JPH0432440A - Image forming device - Google Patents

Abstract

PURPOSE:To judge the state related to the conveyance of a medium easily without performing exclusive processing related to jam detection by making a flag not released by a flag releasing means effective after the lapse of the specified time longer than the time required from the conveyance starting of a medium to its arrival to a detecting means. CONSTITUTION:An engine control part 600 sets a flag related to the conveyance of a medium at the time of starting the conveyance of the medium to be conveyed on a carrier path, and the flag is released by a flag releasing means 600 when the arrival of the medium is detected by a detecting means provided on the carrier path. Accordingly, when the medium is not conveyed appropriately, the flag is maintained by the detecting means without being released. This unreleased flag becomes effective after the lapse of the specified time longer than the time required from the conveyance starting of the medium to its arrival to the detecting means, and thus abnormality related to the conveyance of sheets can be judged.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus applied to a laser beam printer, a copying machine, etc. The present invention relates to an image forming apparatus that appropriately detects abnormalities.

(Prior Art) Laser beam printers, copying machines, and the like have a paper feeding device for feeding sheets of paper, which are media on which images are formed, one by one. A sheet of paper fed from this paper feeding device is conveyed along a conveyance path, and an image is formed in an image forming section. The paper on which this image is formed is conveyed along the conveyance path and is discharged to the discharge section.

In such an image forming apparatus, it is necessary to detect an abnormality in the conveyance of a sheet conveyed through a conveyance path, that is, a jam.

A conventional image forming apparatus has a timer for detecting a jam and a detection switch for detecting paper, and after a predetermined time set by the timer has elapsed, performs a dedicated process related to jam detection by referring to the state of the detection switch. Run it and try to determine if there is a jam.

(Problem to be Solved by the Invention) However, conventional image forming apparatuses must perform a dedicated jam detection process in order to determine the state of paper conveyance, and furthermore, a simple method is required to detect jams. An image forming apparatus that can perform detection has been desired.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an image forming apparatus that can easily and reliably detect a jam without executing a dedicated process related to jam detection.

[Structure of the invention]

(Means for Solving the Problems) Means provided by the present invention for achieving the above object includes a flag setting means for setting a flag indicating a conveyance failure of the medium at the start of conveyance of the medium; the flag setting means, the flag setting means comprising: a detection means provided on a conveyance path for detecting the medium; and a flag cancellation means for canceling the flag set by the flag setting means when the detection means detects the medium; If the flag set by the above is not cleared within a predetermined time, the flag is made valid.

(Function) The present invention sets a flag related to the conveyance of the medium at the start of conveyance of the medium conveyed on the conveyance path, and sets the flag when the arrival of the medium is detected by the detection means provided on the conveyance path. unlock. Therefore, if the medium is not conveyed properly, the flag is maintained without being cleared by the detection means. This flag that has not been cleared is made valid, for example, after a predetermined period of time that is longer than the time required for the medium to reach the detection means after the start of conveyance has elapsed, and an abnormality related to the conveyance of the paper is determined.

As described above, according to the means provided by the present invention, it is possible to easily determine the state related to the conveyance of the medium without executing a dedicated process related to jam detection.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the drawings.

First, the configuration of an image forming apparatus according to the present invention will be explained with reference to FIGS. 2 to 6.

A recessed portion 12 serving as a paper ejection portion is formed in the upper surface portion of the apparatus main body 10 shown in FIG. A recess 13 serving as a paper ejection section is provided on the left side surface, and a paper ejection tray 14 is detachably attached to the apparatus main body 10 in this recess 13. A manual feed guide 32 that can rotate in the direction shown in the figure about a fulcrum 30 provided on the device main body 10 as shown in FIG. A side cover 34 is attached to the lower part, which can rotate in the direction shown in FIG. 5 about a fulcrum 36 provided on the main body 10 of the apparatus. An operation panel 16 is arranged on the right side of the front face in FIG. 2, and a paper cassette 400.degree. 401, which is detachable from the apparatus main body 10, is attached to the lower part. Furthermore, openings 24a and 24b are provided between the paper pressurizers 400 and 401 for inserting a font card for adding functions, a card for application software, etc. (not shown).

As shown in FIG. 3, an inlet-type connector 27 and a power switch 26 for supplying power to the device are provided on the back side of the device body 10, and an opening 20 is provided at the bottom. There is.

A shield plate 28 made of metal is provided in the opening 20 so as to cover the opening 20. This shield plate 28 has a connector 7 connected to a host device (not shown) such as an electronic file device or a word processor.
04a and 704b are attached. Further, a connector 606 is attached to this shield plate for connecting to an additional functional device of this apparatus, such as a large capacity paper feeder, an envelope paper feeder, etc. (not shown).

Next, the operation panel 16 will be explained in detail with reference to FIG.

The operation panel 16 includes a liquid crystal display section 6o and an LED display section 70.
and a switch section 8o.

The online display 71 displays whether or not it is connected to an external device. That is, when the online display 71 is lit, it indicates that the online mode is on, and when it is off, it indicates that the online mode is on.

The ready indicator 72 indicates that the main body of the image forming apparatus is ready for operation. The data display 73 displays that image information is being transferred. Operator display 74 displays a request to call an operator. The service display 75 displays a request to call a service person. The mode display 76 displays manual paper feeding mode or automatic paper feeding mode.

The menu key 81 is the next page key 81a and the previous page key 81.
It is composed of b. This next page key 81. a
Each time , a plurality of menu information displayed on the left half of the liquid crystal display section 60 is incremented. Further, each time the previous page key 81b is operated, the aforementioned plural menu information items are decremented. The value key 83 is composed of a next page key 83a and a previous page key 83b. Each time the next page key 83a is operated, a plurality of pieces of value information corresponding to the menu information described above are sequentially incremented. Further, each time the previous page key 83b is operated, the plurality of value information described above are sequentially decremented and displayed. The operator selects or instructs a desired operation by operating the menu key 81 and value key 83.

As shown in FIG. 5, inside the apparatus main body 10, a drum-shaped photoreceptor 202 is provided as an image carrier. a charging device 204, an exposure section 206 for forming an electrostatic latent image, and a developing device 208 for performing a developing process.
, a transfer device 300 consisting of a corotron, a drum cleaner device 210, and a pre-exposure bag f301 are arranged in this order. Among these, the photoreceptor 202, the charging device 204,
developing device 208, and drum cleaner device f210,
and a pre-exposure device 301 are integrated and arranged as an electrophotographic process unit 200 that can be detached from the apparatus main body 10 as shown in FIG.

A laser diode (not shown) is provided in the laser exposure apparatus 100, and a laser beam 102 emitted from the laser diode is focused by a condenser lens device 118 and sent to a polarizer 108. The polarizing device 108 is equipped with a polyhedral mirror 106 that rotates at high speed.
Laser light 102 reflected by this polyhedral mirror 106
The Fθ lens 110, the reflection mirror 112, and the dustproof lens pass through the lath 114 and scan the exposure portion 206 of the photoreceptor 202.

The developing device 208 includes a magnet roller 220, stirring rollers 222a, 222b, a two-component developer (not shown) consisting of carrier and toner, etc. in a case 224. This electrostatic latent image is developed by conveying toner. Moreover, this developing device 20
8 is attached with a toner replenishing device 226 for replenishing consumed toner.

The drum cleaner device 210 has an elastic blade 232 in a case 230 that is in contact with the photoreceptor 202 and scrapes off toner remaining on the photoreceptor 202 from the photoreceptor 202. This scraped off toner is conveyed by a conveyance roller 236 inside the case 230 to the toner storage section 214 inside the case.

The fixing device 350 includes a heat roller 352 having a built-in heater lamp 351 and a pressure roller 353 that is in pressure contact with the heat roller 352.
The toner image is melted and fixed on the paper P as the paper P passes through the spaces 3 and 3. The heat roller 352 and the pressure roller 353 are connected to the lower casing 354 and the upper casing 3.
56, and has a structure that prevents heat from escaping to the outside so as to ensure a favorable temperature atmosphere necessary for fixing. This heat roller 352 is equipped with a cleaner 35.
8 are in contact with each other, and the heat roller 352 is cleaned to ensure good fixing at all times. Further, the surface temperature of the heat roller 352 is detected by a thermistor 360, and temperature control is performed to maintain the temperature necessary for fixing.

Also, within the upper casing 356 and the heat roller 35
A paper peeling guide 368 is disposed near the downstream side of the contact area between the paper P 2 and the pressure roller 353 to ensure that the leading edge of the paper P guided to the fixing device 350 is peeled off from the heat roller 352. . Note that a paper guide 366 is provided on the paper exit side of the fixing device 350 to guide the fixed paper P to a pair of paper ejection rollers 408.

A gate device 442 is provided on the downstream side of the paper ejection roller pair 408 to switch the conveyance path of the paper P to the paper ejection section on the paper ejection tray 14 side or the paper ejection section on the paper ejection roller pair 409 side. As shown in the figure, two positions, one on the solid line side and the other on the broken line side, can be selected around the fulcrum 444, so that the paper P is conveyed to either of the paper discharge sections.

An image transfer section 209 formed between the photoreceptor 202 and the transfer device 300 is provided within the apparatus main body 10.
On the upstream side of the image transfer section 209, there are a transfer guide roller 422, a paper guide pair 420, and an aligning roller pair 4.
06 is provided. The aligning roller pair 406 constitutes a conveying means for conveying the paper P, and
The aligning roller pair 406 has an aligning switch as a detection means for detecting the arrival of the paper P.

On the downstream side of the image transfer unit 209, a paper conveyance guide 416,
A fixing device 350, a pair of paper ejection rollers 408, and a pair of paper ejection rollers 409 are arranged.

These discharge roller pairs 408 and 409 are provided with static elimination brushes 412 and 413 that come into contact with the non-image forming side of the paper P along the conveyance direction.

The pair of paper discharge rollers 408 and 409 constitute a conveyance means for conveying the paper P. Further, the paper discharge roller pair 408 has a detection switch which is a detection means for detecting the arrival of the paper P.

At the bottom of the device main body 10, a paper feed roller and a paper cassette 4 are installed.
00 and 401, and a paver sensor (not shown) for detecting the paper P in the paper cassettes 400 and 401 is provided near the paper feed roller. In addition, case 45 of paper cassettes 400 and 401
On the side of the 0,470, there is a paper size detection switch (not shown) for detecting the paper size of the stored paper P.
A mounting detection switch (not shown) for detecting whether paper cassettes 400, 401 are mounted on the apparatus main body 10 is also provided.

A paper transport path 42 is provided on the right side of the paper cassettes 400 and 401.
4 is provided, and this paper conveyance path 424 includes paper guides 431, 432, 433, a pair of paper conveyance rollers 440,
It consists of 441.

The paper guide 431 is configured integrally with the side cover 34. On the downstream side of the pair of paper transport rollers 440, there are paper guides 435, 4 that guide the paper P to the pair of aligning rollers 406.
36 are provided. Further, a paper transport path 425 for manual paper feeding is provided above the paper transport path 424, and this paper transport path 425 merges with the paper transport path 424. Further, a pair of paper conveying rollers 440.
441 constitutes a conveyance means.

An aligning switch 630 serving as a detection means is provided near the aligning roller pair 406, and a paper ejection switch 414 is provided near the paper ejection roller pair 408. The paper P is detected.

On the back side of the apparatus main body 10, there is an engine control board (not shown) equipped with an engine control circuit that controls each electrical device installed in the apparatus main body 10 to control operations for completing the electrophotographic process, and a power source. (not shown) etc. are arranged.

