JP2001194941A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device equipped with a thermal roller type fixing device constituted so that a heating roller having a light transmitting substrate can be held by being pressed to a press-fitting roller, the withstand load can be made large and it does not depend on the accuracy of a shaft part or a cylindrical heating roller part with a simple constitution. SOLUTION: This image forming device is provided with the roller type fixing device constituted so that both end shaft parts of a 1st roller having the cylindrical light transmitting substrate are pressed and supported through a rotatable member and brought to press-contact with a 2nd roller opposed to the 1st roller.

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 such as a copying machine, a printer, and a facsimile, and more particularly, to an image forming apparatus configured to form a toner image on a sheet using an electrophotographic method.

[0002]

2. Description of the Related Art A sheet carrying an unfixed toner image is placed on a heat roller-type fixing device including a heating roller maintained at a predetermined temperature range and a pressure roller rotating while being pressed against the heating roller. An electrophotographic system such as a copying machine, a printer, a facsimile, and a multifunction machine having these functions, which is configured to guide and fix the toner image on paper through heating and pressurizing action by the pair of rollers. Known image forming apparatuses are used, and it is also well known that the heat roller type fixing apparatus is widely used from low-speed machines to high-speed machines, and from monochrome machines to color machines.

In recent years, there has been proposed a fixing device incorporating a quick start fixing method which does not require much warming-up time. One type of the fixing device is a heating roller using a light-transmitting substrate made of glass or resin. There has been proposed a configuration in which a toner image is heated and fixed by irradiating a toner image with heat rays from a halogen heater provided inside the heating roller.
No. 1 publication.

In order to cope with a color image, a configuration has been proposed in which an absorbing layer provided on a light-transmitting substrate once absorbs halogen light to generate heat.

[0005]

However, in a heat roller type fixing device (hereinafter sometimes simply referred to as a fixing device) in which a heat roller is formed by using a light-transmitting substrate as described above, the shaft of the heat roller is used. Even if an attempt is made to carry the bearing through a normal bearing or the like, there is a difference in the coefficient of thermal expansion between the material of the bearing and the light-transmitting base, or the accuracy of the light-transmitting base, especially in the shaft part, is sufficiently high. There is a problem that a normal bearing cannot be used because it cannot be obtained.

In other words, in consideration of the low accuracy and the variation, it is considered that the bearing is supported by an appropriate bearing having a large inner diameter. However, in such a case, the frequency of the backlash increases.

At the same time, the parallelism between the pressure roller and the pressure roller which rotates while being pressed against the heat roller is less likely to occur. As a result, the contact between the bearing and the shaft portion of the heat roller becomes point contact, and stress concentration occurs. (Substantially the same as the total load necessary for fixing) has to be reduced, and it has been found that a problem of causing defective fixing occurs.

[0008] Further, if there is a minute defect in the translucent substrate, there is a concern that the substrate may be damaged. Breakage of the translucent substrate may cause disconnection or short circuit of the built-in halogen heater.

As a countermeasure for this, a configuration is conceivable in which an abnormality is detected by monitoring the temperature. However, it takes time until the detection after the circuit for the halogen heater is cut, and the circuit cannot be cut before the short circuit. May occur.

Further, even if a breaker is provided in the circuit, the circuit cannot be cut off until a short circuit occurs, and problems such as breakage of equipment due to the short circuit cannot be prevented.

The above various problems tend to occur particularly when the light-transmitting substrate is glass.

The present invention has been made in view of the above points, and a main object of the present invention is to enable a simple structure to hold a heating roller having a light-transmitting substrate in a pressed state against a pressure roller and to reduce a load resistance. An object of the present invention is to provide an image forming apparatus having a heat roller type fixing device having a configuration which does not depend on the accuracy of a shaft portion or a cylindrical heating roller portion, while increasing the size.

Another object of the present invention is to minimize the adverse effects caused by backlash and stress concentration, even if the shaft of the heating roller having the light-transmitting substrate is held by a bearing having backlash. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

It is still another object of the present invention to provide an image forming apparatus capable of detecting a circuit disconnection before a short circuit of a halogen heater and preventing a danger caused by an electric leakage to an apparatus body or the like.

