JPS61138964A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To enable trouble in the parts to be controlled, etc., to be detected in a short time even when continuous copying is operated by installing the parts to be controlled used for copying operation, a commanding means, a driving means, a retriggerable monostable multivibrator, etc. CONSTITUTION:The microprocessor 46 in a normal state turns on and off a control signal (a) at an interval T1 and repeats it. During the control signal (a) is on, IC50a for controlling an exposure lamp 16' is actuated to produce a trigger pulse and to feed it through a pulse transformer 50b to a TRIAC50c, and it is allowed to conduct in response to the pulse to supply AC power to the lamp 16'. When the microprocessor 46 is in an abnormal state, and continuously turns on the control signal (a), the IC50a continuously produces the trigger pule (b), and the triac 50c is forced to be nonconducting by the action of the monostable multivibrator 48, thus permitting the lamp 16' to be turned off, and heat generation to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic copying machine, and more particularly to an electronic copying machine including a safety device for preventing danger in the event of an abnormality in various controlled parts used for copying operations. .

(Prior art) Loads (or controlled parts) used in copying operations such as exposure lamps, fixing heaters, and high-voltage circuits for charging, transfer, and separation.
An electronic copying machine which is controlled by a microcomputer is disclosed in Japanese Patent Publication No. 59-34303. In this example, a timer is set to derive the output after a certain period of time that is slightly longer than the time from when the load is commanded to operate until it normally completes its operation, and even though the timer has timed out, the output still remains. This method issues an alarm when the load is operating as an abnormality.

(Problem to be Solved by the Invention) In this prior art, the set time is fixed so that the timer derives a high-level output after the sum of the normal operating time of the load and the extra time to allow for safety. It is set as follows. Therefore, the time required to operate the load for one copy is the sum of this setting time and the high level derivation period, so when making continuous copies, the time required for one copy becomes longer, and the continuous copying becomes longer. It was inappropriate.

In order to solve these problems, it is possible to make the time from when an operation command is given until the timer derives the high level as close as possible to the load operating time and to shorten the timer's high level time. . However, if these setting times are shortened, the abnormal state of the load will be detected inaccurately and reliability will deteriorate.

Therefore, the main object of the present invention is to provide an electronic copying machine that can detect abnormalities in the load or controlled parts in a short time even when copying is performed continuously, and is highly reliable.

(Means for Solving the Problems) The present invention includes a controlled section used in a copying operation, a command means, a driving means, a retriggerable monostable multivibrator, and a disabling means.

(Operation) The command means gives an operation command to the controlled section. The drive means drives the controlled section in response to this operation command. Further, the retriggerable monostable multi-high break is triggered in response to an activation command, and produces an output after a certain period of time, which is slightly longer than the normal operating time of the controlled part. The disabling means disables the driving means from driving the controlled part in response to the output of the retriggerable monostable multivibrator. In the normal case, the retriggerable monostable multivibrator is retriggered each time an activation command is given, so that it does not derive any output and is immediately ready for the next copying operation.

(Effects of the Invention) According to the present invention, even in the case of continuous copying, it is possible to reliably detect an abnormality in a controlled part without increasing the time required for one copy, thereby improving the reliability of abnormality detection. can be increased. Therefore, the time required for continuous copying can be reduced.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) FIG. 2 is a structural diagram showing an electronic copying machine to which the present invention is applied. Electronic copying machine 10 includes a body 12 . A document table 14 for placing a document (not shown) thereon is provided on the top surface of the body 12 so as to be movable or slidable in the direction of the arrow. A slit is formed in the upper surface of the body 12.

