JPS63157182A - Image forming device - Google Patents

Abstract

PURPOSE:To quickly restore a temperature after jam release by constituting the titled device so that when a transfer jam, etc. are generated at the time of executing an image forming process by an image forming means, it is detected, and the temperature of a fixing device is lowered to the extent that transfer paper does not begin to burn. CONSTITUTION:In the inside of a body 12 of a printer 10, principal devices such as a toner hopper 33, a photosensitive drum 26, a feed paper cassette 20 for transferring transfer paper 36, a developing device 32, a fixing device 56, etc. are provided. Also, a first jam sensor 49, a second jam sensor 61, a stripping sensor 56, etc., are provided so as to be attached to them, and a jam is generated in the course of executing the process, and therefore, the internal temperature of the body 12 rises due to heating, an input of a heating roller 58 for heating the fixing device 56 is lowered by operating an I/O interface which is not shown in the figure. In such a way, the temperature in the body 12 at the time of a jam processing already falls, and after jam processing, its reoperation waiting time is shorten.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus, and in particular, an image forming apparatus that lowers the temperature of a fixing device when it detects that an abnormality such as a jam of transfer paper has occurred in a conveyance path. The present invention relates to an image forming apparatus.

(Prior art) For example, when a jam occurs, if the temperature of the fixing device is kept at the same temperature as when normal image forming process is being performed, the transfer paper stuck in the conveyance path will be burnt by the heat of the fixing device. , there was a danger that it would eventually flare up. Therefore, for example, in Japanese Patent Publication No. 44-8433, a copying machine is disclosed in which when a jam occurs, the power to the fixing device is cut off to lower the temperature of the fixing device. In the above-mentioned conventional technology, when a jam occurs, the power to the fixing device is immediately cut off, so if it takes time to clear the jam, the temperature of the fixing device will drop to near the room temperature where the copying machine is placed. It goes down to

Therefore, even if an attempt was made to resume copying after the jam was cleared, since the temperature had dropped, it would take a relatively long time to raise the temperature of the fixing device so that copying could be performed. Therefore, once a jam occurs, there is an inconvenience in that it is necessary to wait for a while after the jam is cleared.

Therefore, a main object of the present invention is to provide an image forming apparatus that can reduce the above-mentioned waiting time as much as possible.

(Means for Solving the Problems) To put it simply, the present invention provides an image forming means for executing an image forming process for ejecting a transfer paper onto which a toner image has been transferred, and a transfer paper ejected from the image forming means. A fixing device for thermally fixing the toner transferred to paper, an abnormality detection means for detecting an abnormality in the image forming process in the image forming means, and a temperature of the fixing device at a predetermined level in response to the output of the abnormality detection means. The image forming apparatus includes a temperature lowering means for lowering the temperature.

(Operation) When the image forming means executes the image forming process, if an abnormality occurs in the image forming process, such as a jam of the transfer paper in the transfer paper conveyance path, the abnormality is detected by the abnormality detection means. Then, the temperature lowering means lowers the temperature of the fixing device until the jam is cleared, for example to a low temperature that does not cause the transfer paper to burn out.

(Effects of the Invention) According to the present invention, the temperature of the fixing device is lowered to a predetermined temperature in response to the output of the abnormality detection means, so that abnormalities in the image forming process, such as jamming of transfer paper in the conveyance path, can be detected. When the above conditions are canceled, the temperature of the fixing device can be quickly raised to a high temperature at which fixing can be performed. Therefore, even if an abnormality occurs in the image forming process, once the abnormality is cleared, the image forming process can be restarted without waiting for a long time.

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

(Example) FIG. 2 is an illustrative cross-sectional view showing one embodiment of the present invention.

Although the present invention will be described below as applied to an optical printer, it should be noted in advance that the present invention can also be applied to other image forming apparatuses other than such printers, such as copying machines and facsimile machines. Let me point this out.

