JP2002023548A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which can prevent the trouble that the life of a halogen heater becomes short by very simple constitution. SOLUTION: The time needed to raise the glass tube wall temperature of the halogen heater 23 up to specific temperature is measured in advance and regarded as the shortest blinking time of the halogen lamp 23. Control is so carried out that the blinking of the halogen lamp 23 is not always off within the shortest blanking time. The halogen heater 23 blinks until the glass tube wall temperature reaches the prescribed temperature even if the temperature of the mandrel of a fixing roller 18 reaches set temperature needed for fixation within the shortest blinking time and a series of fixing processes are completed, so that the halogen cycle is carried out always completely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used for fixing a toner image on a transfer material in an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as an electrophotographic copying machine, a fixing device in which a pressure roller is pressed against a heat fixing roller is used. In this type of fixing device, while the heated fixing roller is rotated, the transfer material on which the toner is transferred is passed between the rotating fixing roller and the pressing roller, and the toner is heated and melted to be fused on the transfer material. It is what you wear.

In such a fixing device, generally, a halogen heater using a halogen lamp has been used as a heat source of the fixing roller. In a fixing device using a halogen heater, if the halogen heater is repeatedly turned on and off in a very short cycle, the halogen cycle in the halogen heater ends without being completed. The halogen cycle is a thermochemical circulating reaction between tungsten evaporated from the filament and halogen gas sealed in a halogen lamp. The evaporated tungsten combines with the halogen gas to generate volatile tungsten halide. This tungsten halide has a temperature of 250 ° C to 140 ° C.
Since this state is maintained at 0 ° C., when the glass tube is kept at 250 ° C. or higher, it returns by heat convection near the filament without adhering to the tube wall. In the high temperature region around the filament, the tungsten halide thermally decomposes into tungsten and halogen gas, which deposits on the filament and the halogen gas diffuses and is available for subsequent bonding. This series of cycles is called a halogen cycle. However, when the flashing time of the halogen heater is extremely short and the temperature of the glass tube wall does not reach 250 ° C., the halogen cycle ends incompletely, and the blackening phenomenon of the glass tube occurs. This causes a problem that the life of the filament is shortened.

FIG. 3 is a graph showing the relationship between the temperature of the fixing roller core and the temperature of the halogen heater tube wall and the input power to the halogen heater in a high-speed rising type fixing device using a thin fixing roller. In the halogen lamp having the rising characteristic shown in FIG.
When the fixing process is completed in about 8 seconds after the temperature of the fixing roller core metal reaches that temperature, the glass tube wall of the halogen heater at that time reaches about 205 ° C.
At this point, the blinking of the halogen heater is turned off. As described above, if the fixing process is completed before the glass tube wall of the halogen heater reaches 250 ° C., if this state is repeated, the halogen cycle will not proceed, and the above-described inconvenience will occur.

In view of the characteristics of the halogen heater, the faster the rise of the roller surface temperature relative to the rise of the heater glass tube temperature, the more disadvantageous it is to the halogen cycle. Also, the lower the set temperature of the fixing, the more disadvantageously.

In the technique disclosed in Japanese Patent Application Laid-Open No. Hei 7-334030, the amount of energy to be applied to a halogen lamp is determined based on temperature information obtained by temperature detecting means, and an AC power supply having an amplitude corresponding to the energy amount is applied. A method for controlling the temperature of a halogen lamp has been proposed. In the technology disclosed in Japanese Patent Application Laid-Open No. 8-202200,
There has been proposed a method of controlling the temperature of a halogen lamp by blinking the halogen lamp based on the color temperature obtained by means for detecting the color temperature of tungsten.

However, in the configuration of the above-mentioned conventional technology,
In each case, a temperature detecting means is required, and there is a problem that not only the control becomes complicated but also the cost increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a fixing device which has a very simple structure and can prevent a problem that the life of a halogen heater is shortened.

[0009]

In order to achieve the above object, the image forming apparatus according to the first aspect of the present invention includes a halogen heater therein and blinks the halogen lamp at a predetermined set temperature. In the fixing device having a heating member, the minimum blinking time of the halogen heater at the time of rising until the heating member rises to a predetermined temperature and when fixing the unfixed toner on the transfer material is set. Features.

According to a second aspect of the present invention, in order to achieve the above object, the minimum blinking time is set during standby.

According to a third aspect of the present invention, there is provided a fixing device having a heating member provided with a halogen heater therein and using a halogen lamp to blink at a predetermined set temperature in order to achieve the above object. When the temperature rises to a predetermined temperature and when fixing the unfixed toner on the transfer material, the blinking time of the halogen heater is set so that it does not fall below a predetermined time only for a predetermined ratio of times. It is characterized by becoming.

According to a fourth aspect of the present invention, in order to attain the above object, the flashing time of the halogen heater is set so as not to fall below the predetermined time only at a predetermined ratio of times during standby. It is characterized by.

According to a fifth aspect of the present invention, in order to achieve the above object, the halogen heater is fixed at the time of startup until the heating member rises to a predetermined temperature, and the unfixed toner on the transfer material is fixed. It is turned on only when it is turned on, and turned off during other standby states.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a configuration of an electrophotographic apparatus to which a fixing device according to the present invention is applied. This apparatus supplies a charging unit 2, a cleaning device 3, a laser beam L by a laser optical system 4, and toner around a photoreceptor 1 rotating in the direction of an arrow in the drawing to visualize a latent image on the photoreceptor 1. Developing device 7 including developing sleeve 5
And a transfer means 6. Further, a sheet feeding cassette 1 which is disposed on the lower side of the drawing and is detachable in the direction of arrow a in the drawing.
Sheets P serving as transfer materials are loaded in the sheet 0. These sheets P are supported by an intermediate plate 11 and pressed against a sheet feed roller 13 via an arm 12 by the force of a spring (not shown). When the paper feed roller 13 is rotated based on a command from a control unit (not shown), the uppermost paper in the paper feed cassette 10 is prevented from being double-fed by the separation pad 14 and the registration roller 15 on the downstream side in the paper feed direction is prevented. To the transfer means 6 at a timing synchronized with the image on the photosensitive member 1.

The paper on which the toner image has been obtained from the photoreceptor 1 by the transfer paper means 6 is further conveyed to the fixing means 16, where the heat fixing roller 18 and the pressure roller 19 which presses against the heat fixing roller 18
Pass between The toner image is fixed on the paper by heating and pressing. Thereafter, the sheet on which the image has been formed is discharged from the discharge port 21 onto the discharge tray section 22 by the discharge roller 20 with the image side down, and placed. The ejection stopper is movable in the direction of arrow b in order to correspond to the size of the sheet to be ejected.

An operation surface is disposed on the right side of the figure, an operation panel 30 protrudes from an upper front surface of the exterior part 31 (right side on the apparatus in the figure), and a paper feed tray 32 is rotatable by a pin 33. It is attached to. In a case 34 arranged on the left side of the drawing, electrical equipment such as a power supply 35 and a printed board 36 (engine driver board) and a control device are housed. A controller board 37 is also stored.
The cover 38 constituting the paper discharge tray section 22 can be opened around a rotation fulcrum 39.

FIG. 2 is an axial sectional view of one embodiment of the fixing device according to the present invention. In this apparatus, a pressure roller 19 made of an elastic member such as silicon rubber is pressed against a heat fixing roller 18 by a spring (not shown) with a constant pressing force. The heat fixing roller 18 is connected to the fixing side plate 50 via heat insulating bushes 51, 51 and bearings 52, 52.
The gear 53 is engaged with a drive source (not shown) to perform rotational driving. The fixing roller 18 is based on a thin pipe made of Al or Fe. The thickness of the substrate is about 0.3 to 1.0 mm. A surface release layer is formed on the outer surface of the fixing roller 18.

A halogen heater 23 is provided inside the fixing roller 18. A temperature sensor 60 contacts the fixing roller 18, and a signal detected by the temperature sensor 60 is input to a CPU 63 via an input circuit 61. It is configured to control the power supply to the power supply. Normally, when the device is powered on, the driver 62
Current flows to the halogen heater 23 via the heater, and the temperature of the heat fixing roller rapidly rises to a set temperature at which fixing is performed.
The same applies to a belt or the like as a heating member instead of a roller.

Next, the operation of the present embodiment will be described. As already described with reference to FIG. 3, within the time when the glass tube wall temperature of the halogen heater 23 reaches 250 ° C., the temperature of the fixing roller 18 as a heating member reaches a set temperature required for fixing, and a series of fixing operations is performed. When the process is completed, the blinking of the halogen heater 23 is turned off at that point, and the halogen cycle ends incompletely. Therefore, the glass tube wall temperature of the halogen heater 23 is set to 250 in advance.
The time required to reach ° C. is measured, and this time is defined as the shortest blinking time of the halogen lamp 23. Control is performed so that the blinking of the halogen lamp 23 is not always turned off during the shortest blinking time or less. Therefore, even if the temperature of the core metal of the fixing roller 18 reaches the set temperature required for fixing within the shortest blinking time and a series of fixing process is completed, the halogen heater 23 keeps the glass tube wall temperature at 250 ° C. Flashes and always completes the halogen cycle. The shortest blinking time of the halogen lamp 23 varies depending on the configuration of the halogen heater to be used, input power, and the like, and can be set freely. In the case of performing preheating during standby, the shortest blinking time is set in the same manner as described above. This prevents the halogen cycle from becoming incomplete even when preheating is performed during standby.

As a second embodiment of the present invention, a detecting means (not shown) for counting the number of lighting of the halogen lamp 23 can be provided. With this configuration, control is performed such that the halogen lamp 23 does not turn off within the shortest flashing time or less, only once in a predetermined number of times. In this control, the promotion of the halogen cycle can be performed with the minimum necessary power consumption, and energy saving can be achieved.