A printer control board 602 equipped with a printer control circuit that controls the operation of the engine control circuit is disposed in the board storage section 18 provided between the paper cassettes 400 and 401. Up to two printer control boards 602 can be installed depending on the degree of function addition (for example, adding types of fonts, kanji, etc.). Further functions can be added by inserting font cards (not shown) for adding functions into the 211 font card connectors 610a and 610b provided.

As shown in FIG. 6, the opening 38 on the top surface of the device main body 10
is provided with a top cover 40 that can be opened and closed, and a laser exposure device 100 is attached to the inner surface of this top cover 40. The top cover 40 can be rotated upward up to a maximum of about 60'' using a fulcrum 42 provided at the upper rear end of the apparatus main body 10 as a rotation fulcrum.

When the top cover 40 is rotated upward, the laser exposure device 100 is pulled out from the opening 38 of the device main body 10, and the electrophotographic process unit 200, the fixing device 350, and the paper conveyance path near the fixing device are exposed. Therefore, it is possible to easily and efficiently perform the work of replacing the electrophotographic process unit 200, the work of removing jammed paper P, and the work of maintaining, inspecting, and replacing the equipment.

In the image forming operation, the drum-shaped photoreceptor 202 is rotated and the surface potential of the photoreceptor 202 is kept constant by the action of the pre-exposure device 301, and then uniformly maintained by the action of the charging device 204. charged and laser exposure device 1
The laser beam 102 emitted from the photoreceptor 202
It irradiates and exposes the top of the image to form an electrostatic latent image corresponding to the image signal.

This electrostatic latent image on the photoreceptor 202 is developed by a developing device 208 and visualized as a toner image, which is transferred to the image transfer section 202.
Sent to 9th.

On the other hand, the paper P taken out from the paper cassette 400 or 401 in synchronization with this toner image forming operation is sent to a paper guide 432 or 433, passes through a paper conveyance path 424, passes through a pair of aligning rollers 406, and a pair of paper guides. 420
The toner image is sent to the image transfer unit 209 via the transfer roller 422, and the toner image previously formed on the photoreceptor 202 is transferred onto the paper P by the action of the transfer device 300. Next, the paper P passes through the paper transport path 410 under the guidance of the transport guide 416 and is sent to the fixing device 350, where the toner image is melted and fixed onto the paper P.

Further, the paper P fed from the manual feed guide 32 passes through the manual paper feed conveyance path 425, joins the paper conveyance path 424, and the same operation as described above is performed.

The paper P that has passed through the fixing device 350 is transferred to a pair of paper ejection rollers 408
and sent to the gate device 442.

The position of the gate is selected in advance according to instructions from the host computer, and if the upper position is selected, the paper P is sent to the upper paper ejection section and is passed through the paper ejection roller pair 409 onto the top cover. is discharged. Also, if the lower position is selected as the gate position,
The paper P is discharged onto the paper discharge tray 14.

Note that after transferring the toner image onto the paper P, the photoreceptor 202
The residual toner remaining on the photoreceptor 202 is mechanically removed by a drum cleaner device 210 having an elastic blade 232.
The toner is scraped off from the toner and collected in the toner storage section 214 in the device by the conveyance roller 236.

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

FIG. 1 is a block diagram of the engine control section 600 and its peripheral parts, and FIG. 7 is a block diagram of the engine control circuit 601 and its peripheral parts. In the figure, 603 is a power supply device of the image forming apparatus, which outputs +5V and +24V when the main switch 26 is turned on. +5V is supplied to the engine control circuit 601, and the printer control circuit 70 is further connected to the engine control circuit 601.
1. The engine control circuit 601 includes a flag setting means for setting a flag related to conveyance of the paper when the conveyance of the paper starts, and a flag setting means for canceling the flag set by the flag setting means when the aforementioned detection means detects the arrival of the paper. The apparatus includes a flag canceling means, and a flag validating means for validating a flag that has not been canceled by the flag canceling means after a predetermined time period longer than the time required for the paper to reach the detection means from the start of conveyance of the paper.

On the other hand, +24V is connected to the cover switch 611, then supplied to the engine control circuit 601, and then supplied to the scanner control circuit 101, the high voltage power supply 605, and the mechanism drive circuit 607, and is supplied to the semiconductor laser 120,
Mirror motor 121, high voltage power supply 605, pre-exposure device 30
1. Main motor 612, cassette paper feed solenoid 61
3a, 613b1 is used as a power source for driving an aligning solenoid 614, a toner replenishment solenoid 615, a gate solenoid 617, a cooling fan 616, and the like.

Furthermore, in the power supply device 603, a zero-cross switch type heater lamp drive circuit (not shown) consisting of, for example, a phototriac coupler and a triac is provided for driving the heater lamp 351, and the light emitting side LED of the phototriac coupler is The above +24V is used as a driving power source. In the heater lamp drive circuit with this configuration, when the LED on the light emitting side is turned on and off, the phototriac on the light receiving side turns on and off at the zero cross point of the AC power supply, and the triac, which is the main switch element in the next stage, is turned on and off. AC power is then turned on and off to the heater lamp 351. And a control signal 668 for turning on and off the light emitting side LED.
is supplied from the engine control circuit 601 to the power supply device 603, and a thermistor 360 provided in the fixing device 350 is connected to the engine control circuit 601.

Further, the cover switch 611 is activated when the top cover 40 is rotated upward and when the side cover 34 is rotated upward.
It is designed to turn off when it is opened. Therefore, when the top cover 40 or the side cover 34 is opened, +24V is cut off by the switch 611, so that the semiconductor laser 120 and the mirror motor 121 are
, the high-voltage power supply 605, the main motor 612, the solenoids 613a, 613b, 614, 615, 617, the cooling fan 616, the heater lamp 351, etc. are stopped, and there is no problem even if the operator touches the inside of the device main body 10. It looks like this.

