JP2000134788A - Image forming device - Google Patents

Abstract

(57) [Problem] To provide an image forming apparatus capable of both preventing overcurrent and ensuring the safety of an operator when opening and closing a door. SOLUTION: A main motor 13 is supplied from a DC power supply 134.
2. Current fuses 143 and 139 are provided in a power supply path to the main motor driver 133 and the polygon motor driver 131 which respectively control the polygon motor 106, and a door switch 135 which is linked with opening and closing of a door 136 for accessing the inside of the apparatus housing. Controls the power supply to the main motor driver 133. When the door 136 is closed, the sensor 151 operates before the door switch 135 is closed and power supply to the main motor driver 133 is started, and the polygons are switched by the switching elements 154 and 155 based on the timing generated by the timing control circuit 152. The power supply path on the motor driver 131 side is switched so as not to pass through the current fuse 139.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, in particular, a door that is opened and closed for an operator to access an image forming mechanism in an apparatus housing, and a control unit that controls power supply according to the opening and closing of the door. And an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer or a copying machine, an operation door for paper jam clearance or the like is provided in the apparatus, and the inside of the apparatus can be accessed by opening the door. Is known.

In such a configuration, the operator can contact the movable part of the apparatus by opening the operation door, and the door is shut off by opening the door to ensure the safety of the operator. An interlock mechanism that supplies power to a drive control unit of the apparatus movable unit via a switch connected as described above is used.

On the other hand, in this type of device, the power supply of the control unit is prevented in order to prevent an overcurrent caused by a failure of a circuit element of the control unit or a short circuit to the ground potential due to a wire biting with the housing. A current fuse is arranged on a route to prevent fire, smoke, and the like in the event of an accident.

In such an overcurrent prevention mechanism, especially in the case of a large-sized device that consumes more power, the current value required for output is large, so that the overcurrent output protection value on the power supply side must be large. I can't get it. Therefore, in the event of an accident, it is difficult to ensure safety only by protecting the output on the power supply side.In practice, a current fuse is provided for each control unit as a means of preventing overcurrent. A configuration provided on the power supply path to the power supply is used.

[0006]

Further, in the conventional image forming apparatus, a control unit that cuts off power supply by opening and closing a door switch and a control unit that continuously supplies power regardless of opening and closing of the door switch are separated. It may be necessary to supply power to the control units from the same power supply.

For example, a control unit that drives and controls a drive unit to which a movable unit can come into contact by opening a door needs to shut off the power, but does not control the drive of the movable unit touched by a user by opening the door. In addition, even when the door is open, power must be continuously supplied to a control unit that controls a polygon motor or the like that requires a long drive time and requires drive control.

Therefore, in an apparatus having a control unit having such different properties, the power supply system is separated into two, a power supply system via a door switch and a power supply system without a door switch.

In such a configuration, when the door is opened, power is supplied only to the units connected to the power supply system that does not pass through the door switch, and the power supply system that passes through the door switch remains shut off. . At this time, the capacitor for stabilizing the power supply of the unit connected to the power supply system not passing through the door switch is charged, and the capacitor for stabilizing the power supply of the unit connected to the power supply system via the door switch is discharged. It has become.

When the door switch is closed, power is supplied to the power supply system via the door switch. At the moment when the door switch is connected, the power supply system is connected to the power supply system not via the door switch. The electric charge from the charged power stabilizing capacitor of the unit thus set flows through the power supply and flows into the power stabilizing capacitor of the unit connected to the power supply system via the door switch.

The amount of inrush current is determined by the capacity of the power supply and the capacitor of each unit, and is connected to the capacitor of the unit connected to the power supply system not passing through the door switch and to the power supply system passing through the door switch. Depending on the balance of the capacitors in the unit, a much larger current may flow through the unit than would normally flow. Due to the rush current when this door switch is closed,
A problem arises in that the current fuse provided for preventing overcurrent is blown.

The current rating of the DC fuse is ideally a capacity capable of withstanding such an inrush current in addition to the operating current of the target unit.
The current rating of the fuse must also be increased, and the function of the fuse cannot be fulfilled unless a very large overcurrent flows in the event of an accident, and the damage to the device cannot be kept small. Can be considered.

In particular, the above problem occurs when there is an imbalance in current consumption and inrush current between a control unit that supplies power regardless of whether the door is opened and closed and a control unit that stops supplying power when the door is opened.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to make it possible to prevent both overcurrent and ensure the safety of an operator when opening and closing a door.

