JP2002247752A - Feeder device, heater feeder, fixing device, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability by suppressing the possibility of deterioration or failures of a switching means, even when the switching means such as a relay or a correspondingly similar opening/closing circuit, is opened by an interlock switch such as a door switch. SOLUTION: A device comprises a switching device 75 which is connected to a heater 123C and controls feeding to the heater in response to a feeding control signal; the relay 74 which energizes a feeding line in response to a closing designation voltage +24 V and cuts it off when the closing designation voltage has disappeared; the interlock switch 73 which cuts off the closing designation voltage to the relay; and a Zener diode 79 which switches off the switching device 75 by stopping the feeding control signal in response to a change in loss of the closing designation voltage earlier than the cut-off of the feeding line of the relay 74, in response to the loss of the closing designation voltage, when the interlock switch cuts off the closing designation voltage the device further comprises a capacitor 87 for delaying switching-off of the relay.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying an electric load, and more particularly, but not exclusively, to a heater power supply device, a fixing device, and an image forming apparatus.

[0002]

2. Description of the Related Art There are many types of electrical loads. For example, many heaters or devices using the same consume relatively large power. If the current value is large, an excessive current flows when the circuit is opened and closed, which may damage the relay contacts or the semiconductor switch circuit, or may emit high-level noise and cause malfunction of the weak electric device or the electronic circuit. . Recently, image forming apparatuses such as an electrophotographic printer, a copying machine, and a facsimile are often used, and a fixing device provided therein has a high-load heater. When a trouble occurs in feeding, transporting, or discharging, the front cover or door is opened to remove the jammed paper. At this time, the interlock switch (cover switch or door switch) is opened by opening the front cover or door. The power supply to the fixing device is cut off.

Japanese Patent Application Laid-Open No. 05-064352 discloses a fuse, a triac, a main relay for protecting a load driven by an alternating current (AC) power supply, and a main controller for turning off the main relay when a control abnormality occurs. A main controller discloses a power supply circuit having a safety protection function of turning off a triac to cut off power supply to a load when a control abnormality occurs, and then turning off a main relay. In this case, if the main relay is turned off while the triac is on, a spark (arc) may be generated at the contact portion of the main relay, which may cause a problem such as deterioration of the contact portion or welding of the contact portion. To avoid this, turn off the triac first, and turn off the main relay.

[0004]

This is realized according to the control logic (control program) of the main controller, that is, software control, when the main controller operates normally and determines that the control is abnormal.

However, for example, in the case of the above-described fixing device of the image forming apparatus, when the front door or the like of the image forming apparatus is opened while the heater of the fixing device is being supplied, and the door switch, that is, the interlock switch is opened, the heater to the heater is opened. The power supply relay that cuts off the power supply and the semiconductor switch that controls the power supply to the heater, such as a triac, receive power supply voltage from the door switch, so they are turned off (open) almost simultaneously.
Then, a spark (arc) is generated at the contact portion of the power supply relay, and this spark may give stress to the contact portion and cause problems such as deterioration of the contact portion or welding of the contact portion. When a switching circuit having a semiconductor switch is used instead of the power relay, the semiconductor switch may be broken.

According to the present invention, even when the switch means such as the power supply relay or the corresponding open / close circuit is opened by the shutoff means such as the door switch or the interlock switch, the possibility of deterioration or failure of the switch means is reduced. A first object is to reduce the energy, and a second object is to make this more reliable.

[0007]

[Means for Solving the Problems] (1) Load from power supply (AC)
A semiconductor element (75) interposed in the power supply line to (123C) and controlling the power supply to the load in response to a power supply control signal; interposed in the power supply line and responding to the close instruction signal (+ 24V); Switch means (74) for shutting off the power supply line when the closing instruction signal disappears; means (73) for interrupting the closing instruction signal to the switch means (74);
3) responds to the disappearance of the closing instruction signal when the closing instruction signal is interrupted earlier than the interruption of the power supply line of the switch means (74), and responds to the change to the disappearance of the closing instruction signal. Electrical means for changing the power supply control signal to the non-power supply level (7
9).

[0008] In order to facilitate understanding, symbols in parentheses indicate corresponding elements of the embodiment shown in the drawings and described later, or corresponding elements, or equivalents.

[0009] According to this, the switch means (74) inserted in the power supply line to the load (123C) changes the closing instruction signal (+ 24V).
During a certain period, the power supply line is energized, and the semiconductor element (75) inserted in the power supply line controls the power supply to the load (123C) in response to the power supply control signal. When the shutoff means (73) cuts off the close instruction signal to the switch means (74), the switch means (74) is opened and the power supply to the load (123C) is stopped. At this time, the electric means (79) changes the power supply control signal to the non-power supply level in response to the change to the disappearance of the close instruction signal earlier than the cutoff of the power supply line of the switch means (74) in response to the disappearance of the close instruction signal. Switch means (74) opens and the load (123
Immediately before power supply to C) stops, the semiconductor element (75) stops power supply to the load (123C) in response to the power supply control signal. This prevents an excessive current from flowing through the switch means (74),
The likelihood of deterioration or failure is reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (2) Each of first and second power supply lines from a power supply (AC) to first and second loads (123C1, 123C2) is inserted and responds to a power supply control signal. First and second semiconductor elements (751, 75) for controlling power supply to a load.
2); interposed between the power supply (AC) and the first and second power supply lines, the first and second power supply lines are energized in response to the close instruction signal (+24 V), and the close instruction signal disappears. Switch means (74) for interrupting; means (73) for interrupting a close instruction signal to the switch means (74); and disappearance of the close instruction signal when the interrupting means (73) interrupts the close instruction signal Electrical means for changing the power supply control signal to a non-power-supply level in response to a change to the disappearance of the closing instruction signal earlier than the interruption of the first and second power supply lines of the switch means (74) in response to
(79) A power supply device comprising:

