JPS6211656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for covering the surface of a sheet body such as a card or bill with a plastic film so as to be in close contact therewith.

Generally, for sheet bodies such as "business cards,""identificationcards,""commuterpasses,""minicalendars," and other cards and tags, a surface coating, which can be called a form of packaging, is provided on the sheet body. It is convenient, and often necessary, to impart or improve durability and water resistance, or to prevent falsification of information displayed on the sheet.

In response to such demands, various sheet body surface coating devices have been proposed.

For example, a sheet body surface coating apparatus shown in FIG. 1 is conventionally known. That is, this device is a device for coating both sides, and a pair of hollow rollers 1A and 1B are arranged so as to face each other in a sheet movement path P to constitute a pinch roller 4.
Heaters 5A and 5B are provided in the internal spaces 12A and 12B of A and 1B, and the sheet body 2 with plastic film 3 layered on both sides is
The sheet is sent along the sheet movement path P so as to pass between the rollers 1A and 1B, whereby the plastic film 3 is fused to both sides of the sheet 2 by the heat from the rollers 1A and 1B. Both sides of the sheet body 2 are coated. In addition, in an apparatus for single-sided coating, one of the heaters 5A and 5B may be omitted.

However, in such an apparatus, in order to uniformly heat the sheet body 2 to be processed, the rollers 1A and 1B are usually thick so that the temperature of the outer peripheral surface of each roller 1A and 1B is uniform. Therefore, when using the device when the rollers 1A and 1B are in a cold state due to a relatively long downtime such as at night,
From the time when the main switch (not shown) is operated and the heaters 5A and 5B start operating,
It takes a long time for the temperature of the outer circumferential surface of each roller 1A, 1B to reach the temperature required to perform a sufficient coating process, which has the drawback of requiring a long waiting time.

This drawback can be effectively overcome, for example, by installing a heater inside the roller to heat the roller from within, but by adopting a method that projects radiant heat from a thermal radiation lamp onto the outer peripheral surface of the roller. However, in this case, it is necessary to consider the control method of the thermal radiation lamp, and there is a problem that the generally adopted so-called on-off control method cannot sufficiently stabilize the heating temperature of the roller. There is a point.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet surface coating apparatus that eliminates the above-mentioned drawbacks, has a short standby time, and is capable of stabilizing the heating temperature.

Some embodiments of the present invention configured for double-sided coating will be described below with reference to FIGS. 2, 3, and 4.

In the embodiment shown in FIG.
B constitutes the pinch roller 4, and the sheet body moving path P is arranged so as to cover the outer circumferential surface area of each roller 1A, 1B except for the contact area S with a gap therebetween.
Concave reflecting mirrors 6A and 6B opening on the side are provided,
Inside the reflecting mirrors 6A, 6B, a thermal radiation lamp 7, such as a halogen lamp or an infrared lamp, is provided so as to face the outer peripheral surface of each of the rollers 1A, 1B.
A, 7B are arranged respectively, and an AC power supply that supplies current to these and a phase control mechanism that controls the current from this AC power supply are connected, and the reflecting mirrors 6A, 6 are connected to each other.
The outer surface of B is provided with heat insulating layers 8A and 8B.

The phase control mechanism includes the thermal radiation lamps 7A,
A triax is connected in series to 7B, and a temperature detector 9 is provided in contact with or close to one of the pinch rollers 4, 1B, so as to detect the temperature of the roller 1B. The control circuit 13 (see FIGS. 3 and 4) may be configured to control the generation timing of the gate signal of the triact based on the signal of the temperature detector 9.
Therefore, it is convenient to use a temperature-sensitive resistance element whose resistance value changes depending on the temperature.

FIG. 3 is an explanatory diagram of an example of a phase control mechanism when a positive temperature coefficient thermistor 10 is used as the temperature detector 9. FIG. In this example, the AC power supply is connected to the switch SW and the thermal radiation lamps 7A and 7B.
A series circuit of the positive characteristic thermistor 10, a compensation resistor R1, and a capacitor C1 for controlling triac conduction timing (hereinafter referred to as "control capacitor") is connected, and this control capacitor C1 and compensation resistor R1 are connected. point and thermal radiation lamps 7A, 7
It is constructed by inserting a trigger diode TD between the gate electrode G of the triac TRC connected in series with the control capacitor C1.
A control circuit 13 is constituted by a compensating resistor R1, and a trigger diode TD. Resistance R
2, R3 and capacitor C2 are for easing hysteresis, resistor R4 and capacitor C
3 constitutes a surge current absorption circuit, and
This is to prevent TRC malfunction.

According to the above configuration, the thermal radiation lamp 7
Each roller 1 is heated by radiant heat emitted from A and 7B.
The outer peripheral surfaces of A and 1B are heated, and in this state, when they are fed into the sheet body 2 on which the plastic film 3 is stacked between the pinch rollers 4, the sheet body 2 is pinched and pressed by the heated pinch rollers 4 and is fed. At the same time, the plastic film 3 is pressed onto both sides of the sheet body 2, and the surface coverage of the sheet body 2 is achieved.
The operation of is controlled by the phase control mechanism as follows. That is, when the switch SW is closed, the control capacitor C1 is charged with an AC voltage applied via the positive temperature coefficient thermistor 10 and the compensation resistor R1, and when the charging voltage reaches the breakover voltage of the trigger diode TD, the control capacitor C1 is charged. The control capacitor C1 is discharged and a signal current flows to the gate electrode G of the triax TRC, which makes the triax TRC conductive and the thermal radiation lamps 7A, 7B
A current is supplied to the AC voltage, and this operation is repeated every half cycle of the AC voltage. However, since the temperature of the PTC thermistor 10 depends on the temperature of the outer circumferential surface of the roller 1B, for example, if the temperature rises and the resistance value of the PTC thermistor 10 increases, the voltage applied to the control capacitor C1 decreases. As a result, the charging time for the charging voltage to reach the breakover voltage of the trigger diode TD becomes longer, and as a result, the conduction timing of the triac TRC during a half cycle of the AC voltage is delayed, and as a result, the current flowing through the thermal radiation lamps 7A and 7B increases. The amount of light emission is suppressed in accordance with the temperature rise of the positive temperature coefficient thermistor 10.

Conversely, when the temperature of the outer circumferential surface of the roller 1B decreases and the resistance value of the positive temperature coefficient thermistor 10 decreases, contrary to the above, the conduction timing of the triax TRC becomes earlier and the amount of light emitted from the thermal radiation lamps 7A and 7B increases. Become something.

According to the above configuration, the outer circumferential surfaces of the rollers 1A and 1B constituting the pinch roller 4 are directly heated by radiant heat, and moreover, as a heat source for each roller 1A and 1B, the fully lit state is achieved immediately after the rollers 1A and 1B are turned on. Since the thermal radiation lamps 7A and 7B are used, the switch SW is closed and the thermal radiation lamps are turned off even after a relatively long downtime, that is, when using the rollers 1A and 1B when they are cold. 7A,
7B, the temperature of the outer circumferential surface of each roller 1A, 1B can be raised to the temperature necessary to sufficiently cover the surface of the sheet body in an extremely short period of time. Waiting time can be virtually eliminated, and the roller 1
The temperature of the outer peripheral surfaces of the lamps A and 1B is detected by the temperature detector 9, and the phase control mechanism controls the operation of the thermal radiation lamps 7A and 7B based on the signal, so that the temperature is supplied to the thermal radiation lamps 7A and 7B. Since the electric current (alternating current) applied to the rollers 1A and 1B is controlled in each half cycle, the heat radiation lamp remains actually lit, and the amount of radiant heat changes in response to temperature changes on the outer peripheral surfaces of the rollers 1A and 1B. The temperature changes with extremely high followability to the temperature changes on the outer peripheral surfaces of 1A and 1B. As a result, the rollers 1A and 1B have a very high response speed, and the change in the amount of radiant heat is gradual and the amount of change is suppressed to a small level.
Therefore, the temperature of the rollers 1A, 1B can be maintained extremely stably at the desired temperature, that is, within a very small temperature range.

As a result, very precise temperature control can be achieved in relation to the temperature of the roller surface. For example, when using a cold roller, the temperature of the roller surface will rise rapidly when the heat radiation lamp is turned on, but even when the temperature reaches the set temperature, the heat radiation lamp will not turn off completely. Instead, the amount of radiant heat corresponds to the temperature of the roller surface at that time. Therefore, even if the width of the decrease in the temperature of the roller surface is small, in the next half cycle, the amount of radiant heat corresponds to the temperature of the roller surface at that time. The amount of heat radiated from the thermal radiation lamp is controlled, and as a result, the temperature of the roller surface can be stably maintained within an extremely small temperature range around the set temperature. Therefore, in reality, there is no possibility of overheating.

In addition, when the sheet surface coating process is performed continuously, the temperature of the roller surface decreases, and even at this time, the amount of radiant heat is controlled according to the magnitude of the decrease. Therefore, the temperature of the roller surface can be maintained stably. Therefore, stable and good surface coverage of the sheet body can be achieved even during long-term use.

On the other hand, when a current control mechanism based on an on-off control method is used, the amount of radiant heat is controlled by turning on or off the heat radiation lamp, so the temperature on the roller surface varies over a wide temperature range. changes drastically. For example, when the roller is used in a cold state, the temperature of the roller surface will rise rapidly when the heat radiation lamp is turned on, but when the temperature reaches the set temperature, the temperature switch will immediately open and the current will be cut off. As a result, the temperature of the roller surface rapidly decreases to a temperature that cannot be used in practice. In order to prevent this, in reality, the operating temperature of the temperature switch is set higher than the required set temperature, so that even if the heat radiation lamp goes off, the temperature does not reach the point where it cannot be used immediately. Is required. However, this ends up placing the roller in an overheated state, even if only temporarily, which means that the temperature range involved in the control increases.

Moreover, once the thermal radiant lamp is turned off, it takes a considerable amount of time after the temperature switch is closed again until it is ready to fully radiate radiant heat. Moreover, the response of normal temperature switches is quite low, and in addition to this, the response speed to temperature changes on the roller surface in the on-off control method is extremely small, and as a result, the range of change in temperature on the roller surface related to control is large. This results in getting used to it.

In this way, even if a thermal radiation lamp is used to heat the outer peripheral surface of the roller, the current control mechanism based on the on-off control method will not allow the thermal radiation lamp to be activated in response to temperature changes on the outer peripheral surface of the roller. It can be said that precise control is practically impossible.

FIG. 4 is an explanatory diagram of another phase control mechanism that can be used in the present invention.
In this example, a negative characteristic thermistor 11 is used. That is, a rectifier RC is connected to the AC power supply AC via a switch SW, and a resistor R is connected to the rectifier RC.
A clip circuit consisting of a combination of 9 and R10 and Zener diodes ZD1 and ZD2 is connected, and a series circuit of a resistor R7, a variable resistor VR8, and a negative characteristic thermistor 11 is connected to this clip circuit, while a resistor is connected to the rectifier RC. A control capacitor C1 is connected via R5 and a variable resistor VR6, and the negative characteristic thermistor 11 is connected in parallel with the control capacitor C1 via a diode D1.
Furthermore, one base pole B2 of a unidirectional transistor UJT is connected to the clip circuit via a resistor R11, and the primary winding of a pulse transformer PT is connected to the other base pole B1 of this transistor UJT. The capacitor C1 is connected to the emitter pole E of the transistor UJT, and the secondary winding of the pulse transformer PT is connected to the diode D2.
The control circuit 13 includes a control capacitor C1, resistors R5, R7, and a variable resistor.
The main components are VR6, VR8, diode D1, transistor UJT, and pulse transformer PT. C5 is a capacitor and D3 is a diode.

In the phase control mechanism having such a configuration, the voltage from the clip circuit is applied to the resistor R7 and the variable resistor VR depending on the resistance value of the negative characteristic thermistor 11.
8. Diode D1 and resistor R5, variable resistor VR
6 to the control capacitor C1, and the charging voltage is applied to the emitter pole E of the transistor UJT.
When the voltage exceeds the peak voltage of , the battery is discharged and charged again, and this charging and discharging process is repeated during a half cycle of the AC voltage. Due to this charging and discharging, a pulse signal appearing in the secondary winding of the pulse transformer PT is transmitted to the diode D2.
is applied to the gate electrode G of the triac TRC through the pulse signal G, and the triac TRC is made conductive by the first pulse signal, and this conductive state is maintained during the corresponding half cycle of the alternating current voltage. Since the timing at which the first pulse signal appears depends on the voltage applied to the official capacitor C1 and therefore on the resistance value of the negative characteristic thermistor 11, the conduction timing of the triac TRC is ultimately controlled.

When the temperature of the outer circumferential surface of the roller 1B increases and the resistance value of the negative characteristic thermistor 11 decreases, the voltage applied to the control capacitor C1 decreases, and the conduction timing of the triact TRC is delayed, causing thermal radiation. When the amount of light emitted by the lamps 7A, 7B is suppressed and the temperature of the outer peripheral surface of the roller 1B decreases, the resistance value of the negative characteristic thermistor 11 increases, contrary to the above, so the amount of light emitted from the thermal radiation lamps 7A, 7B decreases. becomes larger. Therefore, even with such a phase control mechanism, the thermal radiation lamps 7A and 7B are controlled in a state in which the amount of radiant heat changes slowly and the amount of change is small, and the same effect as described above can be obtained. can.

In the above embodiments, the case where both sides of the sheet body 2 are covered with the plastic film 3 has been described, but the present invention is not limited to this, and the pair of rollers 1A and 1B forming the pinch roller 4 is By arranging a thermal radiation lamp at a position facing the outer peripheral surface of one of the rollers and arranging a temperature detector in relation to the roller, an apparatus for coating only one side of the sheet body 2 can be obtained.

As understood from the description of the embodiments above, the present invention heats the outer peripheral surface of the roller that transfers heat to the surface of the sheet body using radiant heat from a thermal radiation lamp. It is possible to provide a sheet body surface coating device that can raise the temperature of the surface in a short time and therefore has a short standby time, and after lighting the heat radiation lamp, the current supplied to the lamp can be phased. Since it is configured to be controlled by a control mechanism, the heating temperature can be stabilized, and a great advantage can be obtained in practical terms.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional sheet body surface coating device, Fig. 2 is an explanatory sectional view of an embodiment of the present invention, and Fig. 3 is an example of a phase control mechanism that can be used in the present invention. Circuit diagram, 4th
The figure is a circuit diagram showing an example of another phase control mechanism that can be used in the present invention. 1A, 1B...roller, 2...sheet body, 3...
...Plastic film, 4...Pinch roller,
P...Sheet body movement path, 6A, 6B...Reflector,
7A, 7B...Thermal radiation lamp, 8A, 8B...Insulating layer, 9...Temperature detector, 10...Positive characteristic thermistor, 11...Negative characteristic thermistor, 13...Control circuit, TRC...Triack, C1... Capacitor for controlling triax conduction timing.

Claims (1)

[Scope of Claims] 1. A pair of rollers constituting a pinch roller that conveys a sheet body on which plastic films are stacked, and a thermal radiation lamp disposed opposite to the outer peripheral surface of at least one of the pair of rollers. , a phase control mechanism for controlling the current supplied to the thermal radiation lamp, and the phase control mechanism includes a triax connected in series to the thermal radiation lamp, and an outer periphery of a roller heated by the thermal radiation lamp. A sheet body surface coating device comprising: a temperature detector for detecting the temperature of the surface; and a control circuit for controlling conduction timing of the triax based on a signal from the temperature detector. 2. The sheet according to claim 1, wherein the temperature detector comprises a positive temperature coefficient thermistor, and the control circuit includes a triac conduction timing control capacitor connected in series with the positive coefficient thermistor. Body surface coating device. 3. The sheet according to claim 1, wherein the temperature detector comprises a negative characteristic thermistor, and the control circuit includes a triac conduction timing control capacitor connected in parallel to the negative characteristic thermistor. Body surface coating device.