A light source (exposure lamp) 16, such as a halogen lamp, is fixedly provided within the body 12 in relation to this slit. Associated with the light source 16 is a reflecting mirror whose cross section is elliptical. The light from the light source 16 is reflected by a reflecting mirror and irradiated onto the document placed on the document table 14. Therefore, as the document table 14 moves in the direction of the arrow, the document receives light from the light source through the slit and reflects it. Reflected light from the original, ie, the original image, is projected onto the photosensitive drum 20 and formed into an image through a short focus lens array 18 fixedly provided below the slit. The short focus lens array 18 consists of a focusing photoconductor with a number of closely arranged rod lenses. It goes without saying that such a short focus lens array 18 may be replaced with another plastic lens array or a convex lens.

The photosensitive drum 20 is located approximately in the center of the body 12,
It is rotated clockwise in synchronization with the movement of the document table 14 by a drive source (not shown). The photosensitive drum 20 includes a conductive substrate 20a and a photoconductive layer 20b made of amorphous silicon laminated thereon.
including. Further, around the photosensitive drum 20, charging corotrons 22. Developing device 24. A paper feeding device 26°, a transfer corotrif 302, a separation corotron 32, and a cleaning device 38 are arranged.

The charging corotron 22 is used to uniformly charge the photoconductive ri 20b with a polarity (for example, positive polarity) charge before the original is imaged on the photosensitive drum 20. (not shown). When a document image is irradiated onto the photosensitive drum 20 charged by the charging corotron 22 through the short focus lens array 18, an electrostatic latent image is formed on the photosensitive drum 2o according to the photoconductive properties of the photoconductive N20b. .

The developing device 24 is for developing the electrostatic latent image formed on the photosensitive drum 20 into a visible image using toner charged with a polarity (for example, negative polarity), and as is well known, it is used in a toner box or the like. Including magnetic brushes, etc.

The paper feeding device 26 brings sheets of [27] stacked in a paper feeding cassette (not shown) onto the surface of the photosensitive drum 20 one by one. For that purpose, paper feeder 26 includes a paper feed roller 28 and a register roller 29 . The paper feed roller 28 is rotated clockwise by a drive device (not shown), and takes in the paper 27 in contact with its peripheral surface toward the register roller 29 . The register roller 29 is for feeding the paper 27 fed by the paper feed roller 28 toward the photosensitive drum 20 at an appropriate timing.

The paper 27 fed from the paper feeding device 26 in this way is
The photosensitive drum 2 is in contact with the surface of the photosensitive drum 20.
0 to the position of the transfer corotron 30. The transfer corotron 30 generates an electric charge having a polarity opposite to that of the toner in the developing device 24 . Therefore, the photosensitive drum 2
The toner forming a toner image on the paper 27 is attracted by the electric field of the transfer corotron 30 and is transferred onto the paper 27.

The separation corotron 32 is for separating the paper 27 from the photosensitive drum 20 that is about to come into close contact with the photosensitive drum 20 during transfer, and is made of, for example, an AC corona discharger.

The paper 27 separated by the separation corotron 32 is further transported by a transport conveyor 34 provided on the downstream side in the transport direction.

The conveyor 34 includes a mesh-like endless belt driven by a drive source (not shown) and a vacuum unit provided below the endless belt.

Therefore, the paper 27 is brought onto the mesh belt, sucked by the vacuum unit, and conveyed in the direction of the fixing device 36 as the belt moves.

A cleaning device 38 is provided above the conveyor 34 in association with the photosensitive drum 20 .

The cleaning device 38 is for removing toner remaining on the photosensitive drum 20 after the toner image on the photosensitive drum 20 is transferred to the paper 27.

For that purpose, the cleaning device 38 cleans the photosensitive drum 20
This includes a blade that scrapes off residual toner by coming into contact with the zero surface, a box that stores the scraped off toner, and the like.

The fixing device 36 includes a heating roller with a built-in electric heater,
It also includes a pressure roller for pressing the paper onto which the toner image has been previously transferred against the heating roller. Therefore, when the paper 27 passes between the two rollers, the toner transferred onto the paper is melted by the heating roller and simultaneously pushed into the tissue of the paper by the pressure roller, forming a toner image. It is fixed on the paper 27. Thereafter, the paper 27 is discharged onto the paper discharge tray 40 by a paper discharge roller.