According to this, the first and second loads (123C
Switch means (74) inserted in the power supply line to (1,123C2)
However, the first and second power supply lines are energized while the close instruction signal (+24 V) is present, and the first power supply line inserted into each power supply line is
And the second semiconductor element (751, 752) controls power supply to the first and second loads (123C1, 123C2) in response to the power supply control signal. When the shut-off means (73) cuts off the closing instruction signal to the switch means (74), the switch means (74) opens and the first
And the power supply to the second load (123C1, 123C2) is stopped. At this time, the electric means (79) changes the power supply control signal to the non-power supply level in response to the change to the disappearance of the close instruction signal earlier than the cutoff of the power supply line of the switch means (74) in response to the disappearance of the close instruction signal. Therefore, immediately before the switch means (74) is opened and power supply to the first and second loads (123C1, 123C2) is stopped, the first and second semiconductor elements (751,7) are responded to the power supply control signal.
52) respectively stop supplying power to the first and second loads (123C1, 123C2). As a result, an excessive current does not flow through the switch means (74), and the possibility of deterioration or failure is reduced.

(3) Delay means (8) for slowing down the change speed of the closing instruction signal to disappearance due to the interruption of the interruption means (73).
7) is connected to a closing instruction signal line to the switch means (74).

According to this, when the shut-off means (73) cuts off the closing instruction signal to the switch means (74), the switch means (74) is opened and the power supply to the load (123C) is stopped. Due to the presence of the means (87), the delay time from when the shut-off means (73) starts to shut off the closing instruction signal to when the switch means (74) shuts off the power supply line becomes longer, and the change to the disappearance of the closing instruction signal. The time from the switching of the power supply control signal in response to the power supply level to the non-power supply level to the interruption of the power supply line becomes longer, and the semiconductor device (75) responds to the power supply control signal until the switch means (74) interrupts the power supply line. Has high reliability of stopping the power supply to the load (123C). Thereby, the reliability of preventing the switch means (74) from deteriorating or malfunctioning is high.

(4) A semiconductor switching element (7) inserted into a power supply line from a power supply (AC) to an electric heater (123C) and controlling power supply to the electric heater in response to a power supply control signal.
5); a power supply relay (74) interposed in the power supply line to turn on the power supply line in response to the close command voltage (+24 V) and to cut off the power supply line when the close command voltage disappears;
Means (73) for shutting off the close command voltage to 4); and the shutoff of the power relay (74) in response to the disappearance of the close command voltage when the shutoff means (73) cuts off the close command voltage. A constant voltage element (79) that changes the power supply control signal to a non-power supply level in response to a change of the closing instruction voltage to disappearance earlier.

According to this, the power supply relay (74) inserted into the power supply line to the electric heater (123C) is connected to the closing instruction voltage (+2
4V), the power supply line is energized, and the semiconductor switching element (75) inserted in the power supply line controls power supply to the electric heater (123C) in response to the power supply control signal. The shut-off means (73) cuts off the close command voltage to the power relay (74), and the power relay stage (74) opens to open the electric heater.
Power supply to (123C) stops. At this time, the constant voltage element (79)
However, the power supply relay (74) responds to the disappearance of the close command voltage earlier than the power supply line cutoff, and in response to the change to the disappearance of the close command voltage, it returns from breakdown and cuts off its own power supply. Since the control signal is changed to the non-power supply level, just before the power supply relay (74) opens and power supply to the electric heater (123C) stops, the semiconductor switching element (75) responds to the power supply control signal and the electric Stop supplying power to As a result, no excessive current flows through the contact portion of the power supply relay (74), and the possibility of deterioration or failure is reduced.

(5) A fixing roller (123A), a heater (123C) provided therein, and a pressure roller (123B) pressed against the fixing roller (123A); a power supply (AC) to the heater (123C). A semiconductor element (75) inserted in the power supply line and controlling power supply to the heater (123C) in response to a power supply control signal; power supply in response to a close instruction signal (+24 V) inserted in the power supply line Switch means (74) for energizing the line and interrupting the power supply line when the closing instruction signal disappears;
An interlock switch (73), which is opened and closed by movement of an object, for shutting off a close instruction signal to the camera; and responds to the disappearance of the close instruction signal when the interlock switch (73) interrupts the close instruction signal. An electric unit (79) for changing the power supply control signal to a non-power supply level in response to a change of the closing instruction signal to disappearance earlier than the disconnection of the power supply line by the switch means (74).

According to this, the switch means (74) interposed in the power supply line to the heater (123C) changes the closing instruction signal (+24
The power supply line is energized while V) exists, and the semiconductor element (75) inserted in the power supply line controls power supply to the heater (123C) in response to the power supply control signal. When the interlock switch (73) interrupts the closing instruction signal to the switch means (74), the switch means (74) is opened and the power supply to the heater (123C) is stopped. At this time, the electric means (79) changes the power supply control signal to the non-power supply level in response to the change to the disappearance of the close instruction signal earlier than the cutoff of the power supply line of the switch means (74) in response to the disappearance of the close instruction signal. Switch means
Immediately before (74) is opened and power supply to the heater (123C) stops, the semiconductor element (75) stops power supply to the heater (123C) in response to the power supply control signal. As a result, an excessive current does not flow through the switch means (74), and the possibility of deterioration or failure is reduced.

(6) An electrostatic latent image is formed on the photoreceptor (114),
The electrostatic latent image is visualized into a toner image by a developing device (120), and the toner image is transferred directly or indirectly via an intermediate medium (115) to transfer paper, and the transfer paper is fixed to a fixing device. (123) In the image forming apparatus for performing a fixing process through the fixing device,
(123) is a fixing roller (123A), a heater (123C) provided therein, and a pressure roller (123B) that presses against the fixing roller (123A); power is supplied from a power source (AC) to the heater (123C). A semiconductor switching element (75) inserted in the line and controlling power supply to the heater in response to a power supply control signal; inserted in the power supply line and energizing the power supply line in response to a close command voltage (+ 24V) A power relay (74) that cuts off the power supply line when the closing command voltage disappears; an interlock switch that cuts off the closing command voltage to the power relay (74), opens when the door of the image forming apparatus opens, and closes when closing. (73); and the disappearance of the close command voltage earlier than the cutoff of the power supply relay (74) in response to the disappearance of the close command voltage when the interlock switch (73) cuts off the close command voltage. The power supply control signal in response to the Constant voltage element (79) for changing the level; characterized in that it comprises an image forming apparatus.

According to this, the power supply relay (74) interposed in the power supply line to the heater (123C) is connected to the closing instruction voltage (+ 24V).
The power supply line is energized for a certain time, and the semiconductor switching element (75) inserted in the power supply line controls power supply to the heater (123C) in response to the power supply control signal. When the interlock switch (73) shuts off the closing command voltage to the power supply relay (74), the power supply relay stage (74) opens and the heater
Power supply to (123C) stops. At this time, the constant voltage element (79)
However, the power supply relay (74) responds to the disappearance of the close command voltage earlier than the power supply line cutoff, and in response to the change to the disappearance of the close command voltage, it returns from breakdown and cuts off its own power supply. Since the control signal is changed to the non-power supply level, just before the power supply relay (74) is opened by the opening of the interlock switch (73) and power supply to the heater (123C) is stopped, the semiconductor switching element ( 75) is a heater (1
Stop supplying power to 23C). As a result, no excessive current flows through the contact portion of the power supply relay (74), and the possibility of deterioration or failure is reduced.

(7) In an image forming apparatus having a heating means (123C), a semiconductor switching element (75) for supplying power to the heating means, and a switch means (74) for cutting off the power supply to the heating means, When the power supply to the heating means (123C) is cut off by the switch means (74), the semiconductor switching element (75) for supplying power to the heating means and the switch means (74) for cutting off the power supply to the heating means (123C). An image forming apparatus having a circuit configuration (74 + 73 + 79 + 76) that is turned off in this order.

According to this, since the semiconductor switching element (75) is turned off before the switching means (74), deterioration or failure of the switching means (74) due to an overcurrent when the switching means (74) is cut off. Disappears. Switch means (74)
Is a power supply relay, the occurrence of sparks (arcs) at the contact portions is prevented, and problems such as deterioration of the contact portions or welding of the contact portions are prevented.

(8) In the above (7), the heating means (123)
C) is a plurality (123C1,123C2), and each semiconductor switching element (75) is also a heating means (123C1,123C2).
(751, 752) connected to the heating means (123C)
Switching means (751, 752) for supplying power to the heating means (123C1, 123C2) when the power supply to the heater is interrupted by the switch means (74), and switch means for interrupting the power supply to the heating means (123C1, 123C2) It has a circuit configuration (74 + 73 + 79 + 761,762) that is turned off in the order of (74).

According to this, since the semiconductor switching elements (751, 752) are turned off before the switching means (74), deterioration or failure of the switching means (74) due to an overcurrent when the switching means (74) is cut off. Disappears. When the switch means (74) is a power supply relay, sparks (arcs) are prevented from being generated at the contact portions, and problems such as deterioration of the contact portions or welding of the contact portions do not occur.

(9) In addition to the above (7) or (9), an image forming apparatus in which a delay element is provided in an operation voltage section of the switch means (74).

According to this, the semiconductor switching element (7
The time between the turning-off of 5/751, 752) and the shutting off of the switch means (74) becomes longer, and the reliability that the switch means (74) shuts off after the semiconductor switching element is turned off is high.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0027]

FIG. 1 shows the appearance of a digital copier equipped with a power supply device according to a first embodiment of the present invention. The digital copying machine generally includes an automatic document feeder [ADF] 30 and an operation unit 20.
, A color scanner 10, a color printer 100,
A relay unit 32 and a finisher 34 with a shift tray capable of stacking a large amount of staplers and imaged sheets
, A double-sided reversing unit 33, a paper supply bank 35, a large-capacity paper supply tray 36, and a one-bin discharge tray 31.

FIG. 2 shows the configuration of the color printer 100. A writing optical unit as an exposure unit converts color image data from the scanner 10 into an optical signal, performs optical writing corresponding to a document image, and
4, an electrostatic latent image is formed. The optical writing optical unit is
It comprises a laser light emitter 141, a light emission drive control unit (not shown) for driving the light emission, a polygon mirror 143, a rotation motor 144 for rotating the polygon mirror 143, an fθ lens 142, a reflection mirror 146, and the like. Photoconductor drum 11
4 rotates counterclockwise as shown by the arrow,
Around the photosensitive member cleaning unit 121, a charge removing lamp 114M, a charger 119, a potential sensor 114D for detecting a potential of a latent image on the photosensitive drum, a selected developing device of the revolver developing device 120, a developing density pattern detector 114P, an intermediate transfer belt 115, and the like.

The revolver developing device 120 includes a BK developing device 120K, a C developing device 120C, an M developing device 120M, and a Y developing device 120Y, and a revolver rotary drive for rotating each developing device in a counterclockwise direction as indicated by an arrow. (Not shown). In order to visualize the electrostatic latent image, each of these developing units rotates developing sleeves 120 KS and 120, which rotate by contacting the ears of the developer with the surface of the photosensitive drum 114.
CS, 120MS, 120YS, and a developing paddle that rotates to pump up and agitate the developer. In a standby state, the revolver developing device 120 is set at a position where development is performed by the BK developing device 120, and when a copying operation is started, reading of BK image data is started by the scanner 10 at a predetermined timing, and this image is read. On the basis of the data, optical writing / latent image formation by laser light starts. Hereinafter, the electrostatic latent image based on the Bk image data is referred to as a Bk latent image. The same applies to each of the C, M, and Y image data. In order to enable development from the tip of this Bk latent image, B
Before the leading end of the latent image reaches the developing position of the k developing device 120K, the rotation of the developing sleeve 120KS is started to develop the Bk latent image with Bk toner. Thereafter, the developing operation of the Bk latent image area is continued. When the rear end of the latent image passes the Bk latent image position, the developing operation of the next color developing unit is immediately performed from the developing position of the Bk developing unit 120K. The revolver developing device 120 is driven and rotated to the position. This rotation operation is completed at least before the leading end of the latent image based on the next image data arrives.

When the image forming cycle is started, the photosensitive drum 114 rotates counterclockwise as indicated by an arrow, and the intermediate transfer belt 115 rotates clockwise by a drive motor (not shown). Move. Intermediate transfer belt 11
5, the BK toner image formation, the C toner image formation, the M toner image formation, and the Y toner image formation are sequentially performed, and finally, on the intermediate transfer belt 115 in the order of BK, C, M, and Y. , A toner image is formed. The formation of the BK image is performed as follows. That is, the charger 11
9 uniformly charges the photosensitive drum 114 with a negative charge to about -700 V by corona discharge. Subsequently, the laser diode 141 performs raster exposure based on the Bk signal. When the raster image is exposed in this manner, in the initially exposed portion of the photosensitive drum 114 that is uniformly charged, the charge proportional to the exposure light amount disappears, and an electrostatic latent image is formed. The toner in the revolver developing device 120 is
The toner is charged to a negative polarity by stirring with the ferrite carrier.
Is biased by a power supply circuit (not shown) with respect to the metal base layer of the photosensitive drum 114 to a potential at which a negative DC potential and an AC are superimposed. As a result, no toner adheres to the portion of the photosensitive drum 114 where the charge remains, and Bk is applied to the portion without charge, that is, the exposed portion.
The toner is attracted, and a Bk visible image similar to the latent image is formed. The intermediate transfer belt 115 includes a driving roller 115D, a transfer opposing roller 115T, and a cleaning opposing roller 115.
C and a group of driven rollers, and is driven to rotate by a drive motor (not shown). Now, the photosensitive drum 1
The Bk toner image formed on the belt 14 is transferred onto a surface of an intermediate transfer belt 115, which is driven at a constant speed in a state of contact with the photoconductor, by a belt transfer corona discharger (hereinafter, referred to as a belt transfer unit) 1.
16 transferred. Hereinafter, the transfer of the toner image from the photosensitive drum 114 to the intermediate transfer belt 115 is referred to as belt transfer. A small amount of untransferred residual toner on the photoconductor drum 114 is cleaned by the photoconductor cleaning unit 121 in preparation for reuse of the photoconductor drum 114. The collected toner is stored in a waste toner tank (not shown) via a collection pipe.

On the intermediate transfer belt 115, Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 114 are sequentially aligned on the same surface, and a four-color superimposed belt transfer image is formed. After that, batch transfer is performed on transfer paper by a corona discharge transfer device. By the way, the photosensitive drum 11
On the fourth side, the process proceeds to the C image forming process after the BK image forming process. At a predetermined timing, reading of the C image data by the scanner 10 is started, and the C latent image is written by laser light writing based on the image data. Is formed. C
The developing device 120C performs a rotating operation of the revolver developing device with respect to the developing position after the trailing end of the previous Bk latent image has passed and before the leading end of the C latent image has arrived. Is developed with C toner. Thereafter, the development of the C latent image area is continued, but when the rear end of the latent image has passed, the revolver developing device 120 is driven in the same manner as in the case of the Bk developing device, and the C latent image is developed.
The developing device 120C is sent out, and the next M developing device 120M is positioned at the developing position. This operation is also performed before the leading end of the next M latent image reaches the developing unit. In the process of forming the M and Y images, the operations of reading the image data, forming the latent image, and developing are in accordance with the processes of the Bk image and the C image described above, and a description thereof will be omitted.

The belt cleaning device 115U includes an inlet seal, a rubber blade, a discharge coil, and a mechanism for contacting and separating the inlet seal and the rubber blade. 1
After the Bk image of the color is transferred to the belt, while the images of the second, third, and fourth colors are transferred to the belt, the entrance seal, the rubber blade, and the like are separated from the intermediate transfer belt surface by the blade contact / separation mechanism. .

A paper transfer corona discharger (hereinafter referred to as a paper transfer device) 117 uses an AC corona discharge method to transfer the superposed toner image on the intermediate transfer belt 115 to transfer paper.
+ DC or a DC component is applied to the transfer paper and the intermediate transfer belt.

Transfer paper of various sizes is stored in the transfer paper cassette 182E and the paper supply bank 35, and the registration roller pair 118R is moved from a cassette storing paper of a designated size by a paper feed roller 183E or the like. The paper is fed and transported in the direction. The symbol 112B2 is an OHP
2 illustrates a paper feed tray for manually feeding paper or thick paper. At the time when the image formation is started, the transfer paper is fed from one of the above-mentioned paper feed trays, and the registration roller pair 418 is used.
Waiting at R nip. And the paper transfer unit 11
When the leading end of the toner image on the intermediate transfer belt 115 approaches 7, the registration roller pair 118 </ b> R is driven so that the leading end of the transfer paper coincides with the leading end of the image, and the paper and the image are aligned. In this way, the transfer paper is superimposed on the color superimposed image on the intermediate transfer belt and passes over the paper transfer device 117 connected to the positive potential. At this time, the transfer paper is charged with a positive charge by the corona discharge current, and most of the toner image is transferred onto the transfer paper. Subsequently, the paper transfer device 117
The transfer paper is discharged when passing through a separation static eliminator by a static elimination brush (not shown) disposed on the left side of the printer, and is separated from the intermediate transfer belt 115 and moves to the paper transport belt 122. The transfer paper on which the four-color superimposed toner image is collectively transferred from the surface of the intermediate transfer belt is conveyed to a fixing device 123 by a paper conveyance belt 122, and a fixing roller 123A controlled to a predetermined temperature.
The toner image is melted and fixed at the nip portion of the pressure roller 123B, sent out of the main body by the discharge roll pair 124, and stacked face up on a copy tray (not shown).

A fixing heater (halogen lamp) 123C is provided inside the fixing roller 123A. The fixing heater 123C is energized by a fixing energizing circuit 85 (FIGS. 4 and 5), whereby the fixing heater 123C generates heat. In addition, infrared rays are generated to heat the fixing roller 123C.

The photosensitive drum 114 after belt transfer
The surface is cleaned by a photoconductor cleaning unit 121 including a brush roller, a rubber blade, and the like.
Further, the charge is uniformly removed by the charge removing lamp 114M. Further, the intermediate transfer belt 115 after transferring the toner image to the transfer paper
Again presses the blade with the blade contact / separation mechanism of the cleaning unit 115U to clean the surface.
In the case of the repeat copy, the operation of the scanner and the image formation on the photosensitive member follow the fourth-color image process of the first sheet, and proceed to the second-color image process at a predetermined timing. In the case of the intermediate transfer belt 115, the second Bk toner image is belt-transferred to an area whose surface has been cleaned by the belt cleaning device, following a batch transfer process of the first four-color superimposed image onto transfer paper. So that Thereafter, the operation is the same as that of the first sheet.

FIG. 3 shows an outline of an electric system of the copying machine shown in FIG. One MPU 51 on the main control board 50 and one CPU 12 on the scanner control board 11 are used in the mechanical control section of the copying machine, that is, the main part of the image reading and image forming process control. The MPU 51 controls the image forming sequence, the fixing control, and the system-related control.
The PU 12 performs control related to the scanner. MPU
The 51 and the CPU 12 are connected by an image data interface and a serial interface.

In FIG. 3, reference numeral 20 denotes an operation unit;
Is an I / O control board, 92 is an LD control board for controlling a laser beam for image exposure, 41 is a paper feed control board, 13 is a read control board on which a CCD is mounted, 90 is a motherboard, and 60 and 91.
Reference numeral denotes an application extension unit for realizing a composite function. Reference numeral 91 denotes a facsimile control unit equipped with a facsimile function. Reference numeral 60 denotes a printer function for printing a document of a host such as a personal computer or a word processor, and a composite operation of copy, facsimile, and printer. A printer controller (board) for controlling the mode. 80 is a power supply device.

FIG. 4 shows that the fixing heater 1
23C, I / O control board (input / output interface) 7
0, an outline of a power supply system to a main control board (main controller) 50, a motherboard 90 and a printer controller 60, and an outline of the printer controller 60.

Referring to FIG. 4, an MPU 51, a CPU peripheral ASIC (Application Specific IC) 54, an image processing A
There is an SIC 53 and an I / F (interface) 52 having an interface function with the printer controller 60 and a function of compressing and expanding image data.

The printer controller 60, which controls the system, includes a peripheral ASIC 64 having an interface between the MPU 61 and the main control board 50 for realizing the composite function, a communication function with the operation unit, and a memory control function, and others. is there.

Document scanner 10 for optically reading a document
In the reading unit, the reflected light of the lamp irradiation on the document is condensed on the light receiving element by the mirror and the lens in the reading unit.
The light receiving element (CCD) is provided in a sensor board unit (SBU) 13, and the image signal converted into an electric signal in the CCD is converted into a digital signal on the SBU 13, that is, read image data. , SBU13 to the image processing ASIC 53 on the main control board 50.

The read image data from the SBU 13 is transferred to the image processing ASIC 53, and the image processing ASIC 53
Corrects the signal deterioration due to the quantization into the optical system and the digital signal (the signal deterioration of the scanner system: distortion of the read image data due to the scanner characteristics), and transfers the image data to the printer controller 60. Write to the memory MEM65.
Alternatively, a process for printer output is performed to
0 is given to the LD control board 92.

That is, the image processing ASIC 53 stores the read image data in the memory MEM 65 for reuse, and outputs the job to the video data control (VDC) on the LD control board 92 without storing it in the memory MEM 65. Then, there is a job in which an image is output by the laser printer function. As an example of storing the data in the memory MEM65, when copying a plurality of originals, the scanner 10 is operated only once, the read image data is stored in the memory MEM65, and the stored data is read a plurality of times. . As an example where the memory MEM65 is not used, when only one document is copied, it is only necessary to process the read image data as it is for the printer output, and there is no need to write the data to the memory MEM65.

First, when the memory MEM65 is not used,
The image processing ASIC 53 performs image reading correction on the read image data, and then performs image quality processing for conversion to area gradation. The image data after the image quality processing is transferred to the VDC on the LD control board 92. For the signal changed to the area gradation, post-processing relating to dot arrangement and pulse control for reproducing dots are performed by VDC, and a reproduced image is formed on transfer paper by a laser printer function.

When additional processing, for example, rotation in the image direction, synthesis of images, and the like are performed when the data is stored in the memory MEM 65 and read out from the memory MEM 65, the image data subjected to the image reading correction is stored in the image memory of the printer controller 60. Sent to peripheral ASIC 64 with access control function. Here, under the control of the MPU 61 in accordance with the operation program stored in the flash EEPROM, the access control of the image data and the memory module MEM65 and the development of the print data of the external personal computer PC (character code / character bit conversion). Compress and decompress image data for effective use of memory. The data sent to the peripheral ASIC 64 is stored in the MEM 65 after data compression, and the stored data is read as needed. Read data is expanded,
The image data is returned to the original image data, and is returned from the peripheral ASIC 64 to the image processing ASIC 53.

Upon returning to the image processing ASIC 53, image processing is performed, and pulse control is performed on the VDC on the LCD control board 92, and a visible image (toner image) is formed on transfer paper by the laser printer function.

FAX transmission function, which is one of the composite functions,
Image processing ASI for image data read by the original scanner 10
The image is read and corrected in C53 and transferred to the FAX control unit (FCU) 91. The FCU 91 performs data conversion to a public line communication network and transmits the data to the communication network as FAX data. For FAX reception, the line data from the communication network is converted into image data by the FCU 91, and the image processing ASI
Transferred to C53. In this case, no special image processing is performed, dot rearrangement and pulse control are performed in the VDC on the LCD control board 92, and a visible image is formed on the transfer paper by the laser printer function.

The MPU 51 of the main control board 50 controls the flow of image data,
U61 controls the entire system and manages activation of each resource. The function selection of the digital multifunction copying machine is selected and input by the operation unit 20, and the processing contents such as the copy function and the FAX function are set.

The power supply of the printer controller 60 is supplied with + 5VE which is energized even in the sleep mode. The main control plate 50 is supplied with +5 V, which is turned off in the pause mode. The I / O control plate 70 is supplied with +5 V and +24 V, which are also turned off in the sleep mode.

The DC power supply 80 has a converter output of +2
Switch 8 to 4V and + 5VE (+ 5V voltage) respectively
3, 84 are connected. These switches 83, 8
A control signal for turning on / off the switch 4 is supplied from the printer controller 60 to the switches 83 and 84. When shifting to the sleep mode for energy saving, the printer controller 60 turns off both the switches 83 and 84 by this control signal.

The target temperature of the fixing control 85 is set as a fixing operation temperature determined for the fixing process of the transfer paper on which the toner image has been transferred, and the temperature of the fixing roller is maintained at the target temperature. The delay is substantially delayed in response to a copy start or print command. Standby mode that can start image formation without time,
In the low power mode, in which the target temperature is set to 80% of the fixing operation temperature in order to reduce the power consumption and the rest is in the same state as the standby mode, and when an operation input is made, the mode can immediately return to the standby mode, the printer controller 60
Turns on both switches 83 and 84 by the control signal.

That is, the switches 83,
84 is off, the printer controller 60, the operation unit 2
0, + 5VE is continuously applied to the minimum number of electric elements or circuits to detect the action of the operator or the print command of the personal computer PC, which indicates the possibility of using the copying machine, for detecting the opening and closing of the pressure plate. In the printer controller 60,
+ 5VE is continuously applied to a circuit which waits for the detection and turns on the switches 83 and 84 in response to the detection and a memory for storing data which needs to be held in a nonvolatile manner.

Incidentally, in the low power mode, power is supplied to all, and only the set temperature of the fixing heater 123C is lowered.

The analysis and display of the key-in data from the operation unit 20 are controlled by the MPU 61 of the printer controller 60.
Performs control, and an interface with the operation unit 20 is provided by the peripheral ASIC 64. In this embodiment, the peripheral ASIC 64 and the operation unit 20 are connected via the motherboard 90, the main control board 50, and the scanner control board 11. The printer controller 60 is connected to a pressure plate open / close detection (not shown) via the motherboard 90, the main control plate 50, and the scanner control plate 11, similarly to the operation unit 20.

The pressure plate opening / closing detection is a detection switch for detecting opening / closing of the ADF 30 when the ADF 30 is connected to the scanner, and a detection switch for detecting opening / closing of the pressure plate for document pressing when the ADF 30 is not mounted. . In any case, the pressure plate open / close detection generates a signal indicating whether the ADF or the document pressing platen is open,
This is supplied to the peripheral ASIC 64 of the printer controller 60 via the scanner control board 10, the main control board 50 and the motherboard 90 in any of the image processing operation state, the standby mode, the low power mode, and the sleep mode. Read this signal. The power supply (+ 5VE) for representing a signal indicating whether the state is the open state and the power supply (+ 5VE) for detecting the ON of an input key of the operation unit 20 and generating a detection signal include a motherboard 90, a main control board 50, and a scanner. The control signal is given from the process controller 60 to the open / close detection switch and the operation unit 20 via the control plate 10.

When the ADF 30 is provided, it is connected to the scanner control board 11. A detection signal of a document sensor for detecting whether or not a document is present on the platen of the ADF 30 is also
The peripheral AS of the printer controller 60 is transmitted via the scanner control board 10, the main control board 50, and the motherboard 90.
The signal is given to the IC 64, and the MPU 61 reads this signal. A power supply (+ 5VE) for the document sensor to generate a detection signal indicating the presence or absence of a document is also supplied from the process controller 60 to the document sensor via the motherboard 90, the main control board 50, and the scanner control board 10.

FIG. 5 shows the fixing roller 12 of the fixing device 123.
3A shows a circuit configuration of an electric circuit for energizing the fixing heater 123C provided inside 3A, that is, a fixing energizing circuit 85. An AC voltage is applied to the fixing heater 123C via the power supply relay 74 and the triac 75. Triac 75
Is controlled by the phototriac 77 of the photocoupler 76. The I / O control board 70 includes a relay driver for energizing / de-energizing the relay coil of the power supply relay 74 in response to an on / off instruction signal given by the MPU 51 via the CPU periphery 54. There is a circuit.

