JPH10100471A - Thermal head controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head for realizing a uniform print regardless of fluctuation in power supply voltage. SOLUTION: Every time when a predetermined time elapses, output voltage of a battery subjected to AD conversion is taken in and a value stored in a parameter storage area is updated (S340). Subsequently, a heat storage correction value corresponding to the count of a line counter is updated (S370) and then a line data is generated and stored (S390) in a line data storage area. Finally, a conduction time is calculated (S400) using a head rank correction value, a temperature correction value, a voltage detection value and a heat storage correction value stored in the parameter storage area and a thermal head is driven for the conduction time thus calculated according to the line data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head control device for controlling energization of a thermal head using a battery such as a dry battery or a rechargeable battery as a driving power source.

[0002]

2. Description of the Related Art Conventionally, there has been known a recording apparatus such as a printer constituted by using a thermal head including a plurality of heating elements which generate heat when energized. When such a recording apparatus is made compact, a battery such as a dry battery or a rechargeable battery is used as a power supply for driving the thermal head.

In the case of a thermal head, in order to obtain a uniform print density, the amount of heat generated by the heating element needs to be constant, and the amount of generated heat is determined by the energy applied to the heating element. The applied energy E is obtained by the following equation (1), where V is a voltage applied to the heating element, R is a resistance value of the heating element, and T is a conduction time.

[0004]

(Equation 1)

When a battery is used as a power supply for driving the thermal head, the output voltage of the battery, that is, the applied voltage V decreases in accordance with the consumption of the battery.
Is constant, the energy E applied to the heating element is reduced, the amount of heat generation is reduced, and there is a problem that the print quality is reduced with the consumption of the battery.

On the other hand, for example, Japanese Patent Application Laid-Open No. 2-203
No. 3, JP-A-2-241762, Japanese Patent Publication No.
In Japanese Patent Application Publication No. 20068 or the like, a table in which the applied voltage V and the energizing time T correspond to each other is prepared in advance so that the applied energy E becomes substantially constant, and the detection of the output voltage (applied voltage V) of the battery is performed. There is disclosed an apparatus configured to obtain a uniform printing quality regardless of a decrease in the applied voltage V by obtaining a conduction time T from a table based on the result.

[0007]

However, when the energizing time T is set using a table as in these devices,
At the boundary of the voltage range in which the value of the energization time T switches, there is a problem that the print density greatly changes and the print quality deteriorates.

That is, within the voltage range in which the energization time T is set to a constant value, the applied energy E also changes continuously as the applied voltage V decreases, so that the print density changes remarkably. However, at the boundary of the voltage range where the value of the energization time T switches, the energy E applied to the heating element changes abruptly in a stepwise manner, and as a result, the print density changes greatly, and the print quality deteriorates. It will be lost.

In addition, there is a problem that the lower the applied voltage V, the greater the effect. That is, as can be seen from the equation (1), when the applied energy E is constant, the square value of the applied voltage V and the energizing time T are inversely proportional.
Must increase rapidly. In other words, the smaller the applied voltage V, the larger the change in the applied energy E with respect to the change in the energization time T. Therefore, the change in the print density at the boundary of the voltage range where the value of the energization time T switches becomes larger. It will be.

[0010] The present invention has been made in order to solve the above problems.
It is an object of the present invention to provide a thermal head control device capable of performing uniform printing irrespective of fluctuations in power supply voltage.

[0011]

According to the first aspect of the present invention, there is provided a thermal head having a plurality of heating elements arranged in a row to generate heat when energized. A head driving unit for forming a print pattern on the recording medium by selectively energizing the heating element in accordance with a relative movement with respect to a recording medium disposed to face the head; Voltage detection means for detecting an output voltage of a battery used as a drive power supply; and a voltage detection means based on a detection result of the voltage detection means such that a heating value of the heating element energized by the head driving means is substantially constant. Power supply time setting means for setting a power supply time to the heat generating element within a unit period required for each of the heat generating elements to form one dot on the recording medium. In the thermal head control device,
The energization time setting means is provided with arithmetic means for outputting a calculation result inversely proportional to the parameter using a predetermined arithmetic expression having the detection result of the voltage detection means as a parameter, and calculating the calculation result of the arithmetic means with the energization time It is characterized by setting as.

