JP7484216B2 - Thermal Transfer System - Google Patents

Description

The present invention relates to a thermal transfer system that thermally transfers a transfer layer, such as an overcoat layer, onto a card.

Generally, ID cards have image information such as the card owner's face photo and text information such as the card owner's address, name, and date of birth printed on the card. For example, Patent Document 1 proposes an ID card production device that has multiple printing units and produces ID cards from image information and text information that are associated by an ID number.

In addition, an overcoat layer is thermally transferred onto the card on which the image and text information is printed to protect the image and text information.

JP 2006-137198 A

A known thermal transfer system for thermally transferring an overcoat layer is one that has a platen roller and a heating element consisting of a heating head that clamps an ink ribbon and a card between the platen roller and the heating head to transfer the overcoat layer of the ink ribbon to the card.

In such a thermal transfer system, if the gap between the platen roller and the heating head is too large, it becomes difficult to reliably perform thermal transfer using the ink ribbon. On the other hand, if the gap between the platen roller and the heating head is too small, cracks may occur on the trailing end side in the transport direction of the overcoat layer thermally transferred onto the card. It is believed that such cracks on the trailing end side of the overcoat layer occur because, when the card leaves the gap between the platen roller and the heating head, the heating head suddenly drops toward the platen roller, applying excessive force to the ink ribbon.

The present disclosure has been made in consideration of these points, and aims to provide a thermal transfer system that can prevent cracks at the rear end of the transfer layer transferred to the transfer recipient during thermal transfer.

The present disclosure relates to a thermal transfer system that uses a transfer medium having a support layer and a transfer layer to transfer the transfer layer to a transferee, the thermal transfer system comprising a platen roller provided on the transferee side, and a heating body provided on the transfer medium side, which sandwiches the transfer medium and the transferee between the platen roller and the heating body to transfer the transfer layer of the transfer medium to the transferee, and a gap regulation mechanism that regulates the minimum gap between the platen roller and the heating body is provided between the platen roller and the heating body, and the minimum gap α is 0.5 mm≦α≦0.6 mm due to this gap regulation mechanism.

The present disclosure is a thermal transfer system in which the gap regulation mechanism has a pair of support parts that support the platen roller, and a pair of studs that are attached to the heater side and each of which abuts against a corresponding support part of the platen roller.

The present disclosure is a thermal transfer system in which each stud has a variable protruding length toward the corresponding support.

The present disclosure is a thermal transfer system in which a pressing means is attached to the heating element, which constantly presses the heating element against the platen roller.

According to the present disclosure, it is possible to reliably prevent rear end cracks in the transfer layer transferred to the transfer target during thermal transfer.

FIG. 1 is a side view showing a thermal transfer system according to an embodiment of the present invention. FIG. 2 is an enlarged view of the heater element of the thermal transfer system shown in FIG. FIG. 3 is a perspective view showing a heater of a thermal transfer system. FIG. 4 is a diagram showing the entire card issuing system in which the thermal transfer system according to the present invention is incorporated. FIG. 5 is a cross-sectional view showing an ink ribbon. FIG. 6 is a diagram showing a gap regulation mechanism provided between the platen roller and the heater during thermal transfer operation. FIG. 7 is a view showing the gap regulation mechanism provided between the platen roller and the heater after the thermal transfer operation. FIG. 8A is a side view showing the operation of the thermal transfer system according to the present embodiment. FIG. 8B is a front view showing the operation of the thermal transfer system according to the present embodiment. FIG. 9A is a side view showing the operation of the thermal transfer system according to the present embodiment. FIG. 9B is a front view showing the operation of the thermal transfer system according to the present embodiment. FIG. 10A is a side view showing the operation of the thermal transfer system according to the present embodiment. FIG. 10B is a front view showing the operation of the thermal transfer system according to the present embodiment. FIG. 11 is a side view showing the operation of a thermal transfer system according to a comparative example.

<Embodiments of the present invention>
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 10B. First, an entire card issuing system 35 for issuing cards will be described with reference to Figure 4.