In FIG. 7, the CPU 650 is the engine control section 600.
It performs overall control and operates according to a control program stored in the ROM 651. RAM652 is C
It is used as a work buffer for the PU 650. E2
The PROM 653 stores the total number of prints and the number of sheets used by the electrophotographic process unit 200, that is, the number of sheets printed after the electrophotographic process unit 200 was replaced with a new one. The printer control circuit interface 654 mediates the exchange of an interface signal 667 with the printer control circuit 701.

The laser modulation control circuit 655 controls the semiconductor laser 120 to be forced to turn on periodically in order to generate a laser light detection signal 665 to be described later, and also controls the printer control circuit 7 using the interface signal 667.
It modulates and controls the semiconductor laser 120 according to image data sent from 01, and outputs a laser modulation signal 664 to the scanner control circuit 101. Output register 65
6 is a mechanism drive circuit 607 and a scanner control circuit 101;
, the high-voltage power supply 605, and the control signal 663°666.669,6 that controls the heater lamp drive circuit, respectively.
Outputs 68. The voltage generated by the thermistor 360 and the toner sensor 624 is input to the A/D converter 657, and this voltage value is converted into a digital value.

The input register 658 receives state signals from the vapor empty switches 620a and 620b, the paper ejection switch 414, the attachment detection 428, the size switches 426 and 427, and the aligning switch 630, as well as the +24V on/off state signal. has been done. The option control circuit interface 648 mediates the exchange of an interface signal 662 with an option control circuit (not shown).

Further, the internal bus 659 is connected to the CPU 650 and the ROM 6.
51, RAM652, E2 PROM653, printer control circuit interface 654, laser modulation control circuit 6
55, output register 656, A/D converter 657,
Data is exchanged with the input register 658.

In this embodiment, the CPU 650, ROM 651, RAM
652, an A/D converter 657, and part of the output register 656 and input register 658 are realized by using a 1-chip microcomputer 649.

The mechanism drive circuit 607 is provided with a drive circuit for driving a motor, a solenoid, etc., and the control signal 663 outputted from the output register 656 is
On and off are controlled by the binary values of lJ and rOJ.

For example, each drive circuit is turned on when it is "1" and turned off when it is "0", and the pre-exposure device 301, the main motor 612,
+2 to solenoids 613a, 613b, 614, 615
It is designed to energize or cut off 4V.

The scanner control circuit 101 is provided with a drive circuit for a semiconductor laser 120 and a mirror motor 121, and the semiconductor laser 120 is turned on and off by rlJ rOJ of the laser modulation signal 664 output from the laser modulation control circuit 655. Furthermore, the mirror motor 121 receives the control signal 666 output from the output register 656.
On/off is controlled by rOJ. Further, when the laser beam 102 passes through the laser beam detection sensor 122, it is detected and sent as a laser beam detection signal 665 to the laser modulation control circuit 655.

Further, from the high voltage power supply 605, the developing device section 208
, a developing bias 604a and a charging device 604c to the charging device section 204 and the transfer device section 300, respectively.

Each high voltage of the transfer 604b is output. These on,
When off, the control signal 66 output from the output register 656
Controlled by rlJ rOJ of 9.

As described above, within the engine control unit 600, power is supplied to each electric circuit via the engine control circuit 601, and rOJ is output from the engine control circuit 601.
It is controlled by a binary signal of rlJ. This engine control section 600 and a printer control section 70, which will be described later,
0 is in a state of being coupled by an interface signal 667.

Next, the configuration of printer control section 700 will be explained.

FIG. 8 shows the printer control unit 700 and its peripheral parts. In the figure, the CPU 741 is the printer control unit 7
This controls the entire 00. The ROM 742 stores a control program, and the CPU 741 operates according to this program. In addition, the above ROM7
42 stores data related to the paper P such as a password, top margin, left margin, vapor type, etc., which are verified when changing data. The RAM 74B is used as a page buffer for temporarily storing image data sent from the host device 749, or used as a page buffer for temporarily storing image data sent from the host device 749.
It is used as a working buffer. Expanded memory 74
4 is used when the image data sent from the host device 749 is a large amount of data such as bitmap data.
AM743 is a large capacity memory used when it is not possible to store data for one page. Video RAM74
5 stores image data developed into a bit image, and this output is sent to a serial-parallel conversion circuit 74.
6. The serial-parallel conversion circuit 746 converts the image data developed into a bit image in the video RAM 745 and sent as parallel data into serial data, and sends the serial data to the engine control circuit 601.

The host interface 748 is for exchanging data between the printer control unit 700 and a host device 749, which may be, for example, an electronic computer or an image reading device. It has two types of transfer lines.

Then, it can be used appropriately depending on the type of data transferred to and from the host device 749. The engine interface 751 mediates the exchange of the interface signal 667 between the printer control circuit 701 and the engine control circuit 601.

The connection circuit 753 connects the font card 707 to the connector 7.
10a, 710b or connector 71
When removing the font card 707 from the font card 707, shut off the power supply and signal line to prevent data stored in the font card 707 from being destroyed by noise generated during insertion or removal. It is intended to prevent

The operation panel control circuit 757 controls displaying a guidance message on the liquid crystal display section 60 of the operation panel 16, and
It controls lighting, extinguishing, and blinking of the ED display 70, or controls sending data input from the switch 80 to the CPU 741. In addition, internal bus 752
The above CPU741, ROM742, RAM743,
This is a bus for exchanging data among the expansion memory 744, video RAM 745, operation panel control circuit 757, host interface 748, engine interface 751, and connection circuit 753.

The font card 707 also includes a non-volatile memory,
For example, static RAM with battery backup, E
2 It is composed of PROM, EPROM, mask ROM, etc.

These font cards 707 store, for example, character fonts, emulation programs, and the like.

Next, the configuration of the interface signal 667 will be explained.

FIG. 9 shows each signal of the interface signal 667. In the figure, Do-07 is the engine control circuit 6
The bidirectional data bus transmits status from 01 to printer control circuit 701 and commands from printer control circuit 701 to engine control circuit 601, and status and commands can now be switched at the timing shown in FIG. ing. That is, the engine control circuit 6
When the busy signal BSYO output from 01 is "1",
When the bus direction signal DIR is set to "0", the DO-D7 is switched from the engine control circuit 601 to the printer control circuit 701, and the status is output on the DO-D7, so the printer control circuit 701 reads the status. be able to.

On the other hand, when the printer control circuit 701 sends a command,
When the busy signal BSYO is “1”, the bus direction signal DI
When R is set to "1", DO-D7 is the printer control circuit 7.
Since the direction is switched from 01 to the engine control circuit 601, the command is output, and then the strobe signal 5
Set TBO to "0". At this time, the engine control circuit 60
1, the command on the DO-D7 is read, the busy signal BSYO is set to "0", and processing such as command analysis is performed. When the busy signal BSYO is set to "0", the printer control circuit 701 outputs the strobe signal 5TB.
Return O to "1" and end the command transmission. and,
When the command processing in the engine control circuit 601 is completed, the busy signal BSYO is returned to "1". In addition,
Commands sent while the busy signal BSYO is "0" are not received by the engine control circuit 601. Furthermore, the status on the data bus DO-D7 does not change immediately when there is a change in status in the engine control unit 600, but is updated only after the status change in response to a received command.

The attention signal ATNI is the engine control circuit 601
This is output when the basic status on the print sequence between the printer control circuit 701 and the printer control circuit 701 changes.
It is set to "1" when the engine control circuit 601 becomes able to receive a print command or VSYNC command, which will be described later, and when it has finished receiving image data for one page, and is reset to "0" when it receives an attention reset command. It is now possible to do so.

Therefore, the attention signal ATN1 is transmitted from rOJ to “]
”, the printer control circuit 7゜1 sends an attention reset command to the data bus Do-D7, resets the attention signal ATNI from “1” to “0”, and then the data bus DO-D7 You can read the status above and know the basic status that has changed. 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 basic status changed by the basic status request command prior to the above latency reset command can be known.

The ready signal PRDYO indicates that the engine control unit 600 is ready for operation when it is "0", and indicates that the engine control section 600 cannot operate when it is "1j".
”, the print operation of the engine control unit 600 is possible.

System clear signal 5CLRI is printer control circuit 70
1 reset signal, 200 after +5v rises
It becomes "1" for ~500m5ec, and the printer control circuit 701 is in a reset state during this time.

The prime signal PRIMEO is a reset signal to the engine control circuit 601, and while this signal is "0", the busy signal BSYO is "0" and the ready signal PRDYO is "1".
At the same time, the engine control circuit 601 returns to a predetermined initial state.

The horizontal synchronization signal H8YNCO is the laser light detection signal 6 generated by the laser exposure unit 100 for each scan.
65, the number of lines corresponding to the effective print length in the transport direction of the paper P after receiving the VSYNC command is output in synchronization with the laser light detection signal 665.

The video clock VCLKO is the horizontal synchronization signal H8Y.
This is a synchronization clock for inputting one line of video data (image data) VDO to the engine control circuit 601 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 received by the engine control circuit 601 in synchronization with the falling edge of the video clock VCLKO,
It is stored as a latent image on the photoreceptor 202 by the laser exposure device WIL100. In addition, if the video data VDO is "0"
At this time, it is visualized on paper P as a dot image.

Next, in the above configuration, the operation of the engine control section 600 of the image forming apparatus will be explained with reference to the flowchart shown in FIG.

When the main switch 26 is turned on, a reset signal (not shown) is generated in synchronization with the rise of +5V.
While the engine control circuit 601 is in a reset state, the printer control circuit 701 is further reset by the reset signal 5CLRI, and the printer control circuit 701 is also reset. and,
200 to 500 m s e after +5V rises
After c, the value of the reset signal 5CLRI is inverted, the reset state is released, and the cpU 650 starts executing the program stored in the ROM 651.

First, the data in the RAM 652, etc. is initialized (attack 550), and the status of each switch is read into the input register 658, such as paper jam, cover oven, process unit not installed, and one door empty. The operator call status of is checked (step 551).

If an operator call is occurring, it is checked whether only vapor empty is occurring (step 552), and if an operator call other than vapor empty is occurring, the process returns to step S51 and the operator call status is checked. Wait for it to be released. - way, step S
If only vapor empty occurs in step 52, or if no operator call occurs in step 551, heating of the fixing device 350 is started (step 85).
3) Next, in order to initialize the electrophotographic process, the main motor 612 and the pre-exposure device 301 are turned on (step 554), and the charging 604C is outputted sequentially at time intervals determined by the program. is turned on (step 555), and the developing bias 604a is turned on (step 556). In this state for a certain period of time (about 30
sec) has elapsed (step 5).
57), until the time elapses, it is checked whether or not a cover oven has occurred (step 590), and when a cover oven has occurred, steps 853 to S5 described above are performed.
Turn off each output turned on in step 6 (step 591),
The process returns to step S51 again.

On the other hand, when it is confirmed in step S57 that a certain period of time has elapsed, the output of the charging 604C is turned off (step 558).
The developing bias is sequentially turned off at the timing determined by the program (step 559), and the main motor 6
12, and the pre-exposure device 301 is turned off (step 560). Through the series of operations from steps S53 to S60 described above, the warming-up operation of the image forming apparatus is completed. Then, when the ready signal PRDYO changes from "1" to "0", a print request is set on the data bus DO-D7, and an attention signal AT is set on the data bus DO-D7.
N1 changes from "0" to "1" (step 561), and the print operation becomes ready.

