JP2951384B2 - Thermal development section of thermal development image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) A plurality of heating rollers for guiding one of a pair of endless belts, and the other of the pair of endless belts for guiding the other belt A plurality of pressure rollers for pressing the one of the belts, and a driving unit for rotating the heating roller,
A temperature sensor that contacts at least one of the pair of endless belts and detects the temperature thereof; and a control that drives a heater in the heating roller based on the output of the temperature sensor to control at least one of the pair of endless belts to a predetermined temperature. Department and
By sandwiching the photosensitive material on which the image receiving material is superimposed between a pair of endless belts, the photosensitive material is heated to release the thermally developed diffusible dye applied to the photosensitive material, and the dye is thermally transferred to the image receiving material. The present invention relates to a heat development section of a heat development image forming apparatus.

BACKGROUND OF THE INVENTION Numerous methods have been proposed for diffusion transfer type thermal development in which a diffusible dye is released by thermal development and the dye is thermally transferred to an image receiving element to separate a silver image and a dye to obtain a color image. ing. Further, many techniques have been disclosed for the heat development, the image receiving element, the heat development method and the apparatus.

FIG. 11 is a configuration diagram of a heat development section of a conventional heat development image forming apparatus, and FIG. 12 is a sectional view taken along line AA in FIG. In these figures, reference numerals 1 and 2 denote a pair of endless belts, an upper belt and a lower belt. A plurality of heating rollers for guiding the lower belt 2 are provided inside the lower belt 2. A heater 4 is provided inside the heating roller 3 as a heat source.

Reference numeral 5 denotes a plurality of pressure rollers provided inside the upper belt 1 for guiding the upper belt 1 and pressing the upper belt 1 against the lower belt 2 by the pressing means 6.

Reference numeral 7 denotes a motor as a drive unit having a pinion 8 attached to an output shaft. On the other hand, a gear 9 that meshes with a pinion 8 is attached to the last roller 5 ′ of the pressure roller 5, and the last roller 5 ′ is a driving roller that is driven to rotate by a motor 7.

Reference numeral 10 denotes a photosensitive sheet (photosensitive material) on which an image receiving sheet 11 (image receiving material) is superimposed.

Downstream of each heating roller 3, as shown in FIG. 12, a temperature sensor 12 for detecting the temperature of the lower belt 2 is provided.

Next, attachment of the temperature sensor 12 will be described with reference to FIG. Reference numeral 13 denotes an inner frame of the heat developing section. Reference numeral 14 denotes a temperature sensor support plate disposed on the downstream side of each heating roller 3 substantially in parallel with the rotation axis of each heating roller 3 and attached so as to bridge between the respective sides of the inner frame 13. . In mounting the temperature sensor support plate 14, one end is engaged with a fixing pin 15 erected on one side of the inner frame 13, and the other end is provided with a screw 16 on the other side of the inner frame 13. By loosening this screw, the temperature sensor outlet formed on the other side of the inner frame 13
From 13a, it can be removed.

The temperature sensor 12 is mounted on a heat-insulating temperature sensor support 17 for preventing and removing the influence of disturbance. The temperature sensor support 17 is held by a holder 18. Reference numeral 19 denotes one end attached to the approximate center of the temperature sensor support base 14, the other end attached to the holder 18, and the holder 18
It is a temperature sensor pressurizing unit that urges in the direction.

The temperature sensor 12 is pressed against the lower belt 2 via the temperature sensor protection layer 20. Reference numeral 21 denotes a temperature sensor code having one end connected to the temperature sensor 12 and the other end connected to a control unit (not shown), and transmitting a detection signal of the temperature sensor 12 to the control unit.

 Next, the operation of the above configuration will be described.

The upper belt 1 and the lower belt 2 are heated to a developing temperature of about 150 ° C. by a heating roller 3. Then, the photosensitive sheet 10 on which the image receiving sheet 11 is superimposed is inserted between the upper belt 1 and the lower belt 2, and is conveyed to these belts 1 and 2 while being pressed and heated. The photosensitive sheet 10 is pressurized and heated to release the applied thermally developed diffusible dye, and the dye is thermally transferred to the image receiving sheet 11.

At this time, the temperature sensor 12 always detects the temperature of the lower belt 2, and a control unit (not shown) turns on the heater 4 in the heating roller 3 so that the temperature of the lower belt 2 becomes a predetermined developing temperature (150 ° C.). / OFF control.

(Problem to be Solved by the Invention) In the conventional example of the above configuration, the temperature sensor 12 is pressed into contact with the lower belt 2 via the temperature sensor protection layer 20. On the other hand, since the lower belt 2 is made of a material such as rubber, the lower belt 2 is easily worn.
There is a problem that the pressing portion of the temperature sensor 12 gradually wears.

This wear point is located substantially at the center of the lower belt 2. When the substantially central portion of the lower belt 2 is scraped in this way, thermal transfer at this portion is not sufficiently performed, and the image receiving sheet 11
However, there is a problem that the density in the flow direction at the center of the image area becomes low, resulting in density unevenness.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat developing unit of a heat developing image forming apparatus capable of preventing density unevenness.

(Means for Solving the Problems) The present invention for solving the above problems includes a pair of endless belts,
A plurality of heating rollers for guiding one of the pair of endless belts; and a plurality of heating rollers for guiding the other of the pair of endless belts and pressing the other belt against the one belt. A pressure roller, a driving unit that rotationally drives the heating roller, a temperature sensor that contacts at least one of the pair of endless belts and detects the temperature thereof, and a heater in the heating roller based on an output of the temperature sensor. A control unit that drives and controls at least one of the pair of endless belts to a predetermined temperature, and by sandwiching a photosensitive material on which an image receiving material is superimposed, between the pair of endless belts, In the heat development section of the heat development image forming apparatus which heats and releases the thermally developed diffusible dye applied to the photosensitive material, and thermally transfers the dye to the image receiving material, the temperature sensor includes The image area outside of the position on the belt, is characterized in that from the image region is brought into contact with a position deviated in the width direction of the endless belt.

(Operation) In the heat development section of the heat development image forming apparatus of the present invention, the temperature sensor does not contact the image area of the endless belt.
Wear of the endless belt due to the temperature sensor does not occur in the image area, and density unevenness does not occur.

Example Next, an example of the present invention will be described with reference to the drawings. First
FIG. 2 is a configuration diagram of a heat development section of a heat development image forming apparatus for explaining a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line BB in FIG. 2, and FIG. FIG. 3 is a configuration diagram of a heat development unit of the heat development image forming apparatus to be described, FIG. 3 is a cross-sectional view taken along line CC of FIG. 1, FIG. 4 is an overall configuration diagram of the heat development image forming apparatus of the present embodiment, FIG. Is an explanatory view of the photosensitive material, FIG. 6 is a detailed view of the temperature sensor pressurizing section, FIG. 7 is a view for explaining how to attach the temperature sensor pressurizing section shown in FIG. 6, and FIG. 9 is a block diagram of the second embodiment, and FIG. 10 is a diagram for explaining temperature control of the first and second embodiments.

First, the overall configuration of the heat development image forming apparatus of this embodiment will be described with reference to FIG.

The heat development image forming apparatus includes a photosensitive sheet pickup unit 30 for picking up a photosensitive sheet cut to a predetermined size, and a photosensitive sheet for positioning the picked up photosensitive sheet at a desired position on a transport path and transporting the photosensitive sheet to an exposure system. A sheet transport unit 31, an exposure optical unit 32 for imagewise exposing the photosensitive sheet, a photosensitive sheet transport unit 35 for transporting an imagewise exposed photosensitive sheet to a superimposing unit for overlapping the image receiving sheet, a photosensitive sheet and an image receiving sheet A superimposing unit 36 that conveys the superimposed image to the heat developing unit, an image receiving sheet pickup unit 33 that picks up an image receiving sheet cut to a predetermined size,
An image receiving sheet transport unit 34 that positions the picked-up image receiving sheet at a predetermined position on the transport path and then transports the image receiving sheet to the superimposing unit, and develops the photosensitive sheet at a high temperature while maintaining the close contact between the superposed photosensitive sheet and the image receiving sheet. It has a thermal developing unit 38 for transferring the generated diffusible dye to the image receiving sheet, a peeling unit 41 for peeling off the photosensitive sheet and the transfer sheet in a high temperature state after the thermal development transfer, and a discharge unit 45 for discharging the transfer sheet. ing.

Next, the color photothermographic material used in this example will be described. The color photothermographic material contains a binder, an organic silver salt, a photosensitive silver halide, a developer, a dye-donating substance, and the like in a photosensitive layer or a layer adjacent thereto.

Examples of the organic silver salt include silver galloic acid, silver oxalate, silver behenate, silver stearate, silver palmitate, silver imidazole, silver benzotriazole,
Examples thereof include silver sulfobenzotriazole, silver thione, silver saccharinate, silver 5-nitrotriazole, silver 4-hydroxybenzotriazole, silver thione, and silver 5-chlorosalicylaldoxime.

Examples of the photosensitive silver halide include silver chloride, silver bromide, silver iodide, silver chlorobromide, silver chloroiodide, silver iodobromide, and silver chlorobromoiodide. Preferred grain sizes for the photosensitive silver halide are from about 1.5 microns to about 0.001 microns in grain size.
More preferably, from about 0.5 microns to about 0.05 microns.

Examples of the developer include phenols, sulfamidophenols, polyhydroxybenzenes, naphthols, hydroxybinaphthyls, methylenebisnaphthols, methylenebisphenols, ascorbic acids, 3-pyrazolidones, pyrazolines, pyrazolones, and aminophenols , Paraphenylenediamines, sulfamidoanilines, sulfamic acids, hydrazones alone,
Alternatively, it can be used in combination with the above-mentioned developer. These developers may be used in the form of a precursor.

Examples of the dye-providing substance include compounds capable of releasing a sublimable or diffusible dye by thermal development. Such compounds are disclosed in JP-A-59-12.
No. 4332. This compound is a thermally non-diffusible dye-donating substance capable of releasing a sublimable dye or a sublimable dye precursor by thermal development, and the sublimable dye has a sublimation temperature of 80 ° C to 250 ° C.

As the binder for the photosensitive layer, any of a hydrophilic polymer and a hydrophobic polymer can be used, and these may be used alone or in combination.

The image receiving layer of the image receiving sheet includes a saturated polyester layer. Examples of the saturated polyester include polyethylene terephthalate (PET, melting point: 260 ° C.), polybutylene terephthalate (PBT, melting point: 224 ° C.), poly-1,4-cyclohexanediene. Methylene terephthalate (PCHT, melting point 290 ° C)
Etc. Since the photothermographic material used in the present embodiment is heated to 80 to 200 ° C. during development, the melting point of the saturated polyester used in the image receiving layer must be higher than the above-mentioned development temperature. Incidentally, the saturated polyester described above,
It is distinguished from unsaturated polyesters containing double bonds that can crosslink with a vinyl compound in the molecular structure to form a three-dimensional network.

As described above, the support used for the image receiving layer and the photosensitive layer may be any as long as it can withstand the temperature at the time of the heat development treatment, and may be paper, polyamide film, acetylcellulose film, cellulose ester film, polyvinyl acetal. A method for obtaining a color image with a diffusion transfer type photosensitive material that can use a resin material such as a film, a polystyrene film, a polycarbonate film, and a polyethylene terephthalate film will be described.

In order to obtain a color image with a diffusion transfer type photosensitive material, a photosensitive sheet having a photosensitive layer coated with a photosensitive silver salt milk material on the surface of a support, and a layer for receiving a dye formed by developing the photosensitive sheet are provided. An image receiving sheet having an image receiving layer (referred to as an image receiving layer) coated on a support is required.

First, the photosensitive sheet is exposed imagewise, and then the imagewise exposed photosensitive sheet and the image receiving sheet are overlaid so that the photosensitive layer and the image receiving layer are in contact with each other. A high temperature (120 ° C. to 160 ° C.) is applied for 30 to 120 seconds with the two sheets still overlapping. Due to the high temperature, the photosensitive sheet is developed (image-like diffusible dye is generated). Further, the generated diffusible dye is transferred to the image receiving layer. In order to improve the adhesion between the photosensitive layer and the image receiving layer and improve the transfer rate of the diffusible dye from the photosensitive layer to the image receiving layer, pressure may be applied together with the high temperature. The purpose of this pressure is to keep the photosensitive layer and the image receiving layer in close contact with each other. If the photosensitive layer or the image receiving layer itself has an adhesive force, the pressure need not be continuous but may be intermittent.

After the development and transfer for a predetermined time, the photosensitive sheet and the image receiving sheet are peeled off. The separation between the photosensitive layer and the image receiving layer corresponds to fixing in a general silver halide photographic material. The image receiving sheet to which the diffusible dye has been transferred is the final product.

Next, the configuration of the first embodiment of the heat developing unit 38 will be described with reference to FIGS. Reference numerals 51 and 52 denote an upper belt and a lower belt, which are a pair of endless belts.

As a material of the upper belt 51 and the lower belt 52, silicon rubber having the same carbon fiber or the like as the endless belt used for the heat source portion, or fluorine rubber similarly containing the core is preferable. In the case of a silicon rubber belt, it is preferable that the surface of the silicon rubber belt is polished so as not to affect the obtained image, so that the silicon rubber belt has flatness. The belt may be made of a conductive material to prevent static electricity.

Also, when using a silicon rubber belt with a carbon fiber core, when the belt is rotated in the weave of the core, the deviation in the width direction of the belt changes, so use a core woven with a less deviation weave. It is preferable to use a silicon rubber belt that has been used.

Further, no matter what material and weaving belt is selected, deviation in the width direction occurs, so a guide for guiding the widthwise end of the belt or a liner on the belt is provided. The belt may be prevented from shifting in the width direction.

Inside the lower belt 52, a plurality of heating rollers 53 for guiding the lower belt 52 are provided. These heating rollers 3 have a hollow shape, and a heater 54 such as a halogen lamp or a nichrome wire is provided therein as a heat source. Halogen lamps and nichrome wires emit light at the same time as heat,
Heat roller 53 so that the photosensitive sheet is not exposed to heat source light
It is necessary to provide caps at both ends to prevent light leakage. The material of the cap is required to be hard to transmit light and to have sufficient heat resistance. In addition, it is necessary that the heat source be insulative depending on the wiring conditions. Specifically, silicone rubber, fluorine rubber, phenol resin,
Polycarbonate and the like are desirable.

55 guides the upper belt 51, and the upper belt
These are a plurality of pressure rollers for pressing the lower belt 51 against the lower belt 52.

Reference numeral 57 denotes a motor as a drive unit having a pinion 58 attached to the output shaft. On the other hand, a gear 59 meshing with the pinion 58 is attached to the last roller 55 ′ of the pressure roller 55, and the last roller 55 ′ is a driving roller that is driven to rotate by a motor 57.

Reference numeral 60 denotes a photosensitive sheet (photosensitive material) on which an image receiving sheet 61 (image receiving material) is superimposed (see FIG. 5).

Downstream of each heating roller 53, as shown in FIG. 1, a temperature sensor 62 for detecting the temperature of the lower belt 52 is provided. As the temperature sensor, a thermocouple, a platinum resistance temperature detector, a thermistor, an IC-based temperature sensor, or the like that is optimal for the case is used. Further, as the temperature sensor protective layer 70, a thin sheet having a thickness of 1 μm to 100 μm made of a fluorine-based or polyimide-based material having heat resistance and excellent wear resistance (for example,
Kapton tape) is used.

Next, the attachment of the temperature sensor 62 will be described with reference to FIGS. 63 is an inner frame of the heat developing section. Reference numeral 64 is disposed downstream of each heating roller 53, substantially parallel to the rotation axis of each heating roller 53, a base end is attached to one side of the inner frame 63, and the other end is a free end. Temperature sensor support plate. The temperature sensor support plate 64 is mounted in a so-called cantilever state in which a base end is mounted on one side of the inner frame 13 using screws 66 and the other end is a free end. By loosening the screw 66, the temperature sensor support plate 64 can be removed from the temperature sensor outlet 63a formed on the other side of the inner frame 63.

Incidentally, the heating roller 53 is attached to the inner frame 63 via a bearing.
Insulation is installed between the bearings. Without this heat insulating material, the heat of the heating roller 53 escapes to the outside via the bearing, and the temperature distribution in the axial direction of the heating roller 53 becomes non-uniform or the power consumption increases. In addition, it is more effective to provide a heat insulating material for the heating roller 53. Further, a heater may be provided inside the pressure roller 55 to serve as a heating roller.

As the material of the heating roller 53, aluminum material such as A5056 or S
Iron-based metals such as US304 and STKM are suitable. When an iron-based material is used, rust prevention treatment such as parkerizing is required.

As a method for heating the heating roller 53, the heating roller 53 may be heated from the outside using a surface heater or the like. Further, since the heating roller 53 preferably has a uniform temperature distribution in the axial direction of the roller,
When using a halogen lamp as a heat source, it is preferable to make the distribution density of the internal nichrome wires uniform.

As a method of pressing the pressure roller 55, the pressure roller 55 is made to swing or provided so as to be movable in the vertical direction,
Pressure may be applied by a spring or the like. Since the pressurizing place differs depending on the photosensitive material and the image receiving material, an appropriate place is pressurized according to these.

The temperature sensor 62 is mounted on a heat-insulating temperature sensor support 67 for preventing and removing the influence of disturbance. Reference numeral 69 denotes a temperature sensor pressurizing unit that has one end attached to the temperature sensor support base 64 and the other end attached to the holder 68, and biases the holder 68 toward the lower belt 52. The temperature sensor 62 is pressed against the lower belt 52 via the temperature sensor protection layer 70.

The contact point of the temperature sensor 62 with the lower belt 52 is as follows:
The lower belt 52 is a portion other than the image area G.

Reference numeral 71 denotes a temperature sensor code having one end connected to the temperature sensor 62 and the other end connected to a control unit (not shown), and transmitting a detection signal of the temperature sensor 62 to the control unit.

In this embodiment, the temperature sensor supporting plate 64 is provided with a temperature sensor 72 for detecting the surface temperature of the heating roller 53. The temperature sensor 72 is mounted on a heat-insulating temperature sensor support 77, which is held by a holder 78, in order to prevent and eliminate the influence of disturbance. 79
Is a temperature sensor pressurizing unit that has one end attached to the temperature sensor support 64 and the other end attached to the holder 78, and urges the holder 78 toward the heating roller 53.

The temperature sensor 72 is pressed against the heating roller 53 via the temperature sensor protection layer 80.

This temperature sensor 72 detects the temperature of the heating roller 53,
This is provided to stop the supply of current to the heater 54 when the temperature of the heating roller 53 becomes abnormal. In this case, the upper limit of the temperature may be set to a temperature at which the upper belt 51 and the lower belt 52 melt or the life is extremely reduced.

Instead of the temperature sensor 72, a temperature fuse may be brought into contact with the heating roller 53, and when the heating roller 53 has an abnormal temperature, the supply of current to the heater may be stopped.

In addition, the inner frame 63, which is a housing of the heat development unit, also needs a function of preventing light from entering the inside of the heat development unit and preventing heat generated by the heat development unit from being emitted outside, that is, a heat insulation function. It is. In order to improve the heat insulation function, the housing preferably has a structure in which a heat insulating material made of a nonwoven fabric or the like is attached to the inside and outside of the metal plate. As the material of the nonwoven fabric, it is necessary that the material has low thermal conductivity and does not burn or is difficult to burn, and a nonwoven fabric made of aramid fiber or the like is optimal.
More desirably, a heat reflecting material such as an aluminum foil is provided on the surface of the inner heat insulating material so that heat is not easily transmitted to the nonwoven fabric which is the heat insulating material.

Here, the temperature sensor pressurizing section 69 will be described in detail with reference to FIG. In FIG. 6, reference numeral 80 denotes SUS having a thickness of about 0.1 mm.
This is a temperature sensor pressurizing part / holder which is formed by bending a plate material 304 into a substantially U-shaped cross section. The lower parallel surface (base end portion) of the temperature sensor pressurizing portion and holder 80 is attached to a temperature sensor support plate 64, and the temperature sensor support base 67, the temperature sensor 62, and the like are mounted on the upper parallel surface (tip portion). Is attached.
In the case of such a cantilever shape, the leading end is disposed downstream of the flow of the lower belt 52. Conversely, if this is arranged in the upstream direction of the flow, the leading end will be caught by the lower belt 52 and will rotate around the base end.

Further, as shown in FIG. 8, a temperature sensor pressurizing portion / holder 81 may be used in which a plate of SUS304 having a thickness of about 0.1 mm is bent into a substantially square cross section.

 Next, the operation of the above configuration will be described.

The upper belt 51 and the lower belt 52 are heated to a developing temperature of about 150 ° C. by the heating roller 53. Then, the photosensitive sheet 60 on which the image receiving sheet 61 is superimposed is inserted between the upper belt 51 and the lower belt 52, and is conveyed to these belts 51, 52 while being pressed and heated. The photosensitive sheet 60 is pressurized and heated to release the applied thermally developed diffusible dye, and the dye is thermally transferred to the image receiving sheet 61.

At this time, the temperature sensor 62 always detects the temperature of the lower belt 52, and a control unit (not shown) takes in the signal of the temperature sensor 62 so that the temperature of the lower belt 52 becomes a predetermined developing temperature (150 ° C.). The heater 54 in the heating roller 53 is ON / OFF controlled.

Here, the temperature control of this embodiment will be described with reference to FIG. (A) shows the temperature distribution in the width direction of the lower belt 52. As shown in the figure, the temperature of the lower belt 52 gradually decreases toward both sides. Although the temperature of the image region G is substantially constant, the portion other than the image region G is lower than the portion of the image region G as in the present embodiment. Therefore, when the temperature of this portion is detected and control is performed based on this temperature, the image area G
Is higher than the set temperature.

Therefore, the temperature deviation X between the image area G and the area other than the image area G (measurement unit) is measured in advance, and the temperature is set to be lower by the deviation X.

Further, as shown in (b), a temperature sensor 100 that can move in the vertical direction is provided in the image area G, and the temperature sensor 100 is raised at a time appropriate for measurement, such as a short time immediately before the start of development, and The temperature of the image area G of the belt 52 may be measured, and the deviation X may be obtained from this temperature information and corrected.

Further, a temperature sensor movable in the width direction of the lower belt 52 is provided, and the temperature sensor is moved to the image area G at an appropriate time for measurement, such as a short time immediately before the start of development, so that the image area G of the lower belt 52 is The temperature may be measured, and the deviation X may be obtained from the temperature information and corrected.

Further, the temperature of the portion of the image region G may be equal to the temperature of the portion outside the image region by using the heater 54 having a length capable of heating the portion other than the image region G.

At the end of development, if the developing section stops immediately, the upper belt
51, the lower belt 52 is locally heated and pressurized, which may cause breakage or shorten the life. Therefore, set the temperature switch on the belt 51, 52 or an appropriate part inside the developing unit,
Until the temperature falls below the predetermined temperature, the belts 51 and 52 are driven idle to cool the heater 54 in the OFF state.

According to the above configuration, the temperature sensor 62 presses the portion other than the image area G of the lower belt 52 through the temperature sensor protection layer 70.

Accordingly, the image area G of the lower belt 52 is not worn by the temperature sensor 62, so that the density unevenness in the flow direction at the center of the image area of the image receiving sheet 61 does not occur.

Further, in this embodiment, the length of the temperature sensor support plate 64 is shorter than that of the conventional example,
And is attached to the inner frame 63. Therefore, it is easy to take out from the temperature sensor outlet 63a, and the attachment is also simple.

Next, a second embodiment of the present invention will be described with reference to FIG. In these figures, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference from the first embodiment is the temperature sensor support plate 90. In mounting the temperature sensor support plate 90, one end is engaged with a fixing pin 91 erected on one side of the inner frame 63, and the other end is provided with a screw 66 on the other side of the inner frame 63. The inner frame 63 is detachable from the temperature sensor outlet 63a formed on the other side of the inner frame 63 by loosening the screw.

Even in such a configuration, the temperature sensor 62 is
The part other than the image area G of 52 is pressed through the temperature sensor protective layer 70.

Accordingly, the image area G of the lower belt 52 is not worn by the temperature sensor 62, so that the density unevenness in the flow direction at the center of the image area of the image receiving sheet 61 does not occur.

(Effects of the Invention) As described above, according to the present invention, a temperature sensor that contacts the endless belt and detects the temperature required for driving the heater in the heating roller to control the endless belt to a predetermined temperature. As a position outside the image area on the endless belt,
An endless belt that comes into contact with a position deviated in the width direction of the endless belt from the image area is used. Therefore, the temperature sensor does not come into contact with the image area of the endless belt, and no abrasion occurs in this image area due to sliding contact with the temperature sensor. Therefore, according to the present invention, it is possible to realize a heat developing section of a heat developing image forming apparatus capable of preventing density unevenness.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a heat development section of a heat development image forming apparatus for explaining a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line BB in FIG. 2, and FIG. FIG. 3 is a configuration diagram of a heat development unit of the heat development image forming apparatus illustrating an example, FIG. 3 is a cross-sectional view taken along line CC of FIG. 1, FIG. 5 is an explanatory view of a photosensitive material, FIG. 6 is a detailed view of a temperature sensor pressing section, FIG. 7 is a view for explaining how to attach the temperature sensor pressing section shown in FIG. 6, and FIG. 8 is a temperature sensor. FIG. 9 is a detailed view of another embodiment of the pressing unit, and FIG. 9 is a configuration diagram of the second embodiment. FIG. 10 is a diagram for explaining temperature control in the first and second embodiments, FIG. 11 is a configuration diagram of a heat developing section of a conventional heat development image forming apparatus, and FIG. 12 is AA in FIG. It is sectional drawing. In these figures, 51: upper belt (endless belt) 52: lower belt (endless belt) 53: heating roller 55: pressure roller 57: motor (driving unit) 60: photosensitive sheet (photosensitive material) ) 61: Image receiving sheet (image receiving material) 62: Temperature sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-61752 (JP, A) JP-A-64-66653 (JP, A) JP-A-63-71848 (JP, A) JP-A-1- 167756 (JP, A) JP-A-1-276135 (JP, A) JP-A-63-250644 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03D 13/00

Claims (1)

(57) [Claims] 1. A pair of endless belts (51, 52), a plurality of heating rollers (53) for guiding one of the endless belts (51, 52), and the pair of endless belts (51, 52). A plurality of pressure rollers (55) for guiding the other belt (51) of the endless belts (51, 52) and pressing the other belt (51) against the one belt (52); A driving unit (57) for driving the roller (53) to rotate, and the pair of endless belts (51, 5).
2) a temperature sensor (62) for detecting the temperature by contacting at least one of them, and a heater (54) in the heating roller (53) based on an output of the temperature sensor (62) to drive the pair of A control unit for controlling at least one of the endless belts (51, 52) to a predetermined temperature; and a photosensitive material (60) in which an image receiving material (61) is superimposed between the pair of endless belts (51, 52). Is heated by heating the photosensitive material (60) to release the thermally developed diffusible dye applied to the photosensitive material (60), and the dye is thermally transferred to the image receiving material (61). In the heat developing unit of the image forming apparatus, the temperature sensor (62) is located at a position outside the image area on the endless belt (51, 52), and the width of the endless belt (51, 52) from the image area. A heat development section of the heat development image forming apparatus, wherein the heat development section is brought into contact with a position deviated in the direction.