various statuses to
ob, a switch 100c for instructing various operations, and an online key 100 for switching online/offline.
It is composed of d. The LED display 100b indicates whether or not it is connected to an external device, that is, "Online" indicates online/offline mode, "Ready" indicates that the device body 1 is ready for operation, and indicates that image transfer is in progress. "Data" to indicate, "Operator" to request an operator call, "Operator" to request a service call.
“Service” and “Mode” indicating auto/manual
It is composed of each display unit.

The switch 100c includes, for example, a menu key, a value key, or a numeric keypad (not shown). The menu key is composed of two keys, "Next Item" and "Previous Item", and is displayed on the LCD display 100.
The multiple menu information displayed on the left half of a is incremented each time the "Next Item" key is pressed, and decremented and displayed each time the "Previous Item" key is pressed, and these display operations are performed cyclically. It is repeated. Also, the above value key is also “Next item” and “
It consists of the two keys of the previous item, and the liquid crystal display 10
A plurality of pieces of value information corresponding to the menu information displayed on the left half of 0a are incremented each time the "next item" key is pressed, and decremented each time the "previous item" key is pressed, and each value is displayed on the right side of the liquid crystal display 100a. displayed in half,
These display operations are cyclically repeated.

The operator selects and instructs a desired operation by operating the menu keys and value keys.

Next, the configuration of the engine control section will be explained.

FIG. 4 is a block diagram showing the configuration of main parts of the engine control section 300. In the figure, 302 is a power supply device;
By turning on the main switch 301, power supply voltages of +5V and +24V are output. The power supply voltage of +5V is supplied to the engine control circuit 70, and is further supplied to the printer control circuit 7 via this engine control circuit 70.
1. - side, +24V power supply voltage is sequentially applied to cover switches 303 and 304 to engine control circuit 7.
0. The scanner control circuit 101 and the high voltage power supply 305 are connected via this engine control circuit 70.
, and the mechanical unit drive circuit 30B, respectively. Then, from the scanner control circuit 101, a semiconductor laser 90
and the mirror motor 92, the pre-exposure device 21, the main motor 307, the manual paper feed solenoid 308, the cassette paper feed solenoid 309, the aligning solenoid 31O, and the toner replenishment solenoid 311 from the mechanism drive circuit 30B.
, cooling fan 500, etc., and is used as a driving power source for these. The cassette paper feed solenoid 309 is switched by the mechanism drive circuit 30B to cause the delivery roller 23 to rotate forward or backward.

Further, the power supply device 302 is provided with a zero-cross switch type heater lamp drive circuit (not shown) consisting of, for example, a phototriac coupler and a triac, which drives the heater lamp 501 inside the fixing device 33. The above +24V is used as a driving power source for the light-emitting side LED of the coupler. In the heater lamp drive circuit with this configuration, as is well known, the light emitting side L
When the ED is turned on/off, the phototriac on the light emitting side turns on/off at the zero cross point of the AC power supply, turning on/off the triac, which is the main switch element in the next stage, and supplying AC power to the heater lamp 37a. S1 is energized or cut off.

Then, a heater control signal S2 for turning on/off the light emitting side LED is sent from the engine control circuit 70 to the power supply device 302.
At the same time, a temperature signal detected by a thermistor 37b provided in the fixing device 37 is also supplied to the engine control circuit 70.

Further, the cover switch 303 is turned off when a knob cover (not shown) is rotated upward, and the cover switch 304 is turned off (not shown) when it is opened. Therefore, when the top cover or rear cover is opened, the switch 303.3
04 cuts off the +24V, the semiconductor laser 90, mirror motor 60, high voltage power supply 305, main motor 307, solenoids 308 to 3111, cooling fan 500, heater lamp 37a, etc. stop operating, allowing the operator to Even if the inside of the main body 1 is touched, there will be no problem.