Printer 10 includes a main body 12 . At the top of the main body 12,
A cover 14 and a cover 16, which are divided into two at the center, are provided flush. The cover 14 is fixed to the main body 12 with screws. The cover 16 is provided so that it can be opened upward about the rotation shaft 18 when toner is replenished.

A paper feed section 22 is formed at one end of the main body 12 for removably mounting a paper feed cassette 20, and a paper discharge section 24 is formed at the other end for discharging the paper that has undergone the fixing process. It is formed.

A photosensitive drum 26 (its driving mechanism is not shown) is arranged approximately in the center of the main body 12 and rotates in the direction of the arrow (clockwise). The photoreceptor material of this photoreceptor drum 26 includes:
Amorphous selenium is used.

A light emitting diode (L E
D) A head 28 is provided. The LED head 28 is
For example, it includes an LED array that includes a red element with an emission wavelength of λ-660 nm and is provided in parallel along the length direction of the photoreceptor drum 26 . Further, a short focal length lens such as a Cellhox lens is inserted between the LED array and the photosensitive drum 26. Therefore, the LED
The head 2 normally selectively drives the LED elements of the LED array according to the given print data, and the light from the LED elements is focused by a lens system and irradiated onto the surface of the photoreceptor drum 26. .

A charging corotron 30 is fixedly provided upstream of the LED head 28 in the rotational direction of the photoreceptor drum 26 to uniformly charge the photoreceptor drum 26 positively, for example to about 600 volts. This charging corotron 30
After being positively charged, when light is irradiated from the LED head 28, an electrostatic latent image corresponding to print data is formed on the surface of the photoreceptor drum 26.

A developing device 32 for developing the electrostatic latent image with toner is provided downstream of the LED head 28 . A toner hopper 33 for storing toner is connected above the developing device rIt32. The developing device 32 is supplied with toner from a toner hopper 33 and stores a developer made of a mixture of toner and carrier. This developer is transferred toward the photosensitive drum 26 by the magnet roller 34. At this time, a magnetic brush of the developer, that is, a spike is formed on the portion of the magnet roller 34 that faces the photoreceptor drum 26 . When the spikes come into contact with the photoreceptor drum 26, the negatively charged toner is attracted to the electrostatic latent image formed by the positively charged toner. In this way, the electrostatic latent image formed on the photoreceptor drum 26 is developed as a toner image by the developing device 32.

(a paper feed cassette removably attached to one end of the main body 12)
Transfer paper 36 is placed in a stacked manner within the transfer paper 20 . A support plate 38 on which a transfer paper 36 is placed is provided at the bottom of the paper feed center 20 so as to be swingable in the vertical direction. An opening 40 is formed in the lower part of the support plate 38 . The upper part of the push-up lever 42, whose base end is swingably attached to the internal part of the main body 12, is inserted into the opening 40. In relation to this push-up lever 42, the support plate 3
A spring (not shown) is provided for biasing rotation of 8 clockwise. The support plate 38 supports this push-up lever 42
is pushed upward by. Therefore, the transfer sheets 36 stacked in the paper feed cassette 20 are pushed up by the push-up lever 42, and the uppermost transfer sheet 36 comes into contact with the paper feed roller 44 and is taken in. A paper size detector 46 for detecting the size of the transfer paper 36 stored in relation to the paper feed cassette 20 is provided at a portion corresponding to the leading end of the attached paper feed cassette 20.

A register roller 48 is provided behind the paper feed roller 44 . The paper feed cassette is moved by this register roller 48)
The transfer paper 36 fed from the transfer paper 20 is temporarily stopped, and is fed toward the photosensitive drum 26 in synchronization with the exposure by the LED head 28. A transfer corotron 50 for transferring the toner image developed by the developing device 32 onto the transfer paper 36 is located near the circumferential side of the photosensitive drum 26 at a position where the transfer paper 36 is supplied from the register roller 48. provided. A first jam sensor 49 is provided on the conveyance path between the register roller 48 and the transfer corotron 50. Although not shown, the first jam sensor 49 includes, for example, a light emitting element for irradiating light onto the transfer paper 36 passing directly above it, a light receiving element for receiving light reflected by the transfer paper 36, and the like. Therefore, if the light reflected from the transfer paper 36 is not received by the light receiving element of the first jam sensor 49 after a predetermined period of time after the registration roller 48 is turned on, the registration roller 48 and the first jam sensor 49
A jam occurred between the two.