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

At this time, the time for energizing the heating element within a unit time is controlled according to the output voltage of a battery used as a power supply for driving the thermal head. That is, in the energization time setting means, the arithmetic means outputs a calculation result inversely proportional to the parameter using a predetermined arithmetic expression using the detection result of the voltage detection means as a parameter, and sets the calculation result as the energization time.

The arithmetic expressions used by the arithmetic means include:
Assuming that the value obtained by digitizing the detection result (that is, the applied voltage) of the voltage detecting means is DV, for example, the following equation (2) can be used.

[0015]

(Equation 2)

Here, A, B, and C are constants experimentally determined as described below. That is, first, FIG. 9A shows experimentally the range of the total applied energy E required to obtain sufficient print quality with respect to the applied energy per unit time applied to the heating element. 4 is a graph schematically showing the result. FIG. 9 (b)
This graph is a graph obtained by converting the relationship between the applied voltage V and the energizing time T using Expression (1) in which the resistance value R is constant. As can be seen from FIG. 9A, as the applied energy per unit time is lower, that is, as the applied voltage V is smaller if the resistance value R is constant, the total applied voltage required to obtain a desired print quality is reduced. Energy E tends to increase.

Then, a voltage range to be actually used is determined,
FIG. 9B shows that the calculation result of the equation (2) is within the voltage range.
The constants A, B, and C are set so as to fall within the allowable range of the energization time T shown in FIG. As described above, according to the thermal head control device of the present invention, the energization time is obtained by using the predetermined calculation formula with the detection result of the output voltage of the battery (applied voltage V) as a parameter. The energizing time T also changes continuously according to the applied voltage V. As a result, the applied energy to the heating element, that is, the amount of heat generated by the heating element (and, consequently, the print density) does not suddenly change in a stepwise manner, and uniform printing quality can be obtained.

Also, in the thermal head control device of the present invention, since the energization time is simply inversely proportional to the applied voltage, a linear equation as shown in equation (2) is used as an arithmetic expression for calculating the energization time. The calculation time can be reduced. Next, according to a second aspect of the present invention, in the thermal head control device according to the first aspect, the thermal head control device further includes a count unit that counts the number of unit periods that have been energized in the past, and the arithmetic unit has a function of the count unit. According to another aspect of the present invention, the image processing apparatus further includes a first correction unit that reduces the calculation result as the count value increases according to the count value.

In the thermal head control device according to the second aspect, the counting means includes:
The number of unit periods in which power has been supplied by the head driving unit is counted, and the first correction unit corrects the number of periods according to the counted value so that the larger the count value, the smaller the calculation result by the calculation unit.

Therefore, according to the thermal head control device of the present invention, the temperature of the heating element can be kept substantially constant regardless of the heat storage of the heating element, and uniform printing quality can be obtained. That is, it is desirable that the temperature of the heating element that is energized for printing is always constant, but when continuous printing is performed, the temperature of the heating element rises due to heat storage. For this reason, actually, the energy applied to the heating element is not fixed, but the energy required for printing is
It is desirable that the value obtained by subtracting the energy of the heat storage be the applied energy. The heat storage increases as the period of continuous printing is longer, that is, as the count value of the counting means is larger. Therefore, the heat accumulation of the heating element is corrected by correcting the calculation result of the calculation means to be smaller as the count value is larger. It is possible to keep the temperature almost constant regardless of the heat storage.

In this case, assuming that the heat storage correction value set according to the count value is TD so that the larger the count value is, the larger the count value is, the following equation is obtained.
For example, the following equation (3) can be used.

[0022]

(Equation 3)

It should be noted that the heat storage correction value TD may be set so as to be smaller as the count value becomes larger, and in the equation (1), an arithmetic expression obtained by applying the heat storage correction value TD instead of the constant A or C may be used. Good. Further, as the heat storage correction value TD, the count value of the counting means may be used as it is, or a table in which the count value and the heat storage correction value TD correspond to each other may be prepared in advance and calculated from this table. Is also good.

Next, the invention according to claim 3 is based on claim 2
3. The thermal head control device according to claim 1, wherein the correction value obtained by the first correction unit is such that a heating element corresponding to an image portion of a print pattern formed on a print medium is energized or a heating value corresponding to a non-image portion is generated. It is characterized in that switching is possible depending on whether the element is energized.

In the thermal head control device according to the third aspect of the present invention, uniform print quality can always be obtained irrespective of the heat storage characteristics of the thermal head that change depending on the method of energization. That is, usually, the area of the image area of the print pattern is significantly smaller than the area of the non-image area, so that the power is supplied depending on whether the heating element corresponding to the image area or the non-image area is energized. Although the number of heat generating elements and thus the thermal storage characteristics of the thermal head greatly change, the correction value for correcting the thermal storage can be switched according to the energization method, so that a suitable correction can always be performed. .

Next, a fourth aspect of the present invention is directed to the first aspect.
4. The thermal head control device according to claim 3, further comprising a temperature detecting unit for detecting a peripheral temperature of the thermal head, wherein the calculating unit performs the calculation as the detection value of the temperature detecting unit increases. It is characterized by having second correction means for reducing the result.

In the thermal head control device according to the fourth aspect of the present invention, the temperature detecting means detects the temperature around the thermal head, and according to the detected value,
The second correction means corrects the calculation result by the calculation means so that the larger the detection value is, the smaller the calculation result becomes.

Therefore, according to the thermal head control device of the present invention, the temperature of the heating element can be made substantially constant regardless of the fluctuation of the peripheral temperature of the device, and uniform printing quality can be obtained. That is, even if the energy applied to the heating element is equal, the higher the ambient temperature, the higher the temperature of the heating element or the easier it is to store heat in the heating element. By providing the second correction means for reducing the energization time, it is possible to correct this variation.

Next, a fifth aspect of the present invention is directed to the first aspect.
5. The thermal head control device according to claim 4, wherein the calculating unit increases the calculation result as the resistance value increases in accordance with a resistance value of the heating element measured in advance. It is characterized by having correction means.

In the thermal head control device according to the fifth aspect of the present invention, in accordance with the resistance value of the heating element measured in advance, the third correction means determines that the higher the resistance value, the more the calculation means Is corrected so as to increase the calculation result in. Therefore, according to the thermal head control device of the present invention, even if the resistance value of the heating element constituting the thermal head changes due to the replacement of the thermal head or the like, the resistance value is uniform regardless of the difference in the resistance value. Printing quality can be obtained.

That is, since the resistance value of the heating element varies depending on the manufacturing conditions and the like, the average value of the resistance value of the heating element differs for each thermal head. And
As can be seen from the equation (1), even if the applied voltage V and the energizing time T are constant, the applied energy E and, consequently, the amount of generated heat vary depending on the resistance value R of the heating element. This variation can be corrected by providing a third correction unit that increases the energization time as the distance increases.

It is assumed that a temperature correction value set to a smaller value as the ambient temperature is higher is TT, and a resistance correction value set to a smaller value as the resistance value R of the heating element is larger is TH. For example, the following expression (4) can be used as an arithmetic expression for calculating the energization time T.

[0033]

(Equation 4)

As in the case of the thermal storage correction value TD, for example,
The temperature correction value TT is applied to the position of the constant C in the equation (1), or set so as to be larger as the ambient temperature is higher, and is applied to the position of the constant B in the equation (1). TH may be set so as to increase as the resistance value R increases, and an equation applied to the position of the constant A or C in the equation (1) may be used.

The present invention is not limited to the equations (2) to (4), but uses either the temperature correction value TT or the resistance correction value TH and the heat storage correction value TD, or uses the heat storage correction value TD and the temperature correction value TD.
T and the resistance correction value TH may be used to calculate the energization time T.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plate making apparatus according to an embodiment to which the thermal head control apparatus according to the present invention is applied will be described below with reference to the drawings. The plate making apparatus according to the present embodiment employs a thermal head comprising a number of heating elements. By pressing the surface of the foamed plastic substrate having continuous cells through which ink can pass, selectively heating the heating element according to the designated print dot pattern, and melting and solidifying the portion pressed by the heated heating element, A thin film layer is formed on the surface of the foamed plastic substrate to prevent the transmission of ink. The portion where the thin film layer is formed is the non-image area where the ink is impermeable, and the portion where the thin film layer is not formed is the ink permeable portion. A printing plate is formed as an image portion.