Note that the fixing device 350, which has started heating in step S53, is in a sufficiently good state for a fixing operation in the process leading to step S61. 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 S61, the printer control circuit 70
1 can recognize the print request by sending the above-mentioned attention reset command, resetting the attention signal ATN1 to "0", and then reading the status on the data bus according to the above-mentioned procedure. In FIG. 11, this attention reset command and the reset of the attention signal ATNI (from "1" to "0"
'') and the operation of printing the second sheet are omitted.

Next, it is checked whether a print command has been received (step 562), and if no print command has been received, it is checked whether an operator call has occurred (step 592), and if an operator call has occurred. At this time, the print request is canceled, the operator call status is set, and the ready signal PRDYO is set to "1" (step 59).
4). Then, it is checked whether or not a cover oven has occurred among the operator calls (step 595), and if a cover oven has occurred, the process returns to step S51.

On the other hand, if cover oven is not occurring, step S
The process returns to step 92 and waits for the operator call to be released.

In step S92, if no operator call has occurred, it is checked whether the ready signal PRDYO is "0" (step 593), and this signal is "0".
If it is "0", the process returns to step S62 and waits for a print command; if it is "1", since the not ready state has already been reached in step S94, the process returns to step S61 and the ready state is returned again. That is, the above step 562-S
The flow of 92→S93→S62 is a state of waiting for a print command, a so-called standby state.

When the print command is received in step S62, the print request is reset and a series of print operations are performed. First, the mirror motor 121 is turned on (step 863), and then the main motor 612 and the pre-exposure device 301 are turned on in sequence at time intervals (step 564), and the charging 604c and the cassette feed solenoid 613 (selected at that time) are turned on. The solenoid on the cassette side) is turned on, the basic status of paper transporting is set (step 565), the developing bias 604a is turned on (step 566), and the cassette paper feed solenoid 613 is turned off. (Step 567).

Here, the paper feed roller 402 rotates once during the time when the cassette paper feed solenoid 613 is on, and the paper is fed from the paper cassette 401 or 402.
is taken out and conveyed along the paper conveyance path 424 via a pair of conveyance rollers 440 toward a pair of aligning rollers 406 . Then, after a certain period of time has elapsed since the paper P was fed, it is checked whether or not the aligning switch 630 is on (step 368). If this switch is not on, the paper P is transferred to the alignment roller. versus 4
It is determined that the paper jam has not reached 06 and is treated as a paper jam, and the operator call status (jam) is set and the ready signal PRDYO is set to "1" (step 596).

Further, each device that was turned on in the process from step 363 to step S66 is turned off in sequence at a timing determined by the program (step 597), and the process returns to step S92. Wait for the jam to clear.

On the other hand, when the aligning switch 630 is turned on in step S68, the process advances to step S69 and the above-mentioned V S
At the same time as the YNC request is set, the attention signal ATN1 is inverted from "0" to rlJ.

After receiving the print command in step S62, the series of printing operations from step 863 to step S70 are performed at the first timing in order to obtain a high-quality image.
It is strictly set using a table as shown in Figure 3.

Specifically, as shown in FIG. 14, an instruction ID number is assigned to each operation, and 1-byte 16-way data indicating each operation with an instruction ID number corresponds to this instruction ID. Instruction data indicating the operation content is set. The execution time shown in FIG. 13 is the time from receiving the print command to starting the operation, and is set by 2-byte 16-way data. This execution time is determined by the CPU of the engine control unit 600.
It is set based on the cycle of the free running counter managed by 650.

This free-running counter is a 2-byte counter that is incremented once every 10 seconds, and when it reaches a predetermined value, it continues the incrementing operation from O again. Therefore, the execution time shown in FIG. 13 is, for example, ro
190J means 4000 dragon seconds.

Next, the control processing executed based on the table shown in FIG. 13 will be explained with reference to the flowchart shown in FIG. 15.

When a command related to printing is input from the printer control unit 700 in step SP], the engine control unit 600 stores the value of the free running counter as the start timing of a series of printing operations. Next, in step SP3, the value of the instruction pointer is set from "0" to "1". The value of this instruction pointer indicates how far out of the series of printing operations shown in FIG. 1813 has been completed, and is incremented each time each operation is completed.

At step SP5, the execution time of the next operation is calculated by adding the execution time on the table of FIG. 13 indicated by the value of the instruction pointer and the start timing. In step SP7, step SP
The execution time calculated in step 5 is compared with the value of the free running counter, and when both values match, step SP9
Go to Execute the operation related to printing, that is, the instruction. When the instruction is executed in step SP9, the process advances to step SPI1 and the instruction pointer is incremented. Next step 5P13
Then, it is determined whether the series of printing operations shown in FIG. 13, that is, the sequence has ended, and if it has not ended, the process returns to step SP5.

Similarly, the instruction pointer is incremented each time each operation is executed in a series of printing operations, and when the value of this instruction pointer exceeds the number of instructions shown in Figure 13, the series of printing operations ends. judge things. In this way the 13th
Each instruction set in chronological order in the diagram is executed sequentially.

By storing the value of the free running counter as the start timing of a series of printing operations when a command related to printing is input as described above, each instruction can be reliably executed without providing a dedicated counter.

Referring again to FIG. 11, in step S70, VSY
It is checked whether an NC command has been received. When the VSYNC command is received in step 870, the process advances to step S71, where the VSYNC request is reset, data transfer in progress is set, laser exposure is started, and the video data is transmitted while transmitting the horizontal synchronization signal H8YNCO and video clock VCLKO. VDO reception is started, and video data VDO is recorded on the photoreceptor 202.
An image pattern of O is exposed.

Note that up to step S71, the aligning roller pair 4
Since the roller 06 remains stopped, the paper P stops when its leading edge reaches the pair of aligning rollers 406. Therefore, after a certain period of time has elapsed, the aligning solenoid 614 is turned on (step 572).
), the aligning roller pair 406 begins to rotate, and the paper P
is transported toward the image transfer section 209.

Note that the aligning solenoid 614 is turned on at a timing such that the leading edge of the image on the photoreceptor 202 and the leading edge of the paper P, which were started to be exposed in step S71, coincide with each other. Then, at L5, the output of the transfer 305b is turned on at the timing when the leading edge of the paper P reaches the image transfer unit 209 (
Step 873) The toner image formed on the photoreceptor 202 by the developing device 208 on the sheet P transported in this manner is transferred to the image transfer unit 209 by the transfer device 302.
Transcribed by. When the next sheet of paper can be fed, a print request for the second sheet of paper P is set, and the attention signal ATN1 is inverted from "0" to "1" (step 574).

On the other hand, after a certain period of time has elapsed since the paper P was conveyed from the aligning roller pair 406, it is checked whether the paper ejection switch 414 is turned on (step 575).
If it is not on, it is determined that the leading edge of the paper P has not reached the paper ejection roller unit 408, the print request is reset, the operator call status (jam) is set, and the ready signal PRDYO is set.
is set to "1" (step 898), and each device that has been turned on up to step S74 is turned off in sequence (step 5).
99), the process returns to step S92.

On the other hand, if the paper ejection switch 414 is on, the process waits until one page of the image data that was started to be received in step S71 is captured (step 576). When the reception of the image data is completed, the data transfer status is reset, the attention signal ATN1 is inverted from "0" to "1" (step 577), and then the paper P
At the timing when the rear end passes the aligning roller pair 406, the aligning solenoid 614 is turned off (step 578), and the aligning roller pair 406 stops. Further, at the timing when the trailing edge of the paper P passes the image transfer section 209, the transfer 604b is turned off (step 5).
79).

Next, after a certain period of time has elapsed since the aligning solenoid 614 was turned off, it is checked whether the paper ejection switch 414 is off (step 580), and if it is not off, the trailing edge of the paper P is ejected. Paper roller unit 40
8 has not been passed, the process branches to step 598 and jam processing is performed. On the other hand, when the switch is off, it is determined that the paper P is being ejected normally, the paper conveying status is reset (step 581), the output of the charging 604C is sequentially turned off (step 582),
The developing bias 604a is turned off (step 883),
The mirror motor 121 is turned off (step 584), and the pre-exposure device 301 and the main motor 612 are turned off (step 585), completing a series of printing operations and returning to step S62 to enter the standby state.

Next, the operation of the printer control circuit section 700 according to the data transfer procedure described above will be explained using the flowchart shown in FIG.

For example, if the image forming apparatus is offline and the CP
When it is determined that the U741 is offline (step 5101), the host device 7
It is checked whether the printing process for the data received from 48 has been completed (step 5102), and if it has not been completed, the process branches to step 5112 to continue the printing process.

If the printing process is completed, step 5101.
By repeatedly executing step 5102, an idling state is created and the image forming apparatus waits for it to be brought into an online state.

On the other hand, if the image forming apparatus is online, it is checked whether the data sent from the host device 748 is a command (step 310B), and if it is a command, an operation corresponding to the command is performed (step 5104).
), if it is not a command, the execution of the above command is skipped and the process advances to step 5105. For example, the above command is
It defines the attributes of the following data and controls the printer without sending or receiving data.

Next, it is checked whether the page buffer provided in the RAM 743 as a buffer for data reception is full (step 5105), and if it is not full, the data sent from the host device 749 is image data. It is checked whether there is one (step 5106). If there is no image data, the process returns to step 5101 and waits for a command or image data to be received by repeating the above series of steps. In this state, if it is determined in step 5106 that image data has been received, the received image data is sequentially stored in the page buffer (step 5107). Next, it is checked whether storage for one page has been completed (step 810).
8) If the process has not finished, the data display 73 of the LED display 70 provided on the operation panel 16 starts blinking (step 5IIO). Then step 510
By going back to step 1 and performing the above series of steps,
Wait until image data for one page is accumulated in the page buffer. By repeating the above series of steps, 1
When it is determined that one page of image data has been stored, step 510 turns off the data display 73.
9) End the data reception process. And step 5
1. Proceed to print processing from 2 onwards.

Note that if it is determined in step S5 that the page buffer is full, the data reception operation is stopped (step 5111), and in this case as well, the process moves to the print processing from step 5112 onwards. In this way, during the data reception operation, the data lamp is blinked to notify the operator.

Next, when the storage of one page's worth of image data in the page buffer is completed, it is checked whether the scan buffer provided on the video RAM 745 is full (step S112). Here, if it is determined that the scan buffer is not full, the CPU 741 converts the image data of the character image stored in the page buffer to the video RAM 74 as a scan buffer.
5 (step 3113). On the other hand, if the scan buffer is full, step 8113 is skipped.

Next, it is checked whether the print command has already been sent (step 81.14), and if it has been sent, the process skips the following print command sending process (steps 5115 to S119) and proceeds to step 5120. On the other hand, if the print request has not been sent yet, it is checked whether a print request has been sent (step S115). Here, if it is determined that no print request has been issued, it is determined that the print preparation on the engine side has not been completed, and the process returns to step 5101 to re-execute the above-mentioned steps to request a print request. wait for it to be served. On the other hand, if it is determined that a print request has been issued, a print command is sent (step 511.9).Next, it is checked whether a VSYNC command has been sent (step 51.9).
20). Then, when it is determined that the VSYNC command has not been sent, the VSYNC command is sent from the engine side.
You can check whether a strike has been issued or not (Ste, Tubu 5
121). If it is determined that a VSYNC request has not been issued, the process returns to step S]01 and waits for a VSYNC request to be issued without executing the above series of steps again.

Then, when it is determined in step 5121 that a VSYNC request has been issued, a VSYNC command is sent to the engine side (step 5122)) in step 5101.
The process returns to the state of waiting for input of the horizontal synchronizing signal H8YNCO and video clock VCLKO.

In this state, in step 5120 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 5126), and if the transfer of image data has not been completed, The image data of the bit image stored in the scan buffer is sent to the horizontal synchronization signal HSYNCO.
and is sent to the engine side in synchronization with the video clock VCLKO (step 5125).

On the other hand, the CPU 741 returns to step 5101 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 image data for one page is completed in this way, the process returns to step 5101, and the printer control circuit 700
returns to its initial state and becomes ready to transfer the next page of image data.

Next, a process related to detecting an abnormality related to conveyance of paper P, that is, detecting a jam will be described.

FIGS. 16 to 18 show timing charts when jam detection is performed in accordance with detection information from a detector disposed near the paper P supply section, for example, an aligning switch.

First, the normal operation will be explained with reference to FIG. As shown in FIGS. 16(A) and 16(B), jam flags related to feeding of the leading edge and trailing edge of the sheet are set at time t1 when conveyance of the sheet P is started. When the leading edge of the paper P reaches the aligning switch at time t3 when time T3 has elapsed since the paper P has been conveyed, the aligning switch is reversed from "0" to "1" as shown in FIG. 16(C). . As a result, the jam flag related to the paper feeding at the leading edge of the paper is cleared.

When the trailing edge of the paper P reaches the aligning switch at time t7 when the paper P is further conveyed and a time T7 has elapsed, the aligning switch changes from "1" to "0" as shown in FIG. 16(C). Invert. As a result, the jam flag related to paper feeding at the trailing edge of the paper is cleared.

Next, with reference to FIGS. 17 and 18, the operation when the paper P is not transported normally will be described.

Time of start of conveyance of paper P1. If the leading edge of the paper P does not reach the aligning switch after the jam flags related to the leading and trailing edges of the paper are set in the 17th aligning switch.
As shown in Figure (C), the aligning switch remains at "0", and the jam flag related to the leading edge of the paper remains unchanged without being released. As a result, Figure 17 (D
), the predetermined time T is longer than the required time T3 from the start of transport of the leading edge of the paper P to the alignment switch.
At time t5 after 5 lapses, it is determined that a jam related to the leading edge of the paper P has occurred. This is executed as the instruction ID81 mentioned above.

Similarly, if the trailing edge of the paper P does not reach the aligning switch, the aligning switch remains at "1" even after time T7, as shown in FIG. The jam flag remains as it is without being cleared. As a result, as shown in FIG. 18(D), a time t after a predetermined time T9 has elapsed, which is longer than the required time T7 from the start of conveyance of the trailing edge of the paper P to the alignment switch.
In step 9, it is determined that a jam related to the trailing edge of the paper P has occurred.

19 to 21 show timing charts when jam detection is performed in accordance with detection information from a detection switch disposed near the paper P discharge section. Paper P
Since the distance of the conveyance path from the supply section to the detection switch is longer than the distance to the above-mentioned aligning switch, the first
As shown in FIG. 9, the paper P whose conveyance has started reaches the detection switch after a time T4, which is longer than the time T3. Therefore, if the paper P is not conveyed normally, as shown in FIG. It is determined that a jam has occurred.

Similarly, if the trailing edge of the paper P does not reach the detection switch, as shown in FIG.
At time t10 after 10 elapses, it is determined that a jam related to the trailing edge of the paper P has occurred.

As described above, since the jam detection process is performed according to the detection information from the plurality of detection means provided at appropriate positions on the conveyance path, it is possible to reliably and appropriately determine the occurrence of a jam.

〔Effect of the invention〕

As described above, according to the present invention, the flag that has not been cleared by the flag releasing means is made valid after a predetermined time period that is longer than the time required for the medium to reach the detecting means from the start of conveyance. The state related to the conveyance of the medium can be easily determined without performing any process related to jam detection.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an engine control unit and its surrounding parts, FIG. 2 is a perspective view of an image forming apparatus according to the present invention, and FIG.
The figure is a rear view of Fig. 2, Fig. 4 is an explanatory diagram of the operation panel, Fig. 5 is an internal configuration diagram of the embodiment shown in Fig. 2, and Fig. 6 is a diagram showing how to install or remove the electrophotographic process unit. Figure 7 is a block diagram showing the internal configuration of the engine control circuit, Figure 8 is a block diagram showing the printer control circuit and its peripheral devices, and Figure 9 is the engine control unit and printer control. An explanatory diagram showing interface signals exchanged between circuits; FIG. 10 is a time chart showing the timing of the interface signals; FIG. 11 is a flow chart showing processing in the engine control section;
Fig. 12 is a flowchart showing the processing in the printer control circuit, Fig. 13 is a table showing the execution time of instruction IDs, and Fig. 14 is the content of the instructions corresponding to each assigned instruction ID number. FIG. 15 is a flowchart showing control processing based on the table in FIG. FIGS. 19 to 21 are timing charts when jam detection is performed in accordance with detection information from a detection means disposed near the paper discharge section. 406... Aligning roller pair 408... Paper ejection roller pair 600... Engine control section

Claims (1)

[Scope of Claims] Flag setting means for setting a flag indicating a conveyance failure of the medium at the start of conveyance of the medium; a detection means for detecting the medium provided on a conveyance path on which the medium is conveyed; and flag canceling means for canceling the flag set by the flag setting means when the means detects a medium, and when the flag set by the flag setting means is not canceled within a predetermined time, the flag is determined to be valid. An image forming apparatus characterized in that: