JPS5831574B2 - Flash type fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash type fixing device that fuses toner images using flash light emitted from a flash lamp.

In electrophotographic copying devices, electrostatic recording devices, facsimile IJ, etc., the image to be recorded is formed in the form of an electrostatic latent image, and this electrostatic latent image is turned into a visible image using toner on recording paper using heat. A heat fixing method that fuses the images to form the final image is widely used.

This thermal fixing method includes a thermal a-ra type fixing method in which a recording paper bearing a toner image is inserted between a heating roller and a pressure roller, and the toner image is melted and fixed by the heat received during passing; Various types of fixing methods are known, including a hot plate type fixing method in which the toner image is melted and fixed by the heat from the heating plate, and a lamp type fixing method in which the toner image is melted and fixed by radiation from a heat-generating light source such as an infrared lamp. There is.

One of the heat fixing methods different from these is the flash fixing method.

This fixing method heat-fuses the toner by lighting a flash lamp and irradiating the flash light onto the toner image. Unlike the hot roller type fixing method, there is no shift on the recording paper or the recording paper is stained with toner. It does not get dirty, therefore double-sided copying is possible, there is no need for preheating time for the fixing device to operate properly, only the core is used for fixing, and maintenance of the fixing device is easy. It has many advantages compared to fixed methods.

Furthermore, this method has the advantage in terms of heating that, due to the nature of the emission spectrum of the flash, the toner image is effectively heated, but the portion of the recording paper where there is no toner image is hardly heated.

One form of flash type fixing device includes a franchise lamp and a reflecting mirror for irradiating the toner image with flash light emitted from the flash lamp, and a recording paper conveying means or guide along the recording paper path. A board is provided.

Prior to the flash, a large capacity capacitor is charged in synchronization with the recording operation, and when the toner image reaches a predetermined position on the fixing device, a trigger signal is given to discharge the capacitor, and the stored energy lights up the flash lamp to produce the flash. It is something that generates.

There are cases where the flash is done once, but since that requires a large amount of electricity and the device is large, it is usually not just one flash, but is repeated two to several times depending on the size of the recording paper, so that the entire recording paper is fixed. It has become.

The number of times the recording paper is emitted is determined according to the size of the recording paper, but in factory grids that use this type of fixing device, a method that detects the movement of the recording paper that is in the recording state is used to determine the number of times that the recording paper is in the recording state. We are hiring.

In this method, when a so-called jam phenomenon occurs in which the recording paper gets jammed in the middle of the conveyance path, light is emitted indefinitely, and there is a danger that the recording paper will reach an abnormally high temperature and smoke or catch fire.

Unlike some types of facsimile machines, electrophotographic copying machines feed recording paper of a specific size one sheet at a time, but when this system is adopted, the same problem still exists.

The invention was made in consideration of the shortcomings of the flash type fixing device, and when detecting the presence of recording paper and continuing to emit light, the maximum number of times of light emission can be set in advance, and the size of the recording paper can be adjusted. This problem was solved by setting the number of times of light emission in advance.

For this purpose, the VC of the present invention includes a means for counting the number of times the flash lamp emits light, a means for setting the number of times the flash lamp emits light, and a capacitor that is connected to the capacitor when the number of times the flash lamp is counted is equal to the set value. In a preferred embodiment, for example, the shape of the cassette is partially changed by using the recording paper storage capacity cent, so that the light emission number setting means can be selectively operated in relation to the size of the recording paper. It is preferable to adopt a method such as deforming it to correspond to the size of the recording paper.

According to the present invention, since the flash lamp emits light only a limited number of times for the same recording paper at the fixing position, even if a jam occurs, the recording paper will not reach an abnormally high temperature, smoke, or even catch fire. You can avoid the danger of

Furthermore, as a result, wasteful power consumption and shortening of the life of the capacitor can be prevented.

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of an electrophotographic copying apparatus employing a fixing device according to the present invention, together with a block diagram for the operation of the fixing device.