<Card issuing system>
As shown in Fig. 4, the card issuing system 35 includes a casing 46, a card hopper 31 that is provided in the upper part of the casing 46, stores a large number of cards, and sequentially discharges cards (transfer subjects) 14 (see Fig. 1) such as ID cards, and a printing device 30 that is provided downstream of the card hopper 31 and prints image information and text information on the surface of the card. The printing device 30 has a Y printing section 30a, an M printing section 30b, and a C printing section 30c that print a facial image on the surface of the card 1. Of these, the Y printing section 30a prints yellow on the surface of the card 1, the M printing section 30b prints magenta on the surface of the card 1, and the C printing section 30c prints cyan on the surface of the card 1, and the facial image is printed by the Y printing section 30a, the M printing section 30b, and the C printing section 30c. An ink fixing section 30d is provided downstream of the C printing section 30c. Further, downstream of the ink fixing section 30d, a surface printing section 30e for printing surface information on the surface of the card 1 is provided.

As shown in FIG. 4, downstream of the printing device 30 is a first protective sheet forming section 39 as a thermal transfer system according to the invention, which forms a first protective sheet (also called an overcoat layer) 13b on the surface of the card to protect the image information and text information printed on the surface of the card. Downstream of the first protective sheet forming section 39 is a second protective sheet forming section 40 as a thermal transfer system, which forms a second protective sheet on the first protective sheet 13b. Downstream of the second protective sheet forming section 40 is a sorting mechanism 44 that sorts cards to a stacking section 45.

In this embodiment, an IC chip (not shown) in which the owner's image information and text information are electronically stored may be mounted in the card 14. In this case, the image information and text information may be written to the IC chip of the card 14 by the reader/writer 37 shown in FIG. 4.

In this embodiment, image information or text information of the owner may be printed not only on the front side but also on the back side of the card 14. In this case, image information and text information may be printed on the back side of the card by the back side printing unit 38 shown in FIG. 4.

<Thermal transfer system>
Next, the first protective sheet forming unit 39 and the second protective sheet forming unit 40 which constitute the thermal transfer system according to the present invention will be described with reference to Figures 1 to 3. Below, the first protective sheet forming unit 39 will be described, but the second protective sheet forming unit 40 has substantially the same configuration as the first protective sheet forming unit 39.

As shown in Fig. 1 to Fig. 3, the first protective sheet forming section 39 uses an ink ribbon (also called a transfer medium) 13 including at least a support layer 13a and an overcoat layer (also called a transfer layer) 13b shown in Fig. 5 to heat and transfer the overcoat layer 13b to a card (also called a transferee) 14 such as an ID card, and the first protective sheet forming section 39 constitutes a thermal transfer system according to the present invention. Such a first protective sheet forming section (hereinafter referred to as a thermal transfer system) 39 includes a delivery section 25 that delivers the ink ribbon 13 in the direction indicated by the arrow _R1 , a transfer device 18A arranged downstream of the delivery section 25 in the conveying direction of the ink ribbon 13, and a winding section 26 arranged downstream of the transfer device 18A and winding up the transferred ink ribbon 13 in the direction indicated by the arrow _R2 . As shown in Fig. 1, the ink ribbon 13 is guided from the delivery section 25 to the transfer device 18A by a guide roller 16, and then taken up by the winding section 26 from the transfer device 18A via a peeling roller 17.

Meanwhile, the card 14 is transported to the transfer device 18A via the introduction line 11, and is discharged from the transfer device 18A to the outside via the discharge line 12.

Next, the transfer device 18A will be described. As shown in FIG. 1, the transfer device 18A has a rubber platen roller 19 that supports the card 14, and a heating element 18 that is arranged to face the platen roller 19 with the ink ribbon 13 and card 14 sandwiched between them. As shown in FIG. 1, the heating element 18 is arranged on the support layer 13a side of the ink ribbon 13. The card 14 and the ink ribbon 13 are then nipped (sandwiched) between the heating element 18 and the platen roller 19, and the overcoat layer 13b of the ink ribbon 13 is heated by the heating element 18. As a result, the overcoat layer (transfer layer) 13b of the ink ribbon (transfer medium) 13 is transferred to the card (transferee) 14.

The transfer device 18A will now be described in further detail. As described above, the transfer device 18A has a rubber platen roller 19 and a heating element 18, of which the heating element 18 has a heating head 18a including a ceramic substrate, and a metal plate 20 arranged on the ink ribbon 13 side of the heating head 18a. The ceramic substrate that constitutes the heating head 18a has a surface roughness (arithmetic mean roughness Ra) of 0.1 to 0.3 μm, and a surface friction coefficient of 0.4 to 0.8.

On the other hand, the metal plate 20 has a thickness of 0.3 to 0.5 mm and includes a metal plate body 20a that contacts the ink ribbon 13 and a support plate 20b connected to the metal plate body 20a, forming an overall L-shaped cross section (see Figure 2).

The metal plate 20 is made of copper or aluminum, is made of a thin plate overall, and has excellent thermal conductivity. This allows the heat from the heating head 18a to be smoothly transferred to the ink ribbon 13 side via the metal plate 20.

The metal plate 20 has also been subjected to a buffing process in advance, so that its surface roughness (arithmetic mean roughness) is 0.004 to 0.02 μm.

The metal plate is then subjected to surface treatments such as plating, coating, and deposition, giving the surface of the metal plate 20 excellent slip resistance, abrasion resistance, and heat resistance.

Specifically, the metal plate 20 is surface treated with NIFGRIP, a product of ULVAC, Inc.

This NIFGRIP process involves co-deposition of electroless nickel and fluororesin in a treatment solution, forming a coating on a copper or aluminum base material using this treatment solution, making the coating contain 30% fluororesin by volume, and after the coating is formed, carrying out a heat treatment to firmly bond the electroless nickel and fluororesin in the coating.

This NIFGRIP process is a surface treatment technology that can form a highly functional composite coating that has excellent adhesion between the base material and the coating, as well as excellent release properties, non-stickiness, slipperiness, and corrosion resistance.

By carrying out this surface treatment, the surface of the metal plate 20 as a whole has a surface roughness (arithmetic mean roughness Ra) of 0.004 to 0.02 μm and a friction coefficient of 0.2 or less, preferably about 0.1.

As shown in Figures 2 and 3, the heating head 18a of the heating element 18 is fixed to the support frame 21 by mounting bolts 22 via an intermediate plate 24. The metal plate 20 provided on the ink ribbon 13 side of the heating head 18a is fixed to the support frame 21 by fixing its support plate 20b to the support frame 21 by mounting bolts 23. By fixing the metal plate 20 to the support frame 21 for fixing the heating head 18a in this way, the metal plate 20 can be easily installed, and there is no need to provide a separate support mechanism for installing the metal plate 20.

Next, the structure of the ink ribbon 13, which has a support layer 13a and an overcoat layer 13b, will be described with reference to FIG. 5.

In the present invention, the support layer (substrate) 13a is preferably made of a material that has sufficient mechanical strength to be handled without problems even when heated, since heat is applied during thermal transfer. Examples of materials for such a support layer include polyethylene terephthalate (PET) film, 1,4-polycyclohexylene dimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film, etc. The thickness of the support layer is preferably 2 μm or more and 20 μm or less, and more preferably 4 μm or more and 10 μm or less.

The overcoat layer 13b may be a heat melting coating layer or a heat sublimation coating layer. The overcoat layer 13b covers the image information and text information printed on the surface of the card 14 from above, protecting the image information and text information.

The components of the thermal transfer system 39, such as the transfer device 18A, the delivery section 25, and the winding section 26, are driven and controlled by a control section 35A incorporated in the card issuing system 35.

As shown in Figures 3, 6 and 7, a gap regulation mechanism 50 is provided between the platen roller 19 and the heater 18 to regulate the minimum gap α between the platen roller 19 and the heater 18, specifically, the minimum gap α between the platen roller 19 and the metal plate 20 of the heater 18.

In the present embodiment, the heating element 18 has a heating head 18a and a metal plate 20 provided on the ink ribbon 13 side of the heating head 18a, but this metal plate 20 is not essential, and the heating element 18 may consist of only the heating head 18a. When the heating element 18 consists of only the heating head 18a, the minimum gap α between the platen roller 19 and the heating element 18 is the minimum gap between the platen roller 19 and the heating head 18a.

As shown in Figures 1 to 7, the platen roller 19 has a rotating shaft 19a, which is rotatably supported by a pair of support parts 19A, 19A. In this embodiment, each of the support parts 19A, 19A is made of a ball bearing.

On the other hand, a pair of studs 52, 52 that protrude toward the pair of support portions 19A, 19A of the platen roller 19 are attached to the support frame 21 that supports the heating element 18. Each stud 52, 52 attached to the support frame 21 abuts against the corresponding support portion 19A, 19A of the platen roller 19 to define the minimum gap α between the platen roller 19 and the heating element 18.

In this embodiment, the support parts 19A, 19A on the platen roller 19 side and the studs 52, 52 on the heating element 18 side constitute a gap regulation mechanism 50 that regulates the minimum gap α between the platen roller 19 and the heating element 18.

The studs 52, 52 on the heater 18 side are attached to the support frame 21 so that the protruding length L (Figures 6 and 7) toward the corresponding support parts 19A, 19A is variable.

Furthermore, the support frame 21 that supports the heating element 18 is supported by a fixed structure (not shown) via a spring (pressing means) 54, so that the heating element 18 is constantly pressed toward the platen roller 19 by the spring 54.

As shown in Figures 3, 6 and 7, the gap regulation mechanism 50 is composed of the support parts 19A, 19A on the platen roller 19 side and the studs 52, 52 on the heater 18 side, but this gap regulation mechanism 50 has been removed for convenience in Figures 1 and 2. Also, in Figures 6 and 7, and Figures 8A to 11 described below, the metal plate 20 has been removed from the heater 18 for convenience.

In this embodiment, the minimum gap α between the platen roller 19 and the heater 18 is set to 0.5 mm≦α≦0.6 mm when the thickness a of the card 14 is approximately 0.8 mm.

In this case, if the minimum gap α is smaller than 0.5 mm, excessive tension is applied to the ink ribbon 13 from the heater 18, as described below, causing cracks in the overcoat layer 13b at the rear end of the card 14. On the other hand, if the minimum gap α is larger than 0.6 mm, the overcoat layer 13b of the ink ribbon 13 cannot be reliably transferred to the card 14. For this reason, the minimum gap α is set to 0.5 mm≦α≦0.6 mm.

This minimum gap α can also be adjusted by changing the protruding length L of the studs 52, 52.

<Operation of this embodiment>
Next, the operation of the thermal transfer system 39 according to this embodiment having the above-mentioned configuration will be described.

First, a card 14 such as an ID card, on whose surface image information and text information have already been printed by the upstream printing device 30, is sent to the thermal transfer system 39. At this time, the control unit 35A drives the introduction line 11 to transport the card 14 toward the transfer device 18A, and preheats the card 14 with the heater unit 15. Meanwhile, the control unit 35A drives the winding unit 26 to transport the ink ribbon 13 from the delivery unit 25 toward the transfer device 18A.

At this time, tension is applied to the ink ribbon 13 by the brake mechanism built into the delivery section 25.

When the card 14 reaches between the heating body 18, which is composed of the heating head 18a and metal plate 20 of the transfer device 18A, and the platen roller 19, the control unit 35A drives the heating head 18a of the heating body 18, and the heating head 18a presses the ink ribbon 13 against the card 14 while heating it via the metal plate body 20a of the metal plate 20. This causes the overcoat layer 13b of the ink ribbon 13 to be transferred onto the card 14. As a result, the image information and character information previously printed on the card 14 by the upstream printing device 30 are covered and protected by the overcoat layer 13b.

On the other hand, the ink ribbon 13 transferred by the heater 18 of the transfer device 18A is peeled off from the card 14 via the peeling roller 17 and wound up on the winding section 26.

During this time, the heating head 18a presses the ink ribbon 13 against the card 14 while heating it through the metal plate body 20a of the metal plate 20. At this time, the ink ribbon 13 is heated while running on the metal plate 20, but as described above, the surface roughness (Ra) of the metal plate 20 is 0.004 to 0.02 μm, and its friction coefficient is 0.2 or less. Therefore, the ink ribbon 13 can run smoothly on the metal plate 20 and will not stop due to friction on the metal plate 20 or break due to the application of excessive force. In addition, the ink ribbon 13 will not be scratched and the scratches on the ink ribbon 13 will not be transferred to the card 14. Furthermore, since the metal plate 20 is made of copper or aluminum, which has excellent thermal conductivity, the heat of the heating head 18a can be smoothly transferred to the ink ribbon 13 side.

Next, the thermal transfer action of thermally transferring the ink ribbon 13 to the card 14 between the platen roller 19 and the heater 18 will be described in detail with reference to Figures 8A to 10B and Figure 11.

First, as shown in Figures 8A and 8B, the card 14 and ink ribbon 13 are transported to between the platen roller 19 and the heater 18. At this time, the support frame 21 is waiting above, and the heater 18 is located above and away from the platen roller 19.

Next, when the leading edge of the card 14 reaches between the platen roller 19 and the heater 18, the support frame 21 descends, and the card 14 and ink ribbon 13 are sandwiched between the platen roller 19 and the heater 18. In this state, as shown in Figures 9A and 9B, the card 14 and ink ribbon 13 are conveyed in the conveying direction (to the right in Figure 9A) while being sandwiched between the platen roller 19 and the heater 18.

During this time, the support frame 21 is pressed downward by the spring 54, so the heater 18 is constantly pressed toward the platen roller 19. Therefore, the gap between the platen roller 19 and the heater 18 is set to the card thickness a (approximately 0.8 mm) if the thickness of the ink ribbon 13 is ignored (see Figure 6).

As the card 14 and ink ribbon 13 are conveyed while being sandwiched between the platen roller 19 and the heater 18, the overcoat layer 13b of the ink ribbon 13 is transferred onto the card 14 as described above.

At this time, the gap between the support portion 19A on the platen roller 19 side and the stud 52 on the heater 18 side is b (see Figure 6).

When the overcoat layer 13b of the ink ribbon 13 is transferred onto the card 14 in this manner, the rear end of the card 14 in the transport direction reaches between the platen roller 19 and the heater 18, and then the card 14 leaves between the platen roller 19 and the heater 18 (see Figures 10A and 10B).

In this case, the support frame 21 is constantly pressed downward by the spring 54, so the heater 18 descends toward the platen roller 19. At this time, the stud 52 on the heater 18 side abuts against the support portion 19A on the platen roller 19 side, and the gap between the support portion 19A and the stud 52 becomes zero.

At this time, the gap between the platen roller 19 and the heater 18 is maintained at the minimum gap α.

In this embodiment, the minimum gap α between the platen roller 19 and the heater 18 is defined as α = a - b.

When the thickness a of the card 14 is approximately 0.8 mm, α is set to 0.5 mm≦α≦0.6 mm.

By setting the minimum gap α between the platen roller 19 and the heating element 18 to 0.5 mm≦α≦0.6 mm in this way, even if the trailing end of the card 14 in the transport direction separates from between the platen roller 19 and the heating element 18 and the heating element 18 descends toward the platen roller 19, the distance the heating element 18 descends can be kept small, for example to about 0.2 to 0.3 mm.

In addition, when the rear end of the card 14 in the transport direction leaves between the platen roller 19 and the heater 18, the distance that the heater 18 descends can be kept small, so that the heater 18 does not descend significantly and apply excessive tension to the ink ribbon 13. As a result, it is possible to reliably prevent cracks in the overcoat layer 13b that would occur at the rear end of the card 14 if excessive tension were applied to the ink ribbon 13.

Next, a comparative thermal transfer system will be described with reference to Figure 11.

As shown in FIG. 11, if no studs 52 are provided on the heating element 18 side, the minimum gap α between the platen roller 19 and the heating element 18 is 0. In this case, when the rear end of the card 14 in the transport direction leaves between the platen roller 19 and the heating element 18, it is possible that the heating element 18 will drop toward the platen roller 19 by the thickness a of the card 14 (e.g., 0.8 mm). In this case, the heating element 18 drops significantly, and excessive tension is applied from the heating element 18 to the ink ribbon 13. As a result, excessive tension is applied to the ink ribbon 13, causing cracks in the overcoat layer 13b at the rear end of the card 14.

In contrast, according to this embodiment, when the rear end of the card 14 in the transport direction leaves the gap between the platen roller 19 and the heater 18, the distance that the heater 18 descends can be kept small, so that the heater 18 does not descend significantly and does not apply excessive tension to the ink ribbon 13. As a result, cracks in the overcoat layer 13b at the rear end of the card 14 can be reliably prevented.

The reason why the minimum gap α between the platen roller 19 and the heater 18 is set to 0.5 mm≦α≦0.6 mm can be summarized as follows.

In other words, if the minimum gap α is smaller than 0.5 mm, for example if it is smaller than 0.5 mm, when the trailing end of the card 14 in the transport direction leaves between the platen roller 19 and the heating element 18, the heating element 18 drops significantly, and excessive tension is applied from the heating element 18 to the ink ribbon 13, causing cracks in the overcoat layer 13b at the trailing end of the card 14. For this reason, the minimum gap α is set to 0.5 mm or more, as described above.

On the other hand, if the minimum gap α is greater than 0.6 mm, the thickness of the card 14 will vary, and if the card 14 becomes thinner, the card 14 and the ink ribbon 13 cannot be securely clamped between the platen roller 19 and the heater 18 during the thermal transfer operation, and the overcoat layer 13b of the ink ribbon 13 cannot be securely transferred to the card 14. For this reason, the minimum gap α is set to 0.6 mm or less, as described above.

As described above, according to this embodiment, the minimum gap α between the platen roller 19 and the heating element 18 is set to 0.5 mm≦α≦0.6 mm, so that the minimum gap α can be set to 0.5 mm or more. When the rear end of the card 14 leaves between the platen roller 19 and the heating element 18, the distance that the heating element 18 falls can be kept small, and as a result, no cracks occur in the overcoat layer 13b at the rear end of the card 14. In addition, the minimum gap α can be set to 0.6 mm or less, so that the card 14 and the ink ribbon 13 can be securely sandwiched between the platen roller 19 and the heating element 18, and the overcoat layer 13b of the ink ribbon 13 can be securely transferred to the card 14.

In addition, according to this embodiment, the studs 52 are attached to the support frame 21 so that the protruding length L is variable. By changing the protruding length L of the studs 52, the minimum gap α between the platen roller 19 and the heater 18 can be set to an appropriate value between 0.5 mm≦α≦0.6 mm according to the actual conditions of the device.

REFERENCE SIGNS LIST 11 Introduction line 12 Discharge line 13 Ink ribbon 13a Support layer 13b Overcoat layer 14 Card 15 Heater section 16 Guide roller 17 Peeling roller 18 Heating body 18A Transfer device 18a Heating head 19 Platen roller 19A Support section 19a Rotating shaft 20 Metal plate 20a Metal plate main body 20b Support plate 21 Support frame 22 Mounting bolt 23 Mounting bolt 25 Delivery section 26 Winding section 50 Gap regulation mechanism 52 Stud 54 Spring

Claims (2)

A thermal transfer system for transferring a transfer layer onto a transfer-receiving body using a transfer medium having a support layer and a transfer layer, comprising:
a platen roller provided on the transfer object side;
a heating member provided on the transfer medium side, sandwiching the transfer medium and the object to be transferred between the platen roller and the heating member, and transferring the transfer layer of the transfer medium to the object to be transferred;
the transfer layer is an overcoat layer,
a gap regulation mechanism is provided between the platen roller and the heating body for regulating a minimum gap α between the platen roller and the heating body, and the minimum gap α is 0.5 mm≦α≦0.6 mm by this gap regulation mechanism ;
the heating element is supported by a support frame, and a pair of springs are attached to the support frame to press the support frame toward the platen;
a pair of support portions for supporting the platen roller, and a pair of studs attached to the heater side, each of which abuts against a corresponding support portion of the platen roller; and a pair of springs disposed between the pair of studs on the support frame. 2. The thermal transfer system of claim 1 , wherein each stud has a variable length of protrusion toward the corresponding support.

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