JPH0619246A - Image forming device and heat fixing-device - Google Patents

Abstract

PURPOSE:To achieve improvement in workability and a reduction in cost by sending warm air to an image carrier and controlling the temperature of a photosensitive body. CONSTITUTION:The photosensitive drum 1 (image carrier) is heated by sending warm air to a corona discharger 2 (discharge means) from a blower fan 3 (blowing means) via a heating element 21. Exhaustion is carried out by a suction fan 13 through ducts 121, 122 and 123. The temperature of the photosensitive drum 1 is adjusted by turning on/off the blower fan 3 and the suction fan 13. Since a heat source is apart from the photosensitive drum 1 and heats it with warm air, irregularities in temperature do not occur. Only the photosensitive drum 1 can be attached and detached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a facsimile,
The present invention relates to a temperature control configuration of an image forming apparatus such as a laser beam printer. The present invention also relates to a heat fixing device of an image forming apparatus.

[0002]

[Prior art]

(1) In the conventional image forming apparatus using an electrophotographic photosensitive member, it is necessary to control the temperature of the electrophotographic photosensitive member within a predetermined range as disclosed in Japanese Patent Application Laid-Open No. 62-296180 by the present applicant. The temperature is controlled by using a temperature adjusting member such as a thermostat having a heat source near or inside the surface of the photoconductor. (2) In an image forming apparatus that uses an electrophotographic method, a thermal fixing device is often used as a method for fixing a toner image on a sheet. The thickness of the fixing roller is one factor that determines the performance of the fixing device that performs the heat fixing.

The fixing roller is usually made of a metal material such as aluminum or iron. If the thickness of the fixing roller is reduced, the volume or heat capacity of the fixing roller at that time is reduced. For this reason, the device startup time (warm-up time) is shortened.

Further, in recent years, there has been a demand for a simpler OA device in the market, and there is an increasing need to shorten the warm-up time. For this reason, research and development are being conducted to reduce the thickness of the fixing roller as much as possible.

[0005]

However, in the above-mentioned conventional example (1), in the case where a heat source is provided in the vicinity of the photoconductor such as having a planar heating element in close contact with the photoconductor, it is necessary to shorten the rise time of the temperature. It took time to detach the heat source from the photoconductor when replacing the photoconductor. This drawback is due to the fact that the photoreceptor, such as a photoreceptor having a photosensitive layer containing an organic photoconductor, is
This was large in the case of a photoconductor that has a relatively short life compared with a-Si and has a high replacement frequency.

Further, in an image forming apparatus for forming a multicolor image by disposing a plurality of developing devices around the photosensitive member, the peripheral length of the photosensitive member needs to be long. It cost a lot.

Further, the application of heat to the photoconductor causes local unevenness, and since the place where the wind hits the photoconductor is local, local unevenness occurs in cooling. As a result, there is a drawback that the temperature distribution becomes uneven, the characteristics of the photosensitive member become uneven, and the uneven density on the image occurs due to the uneven sensitivity of the photosensitive member.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus which does not require the trouble of replacing the photoconductor.

Another object of the present invention is to provide an image forming apparatus having no unevenness of humidity on the surface of the photosensitive drum since unevenness of humidity occurs on the surface of the photosensitive drum due to uneven temperature.

The present invention proposes to heat the photosensitive drum by rotating it in order to uniformly heat the photosensitive drum.
Then, the cleaning device rubs against the photosensitive drum having a high temperature, so that the photosensitive member is scraped from the photosensitive drum and the durability of the cleaning device deteriorates. A further object of the present invention is to prevent deterioration of the durability of the cleaning device when the temperature of the photosensitive drum is adjusted by rotating it.

In the conventional example (2), if the thickness of the fixing roller is too thin, the surface temperature of the roller is apt to change rapidly due to an excessively small heat capacity. The temperature rise in the non-sheet passing area becomes large during continuous feeding of small size paper. For this reason, heat fusion of the coating material of the fixing roller,
Deterioration of rubber of pressure roller, melting of members around fixing device,
And there is a risk of heat deterioration. The temperature difference between the axial portions of the fixing roller in the standby state becomes large. In particular, when the temperature reaches the maximum in the central portion of the fixing roller and when copying is performed in this state, high temperature offset occurs, and toner stains on the surface of the fixing roller and toner stains on the transfer paper occur.

Therefore, in the past, a fixing roller having a predetermined thickness or more was used to prevent the above problem. However, for this reason, the wait time at the time of starting the apparatus becomes long. A large amount of material is required for the fixing roller. There were drawbacks such as.

An object of the present invention is to provide a thermal fixing device which prevents partial temperature rise of the fixing roller.

[0014]

The first invention of the present invention comprises an air blowing means for blowing warm air to the image bearing member and a temperature measuring means for measuring the temperature of the image bearing member. The image forming apparatus is characterized in that the blower unit is controlled according to the measurement result of

According to a second aspect of the present invention, a blowing means for blowing warm air to the image carrier, a temperature measuring means for measuring the temperature of the image carrier, and a cleaning means are detached from the image carrier at a predetermined timing. An image forming apparatus comprising: a detaching unit, and controlling the blower unit according to a measurement result of the temperature unit.

A third aspect of the present invention is characterized in that it has a detaching means for detaching the cleaning means from the image carrier, moves the image carrier at a predetermined timing, and operates the cleaning means and the detaching means. Image forming apparatus.

A fourth invention of the present invention is the image forming apparatus according to the first invention or the second invention, wherein the image carrier is an electrophotographic photoreceptor provided with a photosensitive layer containing an organic photoconductor. .

A fifth invention of the present invention is the image forming apparatus according to the first invention or the second invention, in which the blowing means shares the removing means for removing the waste generated by the discharging means.

A sixth invention of the present invention is the image forming apparatus according to the first invention or the second invention, which has means for moving the image carrier when controlling the blowing means.

The seventh invention of the present invention is the image forming apparatus according to the second invention, wherein the timing of removing the cleaning means from the image carrier is during non-image formation.

An eighth aspect of the present invention is to provide a fixing roller, a heating means for the fixing roller, a blower for blowing air to the fixing roller, and a plurality of blowers capable of blowing air from the blower to respective portions in the longitudinal direction of the fixing roller. A passage and a movable air-blocking member that is provided in each of the plurality of air-blowing passages and that can take a position that shuts off the air-blowing passage from the position where the air-blowing passage is opened. The heat-reaction deforming member is changeable in shape and has a heat-reaction deforming member that engages with the wind-blocking member, and an elastic member that urges the wind-blocking member in a direction to block the air passage, In the thermal fixing device, the thermal reaction deformation member moves the air blocking member to a position where an air passage from the air blower to the fixing roller is opened when the temperature reaches or exceeds a predetermined temperature.

A ninth invention of the present invention is the thermal fixing apparatus according to the eighth invention, wherein the heat-reactive deforming member also serves as the wind blocking member.

The tenth invention of the present invention is the thermal fixing apparatus according to the eighth or ninth invention, wherein the heat-reactive deformation member is a shape memory alloy.

An eleventh invention of the present invention is the thermal fixing apparatus according to the eighth invention, wherein the heat-reactive deformation member is a bimetal.

The twelfth invention of the present invention is the heat fixing apparatus as described in any one of the eighth to eleventh inventions, characterized in that at least a part of the heat-reactive deformation member is black. is there.

The thirteenth invention of the present invention is any one of the eighth to twelfth inventions, characterized in that the heat-reactive deformation member engages with another member via a member having a low thermal conductivity. The heat fixing device according to the first aspect.

By the above method, only the high temperature portion of the fixing roller can be cooled by air. For this reason, a thin fixing roller can be used, which shortens the wait time and saves the material of the fixing roller.

[0028]

[First Embodiment] FIG. 1 shows an embodiment, and FIG. 1 is a schematic configuration diagram of a laser beam printer provided with a blowing unit according to the present invention.

The photosensitive drum 1 as an image carrier having an organic photoconductor (OPC) on its surface is rotationally driven in the direction of the arrow. The surface of the photosensitive drum 1 is charged by a corona discharger 2 as a discharging means. On the back surface of the shield member of the corona discharger 2 (the surface opposite to the photosensitive drum 1), an opening portion is provided in the axial direction of the photosensitive drum 1 for substantially the width of the charger.
The air is blown to the photosensitive drum 1 side by the blower fan 3 as the blower means through the air duct 4 and the shield member of the corona discharger 2 provided as the discharge means. An air filter 5 is provided at the opening of the air duct 4 on the air intake side to prevent dust that causes the discharge wire to become dirty.

The surface of the photosensitive drum 1 charged by the corona discharger 2 is subjected to laser beam scanning (main scanning) exposure E based on a control signal by a polygon mirror scanner system (not shown).
And an electrostatic latent image is formed. This electrostatic latent image is reversely developed by a developing device (having a developing bias applied) 6 having toner having the same polarity as the charging polarity of the corona discharger 2.

The developed toner image is transferred to the transfer corona discharger 7
Is transferred to a transfer material P such as paper. The transfer material P is sequentially subjected to static elimination from the surface of the photosensitive drum 1 by the separation corona discharger 8, conveyed to a heating type fixing device (not shown) (for example, FIG. 4), image-fixed and discharged outside the machine as a copy. To be done.

The surface of the photosensitive drum 1 after transfer is decharged by the pre-cleaning corona discharger 9, and the cleaning device 10
Is removed from the photosensitive drum 1 by a detaching means (not shown) which will be described later, and is cleaned by a cleaning device 10 as a cleaning means that is in contact with the photosensitive drum 1, and the entire surface is exposed by a discharging lamp 11 to erase the previous history. Prepared for image formation.

The air suction / exhaust duct 12 including the suction fan 13 has three branch ducts 121, 122 and 123. The branch duct 121 is located downstream of the corona discharger 2 with respect to the moving direction of the peripheral surface of the photosensitive drum 1. Air containing ozone, which is blown from the opening area between the side surface of the shield member and the photosensitive drum 1, is sucked. The branch duct 122 sucks air containing ozone blown from the opening area between the photosensitive drum 1 and the upstream side of the shield member of the corona discharger 2 in the moving direction of the peripheral surface of the photosensitive drum 1. Further, the branch duct 123 is the photosensitive drum 1.
The air in the discharger is sucked from the opening on the back surface of the shield member of the corona discharger 9 on the upstream side of the cleaning device 10 with respect to the moving direction of the peripheral surface. Each branch duct 121,
The axial length of the photosensitive drum 1 at the air suction openings 122 and 123 is approximately equal to the corona discharger 2 and the cleaning device 10.
Is equal to the charging length of the corona discharger 9 on the upstream side. An air filter 14 for blocking the discharge of toner and the like from the apparatus and an ozone filter 15 for blocking the exhaust of ozone are provided at the opening of the duct 12 on the side where the suction fan 13 sucks and exhausts the air.

A blower fan 3 provided as a blower has a heating element 21 on the discharge port side so as not to interfere with blown air, so as to measure the surface temperature of the photosensitive drum 1 apart from the blower and near the photosensitive drum 1. It has a temperature sensor 22 as a temperature measuring means such as a thermistor. In this example, the temperature sensor 22 is arranged at the same position as the corona discharger 9.

The amount of heat generated by the heating element 21 and on / off of the blower fan 3 and the suction fan 13 are controlled by the temperature detected by the temperature sensor 22. For example, when it is desired to control the temperature at 40 ° C. as the central temperature, both the heating element 21 and the blower fan 3 are turned off when the detected temperature T is 39 to 43 ° C., and the fans 3 and 13 are turned on when T> 43 ° C. , T <39 ° C., the fans 3 and 13 and the heating element 21 are turned on.

This operation is called a temperature control operation, and together with the operation of turning on the blower fan 3 and the suction fan 13, it is disclosed in Japanese Patent Laid-Open No.
As shown in JP-A-3-178259, the corona discharge wire of the corona discharger 2 is prevented from adhering toner and dust to prevent uneven discharge, and ozone such as unnecessary substances generated during discharge is corona discharger. It will be discharged to the outside of the shield case of No.2. This operation is called an ozone discharging operation, but in addition to that, the blower fan 3 and the suction fan 13 are operated at the next timing. That is, during image formation, after image formation is completed, after the main power switch of the apparatus is turned off, after a jam has occurred, after the door switch of the apparatus has been opened and closed, and after a sequence control error has occurred, operation is performed for a predetermined time after image formation is stopped.

Regarding the operation of the fans 3 and 13, the sum (OR) of the ozone discharge operation and the temperature control operation is taken.

Although the heating element 21 is provided near the discharge port of the blower fan 3 in this embodiment, the present invention is not limited to this. An area on the photosensitive drum that is efficient for generating heat is provided by having a means combining a blower fan and a heating element near the photosensitive drum, and performing the same control as the control of the fans 3, 13 and the heating element 21 described above. There is an advantage that the heat generating portion can be freely arranged.

Further, by providing a plurality of air-blowing and heat-generating portions, the area of the photosensitive drum on which heat is generated is increased, and the temperature rise of the photosensitive drum can be speeded up.

Further, since the blower section and the heat generating section are separated from the photosensitive drum 1, there is no need to have a structure for separating them when the photosensitive drum 1 is replaced, and the labor is small and the cost can be reduced. This effect is particularly great in the case of a photoreceptor having a relatively short life such as an organic photoconductor.

The above-mentioned air blowing and suction is performed by the photosensitive drum 1.
The noise, durability, and power consumption of the fan become a problem because it is performed for a long time as well as when the photosensitive drum 1 is rotated, and the temperature lowering factor of the photosensitive drum 1 is smaller than that when the photosensitive drum 1 is rotated. Considering that the amount of ozone generated during image formation does not increase while image formation is stopped, the voltage is controlled during fan drive or after heat generation for a certain period of time after image formation, compared to during image formation. By setting the power consumption to 20% to 50% of that during image formation by the above, the above problems can be solved without deteriorating the above effects.

Further, by adopting a sequence in which the photosensitive drum is rotated during heat generation and blowing, it is possible to eliminate temperature unevenness on the photosensitive drum and to speed up the temperature rise.

In this case, by making the rotation speed of the photosensitive drum 1 slower than that at the time of image formation, power saving can be achieved while maintaining the above effect.

[Second Embodiment] FIG. 2 shows a second embodiment. A rod-shaped heater 24 is arranged in the rotary shaft of the photosensitive drum 1, and temperature sensors 25 and 26 such as thermistors for measuring the surface temperature of the photosensitive drum 1 are provided.

On / off of the heater 24 is controlled by the temperature detected by the temperature sensor 25. For example, when it is desired to control the temperature at 40 ° C. as the central temperature, the detected temperature is set to T. If T> 41 ° C., the heater is turned off.

In this embodiment, the photosensitive drum 1 is rotated even during non-image formation, and at the same time, the cleaning device 10 is detached from the photosensitive drum 1.

FIG. 3 shows an example of the structure of the cleaning device 10 according to the present invention, which is detached from the photosensitive drum 1 during non-image formation. The cleaning device 10 is in contact with the photosensitive drum 1. The cleaning device 10 contacts with the copy start signal, scrapes off the residual toner on the photosensitive drum 1 with the cleaning blade 16, receives it with the flexible scooping sheet 17, stores it as waste toner 18 in the housing, and collects waste toner with the screw 19. (Not shown)
Send to.

The structure in which the cleaning device 10 is detached after the image formation is as shown in FIG. 3, for example. Cleaning device 10
Is attached to one end of a lever 22 swingably attached to a shaft 20 attached to a proper position of the housing, and the other end of the lever 22 is engaged with the other end of a tension spring 21 whose one end is locked to a stationary part. And is biased clockwise about the shaft 20,
It is in contact with the photosensitive drum 1. Solenoid 2 fixed to the end of lever 22 to which cleaning device 10 is attached and the main body
The three movable rods 23a are connected by a connecting rod 27 which is a link. When the solenoid 23 is energized, the movable rod 2
3a is pulled into the solenoid, pulls the connecting rod 27, rotates the lever 22 counterclockwise about the shaft 20 against the tension spring 21, and removes the cleaning device 10 from the photosensitive drum 1.

By turning on / off the solenoid 23, the cleaning device 10 can selectively take the contact position and the release position with respect to the photosensitive drum 1, and the solenoid 23 is turned off during image formation (including the pre-rotation preparation operation). After the image formation, the solenoid 23 is turned on and the cleaning device 10 is removed from the photosensitive drum 1.

The timing for removing the cleaning device 10 is not limited to this embodiment. For example, by adhering the cleaning device 10 for a predetermined time after image formation, rotating the photosensitive drum 1 and then separating it, the cleaning device 10 adheres onto the photosensitive drum 1 while maintaining the effect of the present invention, and the image on the photosensitive drum 1 is formed. There is an effect that it is possible to remove the deposits that cannot be completely removed by the rotation during formation.

Since the photosensitive drum 1 is rotated according to the present embodiment, it is possible to eliminate unevenness of the photosensitive drum surface temperature such that the surface temperature of the photosensitive drum 1 is low only near the outlet of the fan blow port.

In the present invention, since the cleaning device 10 is detached at a proper time, when the photosensitive drum 1 is rotated, abrasion of the surface of the photosensitive drum 1 and damage to the cleaning blade caused by constantly contacting the cleaning device 10 with the photosensitive drum 1 are minimized. You can keep it to the limit.

Further, by removing the cleaning device according to the configuration of the present invention, there is no obstacle to the discharge of ozone or the like near the peripheral surface of the photosensitive drum 1, and the discharge of ozone or the like is smoothly performed.

The present invention can be made more efficient by adopting the following configuration.

Only when the difference between the temperatures detected by the plurality of temperature sensors 25 and 26 shown in FIG. 2 exceeds a set value, for example, 3 ° C. or more, it is judged that the surface temperature of the photosensitive drum 1 is uneven, and the photosensitive drum 1 is determined. It is possible to maintain the effect of the present invention while saving electric power by rotating the cleaning device 10 to separate the cleaning device 10 from the photosensitive drum 1. The means for detecting the unevenness of the surface temperature of the photosensitive drum 1 is not limited to this. For example, a configuration having a plurality of radiant infrared ray detecting means may be used.

The embodiment of the present invention is not limited to the laser beam printer as shown in FIGS. The present invention is applied to an image forming apparatus having an image carrier that requires temperature control.

Further, in an image forming apparatus for forming a multicolor image by arranging a plurality of developing devices around the photosensitive drum, it is necessary that the peripheral length of the photosensitive member is long. There was a problem that it became an area and temperature unevenness became large,
By applying the present invention, uniform temperature control can be realized even when the peripheral length of the photoconductor is long.

Furthermore, by providing a means for changing the rotation speed of the photosensitive drum 1 during non-image formation, it is possible to more efficiently obtain a uniform surface temperature.

The timing at which the rotation speed of the photosensitive drum 1 is lowered is set, for example, when the fans 3 and 13 are stopped.

As described above, the operation of the fans 3 and 13 prevents uneven discharge by preventing toner and dust from adhering to the corona discharge wire of the corona discharger 2 as shown in JP-A-63-178259. At the same time, the blower fan 3 and the suction fan 13 are operated to discharge ozone or the like generated during the discharge to the outside of the shield of the corona discharger 2. This operation is called the ozone discharge operation, and the timing of the operation is during image formation, after image formation, after the main power switch of the device is turned off, after a jam has occurred, after the door switch of the device has been opened or closed, and after a sequence control error has occurred. After formation stopped,
Operate for a predetermined time.

After this operation is completed, the rotation speed of the photosensitive drum 1 is reduced to, for example, 1/4.

[Third Embodiment] FIG. 4 is a perspective view of a fixing device. The fixing roller 31 is a side plate 33, 3 in which both ends of a hollow aluminum cylinder having a thickness of 2 mm are rigidly connected by stays 34.
9 is rotatably supported, and a gear 32 that is driven by meshing with a gear (not shown) is fixed to an end of the fixing roller 31 outside the side plate 33. A halogen heater 45 as a heating means is inserted through the central portion of the fixing roller 31, and heat is supplied to the fixing roller 31. A thermistor (not shown) is in contact with the paper feed reference position B in the axial direction of the fixing roller 31, and the paper feed reference position B of the fixing roller 31 is adjusted to 180 ° C. by a temperature control circuit connected to the thermistor.

As shown in FIG. 5, the fixing roller 31 is provided with a pressure roller 40 in which the outer periphery of a core metal is thickly covered with an elastic member and is rotated by pressure contact, and is sent onto a fixing inlet guide 43. The transfer material is a fixing roller 31 and a pressure roller 40.
The unfixed image on the transfer material is heated and pressed at the nip portion of the sheet to be fixed, and the upper separation claw 41 and the lower separation claw 42 prevent the fixing roller 31 and the pressure roller 40 from being wound around and are discharged. It

The stay 34 has a key-shaped cross section in the sheet passing direction, and is provided with square holes 47 (47a to 47d) in the hanging portion. The shutter 37 (37a) serves as a wind blocking member for opening and closing the square holes 47. .About.37d) are rotatably fitted to the shaft 38 supported by the side plates 33 and 39 in parallel with the fixing roller 31. Shape memory spring 35 (3) made of a shape memory alloy provided as a thermal reaction deformable member capable of changing its shape depending on temperature.
5a to 35d) has one end locked to the upper surface of the stay 34,
The other end is locked to the tip of the shutter 37. The spring 36 (36a to 36d) made of stainless steel is a tension coil spring having one end locked to the lower edge of the hanging portion of the stay 34 and the other end locked to the tip of the shutter 37.

Here, the shape memory spring 35 made of the shape memory alloy is set so as to shrink when the temperature exceeds 200 ° C. Further, since it is close to the fixing roller 31, it is almost the same as that of the fixing roller 31. The temperature becomes equal to the surface temperature.

An image forming apparatus equipped with this fixing device, for example, a main body of a copying machine, has a cross flow fan 4 as a blower.
4 is provided in parallel with the fixing roller 31. The cross flow fan 44 has its discharge port 44a collectively covering the respective square holes 47, and has a suction port 44b in the upper part. The casing 44c of the cross flow fan 44 has a side hole 44d at the lower edge of the discharge port 44a. The impeller 44e housed in the casing 44c is rotated by a motor (not shown). The crossflow fan 44 has a discharge wind speed of 5 m / s. With the above configuration, the discharge port 44a, the square hole 47, and the space inside the stay 34 form a ventilation passage from the cross flow fan 44 of the blower.

Next, the operation will be described. The shutter 37 operates as shown in FIGS. 5 and 6 are vertical sectional views of the heat fixing device according to the present invention, which are explanatory views of the opening / closing operation of the shutter 37.

Here, in FIG. 5, the surface temperature of the fixing roller 31 is 200 ° C. or lower, that is, the temperature of the shape memory spring 35 is 2.
This is the case when the temperature is 00 ° C. or lower. In this state, the shutter 37 is closed by the spring force of the spring 36, the square hole 47 is closed, and the shape memory spring 35 is extended. Therefore, the cross flow fan 44 does not blow air to the fixing roller 31.

In FIG. 6, the surface temperature of the fixing roller 31 is 200
This is the case where the temperature is higher than or equal to 0 ° C, that is, the shape memory spring 35 is higher than or equal to 200 ° C. In this state, the shape memory spring 35 contracts and this force overcomes the spring force of the spring 36 to extend the spring 36 and the shutter 37 is rotated about the shaft 38 to open.
For this reason, the suction port 44 is attached to the fixing roller 31 by the impeller 44e.
The air sucked from b passes through the square holes 47 (47a to 47d) opened from the discharge port 44a of the cross flow fan 44 and is blown to the fixing roller 31.

In this way, the shutter 37 (37a-37)
Each of the four d) opens and closes at 200 ° C. as a boundary. As a result, the corresponding shutter 37 (37a to 37d) is opened in the portion where the surface of the fixing roller exceeds 200 ° C., and the corresponding square hole 47 (47a to 47) is opened from the cross flow fan 44.
The air is blown through d) and cooled, and it receives the action of returning to below 200 ° C.

This action is effective mainly in the following two cases.

Problems of small size paper (state in which the sizes B5 and A4 of Japanese Industrial Standard paper are passed through the fixing device in the lengthwise direction, etc.) and continuous paper passing (reference numerals B5R and A4R at the end of the paper in FIG. 4) and their problems Solution In this case, since heat is not transferred to the transfer material in the non-sheet passing portion of the fixing roller 31, if the temperature of the non-sheet passing portion rises and the surface temperature of the fixing roller 31 exceeds 240 ° C., the fixing roller 31 31
Surface coating and thermal melting of surrounding parts.
When the shutter 37 is not operated in this device, the temperature of the non-sheet passing portion rises as shown by the broken line 100 in FIG. 7, but as shown by the shutter open in S of FIG. 7, the shutters 37c and 37d are opened and closed and shown by the solid line 101. It can be kept below 200 ° C.

High temperature offset at the central portion of the fixing roller and its solution after the first sheet from the standby state. In the present apparatus, if the shutter 37 is not provided, the heat is radiated from the central portion in the longitudinal end portion of the fixing roller 31 in the standby state. Since it is large, the central portion temperature becomes high (210 to 220 ° C.) even if the position of B in FIG. 4 is adjusted by the thermistor. (Dashed line 102 in FIG. 8) Here, it is known that the toner used in the copying machine causes high temperature offset at 200 ° C. or higher. The solid line 103 in FIG.
In this state, the shutters 37b and 37c are opened (closed slope portion of the solid line in the figure) and closed, and the surface temperature of the fixing roller 31 becomes 180 ° C. to 200 ° C., and high temperature offset is prevented.

In this way, the thickness of the conventional copying machine is 2 mm.
When the following fixing roller is used, the above problems remain, but the present invention solves this problem as described above. As a result, advantages such as shorter warm-up time and material saving were born.

In the present embodiment, there were four shutters, but the number of shutters may be increased for more accurate temperature control, and if the conditions are rough, three shutters are required.
The same effect occurs even if the number of places is below.

Further, if the shape memory spring 35 is made black in order to improve the responsiveness of opening and closing the shutter, the radiant heat from the fixing roller 31 is effectively absorbed, which is further effective.

[Fourth Embodiment] FIGS. 9 and 10 show a fourth embodiment of the present invention. The configurations of the copying machine main body and the fixing device are the same as those in the third embodiment, and the configurations of the shutters are different. The same functional portions as those in the previous third embodiment are designated by the same reference numerals, and the description thereof will be omitted. To do.

The shutter section has the following configuration. Shutter 516 made of shape memory alloy and leaf spring 51 made of stainless steel
7 and stack a small screw 518 near the lower edge of the hanging part of the stay 34.
Fixed by. The lower portion of the shutter 516 is folded back and bent, and one surface (A surface in the drawing) that is folded back and faces the fixing roller 31 is close to the surface of the fixing roller 31, and the A surface is almost at the surface temperature of the fixing roller 31. The temperature is close. The temperature of the fixing roller 31 is 200
At a temperature equal to or lower than ° C, the shutter 516 has the shape shown in Fig. 9 and closes the square holes 47 (47a to 47d). When the fixing roller 31 is heated to 200 ° C. or higher, the shutter 516 is bent against the spring force of the leaf spring 517 as shown in FIG.
7 (47a to 47d) are opened.

When the surface temperature of the fixing roller 31, that is, the temperature of the shutter 516 is 200 ° C. or lower, the elasticity of the leaf spring 517 causes the shutter to be closed as shown in FIG. When the surface temperature of the fixing roller 31, that is, the temperature of the shutter 516 becomes 200 ° C. or higher, the shape memory capacity of the shutter 516 resists the spring force of the leaf spring 517 to take the state of FIG. The base side is bent, the shutter is opened, and air is blown from the cross flow fan 44 to the fixing roller 31.
To cool.

In this way, the same effect as in the third embodiment can be obtained in the fourth embodiment.

When the surface A is painted black, the heat absorption rate is increased, and the effect is further improved. Further, it has been confirmed that the stay 34 is made of plasx to prevent heat dissipation, which is more effective.

Further, although the shutter 516 is made of a shape memory alloy in this embodiment, the same operation can be performed even if the shutter 516 is a bimetal.

In the third and fourth embodiments, the shape memory spring 35 and the shutter 516 are directly attached to the stay 34 which covers the fixing roller. However, the stay 34 is made of a non-heat conductive material, or the shape memory spring 35 and the shutter 516 are used. When the shape memory spring 35 or the shutter 516 is attached to the stay 34 with a heat insulating material interposed between the stay 34 and the stay 34, the radiant heat of the fixing roller 31 causes the shape memory spring 35 or the shutter 51.
6 is more faithfully transmitted and the control is more accurate.

In the third and fourth embodiments, a plurality of square holes 47 (47a ...
47d), the number of the square holes 47 is almost one over the entire length of the fixing roller 31, and the adjacent shutters 37 (37a to 37a).
37d) may be brought closer.

[0085]

EFFECTS OF THE INVENTION As described above, (1) By providing warm air to the image carrier to control the temperature of the photosensitive member, it is possible to seal the photosensitive member with a planar heating element. Since there is no work to separate the planar heating element from the photoconductor, the labor for replacing the image carrier can be reduced,
Also, the cost could be reduced.

If the cleaning means is detached from the image carrier, the image carrier and the cleaning means will not be damaged in the above.

Further, by rotating the image carrier during non-image formation and operating the detaching means of the cleaning means, the image carrier is scraped, the cleaning means is not damaged, and the unevenness of the surface temperature distribution of the image carrier is removed. There is an effect that can be.

Further, each of the above is suitable for applying an image carrier having a photosensitive layer having a relatively short life such as an organic photoconductor to an image forming apparatus.

It should be noted that the provision of the cleaning device removing means made it possible to smoothly discharge ozone, scattered toner, and the like.

Further, if the blowing means is also used as a means for removing the unnecessary substances generated by the discharging means, ozone, scattered toner, etc. are promptly removed, and the durability of the photoconductor and the discharging means is increased.

When the image carrier is moved and air blowing means is operated, the temperature of the image carrier is adjusted to a uniform temperature.

If the cleaning means is separated from the image carrier during non-image formation, the life of the image carrier and the cleaning means will not be shortened due to movement of the image carrier during non-image formation, and the durability will be increased. .

(2) The surface temperature of the fixing roller is detected by a thermal reaction deformation member (shape memory alloy, bimetal, etc.), and the shape change causes the wind blocking member to open the air passage from the air blower to the fixing roller, so that the air blower blows the air. By blowing air to the fixing roller, it is possible to prevent a partial temperature rise of the fixing roller.

If the heat-reaction deforming member also serves as the wind blocking member in the above, the structure is simple, the reliability is improved, and the cost is reduced.

Further, in any of the above, if the heat-reactive deformation member is a shape memory alloy, it is easy to enlarge the air passage.

If the heat-reaction deforming member is a bimetal, the opening of the air passage changes according to the temperature change of the fixing roller, and the air passage is opened and closed accurately.

Further, if at least a part of the heat-reaction deforming member is made black, the radiation heat of the fixing roller is well absorbed, so that the reaction of the wind blocking member is fast.

Further, when the thermal reaction deformation member engages with another member through the member having a low thermal conductivity, the radiant heat applied from the fixing roller to the thermal reaction member does not escape and reacts without delay when the temperature rises.

Therefore, it becomes possible to use a fixing roller which is thinner than before, and it is effective in shortening the wait time and saving the material of the fixing roller.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a part of the image forming apparatus according to the second and third embodiments of the present invention.

FIG. 4 is a perspective view of a third embodiment of the present invention.

5 is a vertical cross-sectional view showing the operation of FIG.

FIG. 6 is a vertical sectional view showing the operation of FIG.

FIG. 7 is a diagram showing a temperature change of a non-sheet passing portion of a fixing roller.

FIG. 8 is a diagram showing a temperature change in the central portion of the fixing roller during standby.

FIG. 9 is a vertical sectional view of another embodiment 4;

FIG. 10 is a vertical sectional view showing the operation of another embodiment 4.

[Explanation of symbols]

 1 Photosensitive Drum 2 Corona Discharger 3 Blower Fan 10 Cleaning Device 22 Temperature Sensor 31 Fixing Roller 32 Gears 33, 39 Side Plate 34 Stay 35 Shape Memory Spring 36 Spring 37 Shutter 38 Shaft

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G12B 1/00 S 6843-2F

Claims (13)

[Claims] 1. An air blowing unit for blowing warm air to the image carrier,
An image forming apparatus comprising: a temperature measuring unit that measures the temperature of the image carrier, and controlling the air blowing unit according to a measurement result of the temperature measuring unit. 2. An air blowing unit for blowing warm air to the image carrier,
A temperature measuring unit for measuring the temperature of the image carrier and a detaching unit for detaching the cleaning unit from the image carrier at a predetermined timing, and controlling the blower unit according to the measurement result of the temperature measuring unit. An image forming apparatus characterized by. 3. An image forming apparatus, comprising: a detaching unit for detaching the cleaning unit from the image carrier, moving the image carrier at a predetermined timing, and operating the cleaning unit and the detaching unit. 4. The image forming apparatus according to claim 1, wherein the image bearing member is an electrophotographic photosensitive member provided with a photosensitive layer containing an organic photoconductor. 5. The image forming apparatus according to claim 1, wherein the air blowing unit shares the removing unit that removes unnecessary substances generated by the discharging unit. 6. The image forming apparatus according to claim 1, further comprising means for moving the image carrier when controlling the blowing means. 7. The image forming apparatus according to claim 2, wherein the cleaning unit is detached from the image carrier at a non-image forming timing. 8. A fixing roller, heating means for the fixing roller, a blower for blowing air to the fixing roller, a plurality of blowing passages capable of blowing air from the blower to respective portions in the longitudinal direction of the fixing roller, and a plurality of blowing fans. Movable air blocking members, which are respectively provided in the passages and can take a position to block the air passage and a position to block the air passage, and at least a part of the member is near the fixing roller, and the shape can be changed according to the temperature. A heat-reaction deforming member that engages with the wind-blocking member and an elastic member that biases the wind-blocking member in a direction of blocking the air passage, and when the heat-reaction-deforming member reaches a predetermined temperature or higher. A thermal fixing device, wherein the thermal reaction deformation member moves the wind blocking member to a position where an air passage from the blower to the fixing roller is opened. 9. The heat fixing device according to claim 8, wherein the heat reaction deformation member also serves as the wind blocking member. 10. The heat fixing device according to claim 8, wherein the heat-reactive deformation member is a shape memory alloy. 11. The heat fixing device according to claim 8, wherein the heat reaction deformation member is a bimetal. 12. The heat fixing device according to claim 8, wherein at least a part of the heat-reaction deforming member is black. 13. The heat fixing device according to claim 8, wherein the heat reaction deformation member engages with another member via a member having a low heat conductivity.