[0015]

The object of the present invention can be achieved by the following constitutions.

(1) Both end shafts of a first roller having a cylindrical light-transmitting substrate are pressed and supported via a rotatable member, and the first roller is fixed to a second roller facing the first roller. An image forming apparatus, comprising: a roller-type fixing device that is brought into pressure contact with the image forming apparatus.

(2) The image forming apparatus according to (1), wherein the rotatable member is a roller arranged two on each side with respect to a shaft of the first roller.

(3) The image forming apparatus according to (2), wherein an outer peripheral portion of the roller is covered with rubber.

(4) The rollers (2) or (3), wherein the rollers provided in relation to both shaft portions of the first roller and located at opposing positions are coaxially provided. The image forming apparatus according to (3).

(5) A first roller having a cylindrical light-transmitting substrate and a rubber layer covering an outer peripheral portion of the light-transmitting substrate, and the rubber layers at both ends of the first roller interposed therebetween. A roller-type fixing device including a rotatable member that presses and supports the first roller, and a second roller that presses against the first roller via the pressing force of the rotatable member. Image forming device.

(6) The image forming apparatus according to (5), wherein the rotatable member is a roller.

(7) The image forming apparatus according to (6), wherein an outer peripheral portion of the roller is covered with rubber.

(8) The rollers provided in relation to both ends of the first roller and located at opposing positions are
The image forming apparatus according to the above (6) or (7), which is provided coaxially.

(9) A first roller having a cylindrical light-transmitting substrate, a second roller which rotates while being in pressure contact with the first roller, and pressure contact between the first and second rollers. And an endless belt disposed at both ends of the two rollers.

(10) The image forming apparatus according to (9), wherein the endless belt is made of silicone rubber.

(11) The image forming apparatus according to (9) or (10), wherein the cross section of the endless belt is rectangular.

(12) The second roller is a driving roller, and the first roller is formed of the endless belt and the second roller.
The image forming apparatus according to (9), wherein the image forming apparatus rotates by a frictional force with a roller.

(13) The first having a cylindrical light-transmitting substrate which rotates around a halogen heater incorporated in a fixed position.
A second roller rotating while pressing against the first roller;
An image forming apparatus comprising: a roller-type fixing device including a roller; and a disconnection detecting circuit that detects disconnection of the halogen heater.

(14) A triac for controlling on / off of the halogen heater is provided in a closed circuit between the halogen heater and the power supply, and the triac is activated when the disconnection detecting circuit detects disconnection of the halogen heater. The image forming apparatus according to (13), wherein the image forming apparatus is configured to disconnect the closed circuit.

(15) The disconnection detection circuit is of a type that monitors a voltage in the circuit.
Alternatively, the image forming apparatus according to (14).

(16) The image forming apparatus according to (13), wherein the disconnection detecting circuit operates only when the triac is in a conductive state.

(17) The image forming apparatus as described in any one of (1), (5), (9) and (13) above, wherein the cylindrical translucent substrate is glass. apparatus.

[0033]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus including a color printer. In FIG. 1, reference numeral 10 denotes a photosensitive drum (hereinafter simply referred to as a drum) as an image forming body; 11, a scorotron charger as a charging unit for each color; 12, an exposure optical system as an image writing unit for each color;
Reference numeral 3 denotes a developing device as a developing unit for each color, and 14 denotes a transfer belt.

The drum 10 is formed, for example, by forming a transparent conductive layer, an a-Si layer or an organic photosensitive layer (OPC) on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. Photosensitive layer (also called photoconductive layer)
And rotated clockwise as indicated by the arrow in FIG. 1 with the conductive layer grounded.

A scorotron charger 11, which is a charging unit for each color, an exposure optical system 12, which is an image writing unit for each color, and a developing unit 13, which is a developing unit for each color, form a set of yellow (Y) ), Magenta (M), cyan (C), and black (K) are provided for the image forming process, and four sets are provided.
With respect to the 0 rotation direction, Y, M, C, and K are arranged in this order.

The scorotron charger 11, which is a charging means for each color, has a control grid maintained at a predetermined potential and a discharge electrode 11a composed of, for example, a sawtooth electrode. Mounted facing each other,
The charging operation (minus charging in the present embodiment) is performed by corona discharge having the same polarity as the toner, and the photosensitive drum 1 is charged.
A uniform potential is given to 0.

As the discharge electrode 11a, a wire electrode or a needle electrode can be used.

Exposure optical system 1 as image writing means for each color
2 indicates that the exposure position on the drum 10 is the photosensitive drum 10 with respect to the scorotron charger 11 for each color described above.
Is arranged inside the drum 10 so as to be located on the downstream side in the rotation direction of the drum 10.

Each exposure optical system 12 has a linear exposure element 12a in which a plurality of LEDs (light emitting diodes) as light emitting elements of image exposure light arranged in the main scanning direction in parallel with the drum axis are arranged in an array. And a light converging light transmitter (trade name: Selfoc lens array) 12b as an imaging element
And a lens holder (not shown), which is attached to a holding member 120.

In addition to the exposure optical system 12 for each color, a transfer simultaneous exposure unit 12d and a uniform exposure unit 12e are attached to the holding member 120, and are integrally accommodated in the base of the drum 10.

The exposure optical system 12 for each color performs image exposure of the photosensitive layer of the drum 10 from the back side in accordance with image data of each color read by a separate image reading device and stored in a memory, An electrostatic latent image is formed.

As the exposure element 12a, besides LED, F
It is also possible to use a plurality of light-emitting elements such as L (phosphor emission), EL (electroluminescence), and PL (plasma discharge) arranged in an array.

The emission wavelength of the exposure element is usually Y, M,
A toner having a high transmittance in the range of 780 to 900 nm for the C toner is used. However, in this embodiment, since the image is exposed from the back surface, the toner does not have sufficient transmittance for the color toner. 400-780 shorter than this
nm wavelength.

A developing device 13 which is a developing means for each color maintains a predetermined gap with respect to the peripheral surface of the drum 10 and has a cylindrical non-magnetic stainless steel or aluminum which rotates in a forward direction with respect to the rotating direction of the drum 10. A developing sleeve 131 formed of a material, and a developing casing 138. Inside the developing casing 138, one component of yellow (Y), magenta (M), cyan (C) and black (K) or Contains a two-component developer.

Each of the developing devices 13 is kept in a non-contact state with a predetermined gap from the drum 10. By applying a developing bias in which a DC voltage and an AC voltage are superimposed on the developing sleeve 131, A contact reversal development is performed to form a toner image on the drum 10.

14a and 14b are transfer belts 14
The transfer belt 14a receives power from a drive source (not shown) and rotates the transfer belt in the direction of the arrow.

Reference numerals 15 and 16 denote transfer units and static eliminators, which are first and second transfer means disposed opposite to the drum 10 with the transfer belt 14 interposed therebetween, and 17 denotes the drum 10 after the transfer step. AC static eliminator for static elimination, 1
Reference numeral 8 denotes a cleaning device that cleans the drum surface after static elimination, and has a cleaning blade 180.

Reference numeral 20 denotes a cassette containing paper P on which the toner image formed on the drum 10 is transferred,
Reference numeral 5 denotes a paper feed roller.

On the moving path of the paper P, there are provided a pair of transport rollers R1 to R5, the transfer belt 14, a heat roller type fixing device 30, and the like.

Reference numeral 44 denotes an AC static eliminator for separating the paper, which is disposed to face the roller 14a via the transfer belt 14.

The fixing device 30 includes a halogen heater 30
0, and a second roller (second fixing roller) 315 that can rotate around the halogen heater and that can rotate while being in pressure contact with the first roller 305. Have.

T indicates a nip portion. The first roller 30
Numeral 5 is made of a light-transmitting substrate. In the embodiment, the thickness is 1.6 such that the outer diameter of the cylindrical portion having a fixing function is 30 mm and the outer diameter of the shaft portion provided on both outer sides of the portion is 27 mm.
mm of glass.

The cylindrical portion is covered with transparent silicon rubber, and a PFA (perfluoroalkoxy) tube in which carbon is dispersed is covered as an infrared absorbing layer on the outside thereof.

The second roller 315 has a silicon rubber surface and has a built-in heater 310 composed of a xenon lamp or a xenon lamp.

In the drawing, reference numeral 46 denotes a separation claw for reliably separating the sheet P after the transfer, which is fed integrally with the transfer belt 14, and has a leading end with respect to the surface of the transfer belt 14 on the roller 14a. It is positioned in close proximity.

The image forming process in the image forming apparatus having the above configuration is as follows.

A drum drive motor (not shown) is started by the start of image formation, and the drum 10 is rotated clockwise as shown by the arrow in FIG. 1, and at the same time, the yellow (Y) scorotron charger 11 is operated to activate the drum 10 To a predetermined potential.

Subsequently, the image writing by the first color signal, ie, the electric signal corresponding to the Y image data is started via the Y exposure optical system 12, and the Y image of the original image is formed on the surface of the drum 10. A corresponding electrostatic latent image is formed.

The electrostatic latent image is reversely developed by the Y developing unit 13 in a non-contact state, and a yellow (Y) toner image is formed on the drum 10.

Next, a potential is applied to the drum 10 from above the Y toner image by the charging action of a magenta (M) scorotron charger 11, and a second color signal, that is, an M image is applied by an M exposure optical system 12. An electrostatic latent image corresponding to the M image is formed by writing an image using an electric signal corresponding to the data, and is formed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13. A magenta (M) toner image is formed to overlap.

According to the same process, the cyan (C) toner image corresponding to the third color signal is superimposed by the cyan (C) scorotron charger 11, the exposure optical system 12 of C, and the developing device 13 of C. The black (K) toner image corresponding to the fourth color signal is sequentially superimposed thereon by a black (K) scorotron charger 11, a K exposure optical system 12, and a K developing device 13. A superposed color toner image of four colors of yellow (Y), magenta (M), cyan (C) and black (K) is formed on the peripheral surface within one rotation of the photosensitive drum 10. .

These Y, M, C and K exposure optical systems 1
2 for writing an image on the photosensitive layer of the drum 10
It is performed from the inside of the drum 10 through the above-mentioned translucent substrate.

Therefore, the writing of the images corresponding to the second, third and fourth color signals is performed without any influence from the previously formed toner image, and corresponds to the first color signal. It is possible to form an electrostatic latent image equivalent to an image.

The superimposed color toner images formed on the drum 10 as the image forming body by the above image forming process are collectively transferred onto the paper P by the transfer unit 15 in the transfer area.

At this time, a uniform exposure is performed by energizing the simultaneous transfer exposure device 12d provided inside the drum 10 so that good transfer is performed.

After the transfer process, the toner remaining on the peripheral surface of the drum 10 is subjected to a charge removing operation by the AC charge remover 17 and then cleaned by a cleaning device 18, whereby the surface of the drum 10 is moved to the next position. Provided for image formation.

In the embodiment, after cleaning and before the next charging, the uniform exposure device 12e using, for example, a light emitting diode is operated to eliminate the history of the preceding image formation on the drum surface.

The paper P on which the color toner image is formed is A
By the static elimination action by the C static eliminator 44 and the separation claw 46,
The toner image is separated from the transfer belt 14 and conveyed to the fixing device 30, where the toner image is
Settled on top.

The recording paper P on which the double-sided image recording has been performed is sent upside down, and is discharged to a tray on the upper portion of the apparatus by conveyance rollers R3, R4, and R5.

Although the details will be described later, the embodiment of the image forming apparatus in which the fixing device of the present invention is used has been described with reference to color image formation. However, the present invention is not limited to this. It is also applied to formation.

FIG. 2 shows the structure of the first roller 305 and the second roller 315 which are the main elements of the heat roller type fixing device 30,
In particular, FIG. 3 is a schematic side sectional view illustrating a mechanism for pressing and holding the first roller against the second roller, and FIG. 3 is a schematic view illustrating a shaft provided on the first roller.

In the figure, the same members as those described above are denoted by the same reference symbols. In the figure, the first roller 3
Reference numeral 05 denotes a roller that functions as a fixing roller member for fixing the toner image, and second roller 315 is a roller that functions as a lower fixing roller member.

The rollers 305 and 315 are pressed (closely contacted) with a predetermined pressure, and rotate in the same direction at the contact portion (nip portion T) while maintaining the pressure contact state during operation, thereby exerting the above function.

The first roller 305 is formed of a cylindrical (contributing as a fixing means) transparent substrate 3 made of glass.
07, a transparent silicon rubber layer 308 provided outside (outer peripheral surface) of the light-transmitting substrate 307, and an infrared absorbing layer 309 provided further outside.

The second roller 315 comprises a cylindrical metal pipe 316 made of, for example, an aluminum material and an outer peripheral surface of the metal pipe 316 covered with, for example, a silicon rubber layer 317. As a soft roller having a halogen heater 310 disposed therein.

Reference numerals 306 denote shaft portions provided at both ends of the first roller 305. The shaft portions are in pressure contact with the second roller and have an outer diameter smaller than the outer diameter of a cylindrical portion that contributes as fixing means.

Two rotatable members 50 for applying a pressing force through the outer periphery of the shaft portion and holding the position of the first roller are provided above and below the left and right shaft portions 306.

The rotatable member in the embodiment is a roller (a roller having a roller-shaped outer shape and a small width, hereinafter referred to as a roller 50), and is attached to a frame (not shown) via a tension spring.

Outer circumference and / or shaft 3 of the roller 50
From the viewpoint of preventing the translucent substrate from being damaged,
It is desirable to provide an appropriate coating.

For example, in the case of a metal roller, it is conceivable to coat the outer periphery with silicon rubber or a heat-resistant resin, and rubber coating is particularly preferable.

The rollers can be made of a heat-resistant resin. In this case, however, it is preferable that a rubber layer is interposed between the rollers and the shaft.

As described above, both shaft portions of the first roller 305 are
By holding each of the two rollers, the stress applied to the light-transmitting substrate 307 can be dispersed and the load resistance can be improved, and even if the external shape of the substrate is slightly varied, it can be held without rattling. It becomes possible.

Although the structure of the first roller, particularly the dimensions, has been described above, the roller 50 in the embodiment has an outer diameter of 20 mm and a width of 20 mm, and the total load on the second roller 315 is 20 kgf. Configured.

The rollers provided at the shaft portions at both ends of the translucent substrate 307 and opposed to each other with the central cylindrical portion interposed therebetween should preferably be provided coaxially, if possible.
This is preferable in terms of simplification of the mechanism and reliability of holding.

FIGS. 4 to 6 show that the first roller 305 is
FIG. 13 is a schematic side view showing second to fourth modes in which a roller 315 is pressed and held.

In the drawings, the same members as those described above or members having the same functions are denoted by the same reference symbols.

The first roller 305 has the same layer configuration as that of FIG. In the configuration of FIG.
A central portion of the first roller 305, that is, a portion contributing as a fixing unit is formed to be slightly longer, and two rollers similar to those shown in FIG. It is arranged.

This configuration is effective for a finished roller in which the eccentricity between the light-transmitting substrate and the rubber layer is large when the shaft portion of the light-transmitting substrate is held, and the deflection of the entire roller becomes too large.

In this embodiment, it is described that the rollers provided on both sides of the first roller and opposed to each other are provided coaxially, and the configuration of the rollers is desirably rubber-coated. Is the same as

In the configuration shown in FIG. 5, the first roller 305
An endless belt 330 is provided crosswise between shaft portions provided on both sides of the second roller 315 and the second roller 315.

The endless belt 330 is made of silicone rubber and has a rectangular cross section.

In the configuration shown in FIG. 6, the first roller 305
An endless belt 330 is suspended between two shafts 306 and two pulleys 350 provided at a fixing portion of the fixing device.

Although the cross section of the endless belt 330 is also rectangular, a desired function (the first roller can be pressed against the second roller with a predetermined pressing force, and the rotation of both rollers in the pressed state). The cross-sectional shape need not be rectangular, and the thickness or width of the endless belt can be determined as appropriate.

In FIGS. 1 to 6, the second roller 315 is a driving roller, but a power transmission mechanism from a driving source is not shown because a known structure can be used.

As shown in FIGS. 5 and 6, the use of the silicone rubber as the endless belt not only can withstand the temperature rise due to the leakage of heat for fixing, but also has the flexibility of the belt. The influence of backlash due to the low accuracy of the outer shape of the translucent substrate can be suppressed, and a large fixing load can be applied.

The use of the endless belt is a form in which the endless belt transmits a part of the driving force, so that the shear force applied to the rubber layer of the roller can be reduced in the drive transmission due to the friction between the rollers. it can.

The cross-sectional shape of the endless belt is made rectangular so that the contact area with the first roller can be made larger, avoiding stress concentration on the translucent substrate and transmitting a large driving force. Is what you expect.

As the translucent substrate 307 constituting the first roller 305, in addition to glass, which is defined as an inorganic substance obtained by cooling and solidifying a melt without depositing crystals, a halogen heater 300 (halogen) is used. A ceramic material such as Pyrex glass, sapphire (Al ₂ O ₃ ), or CaF ₂ that transmits light from an irradiation member such as a lamp, or a translucent resin using polyimide, polyamide, or the like can be used.

The wavelength of light passing through the translucent substrate 171a is 0.1 to 20 μm, preferably 0.3 to 3 μm.
Therefore, an adjuster for hardness and thermal conductivity is added as a filler, but the particle size is １ ／ of the wavelength of light, preferably 1
Metal oxides such as titanium oxide, aluminum oxide, zinc oxide, silicon oxide, magnesium oxide, calcium carbonate and the like having a heat ray transmission (mainly infrared or far infrared ray transmission) of / 5 or less, preferably 1 μm or less, preferably 0.1 μm or less. The transparent substrate may be formed by dispersing fine particles of the above in a resin binder.

Instead of a PFA tube in which carbon black is dispersed in a resin binder, graphite, iron black (F
e ₃ O ₄ ), various ferrites and compounds thereof, copper oxide, cobalt oxide, powder containing bengara (Fe ₂ O ₃ ), etc., is mixed with a layer having a thickness of 10 to 200 μm, preferably 20 to 100 μm.
The first roller can be formed by baking or coating the outer peripheral surface of the light-transmitting substrate 307 so as to have a thickness of μm, and can be rapidly heated.

FIG. 7 is a circuit diagram for explaining a disconnection detecting circuit for detecting disconnection of the halogen heater 300 and disconnecting the circuit to prevent damage to other parts of the device due to short circuit.

In the figure, reference numeral 600 denotes a power supply for a halogen heater, which is normally connected to a commercial power supply as it is.

Reference numeral 610 denotes a triac for controlling on / off of the halogen heater 300 based on information from a temperature sensor such as a thermistor for detecting the surface temperature of the first roller (not shown). Reference numeral 680 denotes a temperature fuse installed near the roller. , 670 is a main relay which operates without a software through a signal from a temperature sensor for temperature control or a temperature sensor for abnormality detection, and 630 is a solid state relay. These means (members) are normally closed. Halogen heater 300 including a breaker 620
To form a closed circuit.

That is, the energization control (on) of the halogen heater 300 is performed by closing the circuit of the triac 610, and the temperature of the surface of the first roller 305 reaches the predetermined temperature according to the information of the temperature sensor. Then, the triac 610 opens the circuit and controls the energization (off) of the halogen heater.

When the circuit is closed, the anode-side contact 6 of the resistor 640 having ends connected to the anode side and the cathode side of the solid-state relay 630, respectively.
A predetermined voltage is generated at 50.

When the circuit is open, no voltage is generated at the contact. Therefore, the presence or absence of an abnormality is determined by monitoring the information of the sensor (not shown) and the closing / opening of the circuit by the control unit. You.

In the embodiment, the resistance 640,
The contact 650 and the detection circuit 660 for detecting the disconnection of the halogen heater connected to the contact constitute a disconnection detection circuit.

With such a configuration, if the detection circuit 660 outputs that the voltage generated at the contact 650 is equal to or lower than a predetermined voltage while the ON signal is being sent to the triac 610, The triac 610 is configured to be turned off (opened) via the switch.

[0110]

According to the present invention, a light-transmissive substrate which is difficult to be precise or has a risk of breakage can be effectively or safely used as a roller of a heat roller type fixing device.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus including a color printer.

FIG. 2 is a schematic side cross-sectional view for explaining the configuration of a first roller and a second roller, which are main elements of the heat roller type fixing device, and particularly, a mechanism for pressing and holding the first roller against the second roller.

FIG. 3 is a schematic view showing a shaft provided on a first roller.

FIG. 4 is a schematic side view showing a second mode in which a first roller is pressed and held against a second roller.

FIG. 5 is a schematic side view showing a third mode in which a first roller is pressed and held against a second roller.

FIG. 6 is a schematic side view showing a fourth mode in which a first roller is pressed and held against a second roller.

FIG. 7 is a circuit diagram for explaining a disconnection detection circuit for detecting disconnection of a halogen heater, disconnecting the circuit, and avoiding damage to other parts of the device due to short circuit.

[Explanation of symbols]

 Reference Signs List 30 heat roller type fixing device 300 halogen heater 305 first roller 307 translucent substrate 308 silicon rubber layer 309 infrared absorption layer 310 heater 315 second roller 330 endless belt 350 pulley 600 power supply 610 triac

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F16C 13/06 F16C 13/06

Claims (17)

[Claims] 1. A first roller having a cylindrical light-transmitting substrate, which is supported by pressing both end shafts via a rotatable member, and wherein the first roller is mounted on a second roller opposed to the first roller. An image forming apparatus comprising: a roller-type fixing device that is brought into pressure contact. 2. The image forming apparatus according to claim 1, wherein the rotatable member is a roller arranged two on each side with respect to a shaft of the first roller. 3. The image forming apparatus according to claim 2, wherein an outer peripheral portion of the roller is covered with rubber. 4. The roller according to claim 2, wherein the rollers provided in relation to the shaft portions at both ends of the first roller and located at opposing positions are provided coaxially. An image forming apparatus according to claim 1. 5. A first roller having a cylindrical light-transmitting substrate and a rubber layer covering an outer peripheral portion of the light-transmitting substrate, and a rubber layer at both ends of the first roller,
An image, comprising: a roller-type fixing device including a rotatable member that presses and supports the first roller, and a second roller that presses against the first roller via a pressing force of the rotatable member. Forming equipment. 6. The image forming apparatus according to claim 5, wherein the rotatable member is a roller. 7. The image forming apparatus according to claim 6, wherein an outer peripheral portion of the roller is covered with rubber. 8. The roller according to claim 6, wherein said rollers provided in relation to both ends of said first roller and located at opposing positions are provided coaxially.
An image forming apparatus according to claim 1. 9. A first roller having a cylindrical light-transmitting substrate, a second roller rotating while being in pressure contact with the first roller, and a pressure contact between the first and second rollers. And an endless belt disposed on both ends of the two rollers, and a roller-type fixing device. 10. The image forming apparatus according to claim 9, wherein said endless belt is made of silicone rubber. 11. The image forming apparatus according to claim 9, wherein a cross section of the endless belt has a rectangular shape. 12. The second roller is a driving roller,
The image forming apparatus according to claim 9, wherein the first roller rotates by a frictional force between the endless belt and the second roller. 13. A roller type including: a first roller having a cylindrical light-transmitting substrate, which rotates around a halogen heater incorporated in a fixed position, and a second roller which rotates while being in pressure contact with the first roller. An image forming apparatus comprising: a fixing device; and a disconnection detection circuit that detects disconnection of the halogen heater. 14. A triac for controlling on / off of a halogen heater is provided in a closed circuit between the halogen heater and a power supply, and when the disconnection detection circuit detects disconnection of the halogen heater, the triac is activated. 2. The apparatus according to claim 1, wherein the closed circuit is disconnected.
4. The image forming apparatus according to 3. 15. The image forming apparatus according to claim 13, wherein the disconnection detection circuit is of a type that monitors a voltage in the circuit. 16. The image forming apparatus according to claim 13, wherein the disconnection detection circuit operates only when the triac is in a conductive state. 17. The image forming apparatus according to claim 1, wherein the cylindrical light-transmitting substrate is glass.