[0015]

In order to solve the above-mentioned problems, according to the present invention, there are provided first and second control units for controlling predetermined members in an image forming mechanism, respectively, and the first and second control units. A power supply circuit for supplying power to the control unit;
A door that is opened and closed for an operator to access an image forming mechanism in the apparatus housing; and a power supply circuit that supplies power to the first control unit from the power supply circuit when the door is opened, and the power supply circuit when the door is closed. A door switch provided in a power supply path from the power supply circuit to the first control unit so as to cut off power supply from the power supply to the first control unit, and power supply from the power supply circuit to the second control unit during normal operation. An overcurrent protection means provided in a path, and when the door is closed and the power supply circuit starts supplying power to the first control unit when the door is closed, a second power supply circuit A configuration is provided in which a control unit that switches a power supply path toward the control unit to a path that does not pass through the overcurrent protection unit is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. Hereinafter, a configuration of a color image forming apparatus having an image scanner unit will be exemplified.

[First Embodiment] FIG. 2 shows a schematic configuration of a color image forming apparatus having an image scanner unit employing the present invention.

In FIG. 1, reference numeral 201 denotes an image scanner, which is provided on the upper surface of the apparatus, reads an original, and performs digital signal processing. Reference numeral 200 denotes a printer unit, which prints a document image read by the image scanner 201 or an image corresponding to image data sent from an external device such as a computer (not shown) in full color on paper.

In the image scanner section 201, 20
Reference numeral 2 denotes an original pressing plate, which is an original 20 on the original platen glass 203.
4 is pressed against the platen glass 203. Platen glass 20
3 is irradiated with light from a halogen lamp 205. Light reflected from the document is guided to mirrors 206 and 207, and forms an image on a CCD line sensor 210 by a lens 208. The lens 208 has a far infrared cut filter 2
31 are provided.

The CCD line sensor 210 performs color separation of the light information from the original, reads the three primary color full-color information red (R), green (G), and blue (B) components, and sends them to the signal processing unit 209. That is, the CCD line sensor 210 is composed of R, G, B sensors 210-1 to 210-.
Constituting No. 3.

The halogen lamp 205 and the mirror 20
Reference numeral 6 denotes a speed V, and a mirror 207 drives the mirror 207 at 1/2 V mechanically in the vertical direction (hereinafter, the sub-scanning direction) with respect to the electrical scanning direction (hereinafter, the main scanning direction) of the line sensor. Scan.

Reference numeral 211 denotes a standard white plate, which is a CCD line sensor 210 (R, G, B sensors 210-1 to 210-21).
In step 0-3), correction data of the read data is generated. The standard white plate has substantially uniform reflection characteristics from visible light to infrared light, and has a white color when visible.

Using this standard white plate, a CCD line sensor 210 (R, G, B sensors 210-1 to 210-) is used.
3) Correction of output data of visible sensor (shading)
I do. Reference numeral 230 denotes an optical sensor which generates an image tip signal VTOP together with the flag plate 229.

The image signal converted into the electric signal is subjected to the following processing in the image processing unit 209 according to the flow shown in FIG. The signal from the CCD line sensor 210 is A /
D & S / H (A / D conversion and shift register) unit 41
At 0, the image data is converted to digital data, and the shading correction unit 411 and the input masking unit 412 correct the image data. The data obtained from the standard white plate 211 is used for the shading correction. In addition, a scaling process is performed by the scaling unit 413 as needed.

Next, the LOG converter 414 converts the RGB data into magenta (M), cyan (C), and yellow (Y) data (from an additive color system to a subtractive color system), and compresses the image data. Is input to a companding unit 415 that performs storage and expansion.

The image data stored in the buffer memory of the compander 415 is read out in synchronization with each color of the printer described later, and is subjected to a masking process by a masking / UCR unit 416. And edge enhancement unit 4
The output image data of M, C, Y, and black (K) is created by 18 and sent to the printer unit 200. Here, for one original scan in the image scanner unit 201, one component of M, C, Y, and K is sent to the printer unit 200, and one printout is completed by a total of four original scans. .

Next, the configuration and operation of the printer section 200 will be described. When an image signal sent from the scanner unit 201 or an external device such as a computer (not shown) is sent to the image writing timing control circuit 101, the image writing timing control circuit 101 converts the image signals into magenta (M), cyan (C), The semiconductor laser 102 is modulated and driven in accordance with yellow (Y) and black (K) image signals.