A control box 42 is provided within the aircraft body 12. Within the control box 42 are electrical circuits (e.g., a microprocessor 46 shown in FIG. 1, a retriggerable monostable multivibrator 48, a drive circuit 50 and A printed circuit board (not shown) forming a transistor 54, etc.) is housed therein.

Furthermore, a power supply unit 44 is housed in the lower part of the body 12. The power supply unit 44 includes, for example, a drive power supply for supplying power to a drive source such as a motor, a DC high-voltage power supply for applying a DC high voltage to the charging corotron 22 and the transfer corotron 30, and an AC power supply to the separated corotron. This includes AC high-voltage power supplies for applying voltage.

FIG. 1 is a diagram showing the principle of an embodiment of the present invention.

The microprocessor 46 controls these operations by giving operation commands to various controlled units (or loads) used in the copy operation, and the microprocessor 46 is a monostable multi-pie break (hereinafter referred to as "monostable multi-pie break") which can retrigger the operation command signal. , monostable multi) 48 and a drive circuit 50. Drive circuit 50
drives the controlled section 52 during the period in which the operation command (control signal) is given. The controlled section 52 includes, for example, a high-voltage circuit for supplying high voltage to the light source 16 shown in FIG. 2, each corotron 22, 30, 32 for charging and one-transfer separation, a heater for the fixing device 36, etc. is included. The monostable multi 48 is triggered in response to an operation command, and outputs (for example, high level) after a certain period of time that is longer than the normal operating time of the controlled part 52 and shorter than the time when the controlled part 52 causes a problem such as heat generation. is derived. The output of this monostable multi 48 is provided as an input to a disabling transistor 54.

When the microprocessor 46 is operating normally, the monostable multi 48 is triggered every time an activation command is given. Therefore, when an operation command is given at a predetermined cycle for the purpose of continuous copying, the monostable multi 48 will not produce a high level output. Therefore, since the drive circuit 50 is not disabled by the transistor 54, it continues to drive the controlled section 52 during the period when the microprocessor 46 is giving the operation command.

On the other hand, if an abnormality such as a malfunction or runaway occurs in the microprocessor +46, an operation command will not be given even once within the set time of the monostable multiplexer 48 even if continuous copying is required.

Therefore, the drive circuit 50 drives the controlled unit 52 for a longer time than in the normal case of the microprocessor + 46, but the monostable multi 48 derives a high level after the set time and turns on the transistor 54. . In response to the ON operation of the transistor 54, the drive circuit 50 is disabled, and further driving of the controlled section 52 is stopped.

If you want to copy only one sheet, microprocessor 4
6 derives the actuation command only once, the monostable multi 48 derives the high level after a set time. However, in a normal case, the operation command has already been completed and the drive circuit 50 has stopped driving the controlled section 52, so there is no point in turning on the transistors 5 and 4. On the other hand, if an abnormality occurs, for example, because the operation commands are continuous, the transistor 54 is turned on in response to the high level of the monostable multi 48 output after a certain period of time, and the drive circuit 50 is disabled. be activated. Therefore, even when copying one sheet, the controlled section 52 is protected based on abnormality detection.

Next, a more specific example will be described.

FIG. 3 is a circuit diagram of a specific embodiment of the present invention, particularly showing the case where the controlled section is an exposure lamp.

The microprocessor 46 of this embodiment includes a ROM for storing an operating program, a RAM for storing data necessary for a copy operation, and an arithmetic processing unit. The monostable multi 48 has a fixed set time T from when it is triggered in response to an operation command (control signal) until it derives a high level.
2 is appropriately set according to the time constants of the capacitor C and the resistor R. This set time T2 is selected to be longer than one exposure period T1 in the normal case and shorter than the time during which the exposure lamp 16' causes problems such as heat generation. The drive circuit 50 is
Exposure lamp control IC50a, pulse transformer 50b
and a triac 50c connected in series to the exposure lamp 16'.

Figure 4 is a timing diagram for explaining the operation of Figure 3, especially when copying 5 or more sheets continuously.
A case is shown in which an abnormality occurs in the microprocessor+46 when an operation command for making the first copy is derived.

Next, the operation shown in FIG. 3 will be explained with reference to FIG.

When the microprocessor 546 is in a normal state, the microprocessor 46 turns on the control signal a during the copy operation time T1.
Repeat turning off. During the ON period of the control signal a, the exposure lamp control IC 50a is commanded to operate. At the same time, a trigger signal is given to the monostable multi 48 when the control signal a starts to turn on, but since the set time T2 has not elapsed since the monostable multi 48 was triggered, its output remains at a low level. . Exposure run (° control IC50a
generates a trigger pulse during the ON period of the control signal a and applies it to the triac 50c via the pulse transformer 50b. In response, the triac 50c becomes conductive, so that AC power is supplied to the exposure lamp 16' during the ON period of the control signal a. Such an operation is performed every time the control signal a is turned on.

On the other hand, in an abnormal state where the microprocessor 46 turns on the control signal a continuously due to malfunction or runaway, the exposure lamp control IC 50a continuously derives the trigger pulse b, so the triac 50c continuously outputs the trigger pulse b. Conduct. In this case, the monostable multi 48 derives a high level signal C to turn on the transistor 54 after a set time T2 has elapsed since being retriggered. Therefore, the trigger pulse b flows to the ground side through the transistor 54 and is no longer supplied to the pulse transformer 50b. therefore,
Triac 50c is forced non-conducting and exposure lamp 1
6' goes out.

This can prevent the exposure lamp 16' from generating heat due to an abnormality in the microprocessor +46. In addition, in the case of continuous copying, since the monostable multi 48 is retriggered when the control signal a starts turning on, there is no need to wait for a detection time for abnormality detection after the exposure lamp 16' has finished operating. It has the advantage of being able to perform continuous copying, and as a result, reducing the operating time when performing continuous copying.

If the controlled section is a fixing heater included in the fixing device 36, the circuit shown in FIG. 3 can be applied as is by replacing the exposure lamp 16' with the fixing heater.

FIG. 5 is a specific circuit diagram of another embodiment of the present invention, particularly showing the case where the controlled section 52 is applied to a high voltage circuit. In this embodiment, the drive circuit 50 includes an oscillation transistor 50d, and the controlled section 52 includes a high voltage circuit 52a for energizing the corotron. And monostable multi 48
When there is a high level output, the transistor 54 is turned on and the oscillation transistor 50d is grounded, thereby forcing the output of the high voltage circuit 52 to turn off and stopping the generation of high voltage.

The present invention is of course applicable not only to exposure lamps, fixing heaters, and high-voltage circuits, but also to other controlled parts included in electronic copying machines that require safety devices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of an embodiment of the present invention. 2nd t! I is a structural diagram of an electronic copying machine that can be applied to the present invention. FIG. 3 is a specific circuit diagram of an embodiment of the present invention. 41st! I is a timing diagram for explaining the operation of FIG. 3. FIG. 5 is a specific circuit diagram of another embodiment of the invention. In the figure, IO is an electronic copying machine, 46 is a microprocessor, 48 is a retriggerable monostable multivibrator, and 5
0 indicates a drive circuit, 52 indicates a controlled section, and 54 indicates a disabling transistor. Figure 1 Figure 5

Claims (1)

[Scope of Claims] 1. A controlled section used in a copy operation; Command means for giving an operating command to the controlled section; Driving means for driving the controlled section in response to the operating command; The operating command. a retriggerable monostable multivibrator that is triggered in response to and derives an output after a certain period of time longer than the normal operating time of said controlled part; An electronic copying machine comprising an activation means for activating a drive means. 2. The electronic copying machine according to claim 1, wherein the controlled section includes at least one of an exposure means, a high pressure generation means, and a fixing means.