Around a rotating drum 1 having a photoreceptor 1a on its surface, there is a charging electrode 2 for uniformly charging the photoreceptor 1a, and a charging electrode 2 for uniformly charging the photoreceptor 1a, and a charging electrode 2 for directing reflected light from an original (not shown) to be copied onto the photoreceptor ft=1a. An exposure slit 3 for projecting the image, a developing device 4 for converting the electrostatic latent image formed on the photoreceptor 1a into a visible image, and a sheet feeding device 6 for feeding the visible image from a sheet feeding device 5. Recording paper p
Transfer pole 7 for transferring to
Separation claw 8 for separating from 1a and post-transfer recording paper 1a
A removing electrode 9 for removing charges remaining on the surface of the photoreceptor 1a and a cleaning device 10 for removing toner remaining on the surface of the photoreceptor 1a are sequentially arranged.

The recording paper p separated from the surface of the photoreceptor 1a is transferred to the conveying device 1.
1, the sheet is conveyed to a fixing device 12, where it is fixed, and the sheet is discharged onto a sheet discharge tray 14 by a sheet discharge roller 13.

The fixing device 12 is a flash-type fixing device consisting of a 7-run run lamp 12a and a reflector 12b placed behind it, and the capacitor is charged to cause the flash lamp 12a to emit light at the start of copying operation (when the copy button is turned ON). ), but in this embodiment, the recording paper detection device 15 disposed upstream of the fixing device 12 is configured to start in response to a detection signal when the recording paper detecting device 15 detects the leading edge of the recording paper. ing.

The recording paper detection device 15 consists of a light emitter 15a and a light receiver 15b placed at a position to receive this light.When this light is blocked by the passing of the recording paper, its electrical output changes, so it is detected that the recording paper is present. This is a light shielding type detection means that can detect.

This is a reflective type in which a light emitting element and a light receiving element are integrally provided in 75), and the presence of recording paper can be detected by the light emitted from the light emitting element being reflected by the recording paper and received by the light receiving element. Sensing means can also be used.

It is preferable that the recording paper detection device 15 is located immediately before the upstream side of the fixing device 12, but if the above-mentioned optical detection means is used, the strong flash from the flash lamp 12a of the fixing device will not hit either direct light or reflected light. It must be placed in such a position.

This is because when the detection device 15 is exposed to a flash of light, a light receiving element such as a phototransistor may be heated and deformed or damaged, or the presence or absence of recording paper may be incorrectly detected.

20 is a charging/discharging control circuit that starts charging the capacitor upon receiving a detection signal from the recording paper detection device 15 and then outputs a discharge start code after a predetermined time; 21 is a Franche lamp 1;
A power supply circuit for applying a high voltage between the electrodes of 2a, 22
23 is a trigger circuit for lighting the Fransch lamp 12a in response to a signal to discharge, and 23 is a setting circuit that determines the maximum number of times of light emission according to the size of the recording paper P. It is configured.

FIG. 2 shows a circuit for charging the capacitor C for causing the flash lamp 12a to emit light, and the charging/discharging control circuit 20 is shown by a broken line.

The recording paper detection device 15 includes a light emitting diode as a light emitter 15a and a phototransistor as a light receiver 15b, which are arranged opposite to each other across the recording paper path.

The charge/discharge control circuit 20 includes a waveform shaping circuit 20a that shapes the output waveform of the detection device 15, a flip-flop 20b that receives the output of the waveform shaping circuit 20a, and generates an output after a certain period of time after receiving the output of the flip-flop 20b. a timer 20c that generates a signal that drives the power supply circuit 21, an N-adic counter 20e that counts the number of times the Franche lamp 12a emits light, and a comparison that compares the charging voltage of the capacitor C with a set standard [direct]. Logic 0 only when inputs from the circuit 20f, flip-flop 20b, timer 20c, and comparator 2Of are all logic 1.
Nantes gate G1 that outputs , the initial reset circuit 20g, the output rotation of the timer 20c, and the N-adic counter 20
and an OR gate G2 which outputs logic 1 when any of the outputs of e is logic 1.

The initial reset circuit 20g is for keeping the flip-flop 20b in a re-cent state when the charge/discharge control circuit 20 is turned on.

Next, the present invention will be described with reference to FIG. 3, which shows the waveforms of the main parts of the circuit shown in FIG. The operation of such a fixing device will be explained.