The laser beam is emitted from a polygon motor driver 131.
Is reflected by the rotating polygon mirror 103 by a polygon motor 106 driven and controlled by the f-θ lens 104, and is fθ-corrected by the f-θ lens 104.
And scans on the photosensitive drum 105. Since the photosensitive drum 105 is uniformly charged in advance by the primary charger 242, the photosensitive drum 10
5, an electrostatic latent image is formed.

Around the photosensitive member 105, magenta (M) 219, cyan (C) 220, and yellow (Y) 2
21, a developing unit for black (K) 222 is provided, and four developing units alternately contact the photosensitive drum 105 while the photosensitive drum 105 rotates four times, and M, C, Y, and M formed on the photosensitive drum 105 Each of the K electrostatic latent images is developed with a toner corresponding to the color.

On the other hand, the sheet 9 fed and conveyed from the sheet feeding units 224 and 225 is attracted by a suction charging blade 245 connected to a suction high pressure generating unit (not shown) at a timing synchronized with image formation on the photosensitive drum side. Is electrostatically attracted to the transfer drum 108 whose side is charged.

Then, at the transfer position 246, the photosensitive drum 105 is transferred by the transfer charging blade 240 connected to a transfer high voltage generator (not shown) inscribed in the transfer drum 108.
The image is transferred to the paper 9 by being charged to transfer the toner to the side.

After the image forming and transferring operations are repeated four times, the sheet 9 separated from the transfer drum 108 is conveyed to a fixing device 226, where the toner image is heated and fixed on the sheet 9, and is output to a sheet discharge tray 227. Is done.

Here, the cleaner 241 cleans, from the photosensitive drum 105, residual toner that has not been completely transferred or toner of a specific batch for various controls that is formed on the photosensitive drum but does not transfer. Reference numeral 3010 denotes a reflective optical sensor for protecting the cleaner.

The mechanical driving of the paper feed system, the image forming system, and the like can be performed by transmitting the drive from the main motor 132 controlled by the main motor driver 133. A DC power supply 134 for supplying power to the device is connected to each unit and supplies a predetermined current.

In FIG. 2, reference numeral 136 denotes a door provided on the front surface (or the back surface of the housing) of the apparatus, and by opening this door, a movable mechanism such as the above-described paper feed system and image forming system is provided. Contact is possible. It is opened and closed by an operator or a serviceman when removing paper jammed in the transport path in the case of a failure such as a jam.

A door switch 135 that opens and closes by opening and closing the door 136 is inserted in a power supply path from the DC power supply 134 to the main motor driver 133.

In this embodiment, a sensor 151 is further provided near the door switch 135.

The sensor 151 is for detecting the state of the door 136 or the door switch 135, and is composed of a photo interrupter, a magnetic sensor, or the like. When the door 136 is closed, the door switch 13 is closed.
The arrangement position of the sensor 151 (or its internal structure) is determined so that the sensor 151 operates before the operation of the sensor 5.

For example, as shown in FIG. 1, in the configuration in which the projection 136a of the door 136 operates the door switch 135 composed of a limit switch or the like, the sensor 151 composed of a photo interrupter or the like operates the door switch 135. It is conceivable to provide it at a position where it crosses the front of it before doing so.

FIG. 1 shows the door 136 and the DC power supply 1.
The structure of the control system around 34 is shown in detail.

In FIG. 1, the same members as those in FIG. 2 are denoted by the same reference numerals, 134 is a DC power supply, 133 is a main motor driver, 131 is a polygon motor driver, 135 is a door switch, and 136 is a door switch. Is the door.

In FIG. 1, reference numeral 152 denotes a timing control circuit, 137 denotes a control circuit in the polygon motor driver 131, 138 denotes a capacitor in the polygon motor driver 131, and 140 denotes a polygon motor driver 131.
The diode 141 in the main motor driver 133
A control circuit 142 therein is a capacitor in the main motor driver 133.

Reference numeral 151 denotes the door switch 1 as described above.
The sensor 151 operates at a timing different from that of the sensor 35. As for the output of the sensor 151, the state output Vd from the sensor is input to the control circuit 152.

Reference numeral 153 denotes a fuse unit disposed in a power supply path from the DC power supply 134 to the polygon motor driver 131 and the main motor driver 133, and a current fuse 139 and a main motor driver in a path toward the polygon motor driver 131. It has a current fuse 143 in the path towards 133. In the fuse unit 153, reference numerals 154 and 155 are switching elements for switching a power supply path.

As described above, opening the door 136 enables access to the mechanism operated by the main motor, and its opening and closing is detected by the door switch 135 and the sensor 151. As described above, the sensor 151 is configured such that when the door is closed, the state changes earlier than when the door 136 operates the door switch 135.

As shown, in this embodiment, a DC power supply 134 is provided to the polygon motor driver 131.
Is connected without passing through the door switch 135. This is because the polygon motor 106
6, the movable part around the polygon motor cannot be accessed simply by opening the door, and the startup time for the polygon motor 106 to rotate at high speed and stably rotate takes a long time. This is so as not to stop.

The polygon motor driver 131 includes a control circuit 137 for controlling the driving of the polygon motor 106 and a capacitor 138 for stabilizing the power supply.

On the other hand, power is supplied to the main motor driver 133 by opening and closing the door 136.
35 is disposed in the power supply path. This is door 13
When the door 136 is opened, the movable part that operates by driving the main motor 132 that drives a paper feed roller or the like that can be accessed when the door 6 is opened is stopped reliably.

The main motor driver 133 contains a control circuit 141 for controlling the drive of the main motor 132 and a capacitor 142 for stabilizing the power supply. here,
The current of the current fuse in the power supply line to the polygon motor driver is I1, and the voltage is V1. These currents I1
And the voltage V1 have steady values Is and Vs during a steady operation.

Here, in order to facilitate the explanation, FIG. 3 shows a conventional configuration of the same portion as FIG. In the configuration of FIG. 3, the switching circuit in the sensor 151 and the fuse unit 153 is not provided, but the other configuration is the same as that of FIG. 1. In FIG. 3, the same members as those of FIG. I have. In FIG. 3, the polygon motor driver 1
The current supplied to 31 is denoted by I3, and the voltage is denoted by V3.

FIG. 7 shows current and voltage waveforms supplied to the polygon motor driver 131 when the door 136 is closed according to the conventional configuration shown in FIG. 3 and the embodiment shown in FIG. In FIG. 7, the horizontal axis is the time axis, and V
(V1, V3, Vs) is a voltage and I (I1, I3, Is)
Is the current.

In the conventional configuration shown in FIG.
When the switch 36 is opened, the power supply to the main motor driver 133 is cut off by the door switch 135, and the capacitor 142 is discharged. And, as described above, the door 13
6 is closed, the current (-I) indicated by the arrow in FIG.
Since the path p) is formed, an overcurrent in a direction opposite to the normal current flows through the current fuse 139.

The waveform when the fuse 139 is not blown is as shown by the symbol A in FIG. 7. If damage is accumulated in the current fuse by repeating this rush, the fuse is blown as shown by the symbol B and the polygon motor Power supply to the driver 131 is cut off (voltage Vs-> 0).

On the other hand, in the configuration of FIG. 1 provided with the switching circuit, it is possible to prevent a rush current from flowing into the current fuse 139 as indicated by reference numeral C in FIG. That is, in the configuration of FIG. 1, when the door 136 is closed, the switching element 155 is turned on via the sensor 151 and the timing control circuit 152 before the door switch 135 is operated, and the switching element 154 is turned on. Cut off,
The current path from the polygon motor driver 131 to the main motor driver 133 is switched so as not to pass through the current fuse 139. As a result, it is possible to prevent an overcurrent from flowing through the current fuse 139 of the polygon motor driver 131 and to prevent the current fuse 139 from being blown.

FIG. 6 shows the switching elements 154 and 155 based on the detection signal Vd from the sensor 151.
5 shows a circuit configuration example of the control circuit 152 that forms the switching timing, and FIG. 5 shows a timing sequence in the configuration of FIG.

In FIG. 6, reference numeral 161 denotes a D latch,
62 is an 8-bit counter, 163 is a data setter, 16
4 is an 8-bit counter, 165 is a data setter, 166
Is a JK latch, 167 is a transistor, 168 is a D latch, 169 is an AND gate, 170 is an 8-bit counter, 171 is a data setter, and 173 is a transistor.

Here, a common clock CLK is input to each latch and each counter from a clock supply source (not shown). Here, this common clock CLK is 100 kHz.
Clock. In addition, each data setting device 1
63, 165, and 171 can be composed of DIP switches and the like, and here, fixed values are set,
It is assumed that 8-bit data of 10h is set in the data setting unit 163, F0h is set in the data setting unit 165, and FFh is set in the data setting unit 171 ("h" indicates a hexadecimal number). These set values are determined by the timing described later.

In FIG. 6, the input from the sensor 151 is Vd, the input to the switching element 154 connected in series to the current fuse to the polygon motor is Va, and the switching is connected in parallel to the current fuse to the polygon motor. The input to the element 155 is Vb. Further, the J input of the J latch 166 is a-J, and the K input of the J latch 166 is a
The K * output of the K and J latch 166 is aQ *, the J input of the J latch 172 is bJ, and the K input of the J latch 172 is b.
-The Q * output of the K, J latch 172 is set to b-Q *.

Next, the operation of the timing control circuit 152 shown in FIG. 6 when the door 136 is closed will be described with reference to FIG.

When the state of the output voltage Vd of the sensor 151 changes from the L level to the H level due to the closing of the door 136 (t0), the D-latch 168 and the AND gate 169 cause the timing signal b- having a width of one clock. K is generated, and the output bQ * of the J latch 172 changes from H level to K level.

Then, the output voltage Vd of the sensor 151 becomes H
During the level, the three counters 162, 164, and 170 start and continue the counting operation because the H level signal is input to the enable input. Here, since the clock CLK is 100 kHz, the width of 1 CLK is 10 μs.

Then, the counter 162 sets the data setter 1
After counting 16 clocks (= 10h) set to 63, that is, after 160 μs, the counter 162 outputs the carry-up signal a-J, and the output a- of the J-latch 166 is synchronized with the next edge of the clock CLK. Q * changes from L level to H level (t1).

Further, the counter 164 is used by the data setter 1
After counting 240 clocks (= F0h) set to 65, that is, 2.4 ms later, the counter 164 outputs the carry-up signal aK, and the J latches 166a-Q * are synchronized with the next clock edge. Is from H level to L
It changes to the level (t2).

Further, the counter 170 is the data setter 1
After counting 255 clocks (= FFh) set to 71, that is, after 2.55 ms, the counter 170 outputs the carry-up signal bJ, and at the next CLK, the J latch 172b-Q * changes from H level to L level. It changes to the level (t3).

As shown in FIG. 6, JK latches 166 and 1
Transistors 167 and 173 are inserted in the output of 72, and Va for driving switching element 154 is JK
It is an inverted signal of the output a-Q * of the latch 166,
Vb for driving the switching element 155 is an inverted signal of the output bQ * of the JK latch 172.

Then, the switching elements 154 and 155
Are controlled so that the respective switching elements 154 and 155 become conductive when both become low.

With the above-described circuit and timing setting, 160 μs of t0 to t1 and 150 μs of t2 to t3 are secured as a switching time margin between the switching elements 154 and 155, and a time interval for avoiding intrusion when the door switch is closed. As a result, 2.24 ms of t1 to t2 can be secured.

Usually, the switching time of a switching element such as a transistor is several μs or less, and the duration of the rush current when the door switch is closed is on the order of 1 μs or less.
It is possible to avoid an inrush current flowing through 39. Note that the length of t1 to t2 as the time interval for avoiding the inrush current may be determined according to the capacity of the capacitor 142 and the like.

As described above, when the door 136 is closed, the switching element 155 is activated via the sensor 151 and the timing control circuit 152 before the door switch 135 is operated (timing t4 in FIG. 5). Conducting and switching element 154 is cut off,
The current path from the polygon motor driver 131 to the main motor driver 133 can be switched so as not to pass through the current fuse 139, thereby preventing an overcurrent from flowing through the current fuse 139 of the polygon motor driver 131. Fusing can be avoided.

That is, when the door 136 is opened, the movable portion driven by the main motor 132 can be reliably stopped to protect the operator, and when the door 136 is closed, power is supplied only by closing the door 136. It is possible to prevent the current fuse 139 in the path from being blown.

In particular, the two current fuses 139, 143
When there is an imbalance in the current rating required for the current fuse (for example, the current rating of the current fuse 139 is larger than that of the current fuse 139), there is no need to expect an excessive current rating on the current fuse 139 side. The intended overcurrent protection operation can be reliably performed.

In the above embodiment, the door switch 135
Although one control unit is illustrated for each of the power supply system via the power supply system and the power supply system via the door switch, this is merely an example, and the power supply system via the door switch 135 and the power supply system via the door switch are not included. Regarding the power supply system not to be used, each unit is not limited to one. Further, in the present embodiment, the configuration in which the current fuse and the switching circuit are arranged in the fuse unit is exemplified. However, the requirements of the present invention are not limited to this arrangement, and the arrangement is not limited to the output end of the DC power supply or the motor driver. It is needless to say that the same effect can be expected in such a configuration.

Further, in the above embodiment, a case was considered in which one door is provided. However, when a plurality of doors are provided and control units which receive power supply control by these doors are different from each other, power supply control is performed by each door. What is necessary is just to apply the above-described configuration by combining a control unit and a unit that does not receive the control unit. In short, it is only necessary to provide switching means for bypassing the current fuse on the side of the control unit which is not subjected to power supply control by the door, and operate these switching means according to the state of the corresponding door or door switch.

[0074]

As is apparent from the above, according to the present invention, the first member for controlling each of the predetermined members in the image forming mechanism is provided.
And a second control unit, a power supply circuit for supplying power to the first and second control units, a door that is opened and closed for an operator to access an image forming mechanism in the apparatus housing, and a door that opens and closes. A power supply path from the power supply circuit to the first control unit to supply power from the power supply circuit to the first control unit and to cut off power supply from the power supply circuit to the first control unit when the door is closed. A door switch provided in the power supply circuit from the power supply circuit to the second control unit during normal operation, and an overcurrent protection means provided in a power supply path, and when the door is closed, the door switch is operated to activate the door switch. When power supply from the power supply circuit to the first control unit is started, a power supply path from the power supply circuit to the second control unit is switched to a path that does not pass through the overcurrent protection unit. Is provided in a power supply path from the power supply circuit to the second control unit due to an inrush current accompanying the start of power supply to the first control unit when the door is closed. The overcurrent protection means does not need to be set, so that the overcurrent protection means provided in the power supply path toward the second control unit does not need to be set excessively. It is possible to provide an excellent image forming apparatus which can ensure the safety of the operator at the time of the above.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a door and a power supply control system of an image forming apparatus employing the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of an image forming apparatus employing the present invention.

FIG. 3 is a block diagram illustrating a configuration of a door and a power supply control system of a conventional image forming apparatus.

FIG. 4 is an explanatory diagram showing a configuration and an operation of an image processing unit of the apparatus in FIG. 2;

FIG. 5 is a timing chart showing the operation of the timing control circuit of FIG. 1 in detail.

FIG. 6 is a block diagram showing the configuration of the timing control circuit of FIG. 1 in detail;

FIG. 7 is a timing chart illustrating the effect of the image forming apparatus of the present invention.

[Explanation of symbols]

 106 polygon motor 131 polygon motor driver 132 main motor 133 main motor driver 134 DC power supply 135 door switch 136 door 139 current fuse 140 diode 143 current fuse 151 detection sensor 152 timing control circuit 154 switching element 155 switching element

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[Procedure amendment]

[Submission date] November 6, 1998 (1998.11.
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0060

[Correction method] Change

[Correction contents]

[0060] When the state of the output voltage Vd of the sensor 151 by closing of the door 136 is changed from L level to H level, thereby the D latch 168 and AND gate 169, the timing signal b-K of one clock width is generated , J latch 172 change from H level to K level (t0) .

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

Claims (3)

[Claims] A first control unit that controls a predetermined member in the image forming mechanism; a power supply circuit that supplies power to the first and second control units; and an image forming mechanism in an apparatus housing. A door which is opened and closed for access by an operator; and when the door is opened, power is supplied from the power supply circuit to the first control unit. When the door is closed, power is supplied from the power supply circuit to the first control unit. A door switch provided on a power supply path from the power supply circuit to the first control unit to cut off power supply; and an overcurrent protection provided on a power supply path from the power supply circuit to the second control unit during normal operation. Means, when the door is closed and the power supply circuit starts supplying power to the first control unit when the door is closed, the second control unit is provided from the power supply circuit. Image forming apparatus characterized by the provided control means for switching a path which does not pass through the overcurrent protection means the feed path towards the. 2. The image forming apparatus according to claim 1, wherein said overcurrent protection means is a current fuse. 3. The power supply circuit according to claim 2, wherein:
Detecting means for detecting the state of the door or the door switch means for switching the power supply path toward the control unit, which is provided before the door switch means is activated when the door is closed. The image forming apparatus according to claim 1, wherein the detection state is configured to change.