JPH09297521A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical image forming device capable of surely cooling an optical system even in the case of not using an optical system cooling fan or using a cooling fan with low cooling ability. SOLUTION: As for the optical system 2 with a light source 6 for irradiating and scanning an original 4 and the image forming device for performing a cooling operation of cooling the optical system under a prescribed condition, the light source 6 is stopped at a prescribed cooling position D at the cooling operation time, and a ventilating fan 40 for ventilating in the machine is operated at a high speed, and the fixation temperature of a fixing device 19 for fixing an image is changed to a prescribed temperature required at the cooling operation time. That is, since the light source is stopped at the cooling position D separated from a home position B at the cooling operation time, the temperature at the home position is prevented from increasing, and since the ventilating fan is operated at the high speed, the ventilation inside the machine is accelerated, and since the fixing temperature of the fixing device is changed to the prescribed temperature required at the cooling operation time, the temperature rise of the optical system due to the thermal influence of the fixing device is prevented, and the optical system is surely cooled without installing the optical system cooling fan.

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 using electrophotography such as a copying machine, and more particularly to an image forming apparatus characterized by temperature rise prevention control of an optical system.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic technique such as an analog copying machine, a light source of an optical system irradiates and scans an original, and reflected light from the original is passed through a mirror or a lens. The photosensitive member charged by the charger is exposed to form an electrostatic latent image on the photosensitive member, and the electrostatic latent image is developed by the toner of the developing device to form a visible image, which is exposed at the transfer section. The toner image on the body is transferred to a transfer material, and the transferred image is fixed on the transfer material by a fixing device to form a copy image.

In such an image forming apparatus using the conventional electrophotographic technique, a halogen lamp or the like is generally used as a light source for illuminating the original. Halogen lamps are small and can produce a large amount of light, but they are not efficient and generate a lot of heat. For this reason, in order to cool the optical system that normally rises in temperature due to the heat generation of the light source, a cooling fan is provided to control the operation thereof and to control the lighting of the light source to prevent the temperature rise of the optical system. .

Here, as a conventional technique for preventing the temperature rise of the optical system in an image forming apparatus such as an analog copying machine or a document reading apparatus in a digital copying machine, for example,
A temperature detecting means for detecting the temperature of the document placing table, such as the "document placing table temperature rise control device" described in JP-A-61-219967, suspends the exposure lamp during a continuous copying cycle at a predetermined temperature or higher. A device provided with a cycle, such as an "image reading device" described in JP-A-63-172560, drives a cooling fan in synchronism with lighting of a light source of an optical scanning system and selects a document reading mode (sheet reading). , Book), which includes drive control means for variably controlling the drive end time of the cooling fan, like the "exposure scanning device" described in Japanese Patent Application Laid-Open No. 1-179031. And a means for controlling the wind force of the cooling fan is provided.
A device for controlling the cooling fan by calculating the lighting and extinguishing times of the light source and the temperature change of the fixing roller, as in "cooling control device for original reading device" described in Japanese Patent No. 333627.
There is a device such as a "digital copying machine" described in Japanese Patent Publication No. 54099, in which a light source stop position is near a fixing device and both are cooled by a single cooling fan.

[0005]

In the conventional image forming apparatus using the electrophotographic technique, the optical system whose temperature rises due to the heat generated from the light source such as the halogen lamp is cooled by the cooling fan or the like. However, since this type of cooling fan cools the optical system by taking in outside air, dust and dirt from the outside of the machine are taken into the optical system, causing contamination of optical components such as lenses and mirrors. Is known to exist. In addition, the cooling capacity of the cooling fan is set assuming the worst value for safety even in the image forming apparatus which is assumed to be used with a low duty. As a result, particularly in an image forming apparatus that is supposed to be used with a low duty, the operation of the cooling fan often suffers from optical system contamination, noise, and cost increase. Further, this type of image forming apparatus is often required to be maintenance-free, and contamination of the optical system poses a serious problem.

Therefore, the applicant of the present invention has previously proposed that the cooling fan of the optical system of the copying machine should be abolished or replaced with a small fan while ensuring sufficient operability in use. An image forming apparatus having a configuration in which a cooling mode is provided in which the light source is moved to a cooling position when the temperature rises to perform cooling, and further, in the cooling mode, an outside air intake section for taking in outside air is provided in the cooling position for cooling the light source. Proposed (Japanese Patent Laid-Open No. 7-261636). However, in actual use, the technique described in the above publication often does not provide sufficient effect, and a technique such as the present invention described later is required.

The present invention has been made in view of the above circumstances, and it is possible to reliably cool the optical system while eliminating the optical system cooling fan or using a cooling fan having a low cooling capacity. An image forming apparatus is provided. More specifically, the problems to be solved by the invention of each claim are as follows.

According to the first aspect of the present invention, by stopping the light source, which is the heat source, at a position away from the home position, the temperature rise at the home position is prevented, and the exhaust fan is operated at a high speed to remove the waste heat inside the machine. It is an object (objective) to accelerate the temperature drop of the optical system by shortening the time required for the cooling operation by urging the optical system to prevent the temperature rise of the optical system under the influence of heat from the fixing device.

According to the second aspect of the invention, the cooling operation is divided according to the temperature of the optical system so that the operability in actual use due to the cooling operation is not impaired as much as possible.

According to the third aspect of the present invention, the first cooling operation for cooling while forming an image and the second cooling operation for stopping the image formation and cooling the temperature of the optical system are separated according to the temperature of the optical system. Therefore, it is an object (purpose) to reduce the frequency of downtime during actual use.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 has an optical system having a light source for irradiating and scanning an original, and a cooling operation for cooling the optical system under a predetermined condition. In the image forming apparatus for performing the cooling operation, the light source is stopped at a predetermined cooling position during the cooling operation, the exhaust fan for exhausting air inside the machine is operated at high speed, and the fixing temperature of the fixing device for performing the image fixing is set for the cooling operation. The temperature is changed to a predetermined temperature. That is, during the cooling operation, the light source, which is the heat source, is stopped at the cooling position away from the home position, so that the temperature rise at the home position is prevented, and the exhaust fan operates at high speed to promote the waste heat inside the machine. ,Also,
Since the fixing temperature of the fixing device is also changed to the predetermined temperature for the cooling operation, it is possible to prevent the temperature of the optical system from rising due to the heat of the fixing device.

According to a second aspect of the present invention, an optical system having a light source for irradiating and scanning an original and an image forming apparatus for performing a cooling operation for cooling the optical system under a predetermined condition have a plurality of cooling operations. Then, one of the plurality of cooling operations is selected and executed according to the temperature of the optical system. That is, by dividing the cooling operation according to the temperature of the optical system,
It is possible to prevent the cooling operation from impairing the operability during actual use.

According to a third aspect of the present invention, there is provided an optical system having a light source for irradiating and scanning an original, and an image forming apparatus for performing a cooling operation for cooling the optical system under a predetermined condition. , A first cooling operation for continuing the image formation and a second cooling operation for prohibiting the image formation, and the second cooling operation is performed based on the first optical system temperature at which the first cooling operation is performed. The temperature of the second optical system for the cooling operation is set high. Ie. Downtime in actual use due to the separation of the first cooling operation that cools the image while forming an image and the second cooling operation that stops the image formation and cools the temperature of the optical system depending on the temperature of the optical system. It is possible to reduce the occurrence frequency of.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a schematic configuration diagram of a copying machine showing an example of an image forming apparatus using an electrophotographic technique in which the present invention is implemented. This copying machine 1 has a light source 6 for illuminating and scanning a document 4.
The optical system 2 having In FIG. 1, a contact glass 3 is provided on the upper surface of the optical system 2, and an original 4 is placed on the contact glass 3. A pressure plate or an automatic document feeder (ADF) is usually provided on the contact glass 3 of the copying machine 1, but the illustration is omitted.