FIG. 5 is a block diagram showing the configuration of the engine control circuit 70. In the figure, the CPU 350 is an engine M a
It controls the entire section aon, and operates according to a control program stored in the ROM 351. RAM 352 is used as a working buffer for CPU 350. E2 PR
The OM 353 stores information such as the total number of prints. Printer interface circuit 354
mediates the exchange of the interface signal S3 with the printer control circuit 71. The laser modulation control circuit 355 controls the semiconductor laser 90 to be forced to turn on periodically in order to generate a laser light detection signal S4, which will be described later, and also controls the laser light detection signal S4 sent from the printer control circuit 7I by the interface signal S3. It modulates and controls the semiconductor laser 90 according to image data, and sends the laser modulation signal S5 to the scanner control circuit 10.
It is designed to output to 1.

The output register 35B receives control signals S6 and S that respectively control the mechanism drive circuit 30B, the high voltage power supply 305, the scanner control circuit 101, and the heater lamp drive circuit.
7, S8, and S2 are output. The voltage signals S9 and S10 generated by the thermistor 37b and the toner sensor 324 are input to the A/D converter 357, and these voltage values are converted into digital values. The input register 358 includes the paper empty switch 320, the manual feed switch 3211, the paper ejection switch 49a149b1, the mounting switch 323, the aligning switch 48, and the state signals s11, S12, S13, S14, S15, S17 from the paper detector 50. , the +24v on/off status signal S1B is input.

Further, the internal bus 359 connects the CPU 350, ROM
351, RAM352, E2 PROM353,
Printer interface circuit 354, laser modulation control circuit 355, output register 358, A/D converter 3
57 and an input register 858 to exchange data with each other.

The mechanism drive circuit 30B is provided with a drive circuit for driving various motors, clutches, solenoids, etc., and on/off is controlled by a binary control signal S6 output from the output register 35B. Ru. That is, for example, each drive circuit is turned on when it is "1" and turned off when it is "O", and the pre-exposure device 21. main motor 307,
Solenoids 308 to 311, and cooling 77:150
01;l: +24V is turned on or off. The scanner control circuit 101 is provided with a semiconductor laser 90 and a drive circuit for the mirror motor BO. The semiconductor laser 90 is turned on/off by a laser modulation signal S5 outputted from the laser modulation control circuit 355, and the mirror motor 60 is turned on/off by a control signal S8 outputted from the output register 356. It has become so. Furthermore, the laser light detection sensor 312
A PIN diode is used, and when the laser light a passes through the laser light detection sensor 312, a current proportional to the light energy flows. This current signal is used as the laser light detection signal S4 by the laser variable m control circuit 355.
It is now sent to. Furthermore, high voltage power supply 305
, a developing bias power supply section (not shown), a charging device 1B, and a wire high voltage power supply section (not shown) of the transfer device 20.
to, respectively, the developing bias S20. High voltage signals for band its 22 and transfer S24 are output. These on,
Off is the control signal S7 output from the output register 356.
It is controlled by 1 and 0 of .

As described above, within the engine control section 300, power is supplied to each electric circuit via the engine control circuit 70, and each section is controlled by a binary control signal output from the engine control circuit 70. It has become. This engine control section 300 and a printer control section 400, which will be described later, are connected by an interface signal S3.

Next, the configuration of printer control section 400 will be explained.

FIG. 6 is a block diagram showing the configuration of the main parts of the printer control section 400. In the figure, a CPU 401 controls the entire printer control unit 400.

The ROM 402 stores control programs.
The CPU 401 operates according to this program. The ROM 402 also stores data regarding the paper P such as a password to be verified when changing data, top margin, left margin, paper type, message information to notify the operator, and the like. RAM 403 is the host device 409
It is used as a page buffer to temporarily store multiple pages of bone image data sent from.

Further, the RAM 403 is provided with an unprinted number storage area 403a in which the number of unprinted sheets is stored. One page worth of image data from the host device 409 is stored in RAM 40 in the unprinted number storage area 403a.
Each time it is stored in the page buffer in 3, its contents are
Each time one page of image data stored in the page buffer is printed by the engine control unit 300, the content is incremented by "-1". Expanded memory 404
When the image data sent from the host device 409 is a large amount of data such as bitmap data, the above RA
The M403 is a large-capacity memory used when data for one page cannot be stored. Video RAM 4
05 stores image data developed into a bit image, and this output is sent to the serial-parallel converter circuit 4.
It is designed to be supplied to 0B. The serial-parallel conversion circuit 40B converts the image data developed into a bit image in the video RAM 405 and sent as parallel data into serial data, and sends the serial data to the engine control circuit 70.

The host interface 408 is used to exchange data between the printer control unit 400 and a host device 409, which may be a computer or an image reading device, for example, and has two types: a serial transfer line 410a and a parallel transfer line 410b. We are prepared.

Then, it can be used appropriately depending on the type of data transferred to and from the host device f409. The engine interface 411 mediates the exchange of an interface signal S3 between the printer control circuit 71 and the engine control circuit 70. When the IC card 517 is inserted into or removed from the connector 1B, the connection circuit 413
The power supply and signal line supplied to the IC card 517 are cut off, and the noise generated when inserting and removing the IC card 517
This prevents data stored on the device from being destroyed.

The operation panel control circuit 407 controls displaying a guidance message on the liquid crystal display 100a of the operation panel 10G;
Controls lighting, turning off, and blinking of the LED display 100b, or inputs data from the switch 100e to the CPU.
401, etc. Further, the internal bus 412 is connected to the CPO 401° ROM 402,
RAM403, expansion memory 404, video RAM40
5. A bus that exchanges data among the operation panel control circuit 407, host interface 408, engine interface 411, and connection circuit 411.

The IC card 517 also includes a non-volatile memory, such as a static RAM with battery backup, an E2F
It is composed of a ROM SEPROM, a mask ROM, or the like. These IC cards 517 store, for example, character fonts, emulation programs, and the like.

Next, the configuration of the interface signal S3 will be explained.

FIG. 7 shows each signal of the interface signal S3. In the figure, Do-D7 is an engine control circuit 70
This is a bidirectional data bus that transmits status from the printer control circuit 71 to the printer control circuit 71 and commands from the printer control circuit 71 to the engine control circuit 70, and the status and commands are switched and used at the timing shown in FIG. It looks like this. That is, the engine control circuit 70
When the bus direction signal DIR is set to a low level when the busy signal BSYO output from the DO-D7 is at a high level (not busy), the DO-D7 is switched in the direction of transmitting a signal from the engine control circuit 70 to the printer control circuit 71. The status is output on Do-D7. This allows the printer control circuit 71 to read the status.

On the other hand, when the printer control circuit 71 sends a command, the busy signal BSYO' is at a high level (not busy).
When the bus direction signal DIR is set to high level, DO-
D7 is from the printer control circuit 71 to the engine control circuit 7o.
The command is switched to send a signal to
- Output on D7. In this state, strobe signal 5T
When BO is set to a low level, the engine control circuit 70:
The command on DO-D7 is read while the strobe signal 5TBO is at a low level, and the busy signal BSYO is set to a low level (busy state M). In this busy state, the engine control circuit 70 performs processing such as command analysis. When the busy signal BSYO is set to a low level, the printer control circuit 71 returns the strobe signal 5TBO to a high level and ends the command transmission. Then, when the command processing in the engine control circuit 70 is completed, the busy signal BSYO is returned to the high level again.

Note that commands sent while the busy signal BSYO is at a low level are not received by the engine control circuit 7o. Furthermore, the status on the data bus Do-D7 does not change immediately when a state change occurs in the engine control unit 300, but is updated only when the status is returned in response to a command received after the state change. There is.

The attention signal ATN1 is output when the basic status on the print sequence between the engine control circuit 70 and the printer control circuit 71 changes, and the attention signal ATN1 is output when the basic status on the print sequence between the engine control circuit 70 and the printer control circuit 71 changes.
It is set to a high level when it becomes possible to receive a SYNC command and when one page of image data has been received, and is reset to a low level when an attention reset command is received. When the attention signal ATN1 changes from low level to high level, the printer control circuit 71 sends an attention reset command onto the data bus DO-D7 to reset the attention signal ATN1, and then the data bus DO-D7 resets the attention signal ATN1. −
It is now possible to read the status on D7 and know the changed basic status. In addition, the above basic status is also output on the data bus by the basic status request command that requests the basic status, so the content of the changed basic status can be known by the basic status request command prior to the above attention reset command. is now possible.

Letty I PRDYO indicates that the engine control section 300 is in a ready state when it is at a low level, and indicates a not ready state when it is at a high level.When this signal is at a low level, the print operation by the engine control section 300 is It is possible.

System clear signal 5CLRI is printer control circuit 71
200~ after +5v rises with the reset signal of
The level remains high for 500 m5ec, during which the printer control circuit 71 enters the reset state.

The prime signal PRIMEO is a reset signal to the engine control circuit 70. While this signal is at a low level, the busy signal SYO is at a low level, the ready signal PRDYO is at a high level, and the engine control circuit 70 is set to a predetermined initial state. return.

The horizontal synchronization signal H3YNCO is a signal generated every time one line is scanned by the laser exposure unit 22, and is a signal generated every time the laser exposure unit 22 scans one line.
The number of lines corresponding to the effective print length in the transport direction of the paper P after receiving the NC command is output in synchronization with the laser light detection signal S4.

The video clock VCLKO is the horizontal synchronization signal HSY
This is a synchronous clock for inputting one line of video data (image data) VDO to the engine control circuit 70 following the NCO, and is output in a number corresponding to the effective print width of the paper P in the horizontal scanning direction. Then, the video data VDO is taken into the engine control circuit 70 in synchronization with the falling edge of the video clock VCLKO.

In accordance with the video data VDO, the laser exposure unit 22 performs exposure scanning on the photoreceptor drum 17 to form a latent image on the photoreceptor drum 17. In addition,
When the video data VDO is at a low level, it is visualized on the paper P as a dot image.

Next, the operation of the printer control circuit 400 according to the data transfer procedure in the above configuration will be explained with reference to the flowcharts in FIGS. 9(a) and 9(b).

For example, now a laser printer is offline and C
When the PU 401 determines that it is in the offline state (step 5T1), the last host device Wt4
It is checked whether the printing process for the data received from 09 is completed (step 5T2), and if it is not completed, the process branches to step 5T12 to continue the printing process. On the other hand, if the printing process has been completed, steps ST1 and Sr1 are repeatedly executed to create an idling state and wait for the laser printer to be placed on-line.

When the laser printer is brought online in this state, it is checked whether the data sent from the host device 409 is a command (step 5T3), and if it is a command, it performs the operation corresponding to the command. (Step 5T4) If it is not a command, the execution of the above command is skipped and the process proceeds to step ST5. The above command is
For example, it defines the attributes of the following data or controls a printer that does not involve sending or receiving data. Next, it is checked whether the page buffer provided in the RAM 403 as a buffer for data reception is full (step 5T5), and if it is not full, the data sent from the host device 409 is used as an image. It is checked whether it is data (step 5T6). and,
If it is not image data, the process returns to step ST1 and waits for command or image data to be received by repeating the above series of steps. In this state, when it is determined in step ST6 that image data has been received, the received image data is sequentially stored in the page buffer (step 5T7).

At this time, each time one page of image data from the host device 409 is stored in the page buffer in the RAM 403, the contents of the unprinted number storage area 403a in the RAM 403 are incremented by "+1" (step ST7')
. Also, it is checked whether a print request has been issued (step 5T30). Here, if it is determined that a print request has not been issued, it is determined that the print preparation on the engine side has not been completed, and the process returns to step ST1 to re-execute the above series of steps to issue a print request. wait for it to come. On the other hand, when it is determined that a print request has been made,
It is determined that the engine control unit 300 is ready for printing, and a print command is sent (step 5T3).
1).

Next, it is checked whether the storage for one page has been completed (step 5T8), and if the storage has not been completed, the operation panel 1
The "data" lamp of the LED display 100b provided at 00 starts blinking (step 5TIO). Next, the process returns to step ST1 and executes the series of steps described above, thereby waiting until image data for one page is accumulated in the page buffer. When it is determined that storage of image data for one page has been completed by repeatedly executing the above series of steps, the "data" lamp is turned off (step 5T9), and the data reception process is ended. Then, the process moves to the print processing after step 5T12. Note that if it is determined in step ST5 that the page buffer is full, the data reception operation is stopped (step 5T11), and in this case as well, the process moves to the printing process from step 5T12. In this way, during the data reception operation, the "data" lamp is blinked to notify the operator.

Next, when one page's worth of image data has been stored in the page buffer, it is checked whether the scan buffer provided on the video RAM 405 is full (step 5T12). Here, if it is determined that the scan buffer is not full, the CPU 401 converts the image data corresponding to 64 lines of image data stored in the page buffer into bit image data of a character image and scans the image data. It is stored in the video RAM 405 as a buffer (step 5T13). On the other hand, if the scan buffer is full, step 5T13 is skipped.

Next, it is checked whether the vSYNC command has been exited (step 5T20). When it is determined that the VSYNC command has not been exited, it is checked whether a VSYNC request has been issued from the engine side (step 5T21). Then, if it is determined that no VSYNC request has been issued, step S
Return to T1, execute the above series of steps again, and then
Wait for a SYNC request to be issued. Then, when it is determined in step 5T21 that a VSYNC request has been issued, a VSYNC command is sent to the engine side (step 5T22), and the process returns to step STI to output the horizontal synchronization signal H3YNCO and video clock VCLKO.
Shifts to a state where it waits for input.

In this state, in step 5T20 above, VSY
When it is determined that the NC command has already been sent, it is checked whether the transfer of one page of image data has been completed (step 5T26), and if the transfer of image data has not been completed, 6 stored in the scan buffer
The image data of the bit image for four lines is sent to the engine side in synchronization with the horizontal synchronizing signal HSYNCO and the video clock vCLKO (step S72-5). On the other hand, the CPU 401 returns to step 5T13 and waits for the transfer of one page's worth of image data to be completed while executing the above series of steps again. When the transmission of the image data for one page is completed in this manner, the process returns to step STI, and the printer control circuit 71 returns to its initial state and becomes ready to transfer the image data of the next page. At this time, 1 stored in the page buffer in RAM 4H above
Each time the transmission of image data for a page to the engine is completed, the unprinted number storage area 403 in the RAM 403
The content of a is incremented by "-1" (step 5T25').

Further, during the process described above, a paper-out detection signal from the paper feed cassette 22 is sent from the engine control unit 300 to the CPU 4.
01, the CPU 401
The liquid crystal display section 100a of G displays that there is no paper in the paper feed cassette 22. At this time, the CPU 401 uses the RAM 4
The contents of the unprinted number storage area 403a in 0B are read, and if the contents are "0", as shown in FIG. The contents of the number of sheets storage area 403a are “
1'', as shown in FIG. 1(b), the liquid crystal display section 10
At 0a, the message "No paper, print one more sheet" is issued, and the content of the unprinted number storage area 403a is "2".
In this case, as shown in FIG.
If the message "No paper, print 2 more sheets" is given in step a, and the content of the unprinted number storage area 403a is "3" or more, as shown in FIG.
At step a, a message saying "No paper, feed 2 or more sheets" is given.

Next, the operation of the engine control section 300 of the laser printer will be explained with reference to the flowcharts shown in FIGS. 11(a) to 11(e).

First, when the main switch 301 is turned on, a reset signal (not shown) is generated in synchronization with the rise of the +5V power supply.
occurs, and the engine control circuit 70 enters a reset state. In addition, this reset signal causes the printer control circuit 71 to receive a reset signal 5CLRI (see Figure 7).
is output, and the printer control circuit 71 is also reset. Then, after the +5V power supply is turned on, 200 to 50
After 0 m5ec, the value of the reset signal is inverted, the reset state is released, and the CPU 350 starts executing the program stored in the ROM 351.

That is, first, data such as the RAM 352 is initialized (step 5T50). Then input register 358
The state of each switch is read and it is checked whether an operator call state such as paper jam, cover open, process unit not installed, or paper empty has occurred (step 5T51). Here, if an operator call is occurring, it is checked whether only paper empty is occurring (step 5T).
52) If an operator call other than paper empty has occurred, the process returns to step 5T51 and waits for the operator call state to be released. On the other hand, step 5T
When only paper empty occurs in step 5T52, or when no operator call occurs in step 5T51, heating of the fixing device 37 is started (step 5T51).
T53). Next, in order to initialize the electrophotographic process, the main motor 307 and pre-exposure device 21 are turned on (
Step 5T54) Then, the charging S22 is turned on sequentially at time intervals determined by the program (
Step 5T55), and the developing bias S20 is turned on (Step 5T56).

In this state, it is checked whether a certain period of time (approximately 30 seconds) has elapsed (step 5T57), and until the certain period of time has elapsed, it is checked whether or not the cover has opened (step 5T90). Then, when a cover open occurs, step 5T53 to 5T56 described above is performed.
Each output turned on is turned off in step 5T91), and the process returns to step 5T51. On the other hand, when it is confirmed in step 5T57 that a certain period of time has elapsed, the charging S22 is turned off (step 5T58), and then the developing bias S20 is turned off in sequence at the timing determined by the program (step 5T59), and the main motor 307, and the pre-exposure device 21 is turned off (step 5T60). Through the series of operations from step 5T53 to step S60, the warming-up operation of the image forming apparatus is completed.

Then, the ready signal PRDYO is output (changed from high level to low level), a print request is set on the data bus Do-D7, and the attention signal ATN1 is output (changed from low level to high level).
and becomes ready for printing (step 5T61). Note that the fixing device 37, which has started heating in step 5T53, reaches a temperature sufficient for the fixing operation in the process leading to step 5T61.

Further, when an operator call occurs, its contents are outputted onto the data bus as operator call status.

On the other hand, in the state of step 5T61, the printer control circuit 7
1 can recognize the print request by sending the above-mentioned attention reset command to reset the attention signal ATN1 to a low level, and then reading the status on the data bus according to the above-described procedure.

In FIGS. 11(a) to 11(e), the attention reset command, the process of resetting the attention signal ATN1 (changing from high level to low level), and the printing operation for the second sheet are omitted.

Next, it is checked whether a print command has been received (step 5T62). If a print command is not received, it is checked whether an operator call has occurred (step 5T92), and if an operator call has occurred, the print request is canceled and the operator call status is set. The ready signal PRDYO is set to high level (step 5T94). Then, it is checked whether or not a cover oven has occurred among the causes of the operator call (step 5T95), and if a cover open has occurred, the process returns to step 5T51. On the other hand, if the cover has not been opened, the process returns to step 5T92 and waits for the operator call to be released. In step 5T92,
When no operator call occurs, ready signal P
It is checked whether RDYO is low level (step 5T93), and if this signal is low level, step 5
The process returns to T62 and waits for a print command. When the level is high, the not-ready state has already been reached in step 5T94, so the process returns to step 5T61 and the ready state is returned again. That is, the above steps 5T62→5T92→5
The flow from T93 to 5T62 is a state of waiting for a print command, a so-called standby state.

When it is determined in step 5T62 that a print command has been received, the print request is reset and a series of print operations are performed. That is, first, the mirror motor 60 is turned on (step 5T63).
, then sequentially at predetermined time intervals, the main motor 3
07 and the pre-exposure device 21 are turned on (step 5T64
), the charging S22 and the cassette paper feed solenoid 309 are turned on, and the basic status is set to paper conveying (step 5T65). Furthermore, the developing bias S20 is turned on (step 5T66), and the cassette paper feed solenoid 309 is turned off (step 5T6).
7).

Here, while the cassette paper feed solenoid 309 is on, the feed roller 23 rotates once, and the paper P is taken out from the paper feed cassette 22 and conveyed toward the aligning roller pair 25. . Then, after a certain period of time has elapsed since the paper P was fed, it is checked whether or not the aligning switch 48 is on (step 5T68). When the aligning switch 48 is not turned on, it is determined that the paper P has not reached the aligning roller pair 25, and the paper is handled as a paper jam.

That is, the operator call status (jam) is set and the ready signal PRDYO is set to 1 (step 5T96). Furthermore, each device that was turned on in the process from step 5T63 to step 5T66 is turned off in sequence at a timing determined by the program (step 5T97), and the process returns to step 5T92 to wait for the jam to be cleared. -, when the aligning switch 48 is turned on in step S68, the above VSYN
At the same time as the C request is set, the attention signal ATN 1 is output (changed from low level to high level) (step S76). Then, it is checked whether the VSYNC command has been received (step 5T7).
0), when a VSYNC command is received, the VSYNC request is reset, data transfer in progress is set, and laser exposure is started. That is, the horizontal synchronization signal HSYNCO and video clock VCLKO
While transmitting the video data VDO, reception of the video data VDO is started, and an image pattern based on the video data VDO is exposed on the photosensitive drum 17 (step 5T71). Note that until step 5T71, the pair of aligning rollers 25 remains stopped, so the sheet P stops when its leading edge reaches the pair of aligning rollers 25. After a certain period of time has elapsed, the aligning solenoid 31O is turned on (step 5T72), and as a result, the aligning roller pair 25 begins to rotate and the paper P is conveyed toward the transfer device 2fl. Note that the aligning solenoid 310 is operated in step 5T71 above.
It is turned on at a timing such that the leading edge of the image on the photosensitive drum 17 and the leading edge of the paper P coincide with each other when exposure is started.

Then, the transfer S24 is turned on at the timing when the leading edge of the paper P reaches the transfer device 20 (step 5T73).
). The toner image formed on the photoreceptor drum 17 by the developing device 19 is transferred to the sheet P transported in this manner by the transfer device 20 . Further, when the trailing edge of the paper P has completely passed through the paper feed cassette 22 and the next paper P can be fed, a print request for the second paper P is set and an attention signal ATN is set. 1 is output (changed from low level to high level) (step 5T74). On the other hand, after a certain period of time has elapsed since the paper P was conveyed from the aligning roller pair 25, it is checked whether the paper ejection switch 49a1 or 49b is on (step 5T75), and if it is not on, the paper P It is determined that the leading edge of the sheet has not reached the paper ejection roller unit 42, the print request is reset, the operator call status (jam) is set, and the ready signal PRDYO is set to 1.
(step ST9g). And step 5T
Each device that has been turned on up to 74 is turned off in sequence (step 5T99), and the process returns to step 5T92. On the other hand, Ex7
If the paper switch 49a1 or 49b is on,
Wait until one page of the image data 6-6, which was started to be received in step ST71, is captured (step 5T76).
). Then, when the reception of the image data is completed, the data transfer status is reset and the attention signal AT
NI is output (changed from low level to high level) (step 5T77). Next, the aligning solenoid 310 is turned off at the timing when the rear end of the paper P passes the aligning roller pair 25 (step 5T78), and the aligning roller pair 25 stops. Further, the transfer S24 is turned off at the timing when the trailing edge of the paper P passes the transfer device 20 (step 5T79).