The MPU 51 supplies a target temperature signal to the fixing temperature control circuit. This target temperature signal represents a fixing set temperature in the standby mode, and represents 80% of the fixing set temperature in the low power mode. The fixing temperature control circuit generates an on-duty PWM pulse corresponding to the deviation of the detected temperature of a fixing temperature sensor (not shown) connected to the I / O control plate 70 from the target temperature, and the I / O control plate 70 Give to the above light emitting diode driver. The driver responds to the ON instruction level H of the PWM pulse by using
8 cathode is connected to instrument ground. That is, the current path is closed. As a result, the light emitting diode 78
Light is emitted during the high level H (ON instruction) of the WM pulse, and is turned off during the low level L. Only when the light-emitting diode 78 emits light, the phototriac 77 conducts and the triac 75 is on (energized). During the low-level L period of the PWM pulse, the light emitting diode 78 is turned off and the photo triac 77 is non-conductive, and therefore the triac 75
Is off (de-energized; cut off).

The output voltage +24 V of the energy-saving switch SW 83, which is turned off in the sleep mode and turned on in the standby mode and the low power mode, is applied to the relay coil of the power supply relay 74 via the interlock switch 73. The interlock switch 73 is connected to the printer 1
00 is a door switch which is turned off by opening the front door and turned on by closing the front door.

A Zener diode 79 is connected to the light emitting diode 78 of the photocoupler 76, and the output voltage +24 V of the switch SW 83 is applied to the Zener diode 79 via the interlock switch 73.

When the front door of the printer 100 is closed (the interlock switch 73 is closed) during the image forming operation or in the standby mode or the low power mode for waiting for the image forming start instruction, the MPU 51 operates the relay 74. Is turned on (energized), and +24 V is applied to the anode of the zener diode 79 (the pole connected to 78).

In the H section of the PWM pulse generated by the fixing temperature control circuit on the I / O control board 70, the light emitting diode driver on the I / O control board 70 connects the cathode of the light emitting diode 78 to the ground potential. + 24V is applied to the series circuit of the Zener diode 79 and the light emitting diode 78, and the Zener diode 79 breaks down and conducts (energizes).
As a result, + (24−breakdown voltage) V is applied to the light emitting diode 78, the light emitting diode 78 emits light, the phototriac 77 conducts, and the triac 75 conducts. In the L section of the PWM pulse, since the light emitting diode driver cuts off between the cathode of the light emitting diode 78 and the ground potential, no voltage is applied to the series circuit of the zener diode 79 and the light emitting diode 78, and the light emitting diode 78 emits light. Therefore, the triac 75 is non-conductive.

When the interlock switch 73 is opened in the H section of the PWM pulse, the + 24V applied to the relay coil of the power supply relay 74 and the zener diode 79 falls to the equipment ground potential, and the breakdown voltage of the zener diode 79 falls. , The Zener diode 79 turns non-conductive, ie, switches from a low resistance value to a high resistance value, thereby turning off the light emitting diode 78, turning off the phototriac 77, and thus turning off the triac 75. When the voltage is approximately equal to the breakdown voltage of the Zener diode 79, the power supply relay 74 continues to hold the ON position of the relay contact. Therefore, the power supply relay 74 is opened after the triac 75 is turned off. That is, it is turned off. At this time Triac 7
Since the heater current is cut off by turning off 5, the excessive current does not flow through the contact of the power supply relay 74. The contacts are not subjected to stress and do not deteriorate or weld.

-Second Embodiment- FIG. 6 shows a fixing heater energizing circuit according to a second embodiment of the present invention. In this example, the fixing roller has two heaters 123C.
Equipped with 1,123C2. The heater 123C1 is connected to the power supply relay 74 and the triac 751 via the power supply relay 74 and the triac 751.
An AC voltage is applied via 52. Triac 7
The gate potentials of 51 and 752 are controlled by phototriacs 771 and 772 of photocouplers 761 and 762, respectively. The fixing temperature control circuit in the I / O control board 70 generates a PWM pulse addressed to each of the triacs 751 and 752, and the light emitting diodes connected to the light emitting diodes 781 and 782 on the I / O control board 70. Give to the driver.

Also in the second embodiment, when the interlock switch 73 is opened in the H section of the PWM pulse, the triacs 751 and 752 are turned off first, and the power supply relay 74 is opened. That is, it is turned off. At this time, since the heater current is cut off by turning off the triacs 751 and 752, no excessive current flows through the contact of the power supply relay 74. The contacts are not subjected to stress and do not deteriorate or weld.

Third Embodiment FIG. 7 shows a fixing heater energizing circuit according to a third embodiment of the present invention. In this example, a diode 86 is connected in a forward direction from the interlock switch 73 to the +24 V power supply line to the relay coil of the power supply relay 74 and the zener diode 79.
Is inserted, and a capacitor 87 for delaying voltage drop is connected to the cathode thereof. Interlock switch 7
While +3 is closed and + 24V is applied to the diode 86, the capacitor 87 is charged with the voltage. Other configurations are the same as those of the above-described second embodiment.

In the third embodiment, when the interlock switch 73 is opened in the H section of the PWM pulse, the capacitor 87 is thereby connected to the relay coil of the power supply relay 74, the Zener diode 79 and the light emitting diode 7
When the voltage of the capacitor 87 falls below the breakdown voltage of the Zener diode 79, the Zener diode 79 turns off, thereby turning off the light emitting diodes 781 and 782 and turning off the phototriac 771. 772 turns off and thus triacs 751, 752 switch off. When the voltage is about the breakdown voltage of the Zener diode 79, the power supply relay 74 continues to hold the ON position of the relay contact.

After the voltage of the capacitor 87 further decreases, the power supply relay 74 opens. That is, it is turned off.
At this time, since the heater current is cut off by turning off the triacs 751 and 752, no excessive current flows through the contact of the power supply relay 74. The contacts are not subjected to stress and do not deteriorate or weld.

