JPH10109394A - Plate-making device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high speed printing, the high reliability of a device, the sure formation of a thin film layer at non-printing area parts and a sure infiltration of ink without developing solid printing area part. SOLUTION: By reading the setting of a head rank designating switch, the operation expression corresponding to the read setting is set so as to read voltage detected values from a voltage detecting circuit at every energizing to a thermal head in order to calculate an energizing time T on an operation expression: T=(A/(V+B))+C. The energy applying to the thermal head for forming a thin film layer on a printing surface is set to lie within 0.1-1.1mJ under the condition that the powers applying to respective heating elements of the thermal head is limited within a range of 0.5-0.6W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate making apparatus using a thermal head in which a plurality of heating elements that generate heat when energized are arranged.

[0002]

2. Description of the Related Art Conventionally, there has been known a printer constituted by using a thermal head in which a plurality of heating elements which generate heat by energization are arranged. In such a printer,
An ink ribbon formed by applying a heat-meltable ink to the film is interposed between the thermal head and the recording paper, and the ink melted from the ink ribbon by the heat of the thermal head is transferred to the recording paper (thermal transfer printer). Printing is performed by directly contacting the thermal head with the thermal paper and discoloring the thermal paper (thermal printer).

[0003] In recent years, a plate making apparatus for producing a printing plate using such a thermal head has been developed. That is, a plate-shaped porous resin having fine open cells is used, and the surface (marked surface) of the porous resin is heated and melted by a thermal head, so that ink impermeable portions other than the image portion are formed. This is to produce a printing plate in which a thin film layer is formed and ink is transmitted from an image portion.

[0004]

However, in the case of printing with an ink ribbon or thermal paper and the case of melting a porous resin, the energy (heat generation) required by a thermal head is different. If the thermal head used in the above was directly applied to a plate making apparatus, there was a problem that a high quality printing plate could not be produced.

[0005] That is, in the plate making apparatus, if the energy applied to the thermal head is too small, the surface of the printing plate cannot be sufficiently melted, and the formed thin film layer surely blocks the transmission of ink. Therefore, the ink is transmitted even in the non-image area, and on the other hand, if the energy applied to the thermal head is too large, the thin film layer is formed to protrude to the part to be left as the image area,
The image portion will be crushed, and in any case, the printing quality of the printing plate will be reduced.

In order to speed up the processing, it is desired to reduce the energizing time required for applying the energy required to form one dot, and for that purpose, the power applied to each heating element must be increased. Usually, a printer energizes a heating element corresponding to an image area, whereas a plate-making apparatus energizes a heating element corresponding to a non-image area. The number of heating elements to be energized is larger than that, and not only does the energy required for the entire thermal head increase, but in general, the higher the applied power, the lower the maximum rating of the device. , And there is a problem that the thermal head may be broken.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a plate making apparatus capable of performing high-speed printing and having high reliability of the apparatus. According to a second aspect of the present invention, there is provided a plate making apparatus capable of producing a printing plate capable of reliably forming a thin film layer on a non-image portion and also allowing ink to pass therethrough without crushing the image portion. The purpose is to provide.

[0008]

Means for Solving the Problems and Effects of the Invention The present invention according to claim 1 which has been made to achieve the above object,
A thermal head in which a plurality of heating elements that generate heat by energization are arranged in a row; and the thermal head in a state where the thermal head is pressed against a stamped portion of a plate-shaped porous resin having continuous cells through which ink can pass. And a moving drive unit for relatively moving the porous resin, and a head energization control unit for selectively energizing the heating element in accordance with the movement by the movement driving unit. Correspondingly, the stamped surface portion where the surface is melted and solidified by the heating element and the thin film layer is formed is a non-image portion that blocks ink transmission, and the stamped surface portion corresponding to the non-energized heating element is used for ink transmission. In the plate making apparatus for producing a printing plate having an allowable image portion, the power applied to each heating element that is energized by the head energization control means is 0.05 to 0.6.
W (watt).

In the thermal head control device according to the first aspect of the present invention, the head driving means is adapted to move the thermal head relative to the recording medium disposed opposite to the thermal head in accordance with the relative movement. A printing pattern is formed on a recording medium by selectively energizing a plurality of heating elements constituting a thermal head.

FIG. 6A is a graph schematically showing the relationship between the power applied to the heating element and the energy E required to form a thin film layer that reliably prevents the transmission of ink. FIG. 6B shows the relationship between the energy E, the voltage V applied to the heating element, the resistance value R of the heating element, and the energization time T using the equation (1). 7 is a graph obtained by converting a graph shown by a solid line into a relationship between applied power P and conduction time T.

[0011]

(Equation 1)

As shown in FIG. 6, the energy E required for forming the thin film layer is not constant, and the power P applied to the heating element is not constant.
Is smaller, the energization time T is sharply increased. Therefore, if the lower limit of the applied power P to the heating element is set to 0.05 W where the rate of change of the energizing time T with respect to the applied power P is sufficiently small as in the plate making apparatus of the present invention, the energizing time T becomes extremely large. Since it does not increase, high-speed printing can be realized.

[0013] In this range, the applied power P fluctuates somewhat due to the variation of the applied voltage V (△ P).
However, since the change (ΔT) in the energization time T is small,
Energy E applied to the heating element does not vary greatly, and uniform printing quality can be obtained.

On the other hand, as the applied power P to the heating element is increased, the energization time T can be shortened. However, the effect of shortening the energization time T with respect to the increase in the applied power P decreases.
Therefore, if the upper limit of the applied power is set to 0.6 W as in the plate making apparatus of the present invention, the applied power is increased wastefully,
There is no possibility that the thermal head is easily broken.

As described above, according to the plate making apparatus of the present invention,
Since the applied voltage P to the heating element is limited to a predetermined range, high-speed printing can be realized, and a constant printing quality can be obtained irrespective of the variation of the applied voltage (power supply voltage) V. Since the failure of the thermal head is also reduced, the reliability of the apparatus can be improved.

In the present invention, the porous resin is 8
It has a melting point of 0 to 200 ° C., and is preferably, for example, a polyolefin-based resin or a rubber-based porous body. The dimensions of each heating element constituting the thermal head are in the main scanning direction along the arrangement direction of the heating elements. Has a width of 90 to 150 μm,
The width in the sub-scanning direction orthogonal to the main scanning direction is 90 to 200
μm is desirable.

Next, a second aspect of the present invention is the first aspect.
In the plate making apparatus described in 1, the head driving unit determines the energization time in a unit period required to form one dot on the recording medium by the energy applied to each of the heating elements in the unit period. Is 0.1 × 10 ^{−3 to} 1.1 × 10
^-3 J (joules).

According to the plate making apparatus of the present invention thus configured, the thermal head melts the porous resin moderately, and a suitable thin film layer is formed on the surface of the porous resin. It is possible to manufacture a printing plate having good print quality without causing ink to permeate from the portion and preventing the thin film layer from extending to the image portion and forming the image portion.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. First, a printing plate made by the plate making apparatus of the present embodiment will be described. FIG. 3A is a perspective view showing a printing plate before plate making, and FIG. 3B is a perspective view showing a printing plate after plate making.

As shown in FIG. 3A, the printing plate 2 has a thickness of about 1 to 3 mm formed of a hard or semi-hard polyolefin resin having fine open cells (cell diameter: 1 to 100 μm). The peripheral side surface portion 2c excluding the front and back surfaces 2a and 2b having a large area and the peripheral portion 2d of the front surface (hereinafter also referred to as a stamped surface) 2a used as a stamped surface are pressed by a heated mold. By doing so, it is melted and solidified to form an ink impermeable thin film layer.

The material of the porous resin substrate constituting the printing plate 2 is not limited to the above-mentioned polyolefin resin, but the melting point is 8
If it is 0 ° C. to 200 ° C., for example, a fine continuous resin made of a resin such as a polyurethane resin, a vinyl chloride resin, an ABS resin, an ethylene-vinyl acetate copolymer, or a rubber porous material such as butadiene rubber is used. A plastic foam having bubbles may be used. That is, if the melting point of the porous resin substrate is lower than 80 ° C., shrinkage, curing and other changes occur due to the influence of the ambient temperature, so that the preservability of the printing plate 2 deteriorates,
If the temperature is higher than 00 ° C., the amount of heat that can be generated by a commonly used thermal head cannot be sufficiently melted,
This is because a printing plate 2 with good printing quality cannot be produced.

FIG. 3B shows an image portion 4 having a mirror image of a character to be imprinted (here, [ABC]) on the stamp surface 2a of the printing plate 2 by the plate making apparatus of the present embodiment. The ink impermeable thin film layer is formed in the non-image area 6 on the stamp face 2a.

As shown in FIG. 2B, the printing plate 2 is used with its back surface 2b adhered to the lower surface of a stock 8 having a handle on the upper surface. Next, the plate making apparatus 10 of the present embodiment for making such a plate 2 will be described.

FIG. 1 is a perspective view showing the entire structure of a mechanical portion of a plate making apparatus 10 according to the present embodiment. FIG. 2 (a) is a front view thereof, and FIG. 2 (b) is a side view thereof. 2A, the front panel is omitted, and in FIG. 2B, the side panel is omitted and a partial cross-sectional view is shown.

As shown in FIGS. 1 and 2, the plate making apparatus 10 of the present embodiment includes a carriage 14 on which a thermal head 12 is mounted, and a main body 16 for movably supporting the carriage 14. The main body 16 includes a frame 20 including a front panel 20a and side panels 20b and 20c erected at both ends of the front panel 20a, and guide rods 22 for guiding the carriage 14 along the front panel 20a. A head switching rod 26 to which a cam body 24 for operating the elevation of the thermal head 12 mounted on the carriage 14 is attached is supported by the side panels 20b and 20c.

The cam body 24 has a head switching rod 26
It is mounted so as not to rotate with respect to and slidable along the axial direction. The head switching rod 26 is rotatably supported by bearings 28 provided on the side panels 20b and 20c. On one side panel 20b, a driven gear 30 fixed to an end of the head switching rod 26 is provided. An operation gear 34 that meshes and rotates by operating the lever 32 is provided. That is, the operating gear 34 is operated by operating the lever 32.
Is rotated, the head switching rod 26 is rotated via the driven gear 30, and the posture of the cam body 24 is changed.

A step motor 36 which can be rotated forward and backward is attached to the front panel 20a of the frame 20, and a pinion 40 which meshes with a rack 38 provided at the front end of the carriage 14 is provided on the back surface thereof. A reduction gear group 35 for reducing the rotation of the output shaft of the step motor 36 and transmitting the reduced rotation to the pinion 40 is provided. That is, when the step motor 36 is driven, the rotation is transmitted to the pinion 40 via the reduction gear group 35, and the carriage 14 moves along the guide rod 22 by sending the rack 38 out of the pinion 40. .

On the other hand, the carriage 14 is
A case 42 which is slidably mounted along 2 and has the above-mentioned rack 38 formed integrally therewith, and a head radiator plate 44 to which the thermal head 12 is fixed to one end of the upper surface
And a cam contact plate 46 disposed at a position facing the lower surface of the head heat sink 44 and in contact with the cam body 24. The ends of the head radiating plate 44 and the cam contact plate 46 to which the thermal head 12 is fixed can be vertically swung by a support shaft 48 fixed to the case 42 so as to be orthogonal to the head switching rod 26. It is supported. An urging spring 43 is interposed between the head heat radiating plate 44 and the cam contact plate 46.

The case 42 is formed so as to sandwich the cam 24 from both sides along the head switching rod 26, and the cam 24 moves with the movement of the case 42. The thermal head 12 has the same configuration as a thermal head in a conventionally known thermal printer. For example, 96 dot-like heating elements are arranged in one row along a direction orthogonal to a moving direction of the thermal head 12. In addition, the row length is set to be slightly longer than the lateral dimension of the printing plate 2. Furthermore, a head rank indicating the rank of the average resistance value of the heating element is specified for the thermal head 12.

In the carriage 14 configured as described above, the thermal head 12 is held at a predetermined lowering position when the cam body 24 is turned over so that the short meridian portion of the cam body 24 contacts the cam contact plate 46. Then, when the cam body 24 is erected so that the long meridian portion of the cam body 24 comes into contact with the cam contact plate 46, the cam body 24 is held at a predetermined raised position.

The frame 20 is provided with support means (not shown) for fixing the printing plate 2 bonded to the lower surface of the stock 8 above the moving path of the carriage 14.
At the lowered position, the thermal head 12 is separated from the printing plate 2, and at the raised position, the thermal head 12 is separated from the printing plate 2.
Is to be abutted. At this time, the thermal head 12 in contact with the printing plate 2 is urged by the urging spring 43 in a direction in which the thermal head 12 comes into close contact with the printing plate 2.

FIG. 4 is a block diagram showing a configuration of a control system for controlling the movement of the carriage 14 and the driving of the thermal head 12 in the plate making apparatus 10. As shown in FIG. As shown in FIG. 4, the control system of the plate making apparatus 10 includes a thermal head 12
And a voltage detection circuit 5 for detecting an output voltage of a battery 54 used as a thermal head driving power supply.
6, a thermal head drive circuit 58 for energizing each heating element constituting the thermal head 12, a step motor drive circuit 60 for driving the step motor 36 for driving the carriage, a CPU, a ROM, a RAM, a timer, A control device 50 mainly including a known microcomputer including an output interface and the like is provided.

The controller 50 outputs a command to the step motor drive circuit 60 to rotate the step motor 36 at a constant speed, thereby moving the carriage 14 at a constant speed, and inputting data from a keyboard (not shown). In accordance with the print data created in advance, a command is output to the thermal head drive circuit 58, and a print process for selectively energizing the heating elements constituting the thermal head 12 is executed.

That is, the stock 8 to which the printing plate 2 is adhered is held by supporting means (not shown), and the lever 32 is operated to move the heating element of the thermal head 12 to the printing surface 2 of the printing plate 2.
When the printing process is executed after the contact with the printhead a, the thermal head 12 is moved by the movement of the carriage 14 with the heating element in contact with the printing surface 2 a of the printing plate 2. At this time, the stamped surface 2a of the portion facing the energized heating element is melted and solidified, and an ink-impermeable thin film layer is formed on the surface of the stamped surface 2a, as shown in FIG. The printing plate 2 is produced.

In this printing process, energization of the thermal head 12 is performed every predetermined unit cycle, and printing of one line is performed during the unit cycle. It is set for each unit cycle.
That is, first, the set value of the head rank designating switch 52 is read, and an arithmetic expression corresponding thereto is set. An arithmetic expression is prepared for each head rank so as to approximate the shape of the graph shown in FIG. 7, and based on this arithmetic expression, the energization time T is calculated using the voltage detection value V read from the voltage detection circuit 56. I do. However, FIG. 7 is obtained by converting the graph shown in FIG. 6B into the relationship between the energizing time T and the applied voltage V.

Thereafter, every time the power is supplied, the voltage detection value V is read from the voltage detection circuit 56, and based on the voltage detection value V, the power supply time T in the next unit cycle is set. Note that a voltage value V1 at which the applied power P becomes 0.05 W is preset for each head rank, and if the voltage detection value V becomes smaller than the set value V1 due to the consumption of the battery 54, an abnormal condition occurs. And the printing process is prohibited. The output voltage of the battery 54 is set such that the applied power to each heating element is maximized, that is, when the resistance value R (head rank) of the heating element is the minimum value, the applied power P
Is set to 0.6 W so that the applied power P is 0.05 to 0.
It operates in the range of 6W.

An arithmetic expression for calculating the energization time T is, for example, as shown in Expression (2).
Here, A, B, and C are constants determined by the shape of the graph to be approximated (see FIG. 7).

[0038]

(Equation 2)

By the way, the relationship between the applied power P and the energy E required for forming the thin film layer (and hence the conduction time T) is as follows.
As shown in FIG. 5, although the width varies depending on the area of the heating element, the width in the main scanning direction along the arrangement direction of the heating element is 90 to 90 μm × 90 μm to 150 μm × 200 μm.
150 μm, width in the sub scanning direction orthogonal to the main scanning direction is 9
The range of the required energy E is within the range of 0.1 to 1.1 mJ, provided that the applied power P is 0.05 to 0.6 W.

As described above, according to the plate making apparatus 10 of the present embodiment, the electric power P applied to the heating elements constituting the thermal head 12 is set to be 0.05 to 0.6 W. High-speed printing can be realized without the energization time T becoming extremely long.

When the battery 54 is depleted, the voltage is relatively different between when the battery is energized and when the battery is not energized, and the voltage waveform changes with a time constant when the battery 54 is switched. However, in the present embodiment, the voltage detection value V is slightly varied because the change in the energization time T with respect to the change in the voltage (that is, the applied power P) is used in a sufficiently small range. However, even if the energy E applied to the thermal head 12 does not vary greatly, uniform printing quality can be obtained (see FIG. 8A).

Further, according to the plate making apparatus 10 of the present embodiment, the energy applied to the heating elements constituting the thermal head 12 is set so as to fall within the range of 0.1 to 1.1 mJ. Is too low, the thin film layer formed on the stamped surface 2a transmits ink (see FIG. 8B), and the temperature of the heating element is too high, and It is possible to create a printing plate with good print quality without crushing the part (see FIG. 8C).

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist of the present invention. For example, in the above embodiment, a battery is used as a power supply for driving the thermal head. However, a commercial power supply is used, and a voltage stabilized to a constant value is applied to the thermal head via a voltage stabilizing circuit. May be configured.

In the above embodiment, the voltage detection value V,
Although the energizing time T is determined from the head rank (the resistance value R of the heating element), the energizing time T is corrected in consideration of the influence of the ambient temperature and the effect of heat storage due to continuous printing. Is also good.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of a plate making apparatus according to an embodiment.

2A is a front view of a plate making apparatus, and FIG. 2B is a side view thereof.

FIG. 3A is a perspective view showing a printing plate before plate making, and FIG. 3B is a perspective view showing a printing plate after plate making.

FIG. 4 is a block diagram illustrating an electrical configuration of the plate making apparatus according to the embodiment.

FIG. 5 is a graph showing how the relationship between applied voltage and applied energy varies depending on the area of a heating element.

FIG. 6A is a graph obtained by converting the relationship between the applied power and the applied energy necessary for printing, and FIG. 6B is a graph obtained by converting FIG.

FIG. 7 is a graph obtained by converting FIG. 6B into a relationship between an applied voltage and a conduction time.

FIG. 8A is a printing sample using a printing plate created by the plate making apparatus of the present embodiment, and FIG. 8B is a printing sample using a printing plate created when the temperature of the heating element is too low; (C) is a printing sample using a printing plate created when the temperature of the heating element is too high.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Plate making apparatus 12 ... Thermal head 14 ... Carriage 16 ... Main body 20 ... Frame 22 ... Guide rod 24 ... Cam body 26 ... Head switching rod 35 ... Reduction gear group 36
... Step motor 38 ... Rack 40 ... Pinion 42 ... Case
43: biasing spring 44: head radiator plate 46: cam contact plate 48: support shaft 50: control device 52: head rank designation switch
54 ... Battery 56 ... Voltage detection circuit 58 ... Thermal head drive circuit 60 ... Step motor drive circuit

Claims (3)

[Claims] 1. A thermal head in which a plurality of heating elements that generate heat by energization are arranged in a row, and a state in which the thermal head is pressed against a stamped portion of a plate-shaped porous resin having continuous bubbles through which ink can pass. so,
A moving drive unit for relatively moving the thermal head and the porous resin; and a head energizing control unit for selectively energizing the heating element in accordance with the movement by the moving driving unit. The stamped portion corresponding to the heating element and having the thin film layer formed by melting and solidifying the surface by the heating element is a non-image portion for preventing the transmission of ink, and the stamped portion corresponding to the non-energized heating element is ink. In a plate making apparatus for producing a printing plate having an image portion allowing transmission of light, an electric power applied to each heating element, which is energized by the head energization control means, is 0.05 to 0.6 W (watt). A plate making apparatus characterized by the above-mentioned. 2. The method according to claim 1, wherein the head driving means sets an energizing time in a unit period required for forming one dot on the recording medium to be zero when energy applied to each of the heating elements in the unit period is zero. 2. The plate making apparatus according to claim 1, wherein the setting is made so as to be 1 × 10 ^{−3 to} 1.1 × 10 ⁻³ J (joule). 3. The plate making apparatus according to claim 1, wherein the porous resin is made of a polyolefin resin or a rubber porous body.