JPH0351153Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image transfer device suitable for creating a proof in a manufacturing process.

[Background technology and issues to be solved] When creating a printing plate using a plate-making material such as a PS plate from a color manuscript and printing a large number of sheets, a color proof is created and checked.

Known photosensitive materials for creating color proofs include silver halide photosensitive materials, electrophotographic photosensitive materials, and photosensitive materials using photopolymers. After processing, a color proof is obtained by transferring the resulting image to an image receiving sheet.

In this case, a multicolor image is created by creating yellow, magenta, cyan, and black color images using four sheets of photosensitive material, and sequentially transferring them to the same image-receiving sheet.

In this method, unlike a method in which an image is formed by exposing a photosensitive layer transferred onto a transfer paper, the formed image is sequentially transferred one color at a time, so it is necessary to perform image transfer with strict accuracy. That is,
Since the image transferability in this case is greatly influenced by the transfer temperature, it is necessary to maintain the temperature during transfer strictly within a set range.

Conventionally, when using commonly used transfer devices, the heating time is short, so it is necessary to raise the temperature extremely, and the sheet inserted between the rollers is locally stretched, causing the color of the transferred image to change. It had the disadvantage of causing misalignment and uneven transfer.

Furthermore, since it is necessary to raise the temperature extremely as described above, it is necessary to increase the heat capacity of the heater, resulting in a disadvantage that the apparatus becomes large. Further, when the superimposed sheets are inserted between a pair of heat rollers, a local temperature drop of the heat roller occurs, resulting in color shift of the transferred image.

In other words, although it depends on the size of the sheet to which the image is transferred, in general, the heat roller rotates several times while the sheet passes through the transfer device, so the portion of the sheet that the roller touches for the first time and the portion of the sheet from the second time onwards are The surface temperature of the roller differs at the portion in contact with the roller. As a result, the transfer temperature decreases as the roller rotates, causing uneven transfer.

Furthermore, as described above, since four image sheets are usually transferred to one image receiving sheet, there is a drawback that color shift is likely to occur for each color.

For this reason, the applicant has already proposed a transfer device for creating color proofs that transfers images smoothly and does not cause transfer unevenness or color shift (Japanese Patent Application No. 1983).
112021), the present application further aims to obtain an image transfer device that can maintain transfer temperature with high precision and eliminate transfer unevenness and color shift.

[Summary and operation of the invention] The image transfer device according to the present invention is an image transfer device that overlaps an image sheet and an image-receiving sheet and transfers the image to the image-receiving sheet, and a conveyed sheet body made of both the overlapped sheets. a heat roller that presses and heats the heat roller; an auxiliary heater that is arranged corresponding to the heat roller and heats the heat roller; a sensor that detects the sheet to be conveyed; Control means for turning on the auxiliary heater after a time delay, reducing the heating capacity of the auxiliary heater as the transport speed decreases, and increasing the heating capacity of the auxiliary heater as the transport speed increases. There is.

Note that in the present invention, the conveyed sheet body is not limited to the image sheet and the image receiving sheet, but may be one in which other sheets such as an auxiliary heater are superimposed on these, if necessary.

Therefore, in the present invention, the roller that has been cooled by the passage of the conveyed sheet is not heated by the auxiliary heater, thereby causing uneven heating of the conveyed sheet. In particular, since the auxiliary heater is turned on after a predetermined time delay after the leading end of the conveyed sheet is detected, the sensor can be placed near the heat roller, making the overall configuration compact.

In addition, the heating capacity of the auxiliary heater decreases as the conveyance speed of the sheet to be conveyed decreases, and increases as the conveyance speed of the sheet to be conveyed increases, so that the auxiliary heating of the heat roller by the auxiliary heater becomes uniform. .

More uniform heating can be achieved by shortening the delay time as the conveyance speed of the sheet to be conveyed increases and increasing it as the conveyance speed decreases.

Further, the control means may be configured to turn off the auxiliary heater after a predetermined time delay after the sensor detects the rear end of the conveyed sheet. In this case, after the sheet to be conveyed passes, it is possible to prevent the surface portion of the heat roller from being heated by the sheet to be conveyed from being heated.

[Embodiment of the invention] In the image transfer apparatus of the present embodiment shown in FIG.
are supported parallel to each other via the Heaters 17 and 19 are arranged in these small diameter hollow shaft parts 16A and 18A, respectively, so that the image on the image sheet 20 fed therein is transferred onto the image receiving sheet 22.

The image sheet 20 and the image receiving sheet 22 are placed on a thin reinforcing aluminum sheet 24 as necessary, and together with this aluminum sheet 24 constitute a conveyed sheet body S.
is fed between the heat rollers 16 and 18. A guide plate 26 is arranged on the inlet side of the heat rollers 16 and 18 to
0 and is used for guiding the conveyed sheet body S to be fed. This guide plate 2
It is preferable to attach a heater (not shown) to sheet 6 and preheat both sheets before reaching heat rollers 16 and 18.

A sprocket foil 28 is fixed to a hollow shaft portion 18A of the heat roller 18 that protrudes from a bearing 14 attached to the machine base 10. A chain 32 is placed between the sprocket wheel 28 and a sprocket wheel 30, and as shown in FIGS. Output shaft 34A
It is fixed to.

Therefore, the rotational force of the motor 34 is applied to the heat roller 18.
The heat roller 18 applies the rotational force to the heat roller 16, and both heat rollers 16,1
8 rotate at the same speed.

A sprocket foil 36 is fixed to the hollow shaft portion 18A adjacent to the sprocket foil 28, and a part of the chain 38 is wound around the sprocket foil 36. This chain 38 includes an idle sprocket wheel 40 that is pivotally supported on the machine base 10, and a conveyance roller 42 (first
It is wrapped around a sprocket foil 44 fixed to a shaft 42A in the figure. This causes the motor 34
The driving force is also transmitted to the conveyance roller 42.

This conveyance roller 42 is a conveyance roller 4 in which a shaft 42A is inserted into a bearing 46 as shown in FIG.
It is in contact with 8. This conveyance roller 48 is a shaft 48
Since A is inserted into the U-shaped groove 47 of the bearing 46, it comes into contact with the conveying roller 42 due to its own weight, so that the conveyed sheet body S sent out from the heat rollers 16 and 18 is pinched and sent out. It's summery.

The U-shaped bearing 46 is arranged such that the longitudinal axis of the U-shaped groove 47 is inclined toward the heat roller 16 at its upper end. Therefore, when the conveyance roller 48 contacts the conveyance roller 42 due to its own weight, its tangent line is inclined, and both sheets are sent upward.

Auxiliary heaters 5 are installed above and below the guide plate 26.
0 and 52 are arranged to correspond to the outer circumferences of the heat rollers 16 and 18. These auxiliary heaters 50,
52 is at the same height as the axis of the heat rollers 16, 18, and the opposite sides of the heat rollers 16, 18 are covered with reflective covers 54, 56, so that the heat rollers 16, 18 can be heated effectively. It's becoming like that. Note that the bearing 12 is configured to be able to move the bearing 12 and press the heat roller 16 to the heat roller 18 by the action of the pressure means 58.

Heat rollers 16, 18 and conveyance rollers 42, 4
8, guide plates 60 and 62 are disposed above and below with the conveyance locus of the conveyed sheet body S interposed therebetween. As shown in FIG. 2, a notch 64 is formed in the middle of the guide plate 60 so that a contact of a limit switch 66 can protrude to detect the leading and trailing ends of the conveyed sheet S passing through it. It's summery.

Further, a temperature sensor 70 is disposed at the longitudinal end of the guide plate 60 via a bracket 68, so that the temperature of the outer circumference of the heat roller 16 can be detected.

A guide plate 72 is disposed downstream of the conveyance rollers 42 and 48 to guide the conveyed sheet body S, and cooling fans 74 and 76 are disposed corresponding to the upper and lower sides of the conveyed sheet body S that has been conveyed. The conveyed sheet body S is cooled.

As shown in detail in FIG. 4, an adjustment knob 78 is provided on the front surface of the machine base 10. The adjustment knob 78 can be selected in accordance with a plurality of indication scales 80 (-) carved into the base 79. These indication scales 80 are designed to be selected according to the conveyance speed of the conveyed sheet body S, and thereby the limit switch 66
The delay time until the auxiliary heaters 50 and 52 are turned on and off after the leading and trailing ends of the conveyed sheet S are detected by the auxiliary heaters 50 and 52.
52 heating capacity can be changed.
(If necessary, display the conveyance speed on each indication scale,
It may also be used as an index when rotating the knob. ) That is, after the leading edge of the conveyed sheet body S (the leading edge of the image sheet 20, image receiving sheet 22, or aluminum sheet 24) passes between the heat rollers 16 and 18, the rotation of the heat rollers 16 and 18 and the conveyed sheet are performed. The surface temperature of the heat rollers 16 and 18 decreases due to heat dissipation through thermal conduction of the sheet body S, and the outer peripheral portions of the heat rollers 16 and 18 that are in contact with the leading end of the conveyed sheet body S are heated by the auxiliary heater 5.
If the auxiliary heaters 50 and 52 are turned on and heated by the required amount while rotated to the 0 and 52 positions (approximately 3/4 rotations), the temperature of the heat rollers 16 and 18 will be lowered by the conveyed sheet body S. It can recover lost heat and provide uniform heating.

This also applies to the turning off of the auxiliary heaters 50 and 52, and when the temperature drop portion of the heat rollers 16 and 18 in contact with the rear end of the conveyed sheet body S has rotated to the position of the auxiliary heaters 50 and 52. If the auxiliary heaters 50 and 52 are turned off, the heat roller 1
The parts of 6 and 18 that are not deprived of heat will not be heated.

However, in reality, when the limit switch 66 detects the leading ends of the conveyed sheet S, the outer peripheral portions of the heat rollers 16 and 18 that come into contact with these leading ends have not yet reached the corresponding positions of the auxiliary heaters 50 and 52. Not yet. For this reason, limit switch 6
If the auxiliary heaters 50 and 52 are turned on after a predetermined time delay after the tip is detected by 6,
The cooled portions of the heat rollers 16 and 18 that are in contact with the tip of the conveyed sheet body S are auxiliary heaters 50 and 52.
When the position corresponding to is reached, heating assistance from these auxiliary heaters 50 and 52 can be effectively performed. This also applies to the case where the auxiliary heaters 50 and 52 are turned off.

This time delay needs to be shortened as the conveyance speed of the sheet S to be conveyed increases. For this reason, for example, the indication scale is 900 at the conveyance speed of the conveyed sheet body S.
mm/min, the delay time is set to 5 seconds, and the indicator scale corresponds to the case where the conveyance speed is 450 mm/min, the delay time is set to 10 seconds, and the lighting time of the auxiliary heaters 50 and 52 is delayed by a control device (not shown). control. The indication scale corresponds to other conveyance speeds, and the corresponding delay time is set.

The delay in the turn-off time of the auxiliary heaters 50 and 52 after the rear end of the conveyed sheet body S is detected can be made approximately equal to the delay in the turn-on time of the auxiliary heaters 50 and 52.

Furthermore, depending on these conveyance speeds, the auxiliary heater 5
It is necessary to change the heating capacity of 0.52. That is, when the conveyance speed is fast, the auxiliary heater 50,
The surface temperature of the heat rollers 16 and 18 is made uniform by increasing the heating capacity by the heat rollers 52 and by decreasing the heating capacity when the conveyance speed is slow. Therefore, on the indication scale, the heating capacity is increased at a speed of 900 mm/min.
470W, and the conveyance speed is 450mm/min according to the indication scale, so the heating capacity is set to 350W. The heating capacity of the other indicator scales is similarly changed according to the set conveyance speed.

The indicator scale 80 allows the stop position of the adjustment knob 78 to be changed steplessly, and the delay time and heating capacity can be controlled steplessly according to the conveyance speed.

Specifically, the combination of this adjustment knob 78 and the indicator scale on the base 79 and the control device include a timer for operating the auxiliary heaters 50 and 52 and a resistor for controlling the heating power source for the auxiliary heaters 50 and 52. A volume of can be used.

Next, the operation of this embodiment will be explained.

The image sheet 20 that has already been exposed and developed is overlapped with the image receiving sheet 22 and placed on the aluminum sheet 24 to form a conveyed sheet body S, which is then fed between the heat rollers 16 and 18. heat roller 1
6 and 18 have already been heated to a predetermined temperature by the heaters 17 and 19, and the image on the image sheet 20 can be transferred to the image receiving sheet 22.

When the limit switch 66 detects passage of the leading end of the conveyed sheet S, the auxiliary heaters 50 and 52 are heated after a predetermined delay time. Therefore, the surfaces of the heat rollers 16 and 18 whose temperature has decreased due to heat conduction to the conveyed sheet body S are connected to the auxiliary heaters 50 and 52.
When the auxiliary heater 5 has advanced to the position corresponding to
0 and 52 are heated, and after the temperature-reduced portion reaches the required temperature again, it moves to the position where the conveyed sheet body S is held. Since the heating capacities of the auxiliary heaters 50 and 52 are controlled according to the conveyance speed, the surface temperatures of the heat rollers 16 and 18 are always uniform.

Further, after the rear end of the conveyed sheet body S is detected by the limit switch 66, the auxiliary heater is turned off after a predetermined time delay.

In this way, the auxiliary heaters 50, 52 are activated after a predetermined delay time has elapsed after the leading edge of the conveyed sheet body S is detected.
is turned on and the auxiliary heaters 50 and 52 are turned off after a predetermined delay time has elapsed after the rear end is detected.
It can be placed near 6 and 18, making the design easier.
Compactness of the entire device is achieved.

The conveyed sheet body S that has been sent out is conveyed by the conveyance roller 4
2, 48, the cooling fans 74, 7
It is cooled and taken out at step 6.

It goes without saying that other sensors such as a photo sensor can be used in place of the limit switch 66 of the above embodiment.

[Effects of the invention] As explained above, the present invention is an image transfer device that overlaps an image sheet and an image-receiving sheet and transfers an image to the image-receiving sheet, and processes a conveyed sheet body consisting of both overlapping sheets. A heat roller that performs pressure heating, an auxiliary heater that is arranged in correspondence with the heat roller and heats the heat roller, a sensor that detects the conveyed sheet, and a predetermined time delay after the sensor detects the leading edge of the conveyed sheet. and a control means that turns on the auxiliary heater and decreases the heating capacity of the auxiliary heater as the transport speed decreases and increases the heating capacity of the auxiliary heater as the transport speed increases. It has an excellent effect of maintaining accuracy and eliminating uneven transfer and color shift.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the image transfer device according to the present invention, FIG. 2 is a plan view, FIG. 3 is a side view showing the driving part as seen from the left side of FIG. 2, and FIG. FIG. 2 is a front view corresponding to the X-ray arrow view in FIG. 1 showing the adjustment knob. 16, 18... Heat roller, 17, 19... Heater, 20... Image sheet, 22... Image receiving sheet, 24... Aluminum sheet, 50, 52...
...Auxiliary heater, 66...Limit switch, 78
... Adjustment knob, 80 ... Indication scale, S ... Sheet body to be conveyed.

Claims (1)

[Claims for Utility Model Registration] (1) An image transfer device that overlaps an image sheet and an image-receiving sheet and transfers the image to the image-receiving sheet, which pressurizes and heats the conveyed sheet body made of the overlapping sheets. an auxiliary heater disposed corresponding to the heat roller to heat the heat roller; a sensor for detecting the conveyed sheet; and a predetermined time delay after the sensor detects the leading edge of the conveyed sheet. An image transfer device comprising: control means for turning on an auxiliary heater, decreasing the heating capacity of the auxiliary heater in response to a decrease in conveyance speed, and increasing the heating capacity by the auxiliary heater in accordance with an increase in conveyance speed. . (2) The image transfer according to claim 1, wherein the sensor also detects the rear end of the conveyed sheet, and the auxiliary heater is turned off after a predetermined time delay after detecting the rear end. Device. (3) The control means shortens the predetermined time delay in turning on the auxiliary heater in response to an increase in the conveyance speed of the sheet to be conveyed, and shortens the predetermined time delay in turning on the auxiliary heater in response to a decrease in the conveyance speed of the sheet to be conveyed. The image transfer device according to claim 1 or 2, wherein the time delay is lengthened.