In any of the embodiments, the power supply is turned on only when the copier or the printer is in use, and the power is turned off when the copier or the printer is not in use. When combined with the fixing device according to the embodiment of the present invention, the power consumption is reduced. Can be further suppressed, and further energy saving can be achieved.

[0022]

As described above, the fixing device according to the first aspect of the present invention has the shortest blinking time set in advance so that the blinking time of the halogen heater does not always fall below a predetermined time. In addition, there is an effect that the life of the halogen lamp can be prolonged by keeping the halogen cycle always occurring without the need for complicated control and temperature detecting means.

In the fixing device according to the second aspect of the present invention, as described above, when preheating is performed during standby, the fixing roller is preheated within the time when the glass tube wall temperature of the halogen heater reaches 250 ° C. Even if the temperature rises, the halogen lamp is kept blinking until the set shortest blinking time, so that the halogen cycle can be prevented from being incomplete. The preheating temperature is usually lower than the set fixing temperature, and the preheating temperature rises quickly with the preheating temperature. Therefore, in such a case, the above effects can be utilized.

As described above, the fixing device according to the third aspect of the present invention uses a halogen when the heating member rises to a predetermined temperature and when the unfixed toner on the transfer material is fixed. The flashing time of the heater is set so that it does not fall below the predetermined time only for a predetermined ratio, and the flashing time of the halogen lamp can be shortened to an extent that the halogen cycle is appropriately performed. Since the lighting time is reduced, there is an effect that not only power consumption is suppressed but also the life of the halogen lamp can be extended.

As described above, the fixing device according to the fourth aspect of the present invention is set so that the blinking time of the halogen heater does not fall below the predetermined time only at the predetermined ratio of times during standby. Therefore, even when preheating is performed, the halogen cycle can be prevented from being incomplete.

In the fixing device according to the fifth aspect of the present invention, as described above, the halogen heater is used at the time of rising until the heating member rises to a predetermined temperature and the unfixed toner on the transfer material. Power is turned on only when fixing, and turned off during other standby periods. Not only is suppressed, but also the life of the halogen lamp can be extended. In an image forming apparatus having an energy-saving type system that does not perform preheating, a high-speed start of a halogen lamp is required, and the above effects of the present invention can be utilized with such lamp characteristics.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an electrophotographic apparatus to which a fixing device according to the present invention is applied.

FIG. 2 is an axial sectional view of a fixing device according to an embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a core of a fixing roller and a temperature rise of a halogen heater tube wall and input power to a halogen heater in a fixing device of a high-speed rising type using a thin fixing roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 3 Cleaning device 4 Laser optical system 5 Developing sleeve 6 Transfer means 7 Developing device 10 Paper feed cassette 11 Middle plate 12 Arm 13 Paper feed roller 14 Separation pad 15 Registration roller 16 Fixing means 18 Fixing roller 19 Pressure Roller 20 Discharge roller 21 Discharge port 22 Discharge tray section 23 Halogen heater 24 Heater holding member 25 Support member for reinforcing member 26 Fixing roller surface release layer 27 Fixing roller core metal 28 Halogen heater glass tube 29 Halogen heater filament 30 Operation Panel 31 Exterior part 32 Feed tray 33 Pin 34 Case 35 Power supply 36 Printed board 37 Controller board 38 Cover 39 Rotating fulcrum 50 Side plate 51 Insulated bush 52 Bearing 53 Gear 60 Sensor 61 Input circuit 62 Drive 6 CPU

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Jun Yura 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H033 AA23 BA25 BB17 CA03 CA04 CA05 CA20 CA22 CA26 CA48 3K058 AA45 BA18 CA23 CE16 DA02 GA06

Claims (5)

[Claims] 1. A fixing device having a halogen heater therein and having a heating member used to blink the halogen lamp at a predetermined set temperature, at the time of startup and transfer until the heating member rises to a predetermined temperature. A fixing device, wherein a shortest blinking time of the halogen heater when fixing an unfixed toner on a material is set. 2. The fixing device according to claim 1, wherein the shortest blinking time is set during standby. 3. A fixing device having a heating member provided with a halogen heater inside and using a halogen lamp to blink at a predetermined temperature, wherein the heating member rises to a predetermined temperature and a transfer material. A fixing device, wherein when the above-mentioned unfixed toner is fixed, the blinking time of the halogen heater is set so as not to fall below a predetermined time only for a predetermined ratio. 4. The fixing device according to claim 3, wherein the flashing time of the halogen heater is set so as not to fall below the predetermined time only in a predetermined ratio during the standby time. 5. The halogen heater is turned on only when the heating member rises to a predetermined temperature and when unfixed toner on a transfer material is fixed, and is turned off during other standby periods. The fixing device according to claim 1, wherein: