JPH07199439A - Heating method - Google Patents

Abstract

(57) [Abstract] [Purpose] The development density of the leading edge and the trailing edge of the sheet to be processed in the heat treatment direction becomes uniform, and a good quality image is obtained, which is suitable for development of heat developable diazo thermal paper. A flat heater type heating method is also provided. A sheet to be processed is supplied between a flat heater and a backup roll that rotates in pressure contact with the flat heater, and is driven by the frictional force of the backup roll to perform heat treatment while sliding the sheet to the flat heater. In the heating method, the temperature of the backup roll during the heat treatment is detected, and the input power of the flat heater is increased in real time according to the temperature decrease of the backup roll.

Description

Detailed Description of the Invention

The present invention relates to a method of subjecting a sheet to be treated such as paper or film to heat treatment such as heat development and heat fixing,
Further, the present invention relates to a heating method using a heating device of a plane heater type suitable for developing a heat developing type diazo thermal paper.

[0002]

2. Description of the Related Art Conventionally, a heating device of a hot roll type has been mainly used to heat a sheet to be processed such as heat development and heat fixing. The heating device of the heat roll type has a pair of rolls, a heat roll for heating the sheet to be treated and a backup roll for pressing the sheet to be treated against the heat roll. Then, the sheet to be treated is supplied between both rotating rolls, and is heat-treated while moving in a pressure-bonded state to the heat roll. This backup roll is made of a material with a high elasticity such as silicon rubber so that the sheet to be processed can be pressed securely, and it is also called a soft roll. In order to improve it, many aluminum pipes are coated with Teflon,
It is also called a hard roll, and a tubular heater lamp such as a halogen bulb is arranged inside the hard roll along the axial direction.

When the required heating time is relatively short as in the heat fixing of PPC or laser printer, a predetermined heating time can be secured only by heating between a pair of rolls. When a heat treatment that requires a relatively long heating time is performed, such as in the case of developing a type diazo thermal paper, it is necessary to reduce the rotation speed of the roll, which causes a problem that the development time becomes long. In order to solve this problem, a plurality of backup rolls are arranged around the heat roll, and a guide member slightly spaced from the peripheral surface of the heat roll is provided between the backup rolls, and the sheet to be processed is wound around the heat roll. The heating time is lengthened by pressing it so that it sticks.

The hot roll method is 120 to 130 ° C.
Since it is processed at a relatively low temperature, and the heating time is long, it is possible to obtain a uniform and good copied image. However, since a heat roll having a large heat capacity is heated, there is a problem that the warm-up time is long and the power consumption is large. In order to meet the recent demand for high-speed processing, it is necessary to increase the size of heat rolls, backup rolls, etc., resulting in higher weight and higher power consumption.

For this reason, recently, a heating device using a flat heater has been attracting attention. The flat heater type heating device is composed of, for example, a flat heater in which a heating resistor is screen-printed on an alumina substrate and a backup roll that rotates in pressure contact with the flat heater, and is supplied between the flat heater and the backup roll. The processing sheet is driven by the frictional force of the backup roll and is heated while sliding on the flat heater.

Since the flat heater type heating device can reduce the heat capacity of the entire heating portion, the warm-up time can be shortened, and the structure can be simplified and the size and weight can be reduced. In addition, since the sheet to be processed can be intensively and efficiently heated, it has advantages that high speed processing is possible and power consumption is low.

[0007]

However, when a heat treatment requiring a relatively long heating time is carried out, such as in the case of developing a heat-developable diazo thermal paper, only a short time heating by a flat heater is sufficient. It was found that a copy image could not be obtained, and it was necessary to heat the sheet to be processed from the back side by the heat of the backup roll preheated by the flat heater.

FIG. 4 shows an example of the electric power supplied to the flat heater and the temperature changes of the flat heater and the backup roll. During the heat treatment, heat is taken away by the sheet to be processed which contacts the flat heater. During the heat treatment, the electric power of 3 to 4 times is supplied as compared with the standby time so that the temperature of the flat heater is controlled to a constant temperature of 200 ° C., for example. Incidentally, the heat treatment time in the case of heat-treating the sheet to be treated of A ₁ plate at a speed of 70 mm / s is about 12 seconds. on the other hand,
Since the backup roll does not have a heating mechanism, heat is taken by the sheet to be processed, and as a result, the backup roll preheated to 170 ° C. is lowered to about 150 ° C. at the time when the heat treatment is completed. The degree of temperature decrease of the backup roll depends on the paper quality, thickness, processing speed and the like.