Next, after a certain period of time has elapsed since the aligning solenoid 310 was turned off, the paper ejection switch 49a1 or 49a1
9b is off (step 5T80). If it is not turned off, it is determined that the trailing edge of the paper P has not passed the paper discharge roller unit 42, and the process branches to step 5T98, where jam processing is performed. On the other hand, when the switch is off, it is determined that the paper P has been ejected normally, the paper conveying status is reset, and the charging S22 is sequentially turned off (step 5).
T82), and the developing bias 520 is turned off (step 5).
T83), and the mirror motor 60 is turned off (step 5T).
84), and the pre-exposure device 21 and the main motor 30
7 is turned off (step 5T85), a series of printing operations is completed, and the process returns to step 5T62 to enter the standby state.

As mentioned above, by receiving image data from the host device, when printing continuously on multiple sheets of paper, the number of sheets of unprinted image data is displayed when the paper runs out during continuous printing. Since it has been
The user can finish printing by checking the number of sheets and replenishing the number of sheets. As a result, when the paper feed cassette runs out of paper, if there is not a large amount of paper nearby and it is thought that printing will be completed with just a few more sheets, the number of sheets can be confirmed, so paper can be replenished efficiently.

[Effects of the Invention] As explained above, according to the present invention, by receiving image data from an external device, it is possible to perform continuous image formation on a plurality of image forming media. ,
It is possible to provide an image forming apparatus capable of knowing the number of unimaged image data when the image forming medium stored in the storage means becomes empty.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a configuration diagram showing the internal structure of a laser printer, FIG. 2 is an external perspective view of the laser printer, and FIG. 3 is a plan view showing the configuration of an operation panel. FIG. 4 is a block diagram showing the configuration of the main parts of the engine control section, FIG. 5 is a block diagram showing the structure of the engine control circuit, FIG. 6 is a block diagram showing the structure of the main parts of the printer control section, and FIG. The figure shows each signal that makes up the interface signal, Figure 8 is a timing chart to explain the switching timing of the data bus, Figure 9 is a flowchart showing the operation of the printer control circuit, and Figure 10 is the paper feed cassette. FIG. 11 is a flow chart showing the operation of the engine control section. 17... Photosensitive drum, 21... Charging device, 12...
...Laser exposure unit, 19...Developing device, 20.
... Fixing device, 22... Paper feed cassette (storage means),
23... Delivery roller, 25... Aligning roller pair, 48... Aligning switch, 50... Paper detector (detection means), 70... Engine control circuit, 7
DESCRIPTION OF SYMBOLS 1... Printer control circuit, 300... Engine control unit, 306... Machine rear drive circuit, 309... Cassette paper feed clutch, 400... Printer control unit, 401
...CPU, 402...ROM, 403...RA
M. 403a...unprinted number storage area (counting means)
, 405...Video RAM, 409...Host device (external device), P...Paper (image forming medium).

Claims (1)

[Scope of Claims] Receiving means for sequentially receiving page-by-page image data from an external device, counting means for counting the number of pages received as image data by the receiving means, and an image forming medium are housed. a storage means, a transport means for taking out and transporting the image forming medium stored in the storing means, and forming an image on the image forming medium transported by the transport means using the image data received by the receiving means. an image forming means for performing image formation, a processing means for subtracting the counted contents of the counting means each time an image is formed by the image forming means, and a processing means for subtracting the count content of the counting means, and an image forming medium stored in the storage means being emptied. and a display means for displaying the counted value of the counting means when the detecting means detects that the storage means is empty of image forming media. image forming device.