When the image forming operation is executed, the exposure lamp 6 which is the light source of the optical system 2 moves along the lower surface of the contact glass 3 and scans the original 4 while irradiating it. Then, the light emitted by the exposure lamp 6 is reflected by the original 4 and guided to the photoconductor 12 via the mirrors 7a to 7f and the lens 8, and is exposed to the photoconductor 12 charged by the charger 9 to be statically charged. Form a latent image. This electrostatic latent image is developed by the toner in the developing device 14 and is visualized. And this visible image (toner image) is
Transferred by the transfer device 15 onto the transfer paper fed from the paper feed tray 18 and conveyed through the conveyance roller and the registration roller. The transfer sheet onto which the toner image has been transferred is conveyed to the fixing device 19, the toner image is fixed by the fixing roller 19a and the pressure roller 19b of the fixing device 19, and the sheet is discharged onto the discharge tray. On the other hand, the photoconductor 12 after transfer is cleaned of residual toner by the cleaning device 10, and the static eliminator 11 is removed.
Is discharged by.

The air in the machine heated by the fixing device 19 or the like during the image forming operation or during the standby is exhausted by the exhaust fan 40.
Is sucked out of the machine and prevents the temperature inside the machine from rising. Further, the optical cooling fan 21 takes in outside air from the outside air intake port 26 or 26 ′ and cools the optical system 2. The optical cooling fan 21 may be unnecessary in some embodiments of the present invention.

FIG. 2 shows the optical system 2 as a contact glass 3
2 is a plan view when viewed from above, and an irradiation range of the exposure lamp 6 is indicated by A. FIG. The temperature detecting element 5 for detecting the temperature of the optical system 2 is placed outside the irradiation range (A range) of the exposure lamp 6. The normal stop position of the exposure lamp 6 is the B position, which is called the scanner home position. At the time of document exposure, the exposure lamp 6 starts to be turned on at this position B so that the light amount rises to a constant level before the exposure of the front edge of the document.
After the scanning is completed, it is returned to this B position. For this reason, the irradiation time for exposure is long, and the temperature near the scanner home position (position B) where the heated portion is stopped even after the light is turned off is sharply increased.

Further, as is apparent from FIG. 1, this B position portion is a portion affected by the heat of the fixing device 19. That is, the fixing roller 19a of the fixing device 19 is controlled by the built-in fixing heater 42 so as to always have a high temperature of 185 ° C., and a part of the heat is fixed.
Will heat the optical system 2 on the upper part of. In particular, immediately after the end of copying, the fixing roller 19a stops rotating, and the transfer paper, which is a factor of depriving heat, has just passed, so that there is an excessive supply of heat, and the temperature tends to rise above the normal temperature. By the time, the temperature in the vicinity of the fixing device (particularly, the optical system at the home position above the fixing device) tends to rise. Therefore, it is necessary to perform a cooling operation for cooling the optical system 2 under a predetermined condition.

Next, the cooling operation will be described. 1 and 2
The copying machine 1 having the configuration shown in FIG. 1 includes control means as shown in FIG. This control means has a temperature detecting element 5 of the optical system 2, a fixing temperature detecting element 41 of the fixing device 19, and a function of converting an analog signal of them into a digital signal.
A central processing unit (CPU) 33 that performs overall control, a scanner motor 34 that performs scanning driving of the exposure lamp 6 and mirrors of the optical system 2 and its drive circuit 35, a lighting circuit 36 of the exposure lamp 6, and a fixing device 19 are heated. Fixing heater 42 and its driving circuit 43, and an exhaust fan 4 for exhausting the air inside the machine.
0, its drive circuit 44, the optical cooling fan 21 for cooling the optical system 2, its drive circuit 37, and the like. As will be described later, there is an embodiment in which the optical cooling fan 21 for cooling the optical system and the drive circuit 37 are not required.

The above components of the control means are controlled by a program (and control data) stored in a memory (ROM, RAM) not shown. First, claim 1
4, an embodiment of the control operation of the copying machine according to the invention of FIG.
A description will be given based on the flowcharts of the control programs shown in 5 and 6.