Therefore, the amount of heat transferred from the flat heater to the sheet to be processed is constant during the heating process, but the amount of heat transferred from the backup roll to the sheet to be processed decreases as the heating process progresses. Therefore, there is a problem that the amount of transferred heat is insufficient at the rear end portion of the sheet to be processed in the heat treatment direction, the development is insufficient, and the development density at the rear end portion of the sheet to be processed becomes low. For example, the development density measured with a Macbeth densitometer is 1.
36, while the rear end is 1.30,
It will decrease by 0.06 points (5%).

Therefore, according to the present invention, the development density of the front end portion and the rear end portion of the heat treatment of the sheet to be processed becomes uniform, a high quality image is obtained, and it is a flat surface suitable for the development of the heat developable diazo thermal paper. An object of the present invention is to provide a heating method of a heater system.

[0011]

In order to achieve such an object, the present invention supplies a sheet to be treated between a flat heater and a backup roll which rotates in pressure contact with the flat heater, and uses a friction force of the backup roll. In the heating method that drives and heats the sheet to be processed while sliding it on the flat heater, the temperature of the backup roll during the heat treatment is detected, and the power supplied to the flat heater is changed in real time according to the temperature decrease of the backup roll. Increase.

[0012]

In other words, since the electric power supplied to the flat heater is increased in real time according to the temperature decrease of the backup roll, the amount of heat transferred from the backup roll can be compensated by the heat transferred from the flat heater as the heating process progresses. Therefore, the total amount of heat transferred to the sheet to be processed can be made constant. Therefore, the development densities of the front end portion and the rear end portion of the heat treatment of the sheet to be processed become uniform, and a high quality image is obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings. FIG. 1 shows a heat-developing diazo copying machine. In FIG. 1, a casing 1 injection-molded with a synthetic resin has an inverted W-shape in which the upper part has two peaks 11 and 12 arranged side by side. There is an exposure device A in Maeyama 11
A heat developing device B, which is the heating device of the present invention, is housed in the rear mountain 12. The front slope 11a of the front mountain 11 has an exposure inlet 13 for supplying the diazo photosensitive paper (sheet to be processed) coated with the diazo sensitive material and the original image to the exposure apparatus A by superimposing them on each other.
And an exposure outlet 14 for discharging after exposure, and further, a developing inlet 15 for separating the exposed diazo photosensitive paper from the original image and supplying it to the heat developing apparatus B is provided on the front slope 12a of the rear mountain 12. A developing outlet 16 is provided at the lower end portion and through which the heat-developed diazo photosensitive paper is discharged. The developing outlet 16 is provided on the rear slope 12b of the rear mountain 12. A bottom plate 17 is attached to the lower surface of the casing 1 and accommodates drive motors (not shown) and electrical components constituting various control units, etc., inside the bottom plate 17.

In the exposure apparatus A, a cylinder 21 made of transparent Pyrex glass is rotatably arranged, inside of which a rating of 100 W and a wavelength of 4 is provided along the axis.
One tube-shaped fluorescent lamp 22 that strongly emits 20 nm light is arranged. And four idle rolls 23 and 1
An endless backup belt 25 is wound around the drive roll 24 and the cylinder 21 of the book,
This backup belt 25 holds the cylinder 21. Then, the roll 2 is driven by a motor (not shown).
When 4 is driven and rotated, cylinder 21 rotates with backup belt 25 in the direction of the arrow.

Next, as a heating portion of the heat developing device B, a heating device comprising a flat heater 4 and a backup roll 3 which is pressed against the flat heater 4 to rotate is arranged. A carry-in guide 5 and a discharge guide 6 are arranged around the backup roll 3, and a discharge roll 71 and a discharge plate 72 are arranged on the downstream side of the discharge guide 6. Then, the backup roll 3 and the discharge roll 71 rotate in the direction of the arrow by a motor (not shown). Further, the temperature sensor 8 composed of a thermistor comes into contact with the backup roll 3 so that the temperature of the backup roll 3 can be detected.

The structure of the flat heater 4 will be described with reference to FIG. 2. The surface of the alumina substrate 41 having a width of 10 mm has a width of 3 m.
A heating resistor 42 of m is screen-printed, and its surface is covered with an overcoat layer 43. The alumina substrate 41 is held by a heat-resistant resin material 44 for preventing heat of the heat-generating resistor 42 from escaping to other than the pressure-contacting portion, and the heat-resistant resin material 44 has rigidity to withstand the pressure-contacting force of the backup roll 3 or the like. It is fixed to the support frame 45. Although the rated power of the heating resistor 42 is 1200 W, a thermistor (not shown) detects the temperature of the flat heater 4 and controls it to a predetermined temperature by phase control.

Next, the backup roll 3 has an outer diameter of 4
It is a long roll with a diameter of 0 mm and a length of 700 mm, but an intermediate layer 33 made of foam sponge with a thickness of 8.5 mm is arranged on the outer circumference of a stainless steel core pipe 31, and the intermediate layer 33 has a thickness of 2 mm. Solid layer of skin made of silicone rubber 3
Covered with 2.

Then, the power switch (not shown) is turned on.
When the heating resistor 42 is energized and the backup roll 3 is rotated, the backup roll 3 is heated by the flat heater 4 after the warm-up time has elapsed, but when the backup roll 3 rises to a predetermined temperature and copying becomes possible, copying is performed. OK
Is displayed. Here, since the heat capacity of the solid layer 32 of the skin of the backup roll 3 is small, the warm-up time is greatly shortened compared to the conventional case.

Thereafter, the diazo photosensitive paper coated with the diazo light-sensitive material and the original image were superposed and inserted from the exposure inlet 13, moved by being pressed against the cylinder 21 by the backup belt 25 and passed through the cylinder 21 in this process. The light from the fluorescent lamp 22 passes through the original image to expose the photosensitive paper, and the light is discharged from the exposure outlet 14.

Next, when the diazo photosensitive paper which is the sheet to be processed is separated from the original drawing and supplied from the developing inlet 15, it is guided to the carry-in guide 5 and the backup roll 3 and the flat heater 4 are introduced.
Supplied during. Then, the diazo photosensitive paper is driven by the frictional force of the backup roll 3, and the flat heater 4
It slides in a state of being pressed against and is heated by the flat heater 4 and the preheated backup roll 3 to be thermally developed. The diazo photosensitive paper, which has been colored as shown in the original drawing, is guided to the discharge guide 6, the rotating discharge roll 71 and the discharge plate 72, and is discharged from the developing outlet 16.

Here, during the heat treatment, as shown in FIG. 3, the temperature of the backup roll 3 decreases from 170 ° C. at the beginning of the heat treatment to 150 ° C. at the end of the heat treatment, but this temperature is detected by the temperature sensor 8. Detect with. The degree of temperature decrease of the backup roll 3 depends on paper quality and thickness,
It depends on the processing speed. Then, the input power of the flat heater 4 is increased in real time according to this temperature decrease. For example, as shown in FIG. 3, the input power is increased from 600 W at the beginning of the heat treatment to 800 W at the end of the heat treatment, and the temperature of the flat heater 4 is increased from 200 ° C. at the beginning of the heat treatment to 220 ° C. at the end of the heat treatment. The amount of increase in input power is calculated based on the temperatures detected by the backup roll 3 and the flat heater 4, and is determined so that the total amount of heat transferred from the backup roll 3 and the flat heater 4 to the sheet to be processed is substantially constant. Therefore, as the heat treatment progresses, the amount of heat transmitted from the backup roll is compensated by the heat transmitted from the flat heater, and the development density at the leading end portion and the trailing end portion of the sheet to be treated becomes uniform. , Good quality images can be obtained. Incidentally, the development density measured by a Macbeth densitometer was 1.36 at both the front end portion and the rear end portion of the sheet to be processed in the heat treatment direction, and it was confirmed that a constant development density was obtained.

[0022]

As described above, in the flat heater type heating method of the present invention, the power supplied to the flat heater is increased in real time in response to the temperature decrease of the backup roll. Can be kept constant during the heat treatment, and the development density of the front end portion and the rear end portion of the sheet to be processed in the heat treatment direction becomes uniform, so that a high-quality image can be obtained. The heating method suitable for developing can be used.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a heat development type diazo copying machine.

FIG. 2 is a sectional view of a main part of a heat development type diazo copying machine.

FIG. 3 is an explanatory diagram of data according to the embodiment of the present invention.

FIG. 4 is a data explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Casing 21 Cylinder 22 Fluorescent Lamp 3 Backup Roll 31 Core Pipe 32 Solid Layer 33 Intermediate Layer 4 Planar Heater 5 Carrying Guide 6 Discharge Guide 8 Temperature Sensor

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Shigeo Kijima 262 Kondo, Tatebayashi, Gunma Gunma Ushio Electric Co., Ltd. 72) Inventor Taro Hayashi, 262 Kondo, Tatebayashi City, Gunma Prefecture Gunma Ushio Electric Co., Ltd. (72) Inventor, Hiroshi Shimizu 262, Kondo, Tatebayashi City Gunma Prefecture, Gunma Ushio Electric Co., Ltd. 2-26-30 Nishi-Azabu, Minato-ku Fuji Shashin Film Co., Ltd.

Claims (1)

[Claims] 1. A sheet to be treated is supplied between a flat heater and a backup roll which is rotated in pressure contact with the flat heater and is driven by a frictional force of the backup roll,
In a heating method of performing heat treatment while sliding a sheet to be processed on a flat heater, the temperature of the backup roll during the heat treatment is detected,
A heating method characterized in that the electric power supplied to the flat heater is increased in real time according to the temperature decrease of the backup roll.