Normally, in the flash type fixing method, the recording paper is divided into a plurality of areas in the direction of movement, and each area is fixed in sequence when the fixing position VC is reached, but in the embodiment described below, the recording paper P is divided into three areas P1 s. It is assumed that the image is divided into P2 y P3 K and fixed.

After the toner image is transferred onto the recording paper P in the transfer process, it is conveyed and approaches the fixing device 12 .

When the leading edge of the recording paper P reaches the first position of the detection device 15 as shown in FIG. It becomes conductive and its collector potential becomes high level H.

This high level detection signal is applied to the waveform shaping circuit 20a, where the waveform is shaped and applied to the cent terminal S of the flip-flop 20b.

As a result, the output level of the flip-flop 20b becomes a high level as shown in FIG. 3, and the output is given to the timer 20c and the Nant gate G1.

On the other hand, the timer 20c is set for a certain period of time T.

Since the logic O is generated at the Q terminal and the logic LQ terminal after , the detection device 15 detects the leading edge of the recording paper P at time t.

In this case, a logic 1 appears at the Q terminal.

Therefore, a high level input is given to the Nant gate G1 from the Q terminal.

Furthermore, at this point t.

Then, since capacitor C is not charged, comparator 20
Since the voltage at point A, which is obtained by dividing the terminal voltage of capacitor C applied to one input terminal of f by resistors R1 and R2, is smaller than the reference voltage determined by trimmer R3 applied to the other input terminal, the output terminal As shown in FIG. 3, a high level H output appears.

Therefore, all inputs of the NAND game G1 become logic 1, and a logic O appears at the output, so the power supply drive circuit 20d operates and sends a drive signal to the power supply circuit 21.

As a result, the power supply circuit 21 is closed and the capacitor C starts charging.

The charging characteristic of capacitor C is determined by a time constant determined by the capacitance of capacitor C and the resistance value of resistor R4.

Time T. If the terminal voltage of capacitor C reaches the voltage set by trimmer R3VC before
Since the output level of is low level LVC, Nantes Gate G
1 is closed and a logic 1 appears at its output, and as a result, the power supply drive circuit 20d stops the drive signal, so the power supply circuit 21 is opened.

Capacitor C is thus charged and maintains a specified charging voltage (usually several hundred volts).

During this time, the recording paper P is being advanced by the conveyance device 11.

After that, the leading edge of the recording paper P is detected at time t.

From time t. Press the button at the time t□ that has elapsed, and timer 2
0c inverts the output and sets the Q terminal to logic 1. Logic O on Q terminal
Output.

As a result, the trigger circuit 22 is driven, and the trigger circuit 2
A trigger signal is output from 2 and the Franch lamp 12a
Since the trigger voltage (TK) is applied to the trigger electrode of the capacitor CK, the charge accumulated in the capacitor CK is
The flash lamp 12a emits a flash of light between the two types i.

At this time, the recording paper P reaches the position shown in FIG. The image is fused and fixed onto the recording paper.

In this way, the fixing of the first area P1 of the recording paper P is completed.

As can be seen from the above explanation, the set time T of the timer 20c.

needs to be set so that it is equal to the time from when the leading edge of the recording paper P is detected by the detection device 15 until the first area p1 of the recording paper P reaches the fixing position, and this time is equal to the time required for the recording paper P to reach the fixing position. This can be easily determined from the conveyance speed and the distance from the detection device 15 to the most downstream end position of the fixing device 12.

The logic 1 appearing at the Q terminal of the timer 20c is added to the N-ary counter 20eK, counted as the number of times of light emission as 1, and also added to the OR gate 02, and the flip-flop 20
It is applied to the recent terminal R of b.

Since the flip-flop 20b is of the recent priority type, the input to the recent terminal R causes the output level to become low level L.

When the button is pressed at time t2, which is a further time T1 (the time from the end of discharging to the start of the next charging) after time t1, the output of the Q terminal of the timer 20c becomes zero again, so the - input terminal of the NAND game) G□ A logic 0 is applied to the flip-flop 20b, and a logic 0 is also applied to the recent terminal R of the flip-flop 20b via the OR gate G1.

As a result, a high level H output appears at the output terminal of the Noritsu flop 20b again.