FIG. 4 is a flow chart of a program for cooling the optical system. When the optical system cooling operation program is executed, the CPU 33 monitors (detects) the output of the optical system temperature detecting element 5 and determines whether the temperature of the optical system 2 exceeds the predetermined value Topt0. If it is equal to or higher than Topt0, the optical system cooling operation is started. In the optical cooling operation, first, a new image forming operation is prohibited, and the completion of the current image forming operation is awaited. Then, when all the image forming operations are completed, the exposure lamp 6 is moved to the position D in FIGS. Further, a heater-off command is issued to the fixing temperature control to instruct the exhaust fan control unit to operate at high speed. Then, the output of the optical system temperature detecting element 5 is monitored (detected) again, and it is determined whether the temperature of the optical system 2 has become equal to or lower than a predetermined value Topt1 (≤ Topt0). Then, when it becomes equal to or lower than Topt1, the optical system cooling operation is ended.

During the above-described optical system cooling operation, the exposure lamp 6 is moved to the position D in FIGS. 1 and 2, and this position D is the maximum position for scanning the original, and the copying machine of this embodiment is used. Will be B4 size. On the other hand, the maximum manuscript size is legal size (8.5 x 1
It is 4 inches), and it does not scan to the position of D at the same size copying. There is a possibility to scan to the maximum position only when reducing. Therefore, since it is unlikely that the temperature at this position has risen due to the exposure irradiation, the cooling effect is significantly greater than the normal scanner home position (position B). Further, since the image forming operation is prohibited during the cooling operation of the optical system, it is not necessary to keep the fixing device 19 in a fixable state.
Therefore, there is no problem even if the fixing control temperature is significantly lowered or the heating is stopped. As a result, the temperature rise near the scanner home position due to the heat of the fixing device 19 is reduced. Further, by operating the exhaust fan 40 at a high speed to enhance the exhaust effect, cooling inside the machine can be promoted, and the cooling effect of the optical system can be further enhanced. The optical cooling fan 21 is not necessary for this cooling operation.

FIG. 5 is a flow chart of a program for controlling the temperature of the fixing device. The CPU 33 monitors (detects) the output of the fixing temperature detecting element 41 of the fixing device 19, compares it with the fixing control temperature Tfuser, and controls the fixing heater drive circuit 43 based on the result and controls the lighting of the fixing heater 42.
The control method includes on-off control in which the fixing heater 42 is turned off when the temperature is higher than the fixing control temperature Tfuser, and is turned on when the temperature is lower than the fixing control temperature Tfuser, and the fixing heater 42 is turned on in accordance with the difference between the fixing control temperature Tfuser and the current temperature. There is a control to change the lighting time, but the former example is briefly given here. The fixing control temperature Tfuser is instructed from other parts including the program of FIG. Therefore, the fixing temperature can be changed by the control instruction of FIG. If there is an instruction to turn off the fixing heater according to the control program shown in FIG.
The fixing heater 42 is turned off.

FIG. 6 is a flow chart of a program for controlling the operation of the exhaust fan. Normally, the control of the exhaust fan 40 is performed at high speed during image formation to enhance the cooling and exhaust effect inside the machine, and because the temperature inside the machine is small during standby, it is operated at low speed to reduce noise due to rotation of the exhaust fan. There is. The low speed operation is realized by dropping the voltage applied from the exhaust fan drive circuit 44 to the exhaust fan 40 by the resistor R. In the program of FIG. 6, commands from other parts including the program of FIG. 4 are monitored, and if a high speed operation instruction is issued, the driver in the exhaust fan drive circuit 44 of FIG. By applying a full voltage to the fan 40, a high speed operation is performed. When a low speed instruction is issued, the driver is turned off and a voltage is applied via the resistor R, so that a low voltage operation is performed by a voltage drop due to the resistor R. The copying machine of this embodiment does not need to have this function because it is not necessary to stop the exhaust fan 40.

Next, one embodiment of the control operation of the copying machine according to the present invention will be described with reference to the flow charts of the control programs shown in FIGS. Note that this control shows an embodiment in which an optical fan is provided.

FIG. 7 is a flowchart of a program for determining what kind of optical system cooling operation is to be performed. There are two types of cooling operation, cooling operation 1 and cooling operation 2, and the processing to be executed is selected depending on the optical system temperature.

The CPU 33 monitors (detects) the output of the optical system temperature detecting element 5 and determines the temperature level of the optical system 2. Topt2 and Topt3 are temperature data for executing the cooling operation, and are set to Topt2 <Topt3. Optical system 2
If the temperature is less than Topt2, the cooling operation is not performed and the optical cooling fan 21 is stopped. The temperature of the optical system 2 is Topt2
If it is less than Topt3, the control shifts to the optical system cooling operation 1 in FIG. If the temperature of the optical system 2 is equal to or higher than Topt3, the control shifts to the optical system cooling operation 2 of FIG. Then, after the cooling operation 2 is performed, the temperature of the optical system 2 is changed to Topt4 (≤Top
If t2) or less, the cooling operation ends.

FIG. 8 is a flow chart for explaining the program for the cooling operation 1. In the cooling operation 1, while the optical system 2 is being cooled by the optical cooling fan 21, the image forming operation is continued. Here, the optical cooling fan 21 is rotated, but since it is not necessary to assume the worst value as described above for this fan, it is possible to select an appropriate balance between cooling capacity and dirt and noise. By the operation of this fan, the temperature rise of the optical system 2 is suppressed, but in the case where many copies are continuously taken, the temperature may rise further. Therefore, as shown in the program of FIG. 7, if the temperature of the optical system 2 rises to Topt3 or higher even after the cooling operation 1 is executed, the second cooling operation is necessary.

FIG. 9 is a flow chart for explaining the program of the cooling operation 2. In the cooling operation 2, first, the optical cooling fan 21 is operated to prohibit a new image forming operation, and waits until the current image forming operation is completed. And
When all the image forming operations are completed, the exposure lamp 6 is moved to the position D in FIGS. Further, a heater off command is issued to the fixing temperature control to instruct the exhaust fan control unit to operate the exhaust fan 40 at high speed.

In the cooling operation 2, the exposure lamp 6 is moved to the position D in FIGS. 1 and 2, but this position D is the maximum position for scanning the original, and in the copying machine of this embodiment, it is B4. It will be the size. On the other hand, the maximum document size is legal size (8.5 x 14 inches) used in North America.
Therefore, at the same size copy, scanning is not performed up to the position D. There is a possibility to scan to the maximum position only when reducing. Therefore, since it is unlikely that the temperature at this position has risen due to exposure irradiation, the cooling effect is significantly larger than that at the normal scanner home position (position B). further,
Since the image forming operation is prohibited during the cooling operation of the optical system,
It is not necessary to keep the fixing device 19 in a fixable state. Therefore, there is no problem even if the fixing control temperature is significantly lowered or the heating is stopped. As a result, the temperature rise near the scanner home position due to the heat of the fixing device 19 is reduced. Further, the exhaust fan 40 is operated at a high speed to enhance the exhaust effect, so that the cooling inside the machine can be promoted and the cooling effect of the optical system can be further enhanced.

Next, another embodiment of the control operation of the copying machine according to the present invention will be described with reference to the flow charts of the control programs shown in FIGS.
Here, a method that does not require an optical cooling fan will be shown.

FIG. 10 shows a program for determining what kind of optical system cooling operation is to be performed. There are two types of cooling operation, cooling operation 1 and cooling operation 2, and the processing to be executed is selected depending on the optical system temperature.

The CPU 33 monitors (detects) the output of the optical system temperature detecting element 5 to determine the temperature level of the optical system 2. Topt2 and Topt3 are temperature data for executing the cooling operation, and are set to Topt2 <Topt3. Optical system 2
If the temperature is less than Topt2, the cooling operation is not performed and the optical cooling fan 21 is stopped. The temperature of the optical system 2 is Topt2
If it is less than Topt3, the control shifts to the optical system cooling operation 1 in FIG. When the temperature of the optical system 2 is equal to or higher than Topt3, the control shifts to the optical system cooling operation 2 of FIG. After the cooling operation 2 is performed, the temperature of the optical system 2 is changed to Topt4 (≤
If it becomes less than Topt2), the cooling operation is ended.

FIG. 11 is a flow chart for explaining the program for the cooling operation 1. In the cooling operation 1, the scanner motor drive circuit 35 is instructed to perform the second scan operation. Here, the scanner stop position, which is the reference position during scanning, is set to B
The position is changed to the D position, and the image forming operation under the scan control with the D position as the home is continued. FIG. 13 shows a time chart of the B position reference scanning operation and the D position reference scanning operation. As shown in the upper part of FIG. 13, the document scanning normally starts from the position B, and returns to the position B after scanning a predetermined amount.
In the cooling operation 1 of No. 1, as shown in the lower part of FIG. 13, the operation returns from the position D to the position B once, scans the document from there, and stops at the position D. In the case of this control action,
Since it takes a long time to scan, the number of copies per unit time is slightly reduced, but it is important that the image forming operation can be continued because the temperature rise of the optical system is suppressed.
That is, the D position is a position suitable for cooling as described later, and when the document scanning is started from here, it is not necessary to turn on the exposure lamp 6 while keeping the stop at the B position to secure the rising time of the light quantity. , It is only necessary to turn on the exposure lamp 6 while ensuring the rising time during the operation of moving from the D position to the B position, so that the temperature rise at the B position is also suppressed. Therefore, the temperature rise of the optical system is suppressed. However,
When many copies are taken continuously, the temperature may rise further. Therefore, as shown in the program of FIG. 10, when the temperature of the optical system 2 rises above Topt3, the second cooling operation becomes necessary.

FIG. 12 is a flow chart for explaining the program for the cooling operation 2. In the cooling operation 2, first, a new image forming operation is prohibited and the completion of the current image forming operation is awaited. When all the image forming operations are completed, the exposure lamp 6 is moved to the position D in FIGS. Further, an instruction to turn off the fixing heater 42 is issued to the fixing temperature control, and a high speed operation is instructed to the control unit of the exhaust fan 40.

In the cooling operation 2, the exposure lamp 6 is moved to the position D in FIGS. 1 and 2, but this position D is the maximum position for scanning the original, and in the copying machine of this embodiment, it is B4. It will be the size. On the other hand, the maximum document size is legal size (8.5 x 14 inches) used in North America.
Therefore, at the same size copy, scanning is not performed up to the position D. There is a possibility to scan to the maximum position only when reducing. Therefore, since it is unlikely that the temperature at this position has risen due to exposure irradiation, the cooling effect is significantly larger than that at the normal scanner home position (position B). further,
Since the image forming operation is prohibited during the cooling operation of the optical system,
It is not necessary to keep the fixing device 19 in a fixable state. Therefore, there is no problem even if the fixing control temperature is significantly lowered or the heating is stopped. As a result, the temperature rise near the scanner home position due to the heat of the fixing device 19 is reduced. Further, the exhaust fan 40 is operated at a high speed to enhance the exhaust effect, so that the cooling inside the machine can be promoted and the cooling effect of the optical system can be further enhanced.

[0038]

As described above, in the image forming apparatus according to the first aspect, the temperature of the home position rises by stopping the light source, which is the heat source, at the cooling position away from the home position during the cooling operation. To prevent waste heat inside the machine by changing the fixing temperature of the fixing device to a predetermined temperature for cooling operation, and to prevent the optical system from being affected by heat from the fixing device. By preventing the temperature from rising in response to this, the temperature drop of the optical system is accelerated, and the time required for the cooling operation can be shortened without the optical cooling fan, and the optical system can be cooled reliably. Therefore, it is possible to provide a practical image forming apparatus.

In the image forming apparatus according to the second aspect,
Since there is a plurality of cooling operations and one operation is selected from the plurality of cooling operations according to the temperature of the optical system to be executed, it is possible to appropriately reduce the operability in actual use by the cooling operation. It is possible to provide a practical image forming apparatus that can provide control and can surely cool the optical system while eliminating the optical system cooling fan or using a cooling fan having a low cooling capacity.

In the image forming apparatus according to the third aspect,
Depending on the temperature of the optical system, the first cooling operation for cooling while performing image formation and the second cooling operation for stopping the image formation and cooling the temperature of the optical system are separated to reduce downtime in actual use. (EN) It is possible to provide a practical image forming apparatus that can reduce the frequency of occurrence and can reliably cool an optical system while eliminating an optical system cooling fan or using a cooling fan with a low cooling capacity. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a copying machine showing an example of an image forming apparatus using an electrophotographic technique in which the present invention is implemented.

FIG. 2 is a plan view of an optical system of the copying machine shown in FIG. 1 when viewed from above a contact glass.

3 is a block diagram showing an example of control means of the copying machine shown in FIG.

FIG. 4 is a diagram showing an embodiment of a control operation of the copying machine according to the invention of claim 1, and is a flow chart of a program for performing a cooling operation of an optical system.

FIG. 5 is a diagram showing an embodiment of the control operation of the copying machine according to the invention of claim 1, and is a flowchart of a program for controlling the temperature of the fixing device.

FIG. 6 is a diagram showing an embodiment of the control operation of the copying machine according to the invention of claim 1, and is a flowchart of a program for controlling the operation of the exhaust fan.

FIG. 7 is a diagram showing an example of the control operation of the copying machine according to the second and third aspects of the present invention, and is a flowchart of a program for determining what kind of optical system cooling operation is to be performed.

8 is a flowchart illustrating a program for cooling operation 1 in the control program shown in FIG.

9 is a flowchart illustrating a program for cooling operation 2 in the control program shown in FIG.

FIG. 10 is a diagram showing another embodiment of the control operation of the copying machine according to the second and third inventions, and is a flowchart of a program for determining what kind of optical system cooling operation is to be performed.

11 is a cooling operation 1 in the control program shown in FIG.
3 is a flowchart illustrating the program of FIG.

12 is a cooling operation 2 in the control program shown in FIG.
3 is a flowchart illustrating the program of FIG.

FIG. 13 shows a normal B position-based scanning operation, and FIG.
6 is a time chart of a D-position-based scanning operation in the control operation of FIG.

[Explanation of symbols]

 1: Copier (image forming apparatus) 2: Optical system 3: Contact glass 4: Original document 5: Optical system temperature detection element 6: Exposure lamp (light source) 7a to 7f: Mirror 8: Lens 9: Charger 10: Cleaning device 11: Static eliminator 12: Photoconductor 14: Developing device 15: Transfer device 18: Paper feed tray 19: Fixing device 19a: Fixing roller 19b: Pressure roller 21: Optical cooling fan 33: Central processing unit (CPU) 34: Scanner Motor 35: Scanner motor drive circuit 36: Exposure lamp lighting circuit 37: Optical cooling fan drive circuit 40: Exhaust fan 42: Fixing heater 43: Fixing heater drive circuit 44: Exhaust fan drive circuit

Claims (3)

[Claims] 1. An optical system having a light source for irradiating and scanning an original, and an image forming apparatus for performing a cooling operation for cooling the optical system under a predetermined condition, wherein the light source is at a predetermined cooling position during the cooling operation. The image forming apparatus is characterized by changing the fixing temperature of the fixing device for fixing an image to a predetermined temperature for the cooling operation by stopping the operation of the exhaust fan inside the machine at a high speed. 2. An optical system having a light source for irradiating and scanning an original, and an image forming apparatus for performing a cooling operation for cooling the optical system under a predetermined condition. The optical system has a plurality of cooling operations. According to the image forming apparatus, one operation is selected from the plurality of cooling operations and executed. 3. An optical system having a light source for irradiating and scanning an original, and an image forming apparatus for performing a cooling operation for cooling the optical system under predetermined conditions, the image formation is continued by the temperature of the optical system. A second cooling operation, which has two cooling operations, a first cooling operation and a second cooling operation that prohibits image formation, and is performed based on the first optical system temperature at which the first cooling operation is performed. The image forming apparatus is characterized in that the optical system temperature is set high.