The transfer corotron 50 is integrally provided with a separation corotron 52. The separation corotron 52 is used to separate the transfer paper 36, which is attracted by residual charges, from the photoreceptor drum 26 by applying alternating current discharge to neutralize the charges.

On the downstream side of the separating corotron 52, there is a vacuum conveyor 5 for conveying the transfer paper 36 onto which the toner image has been transferred.
4 is provided. The transfer paper 36 is conveyed toward the fixing device 56 by the vacuum conveyor 54 . The photosensitive drum 2 is located downstream of the separating corotron 52 and above the vacuum conveyor 54.
A peeling sensor 53 is provided near the circumferential side of 6 . Like the first jam sensor 49, this peel sensor 53 also includes a light emitting element and a light receiving element. This peeling sensor 53 is for detecting whether the transfer paper 36 has been peeled off from the surface of the photosensitive drum 26 by the separating corotron 52. In other words, if the transfer paper 36 is not peeled off even after passing through the separating corotron 52, the transfer paper 36 is not conveyed to the vacuum conveyor 54 and the photosensitive drum 26
The photoreceptor drum 26 is transferred upward as the photoreceptor drum 26 rotates while being adsorbed to the surface. In this way, if the transfer paper 36 is transferred upward, the light receiving element of the peeling sensor 53 receives the reflected light from the transfer paper 36.

The fixing device 56 includes a heating roller 58 having a built-in heater, and a pressure roller 60 that is pressed against the heating roller 58. The transfer paper 36 on which the toner image has been transferred is inserted between the heating roller 58 and the pressure roller 60, and is heated and pressurized to fix the toner image. On the downstream side of the fixing device 56, a paper discharge roller 62 is provided for discharging the fixed transfer paper 36 to the outside. A second jam sensor 61 is provided on the conveyance path between the heating roller 58, the pressure roller 60, and the discharge roller 62. This second jam sensor 61 also
Like the jam sensor 49 and the peel sensor 53, it includes a light emitting element and a light receiving element. The second jam sensor 61 includes a separating corotron 52, a heating roller 58, and a pressure roller 6.
This is to detect whether a jam has occurred on the conveyance path between 0 and 0. That is, the transfer paper 36 is separated by the separating corotron 5.
2, if the reflected light from the transfer paper 36 is not received by the light receiving element of the peeling sensor 53 after a predetermined period of time,
The transfer paper 36 is peeled off by a separating corotron 52,
This means that it has been conveyed to the vacuum conveyor 54. Thereafter, if no reflected light is detected by the light receiving element of the second jam sensor 61 after a certain period of time, it is detected that the transfer paper 36 has jammed on the vacuum conveyor 54 or in the fixing device 56 .

A cleaning device 64 is provided above the vacuum conveyor 54 and near the circumferential side of the photoreceptor drum 26 . This cleaning device 64 cleans the transfer paper 36
Toner remaining on the photosensitive drum 26 without being transferred is removed. The cleaning device 64 includes a blade 66 for scraping off residual toner on the photoreceptor drum 26 and a screw conveyor 68 for conveying the toner scraped off by the blade 66 to a waste toner container.

An erase lamp 70 is provided on the upstream side of the cleaning device 64 to remove residual charges on the surface of the photoreceptor drum 26 from which residual toner has been removed. The erase lamp 70 uses blue light, for example, with wavelength λ=
A fluorescent glow lamp producing 450 nm light is used.

A main motor 72 for driving the photosensitive drum 26, the magnet roller 34 of the developing device 32, and the like is provided above the fixing device 56.

The photosensitive drum 26 and the magnet roller 34 are driven by a main motor 72 through a belt or chain.

A control box 74 is provided above the main motor 72. A control section for controlling the overall operation of the printer is provided within the control box 74.