In the third embodiment, the charging voltage of the capacitor 87 delays the reduction of the relay coil current immediately after the interlock switch 73 is switched from the closed state to the open state. The time from returning to the high resistance before breakdown and turning off the light emitting diodes 781 and 782 until the power relay 74 is opened (interrupted) is long, and the time when the interlock switch 73 is opened is long.
Triac 751, 7 preceding opening of power supply relay 74
52 is reliably realized, and the reliability is high.

As in the third embodiment, in the first embodiment, the power supply relay 74
+2 to the relay coil and zener diode 79
A diode 86 is inserted into the 4V power supply line in the forward direction,
It is preferable to connect a capacitor 87 for delaying voltage drop to the cathode.

[Brief description of the drawings]

FIG. 1 is a plan view showing the appearance of a digital copier equipped with a power supply device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an outline of a mechanism of the color printer 100 shown in FIG.

FIG. 3 is a block diagram showing a system configuration of an electric system of the digital copying machine shown in FIG.

FIG. 4 is a block diagram showing an outline of a configuration of a DC power supply 80 shown in FIG.

FIG. 5 is an electric circuit diagram of a power supply circuit 85, which is the power supply device of the first embodiment, shown in FIG.

FIG. 6 is an electric circuit diagram of a power supply circuit 85 which is a power supply device according to a second embodiment of the present invention.

FIG. 7 is an electric circuit diagram of a power supply circuit 85 which is a power supply device according to a third embodiment of the present invention.

[Explanation of symbols]

100: color printer 123: fixing device 123A: fixing roller 123B: pressure roller 123C: fixing heater 73: interlock switch 74: power relay 75: triac 76: photo coupler 77: photo triac 78: light emitting diode 79: zener diode 86 : Diode 87: Capacitor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 3/00 H02J 3/00 DF term (Reference) 2H027 DA26 ED25 EF16 EJ18 ZA01 ZA04 2H033 AA42 BA39 CA06 CA23 CA38 CA45 2H071 AA17 BA20 DA12 DA34 5G053 AA13 BA04 CA01 EB02 EC01 EC04 FA06 5G066 LA03 LA10

Claims (6)

[Claims] 1. A power supply line from a power supply to a load,
A semiconductor element for controlling power supply to the load in response to a power supply control signal; inserted into the power supply line to turn on the power supply line in response to a close instruction signal, and cut off the power supply line when the close instruction signal disappears Switch means; means for interrupting the close instruction signal to the switch means; and more than the interruption of the power supply line of the switch means in response to the disappearance of the close instruction signal when the interruption means interrupts the close instruction signal. An electric means for quickly changing the power supply control signal to a non-power supply level in response to the change of the closing instruction signal to disappearance. 2. A first and a second semiconductor which are interposed in first and second power supply lines from a power supply to first and second loads, respectively, and control power supply to each load in response to a power supply control signal. Switch means interposed between the power supply and the first and second power supply lines to turn on the first and second power supply lines in response to a close instruction signal and to cut off when the close instruction signal disappears; Means for interrupting a closing instruction signal to the means; and first and second switches of the switch means responsive to the disappearance of the closing instruction signal when the interrupting means interrupts the closing instruction signal.
An electric means for changing the power supply control signal to a non-power supply level in response to the change of the closing instruction signal to disappearance earlier than the interruption of the power supply line. 3. The switch according to claim 1, wherein delay means for reducing a change speed of the closing instruction signal to disappearance due to interruption of the interruption means is connected to a closing instruction signal line to the switch means. Power supply. 4. A semiconductor switching element interposed in a power supply line from a power supply to an electric heater and controlling electric power supply to the electric heater in response to a power supply control signal; A power supply relay that turns on the power supply line in response and shuts off the power supply line when the closing instruction voltage disappears; a means for interrupting the closing instruction voltage to the power relay; and when the interruption means interrupts the closing instruction voltage. A constant voltage element that changes the power supply control signal to a non-power supply level in response to a change to the disappearance of the close instruction voltage earlier than the shutoff of the power supply relay in response to the disappearance of the close instruction voltage. apparatus. 5. A fixing roller, a heater provided therein, and a pressure roller which presses against the fixing roller; inserted into a power supply line from a power supply to the heater, and supplies power to the heater in response to a power supply control signal. A switching element that is interposed in the power supply line, turns on the power supply line in response to the close instruction signal, and shuts off the power supply line when the close instruction signal disappears; An interlock switch to be shut off, which is opened and closed by movement of an object; and an interlock switch which responds to the disappearance of the close instruction signal when the interlock switch shuts off the close instruction signal, earlier than the interruption of the power supply line of the switch means. An electric means for changing the power supply control signal to a non-power supply level in response to the change of the closing instruction signal to disappearance. 6. An electrostatic latent image is formed on a photoreceptor, the electrostatic latent image is visualized into a toner image by a developing device, and the toner image is transferred directly or indirectly via an intermediate medium. And an image forming apparatus for performing a fixing process by passing the transfer paper through a fixing device, wherein the fixing device includes a fixing roller, a heater provided therein, and a pressing roller that presses against the fixing roller; A semiconductor switching element interposed in the power supply line to control power supply to the heater in response to a power supply control signal; inserted in the power supply line to turn on the power supply line in response to a close command voltage; A power relay for shutting off a power supply line when the command voltage disappears; opening a door or a front cover of the image forming apparatus to shut off a closing command voltage to the power relay;
An interlock switch that is closed by closing; and a change to the disappearance of the close instruction voltage earlier than the interruption of the power supply relay in response to the disappearance of the close instruction voltage when the interlock switch shuts off the close instruction voltage. A constant voltage element for changing the power supply control signal to a non-power supply level in response to the power supply control signal.