This is because the recording paper P is in the middle of being conveyed and the output of the detection device 15 is at a high level HK.

Since the time T1 is an extremely short time of about 0.11, the distance the recording paper moves during this time is extremely small.

The operation after time t2 is the time t already described.

The subsequent operations are exactly the same.

That is, at time t2, the button is pressed, capacitor C starts charging, and charging is completed when the voltage at point A reaches the set voltage, and then from time t2 to time t.

At a later time t3, the trigger electrode T is energized by a trigger signal output from the trigger circuit 22, and the flash lamp 12a emits light.

At this time, the second area p2 of the recording paper P has reached the fixing device 12 as shown in FIG.
2 fixation is performed.

After that, charging starts again at time t4, and at time t5
At this point, a trigger signal is issued from the trigger circuit 22, the flash lamp 12a emits light, and the third area p3 is fixed by the flash light at that time.

In this way, the recording paper P lights up the flash lamp at the time jl.
By emitting light at t3 z j5, the area p1.
p2. p3 is fixed one after another to complete the entire fixing.

Since the trailing edge of the recording paper P finishes passing through the recording paper detection device 15 immediately before the fixing of the area p3 is completed, the output of the detection device 15 becomes a low level LK, and charging is not performed thereafter.

Note that the number of times the flash lamp 12a emits light is counted by the N-ary counter 20e, but the low level output of the detection device 15 caused by the detection of the trailing edge of the recording paper is added to the recent terminal RK of the N-ary counter 20e. The memory contents are cleared for each recording paper.

The above is a normal fixing operation, but next we will explain the fixing operation when a jam phenomenon occurs.

If a jam occurs just before the second area p2 is fixed, the recording paper P will stop at the position shown in FIG. 4, and the flash lamp 12a will emit light at time t3.

After that, since the detection device 15 outputs a high level H output indicating the passing state of the recording paper P, the rechargeable control circuit 20 operates in exactly the same way as the next fixing of the third area P3, so that the time t is reached.

The flash lamp 12a emits light and the second region P2 receives flash light again and is heated.

After that, the detection device 15 continues to output a high level H output, so the Franche lamp 12a emits light and flashes at regular intervals, but since the recording paper P remains stationary, the second area p2 flashes repeatedly. Since the receiver is heated, recording paper with a high image density will eventually smoke or catch fire.

Therefore, in this embodiment, the VC button is pressed by operating the maximum number of light emission setting circuit 23 prior to the copying operation to preset the maximum number of light emission times.

Specifically, depending on the size and paper quality of the recording paper P used, the maximum number of times of light emission is set by closing either switch Sw1.8w2 or 8w3, and the button is pressed to release the set maximum light emission. The number of times is stored in the N-ary counter 20e.

On the other hand, since the number of times the flash lamp 12a emits light is counted by the N-ary counter 20e, when the actual number of times the flash lamp 12a emits light matches the preset maximum number of times, the N-ary counter 20
An output signal is output from e and applied to the recent terminal RK of the flip-flop 7''20b via the OR gate G2.

As a result, the output of the flip-flop 20b becomes logic O, so the charge/discharge control circuit 20 becomes inactive, and the power supply circuit 21
The signal supplied to the button and trigger circuit 22 becomes zero, and the capacitor C is not charged or discharged at all.

Note that the N-ary counter 20e is reset when the recording paper is no longer at the detection position.

Therefore, since the flat lamp 12a does not emit light after the number of times it emits light reaches the set maximum number of times, it is possible to avoid the risk of the recording paper P becoming abnormally hot and emitting smoke or emitting light.

The maximum number of times of light emission may not be set selectively according to the size and quality of the recording paper, but may be set to a fixed value in consideration of the eruption temperature of the recording paper.

Next, the embodiment shown in FIG. 5 is another embodiment for preventing abnormally high temperature of the recording paper when a jam phenomenon occurs, as well as smoke and ignition. This is an example of setting.

For this purpose, a light emission number setting circuit 23' is provided in place of the circuit 23 in the embodiment of FIG. 2, and a switch SwI is provided.

It consists of 8w2 and 8w3 and is designed to be selectively closed depending on the size of the recording paper.

In a preferred embodiment, a cassette is used to load the recording paper, and by changing part of the shape of the cassette for each size, when each cassette is installed, one of the switches corresponding to the cassette, that is, the recording paper size is activated. Sw1
．． It is preferable to configure it so that 8w2 or 8w3 is closed.

The difference in configuration between this embodiment and the embodiment shown in FIG. 2 is that the output of the waveform shaping circuit 20a is not directly used to reset the N-ary counter 20e.
The only difference is that the output from the reset pulse generator 20h is put into the reset pulse generator 20h, and the reset pulse output from the reset pulse generator 20h is used, and the output from the Q terminal of the timer 20c is not applied to the OR gate G2VC. .

Therefore, the fixing operation is almost the same as the embodiment shown in FIG. 2, except that the 7-lip front knob 20h is not reset every time the timer 20c outputs, as can be seen from the waveform of the main part of the circuit shown in FIG. Since the only difference is in, the explanation will be omitted.

The present invention has been described above with reference to two embodiments. However, as in the present invention, by setting the maximum number of flash lamps to emit in advance or by setting the number of times to emit light in advance according to the size of the recording paper, Even when a jam phenomenon occurs, the flash lamp can stop emitting light after a predetermined number of times, so it is possible to prevent the recording paper from being abnormally overheated, and furthermore, from causing smoke or fire.

In the embodiment, the charging of the capacitor for the Franche lamp emission was developed based on the recording paper detection signal from the recording paper detection device provided immediately before the fixing device, but the fixing device of the present invention is of this type. Of course, the present invention can also be applied to a type in which charging of a capacitor is started by a copying operation start signal, and the same effect can be obtained.

[Brief explanation of drawings]

FIG. 1 of the accompanying drawings is a schematic configuration diagram of an electrophotographic copying apparatus employing a fixing device according to the present invention, FIG. 2 is a block diagram of an embodiment of the fixing device operating circuit, and FIG. 3 is a diagram of the same operating circuit. FIG. 4 is an explanatory diagram showing the fixing operation step by step. FIG. 5 is a block diagram of another embodiment of the fixing device operating circuit. FIG. 6 is a main part VC of the operating circuit. It is a button signal waveform diagram. 1... Rotating drum, 1a... Photoreceptor,
2...Charging electrode, 4...Developing device, 5...
...Paper feeder, 6...Paper feeder, 7...
...Transfer pole, 9...Removal electrode, 10...
・Cleaning device, 11... Conveyance device, 12
...Fixing device, 12a...Flash lamp, 12b...Reflector, 14...
・Paper discharge tray, 15...Recording paper detection device, 15a・
...Emitter, 15b...Receiver, 20.
...Charge/discharge control circuit, 20a...Waveform shaping circuit, 20b---Flip-flop, 20
c...Timer, 20d...Power supply drive circuit, 20e...N-ary counter, 20f...
... Comparator, 21 ... Power supply circuit, 22 ...
...Trigger circuit, 22a...Ring, 22
b1, 22b2... Magnet, 23... Setting circuit.

Claims (1)

[Scope of Claims] 1. A capacitor is filled in connection with a recording operation, and the charge accumulated in the capacitor is discharged after a predetermined period of time to cause a flash lamp to emit light, and the flash light from the flash lamp is transferred onto a recording paper. Means for setting the number of times the seven lash lamps emit light, and means for counting the number of times the seven lash lamps emit light, for a flash type fixing device that fuses the toner image and fixes it on a recording paper by irradiating the toner image.
A flash-type fixing device characterized in that the flash type fixing device includes means for preventing discharge of the capacitor when a counted value of the number of times of light emission becomes equal to a setting (UM). 2. The number of light emission setting means is related to the size of the recording paper. 3. The flash type fixing device according to claim 1, wherein the recording paper is stored in a cassette If, and the flashing number setting means is linked to the mounting of the cassette. 4. The flash type fixing device according to claim 2, wherein the flashing number setting means is a switch operated by a recording paper storage capacity center, and the flashing number counting means is a switch operated by a recording paper storage capacity cent. 3. The flash type fixing device according to claim 2, wherein the flash type fixing device is a kakunta activated by a lamp emission signal.