FIG. 1 is a circuit diagram showing one embodiment of the present invention. This printer is controlled by a microcomputer (not shown), and commands from the microcomputer are I1
0 interface 76, and the I10 ink face 76 also provides the following various sensor signals to the microcomputer.

The output of the abnormality detection circuit 78 is applied to the input port (1) of the I10 interface 76. The abnormality detection circuit 78 is a circuit for detecting an abnormality that can be easily recovered by an operator without the need of a specialized service person. Therefore, the abnormality detection circuit 78 includes, for example, a jam detection circuit 78a, a) toner shortage detection circuit 78b, and a waste toner container full detection circuit 78c.

The jam detection circuit 78a includes the first jam sensor 49. shown in FIG. Peeling sensor 53 and second jam sensor 61
The occurrence of a jam on the conveyance path is detected in response to a signal from the conveyance path.

The toner shortage detection circuit 78b detects that the toner stored in the toner hopper 33 of the developing device is empty.

The waste toner container full detection circuit 78c detects that a waste toner container (not shown) is full of waste toner. That is, the residual toner after the transfer is scraped off from the surface of the photoreceptor drum 26 by the blade 66, conveyed by the screw conveyor 68 in a direction perpendicular to the paper surface, and collected as waste toner in a waste toner container (not shown). The waste toner container full detection circuit 78c detects that the waste toner container is full.

When there is an output from any of the jam detection circuit 78a, toner shortage detection circuit 78b, and waste toner container full detection circuit 78c, the output of the abnormality detection circuit 78 changes from high level to low level. In addition, in the embodiment, the abnormality detection circuit 7
8 detects abnormalities in the image forming process such as jam, out of toner, and fullness of the waste toner container, but other abnormalities may be detected as necessary.

The heating roller 58 shown in FIG. 2 has a built-in heater 58a shown in FIG.
8a. A thermal fuse 80 and a non-contact relay 82 are connected in series to the heater 58a, and an alternating current voltage AC is applied thereto. The non-contact relay 82 is composed of a bidirectional control element such as a triac, for example. This non-contact relay 82 is connected to the gate control circuit 8
The alternating current voltage AC applied to the heater 58a is controlled to be turned on or off (conducted or cut off) by the gate voltage applied from the heater 58a.

The temperature of the heating roller 58 heated by the heater 58a is detected by the thermistor 86.

Since the resistance value of the thermistor 86 changes depending on the temperature, the temperature of the heating roller 88 can be determined from the partial pressure value of a resistor connected in series with the thermistor 86, which will be described later.

The (+) terminal of comparator 88 has resistors 90.92 and 9
One end of 4 is commonly connected. A DC voltage is applied to the other end of the resistor 90, and the other end of the resistor 92 is grounded. The resistors 90 and 92 provide a divided voltage value of the DC voltage to the (+) terminal of the comparator 88 as a reference voltage. That is, this partial pressure value sets the upper limit temperature of the heating roller 58 heated by the heater 58a to, for example, 185° C. in a steady state.

The other end of the resistor 94 is connected to the anode of a diode 96 whose cathode is connected to the output terminal 0. of the I10 interface 76. connected to. The resistor 94 is
When the abnormality detection circuit 78 detects an abnormality, that is, when the diode 96 is turned on, a divided voltage value is applied to the (+) terminal of the comparator 88 by the cooperation of the resistors 90 and 92. This partial pressure value is determined by the heating roller 5 heated by the heater 58a when the abnormality detection circuit 78 detects an abnormality.
The upper limit temperature of No. 8 is set to, for example, 80°C.