Here, a printing plate made by the plate making apparatus of this embodiment will be described first. 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 is made of a foamed plastic substrate having a thickness of about 1 to 3 mm formed of a hard or semi-hard polyolefin resin having fine open cells, and has a large area. A peripheral side surface portion 2c excluding the back surfaces 2a and 2b, and a peripheral portion 2d of a front surface (hereinafter also referred to as a stamped surface) 2a used as a stamped surface are melted and solidified by pressing the surface with a heated mold, and ink impermeable. A thin film layer is formed. The material of the foamed plastic substrate constituting the printing plate 2 includes, for example, fine open cells made of other resins such as a polyurethane resin, a vinyl chloride resin, an ABS resin, and an ethylene-vinyl acetate copolymer. Plastic foam may be used.

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

As shown in FIG. 2, 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, a description will be given of the plate making apparatus 10 of the present embodiment for making such a plate 2.

FIG. 1 is a perspective view showing the entire structure of the mechanical part of the plate making apparatus 10 of the present embodiment, FIG. 2 (a) is a front view thereof, and FIG. 2 (b) is a side view thereof. In order to make the drawing easy to see, FIG.
In (b), 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 forward / reverse rotatable step motor 36 is attached to the front panel 20a of the frame 20, and a pinion 40 meshing 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 body 24 from both sides along the head switching rod 26, and the cam body 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 diameter portion of the cam body 24 contacts the cam contact plate 46. Then, when the cam body 24 is erected so that the long diameter portion of the cam body 24 contacts 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.

Next, 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. 4, the control system of the plate making apparatus 10 includes a CPU 51, a ROM,
A control device 50 mainly composed of a known microcomputer including a RAM 52, a RAM 53, a timer 54, an input / output interface 55 and the like is provided.

An input / output interface 55 of the control device 50 has an LCD driver 61 for driving a liquid crystal display (LCD) 60 to perform various displays, and a keyboard 62 for inputting various commands to the control device 50. ,
A head rank specifying switch 63 set to a value corresponding to the head rank of the thermal head 12 and an output voltage of a battery 64 used as a power supply for driving the thermal head are detected, and the AD detected voltage detection value DV is sent to the control device 50. The voltage detection circuit 65 to be supplied and the peripheral temperature of the plate making apparatus 10 are detected, and the AD detected temperature detection value DT is supplied to the control unit 50.
, A register 67 for holding the line data LD for driving the thermal head, and a thermal head 1 for a period (Low level) during which the strobe signal STB is input in accordance with the contents held in the register 67.
A thermal head drive circuit 68 for energizing each of the heating elements constituting the second element 2 and a step motor drive circuit 69 for driving the carriage drive step motor 36 according to the drive signal MD are connected.

The keyboard 62 is used to input print data,
In addition to character keys, numeric keys, and symbol keys for editing, a medium switching key for designating either the printing plate 2 or thermal paper as a printing medium, and printing for starting a printing operation by the thermal head 12 A key and the like are provided. Note that the medium switching key is operated when printing on thermal paper to check the finished condition before printing (plate making) on the printing plate 2.

Then, the control device 50 controls the keyboard 62
(CGROM) 5 for storing display dot pattern data corresponding to a character code generated by operating a character key, numeric key, symbol key, etc.
The ROM 52 has a keyboard 6
5, the thermal head 12 and the stepping motor 36 are driven to input data from the printer 2, and various control programs such as a print control program for printing on the printing plate 2, as shown in FIG.
From various tables used for calculating the energization time T to the heating element, that is, a temperature correction table TB1 for obtaining a temperature correction value TT from the temperature detection value DT of the temperature detection circuit 66, and a set value DH of the head rank designation switch 63 A head rank correction table TB2 for obtaining a head rank correction value TH, and a heat storage correction table TB for obtaining a heat storage correction value TD from a count value NL of a unit period counter described later.
3 is stored.

The temperature correction table TB1 is set such that the larger the detected temperature value DT is, the smaller the temperature correction value TT is.
The head rank correction value TH is set to be smaller as the resistance value indicated by the head rank set value DH is larger. Further, in the heat storage correction table TB3, the heat storage correction value TD is set to be larger as the count value NL is larger. ing. The heat storage correction table TB3 is composed of two types of tables, one of which is used in accordance with the operation of a medium switching key provided on the keyboard 62.

On the other hand, in the RAM 53, a text data storage area AR1 for storing edited text data inputted from the keyboard 62, and the text data and the CG
A line data storage area AR2 that is created based on the dot pattern data stored in the ROM 55 and stores line data LD necessary for printing one line by the thermal head 12, the above-described voltage detection value DV, and the temperature correction value T
T, a parameter storage area AR3 for storing a head rank correction value TH, and a heat storage correction value TD, and a strobe signal STB.
And a line counter LC for counting the number of times that the thermal head 12 is energized (ie, the number of printing lines) when the power supply is turned on.

Next, FIG. 6 is a flowchart showing the main processing executed by the CPU 51 of the control device. In addition,
This process is started after the power is turned on. As shown in FIG.
When the present process is started, first, in S110, for example, initial settings such as driving the step motor 36 to move the carriage 14 to a predetermined origin position are performed.

In the following S120, the set value DH of the head rank designation switch 63 is fetched, and in S130,
The head rank correction value TH corresponding to the set value DH is obtained using the head rank correction table TB2, and is stored in a predetermined area (TH storage area) of the parameter storage area AR3.

At S140, it is determined whether or not the medium switching key provided on the keyboard 62 has been operated. If not, the process proceeds to S150, where the print key provided on the keyboard 62 is operated. It is determined whether or not it has been performed. Then, if the print key has not been operated, the process proceeds to S160 to perform a text editing process in accordance with the operation of other various keys provided on the keyboard 62, and returns to S140. In this text editing process, the arrangement and size of characters, numbers, and symbols to be formed as the image portions of the printing plate 2 are edited, and the edited text data is stored in the text data storage area AR1. Is done.

On the other hand, if it is determined in S140 that the medium switching key has been operated, the flow shifts to S170 to switch the heat storage correction table TB3 to be used in accordance with the selected printing medium, and then to S180. Then, when the printing plate 2 is selected as the printing medium, the heating element corresponding to the non-image area generates heat during printing, and when the thermal paper is selected, the heating element corresponding to the image area is generated. After the print mode is switched so as to generate heat, the process returns to S140. By switching the print mode, each bit of the line data LD created by the processing described later is actually turned on / off.
The off state is reversed. If it is determined in step S150 that the print key has been operated, the process proceeds to step S190.
After performing the printing process described later, the process returns to S140.

Next, the details of the printing process executed in S190 will be described with reference to the flowchart shown in FIG. FIG. 8 is a time chart showing the state of each unit when the printing process is being performed. As shown in FIG. 7, in this processing, first, in S210, the count value N of the line counter LC is reset to 0.

At S220, after the temperature detection value DT is fetched from the temperature detection circuit 66, at S230, a temperature correction value TT corresponding to the temperature detection value DT is determined using the temperature correction table TB1, and the parameter is stored. Area AR
3 in a predetermined area (TT storage area).

In the next step S240, the voltage detection value DV is fetched from the voltage detection circuit 65, and this voltage detection value DV is stored in a predetermined area (DV storage area) of the parameter storage area AR3. T
Using B3, a heat storage correction value TD corresponding to the count value N (here, 0) of the line counter LC is obtained, and a predetermined area (TD storage area) of the parameter storage area AR3 is obtained.
To be stored.

At S260, the text data stored in the text data storage area AR1 and the CGROM 55
The line data LD for one line is created based on the dot pattern data stored in the step S180 and in accordance with the print mode switched in step S180.

In the following S270, the previous S130, S23
From 0 to S250, the energizing time T is calculated based on the following equation (5) using the head rank correction value TH, temperature correction value TT, voltage detection value DV, and heat storage correction value TD stored in the parameter storage area AR3. I do.

[0063]

(Equation 5)

Note that α, β, and γ are constants, which are set in advance so that the calculation result of the equation (5) falls within the allowable range of the energization time T shown in FIG. 9B. It is. In S280, the motor drive process executed in parallel with the present process is started to start the step motor 36. In S290, every time the time required for printing one line (basic cycle) elapses. After starting the basic cycle timer for notification, the process proceeds to S290. Thereafter, the motor drive processing is performed by the motor drive signal M
By supplying D at a constant cycle and rotating the step motor 36 at a constant speed, the carriage 14 moves at a constant speed along the guide rod 22, and every time the basic cycle elapses, a notification by the basic cycle timer is sent. Is performed.

In S300, the line data storage area A
The line data LD stored in R2 is stored in the register 67
Then, in step S310, the strobe signal STB is turned on to start energization of the thermal head 12. In S320, an energization timer set to timeout when the energization time T calculated in S270 elapses is started, and in S330, it is determined whether or not the energization timer has stopped. And
If the energization timer has not stopped, the process waits by repeatedly executing S330. If it is determined that the energization timer has stopped, the process proceeds to S340.

In step S340, the voltage detection value DV is fetched and the stored value in the parameter storage area AR3 is updated, and the strobe signal STB is turned off in step S350. As a result, energization of the thermal head 12 is stopped.

In S360, the count value N of the line counter LC is incremented. In S370, the heat storage correction value TD corresponding to the count value N is obtained by using the heat storage correction table TB3 just like in S250. The stored value of the parameter storage area AR3 is updated.

Then, in S380, it is determined whether or not data to be processed exists in the text data storage area AR1, and if data to be processed still exists, the process proceeds to S390.
Move to In S390, as in S260, the line data LD is created and the line data storage area AR is created.
2 and then in S400, the previous S130, S23
By using 0, S340, and S370, the head rank correction value TH, the temperature correction value TT, the voltage detection value DV, and the heat storage correction value TD stored in the parameter storage area AR3 are used, based on the equation (5) in the same manner as S270. To calculate the energization time T.

At S410, whether or not the basic cycle has elapsed is determined based on the notification from the basic cycle timer. If not, S410 is repeatedly executed, and the process waits until the basic cycle has elapsed. Is determined to have elapsed, the process proceeds to S300, and thereafter, the above-described S300 to S300
The processing of 410 is repeated until there is no more data to be processed in the text data storage area AR1.

If it is determined in step S380 that there is no data to be processed in the text data storage area AR1, the process proceeds to step S420 and the step motor 3
6 is stopped, and in S430, the basic cycle timer is stopped, followed by terminating the present process.

That is, the printing plate 2 is supported by supporting means (not shown).
Is held, 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.
a), the thermal head 12 melts and solidifies the portion of the stamp surface 2a facing the energized heating element, and forms an ink-impermeable thin film layer on the surface of the stamp surface 2a. FIG. 3 by moving while forming
The printing plate 2 as shown in FIG. Further, after the thermal paper is held by the supporting means in place of the printing plate 2, the print mode is switched by operating the medium switching key, and then the above-described printing process is executed. The printed matter obtained by coloring the heat-sensitive paper is obtained.

As described above, in the plate making apparatus 10 of this embodiment, the energizing time T
Is calculated using the arithmetic expression shown in (5) using the voltage detection value DV, the temperature correction value TT, the head rank correction value TH, and the heat storage correction value TD as parameters. Moreover, the output voltage of the battery 64 is used as the voltage detection value DV.
Since the converted value is used as it is, the calculated energization time T is determined by the output voltage of the battery 64 (that is, the voltage detection value DV).
It changes continuously according to.

Therefore, according to the plate making apparatus 10 of the present embodiment, the printing quality rapidly changes due to the fluctuation of the power supply voltage as in the conventional apparatus using the table corresponding to the energizing time T for each predetermined voltage range. The heating element constituting the thermal head 12 can always generate heat at a substantially constant temperature. As a result, in the case of printing on the printing plate 2 (plate making), a uniform thin film layer 5 can be formed on the surface of the printing plate 2, and in the case of printing on thermal paper,
The thermal paper can be colored at a uniform density, that is, a uniform print quality can be obtained in any case.

According to the plate making apparatus 10 of this embodiment,
Each time a printing process is performed, the set value DH of the head rank specifying switch 63 that can be set according to the head rank of the thermal head 12 is read, and the head rank correction value TH is updated. Even if the thermal head 12 is turned on, the energizing time T suitable for the head rank of the thermal head 12 can be easily calculated simply by changing the setting of the head rank specifying switch 63, and the uniform print quality can be obtained regardless of the characteristics of the thermal head 12. Can be obtained.

Further, according to the plate making apparatus 10 of this embodiment,
Since the ambient temperature of the apparatus is detected and the temperature correction value TT is updated for each printing process, uniform print quality can be obtained regardless of the ambient temperature. The reason that the update is performed only once for each print process, not for each basic cycle, is that the ambient temperature does not greatly change in a short period of time similar to the print process.

Further, in the plate making apparatus 10 of this embodiment,
The number of times that the thermal head 12 is energized is counted, and the thermal storage correction value TD is updated every unit cycle in accordance with the count value N. Therefore, the thermal head 12 is repeatedly energized. And uniform printing quality can be obtained.

Further, in the plate making apparatus 10 of this embodiment, since the arithmetic expression for obtaining the energizing time T is a linear expression, the energizing time T
Can be calculated in a short time. As a result, the basic cycle required for printing one line can be shortened, and high-speed printing processing can be realized.

[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 a plate making apparatus according to an embodiment.

FIG. 5 is an explanatory diagram showing a logical configuration of a ROM and a RAM, and a data flow.

FIG. 6 is a flowchart illustrating a main process executed by the control device.

FIG. 7 is a flowchart illustrating a print processing routine executed by the control device.

FIG. 8 is an explanatory diagram showing the timing of a print processing operation.

9A is a graph showing a relationship between applied energy per unit time and energy required for printing, and FIG. 9B is a graph showing a relationship between a voltage and a conduction time when a resistance value is assumed to be constant.

[Description of Signs] 10: Plate making device 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 61 ... LCD driver 62 ... keyboard 63 ... head rank designation switch 64 ... battery 6
5: Voltage detection circuit 66: Temperature detection circuit 67: Register 68: Thermal head drive circuit 69: Step motor drive circuit

Claims (5)

[Claims] 1. A heating head according to claim 1, wherein said heating element is provided with a plurality of heating elements that generate heat when energized. A head driving unit that forms a printing pattern on the recording medium by energizing; a voltage detecting unit that detects an output voltage of a battery used as a power supply for driving the thermal head; Based on the detection result of the voltage detecting means, each heating element in a unit period required to form one dot on the recording medium so that the amount of heat generated by the heating element becomes substantially constant. An energization time setting means for setting an energization time to the heating element, wherein the energization time setting means includes a detection connection of the voltage detection means. A calculation means for outputting the operation result that is inversely proportional to the parameter with a predetermined arithmetic expression to a parameter provided, the thermal head control device and sets the calculation result of said calculating means as said energizing time. 2. The thermal head control device according to claim 1, further comprising: count means for counting the number of unit periods that have been energized in the past, wherein said arithmetic means is responsive to a count value of said count means.
A thermal head control device, comprising: a first correction unit that reduces the calculation result as the count value increases. 3. The thermal head control device according to claim 2, wherein the correction value obtained by the first correction unit determines whether a heating element corresponding to an image portion of a print pattern formed on a print medium is energized. A thermal head control device, which can be switched according to whether to energize a heating element corresponding to a non-image area. 4. The thermal head control device according to claim 1, further comprising a temperature detection unit for detecting a temperature around the thermal head, wherein the calculation unit includes the temperature detection unit. A second correction means for decreasing the calculation result as the detection value of the thermal head increases. 5. The thermal head control device according to claim 1, wherein the calculating means is configured such that, according to a resistance value of the heating element measured in advance, the larger the resistance value, the larger the resistance value. A thermal head control device comprising a third correction means for increasing a calculation result.