One ends of resistors 98 and 100 are commonly connected to the (-) terminal of comparator 88 . The other end of the resistor 98 is connected to the other terminal of a variable resistor 102 whose one terminal is grounded. Note that the slider of this variable resistor 102 is connected to the grounded terminal side. This slider sets the lower limit temperature of the heating roller 58 to, for example, 180° C. in a steady state.
In addition, when a jam occurs, the heating roller 5
This is to set the lower limit temperature of No. 8 to 75°C. The other end of the resistor 100 is connected to the other end of a thermistor 86 to which a DC voltage is applied at all ends. Therefore, the (-) terminal of the comparator 88 is connected to the thermistor 86. resistance 100
．． A voltage divided by the resistor 98 and the variable resistor 102, that is, a voltage across the resistor 98 and the variable resistor 102 is applied. Since the resistance value of the thermistor 86 changes depending on the temperature, when the temperature of the heating roller 98 falls and the resistance value decreases, the partial pressure value applied to the (-) terminal of the comparator 88 increases. That is, the comparator 88 is (+)
the reference voltage applied to the terminals, i.e. resistors 90 and 92;
Alternatively, the voltage divided by 94 and the voltage applied to the (-) terminal are compared. When the voltage applied to the (-) terminal becomes larger, the output terminal becomes "H". Two resistors 1 connected to the (+) terminal of the comparator 88
01 and 103 are for providing a hysteresis characteristic, that is, a dead zone in this comparator 88.

A capacitor 106 whose one end is grounded and the base of an NPN transistor 108 are connected to the output terminal of the comparator 88 via a resistor 104. transistor 1
The emitter of 08 is grounded, and the collector is connected to the input terminal 2 of the I10 interface 76 and also to the input terminal of the gate control circuit 84. The gate control circuit 84 outputs a gate voltage for turning on the non-contact relay 82 only when the transistor 108 is in the off state, that is, only when "H" is supplied to the input terminal.

In operation, when the abnormality detection circuit 78 shown in FIG. 1 detects an abnormality, the input terminal I of the ■/○ interface 76
, becomes "L". For example, when the jam detection circuit 78a detects a jam, that is, the first jam sensor 49 shown in FIG. The light receiving element of either the peeling sensor 53 or the second jam sensor 61 detects that the transfer paper 36 is removed after a predetermined period of time.
When no reflected light is detected, transfer paper 3 is placed on the transport path.
6 jam is occurring. Then, the output terminal of the abnormality detection circuit 78 switches from "H" to "L".

When the output terminal of the abnormality detection circuit 78 becomes “L”, I10
Since "L" is applied to the input terminal (2) of the interface 76, the output terminal OI becomes "L" accordingly. Therefore, the diode 96 is turned on, and the (+) terminal of the comparator 88 is given a divided voltage of the DC voltage by the cooperation of the resistors 90.degree. 92 and 94 as a reference voltage. This reference voltage is used to maintain the upper limit temperature of the heating roller 58 at, for example, 80°C. When the reference voltage applied to the (+) terminal of the comparator 88 decreases, the voltage applied to the (-) terminal remains unchanged (that is, even if there is no abnormal temperature rise of the heating roller 58, the output of the comparator 88 does not change). The terminal becomes H''.

When the output terminal of the comparator 88 becomes "H", the capacitor 1
Since the gate voltage is established by charging 06, transistor 108 turns on. When the transistor 108 is turned on, "L" is applied to the input terminal I2 of the I10 interface 76 and the input terminal of the gate control circuit 84. “ to the input terminal I2 of the I10 interface 76
When "L" is applied, it is input to the microcomputer connected to the I/○ interface 76 that a jam has occurred.

On the other hand, when "L" is applied to the gate control circuit 84, the gate control circuit 84 stops supplying the gate voltage.
Non-contact relay 82 is turned off. Therefore, even if the jam is left as it is, the temperature of the heating roller 58 will be 8.
Since the temperature can be lowered to 0° C., the transfer paper will not be scorched by the heat of the heating roller 58 and will not catch fire. In other words, it is safe even when a jam occurs.

When the jam is cleared by the operator, the signal generated from the jam detection circuit 78a is cleared, so the output of the abnormality detection circuit 78 returns to "H". Then, I
The output terminal 01 of the 10 interface 76 also becomes "H", and the (+) terminal of the comparator 88 is given a predetermined partial pressure value, that is, a reference voltage necessary to heat the heating roller 58 to 185.degree. Then, the output terminal of the comparator 88 becomes "L" and the transistor 108 is turned off again. When the transistor 10B is turned off, "H" is applied to the gate control circuit 84, so that the gate voltage for turning on the non-contact relays 7-82 is output from the output of the gate control circuit 84. Therefore, heating roller 5
The temperature at No. 8 is raised again to around 185° C. where fixing can be performed.

That is, as shown in FIG. 3, if a jam occurs at time 1, for example, the temperature of the fixing device 56, that is, the temperature of the heating roller 58, is lowered from around 185°C to around 80°C; The temperature around ℃ remains constant until the jam is released. Since this temperature of around 80° C. does not cause the transfer paper 36 to burn, it is safe even if the jam is left for a long time.

Therefore, when the jam is cleared at time t2, the temperature of the heating roller 58 is raised again to 185°C. Then, at time t, the temperature of the heating roller 58 reaches 185°C.

In the conventional apparatus such as the above-mentioned Japanese Patent Publication No. 44-8433, if a jam occurs at time t, the heater is not fully energized from then on. The temperature continues to drop to room temperature, 25°C, as shown by the dotted line. Even if the jam is cleared at time t2, since the temperature of the fixing device has dropped considerably, it will not be possible to print out until time t4. In comparison, in the device of the embodiment, even if a jam occurs, the temperature of the heating roller 58 is maintained at around 80°C, so when the jam is cleared at time t2,
Printout becomes possible at time t3. That is,
In the device of the example, time 1 = 14-1. The time required to print out can be shortened by J minutes.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention. FIG. 2 is a structural diagram of this embodiment. FIG. 3 is a timing chart for comparing and explaining the operation of this embodiment and the conventional operation. In the figure, 26 is a photosensitive drum, 33 is a toner hopper, 49 is a first jam sensor, 53 is a peeling sensor, 58 is a heating roller, 58a is a heater, 61 is a second jam sensor, 66 is a blade, 68 is a screw conveyor, and 76 is a I10 interface, 78 is an abnormality detection circuit, 82 is a non-contact relay, 84 is a gate control circuit, 86 is a thermistor, and 88 is a comparator. Patent applicant Sanyo Electric Co., Ltd. agent Patent attorney Yama 1) Yoshito (1 idiot) Figure 2 W Hanging 31

Claims (1)

[Scope of Claims] 1. An image forming means for executing an image forming process for discharging a transfer paper onto which a toner image has been transferred, and thermally fixing the toner transferred to the transfer paper discharged from the image forming means. a fixing device, an abnormality detection means for detecting an abnormality in the image forming process in the image forming means, and a temperature drop for lowering the temperature of the fixing device to a predetermined temperature in response to the output of the abnormality detection means. have the means,
Image forming device. 2. The image forming means includes toner developing means for developing the electrostatic latent image formed on the photoreceptor with toner, and the abnormality detecting means includes means for detecting toner shortage in the toner developing means. Claim 1
The image forming apparatus described in Section 1. 3. The image forming means includes a transfer paper conveyance means for conveying the transfer paper along a predetermined path, and the abnormality detection means detects a jam of the transfer paper in the transfer paper conveyance path by the transfer paper conveyance means. An image forming apparatus according to claim 1 or 2, comprising means for:. 4. The image forming means includes a cleaning means for removing waste toner from the photoreceptor after transferring the developed toner image onto the transfer paper, and a waste toner container for storing the waste toner removed by the cleaning means. 4. The image forming apparatus according to claim 1, wherein the abnormality detection means includes means for detecting whether the waste toner container is full. 5. Claims in which the temperature lowering means includes a setting means for setting a temperature lower than the normal fixing temperature, and a holding means for maintaining the temperature of the fixing device near the temperature set by the setting means. The image forming apparatus according to any one of items 1 to 4. 6. Claim 5, wherein the holding means includes means for stopping heating of the fixing device when the temperature exceeds the set temperature, and heating the fixing device when the temperature falls below the set temperature. The imaging device described.