JPH04216088A - Thermal printer - Google Patents

Abstract

PURPOSE:To perform a new printing without the need for erasing former printing information by adjusting a conduction time of an electric current to be applied to each electric resistor incorporated in a dot. CONSTITUTION:An output side of an output port 4 is connected to an AND circuit 7 to which clock pulses CP1 are inputted. An output side of the AND circuit 7 is connected to an N-ary counter 8 for partitioning printing data for every line and to a shift register R for recording the printing data per line. From an output side of the N-ary counter 8, the data is outputted to a two-port RAM 5, an input port 6, and a latch L. The latch L is provided between the shift register R and the driver D controlling the ON/OFF state of an electric conduction to electric resistors r1-rn. When a new printing is conducted, the printing is made after each dot is heated to either a color-forming temperature range or a color-erasing temperature range. In this manner, a new printing can be made while a previous printing is erased.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a thermal printing device.
In particular, it relates to those whose printed contents can be rewritten.

0002

2. Description of the Related Art Conventionally, this type of thermal printing apparatus uses a thermal head to print on a recording medium such as recording paper coated with a thermal agent. This thermal head has a large number of dots, and the predetermined dots generate heat in correspondence with predetermined characters, symbols, patterns, etc. to be printed.

[0003] Furthermore, in recent years, as a result of improvements in heat-sensitive agents, heat-sensitive agents have been proposed that can erase (decolor) the previously printed content and print new content (4th Non-Impact Printing Technology Symposium). Collection of papers P.57~
60 July 23 and 24, 1986, hosted by the Electrophotography Society).

[0004] When rewriting such a rewritable thermal recording medium, the entire printed surface is heated to a predetermined decoloring temperature lower than the printing temperature to erase the characters, and then the printed surface is rewritten. The new printing content is heated to a predetermined coloring temperature and printed (for example, Japanese Patent Application Laid-Open No. 1-30499
Publication No. 6).

[0005] As described above, the conventional rewritable thermal printing device allows printing to be rewritten any number of times, which is advantageous when the printing space is small. For example, when printing the balance value on a prepaid card or stored fair card, the previous balance value can be erased and a new balance value can be printed.

[0006]

[Problem to be Solved by the Invention] However, in the above-mentioned conventional rewritable thermal printing device, new printed content is
The entire printing surface was heated to erase the characters with a roller or heating plate heated to the color erasing temperature, and then the thermal head heated to the coloring temperature was used to print again, making the configuration complicated and the printing process difficult. This method requires a lot of time and has drawbacks such as difficulty in partially or selectively erasing characters.

[0007] In particular, when printing on prepaid cards inserted into station equipment such as automatic ticket gates and automatic ticket vending machines, the longer the printing processing time, the lower the customer service efficiency. The arrival of a short thermal printing device was awaited. Therefore, the present invention has been made to meet the above-mentioned needs, and its purpose is to provide a thermal printing device that can print new characters without requiring an erasing process.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention develops color when heated to a predetermined coloring temperature range, and when heated to a predetermined coloring temperature range different from the coloring temperature range. In a thermal printing device that prints on a recording medium coated with a heat-sensitive agent that erases color when the temperature changes, a thermal head having a large number of dots arranged in a row prints on a recording medium. The apparatus is characterized in that it has a colored dot heating means that heats the dots up to the temperature range, and a color erasing dot heating means that heats dots other than the dots forming the print to the erasing temperature range. Further, the color forming dot heating means and the color erasing dot heating means are characterized in that a coloring temperature band and a color erasing temperature band are obtained, respectively, depending on the current application time to the dots. Further, the color forming dot heating means and the color erasing dot heating means are characterized in that a coloring temperature band and a color erasing temperature band are respectively obtained by the energization time and applied voltage applied to the dots.

[0009]

[Operation] In the above configuration, when printing new information with the thermal head, the dots forming characters, etc. are heated to the coloring temperature by the coloring dot heating means, and the recording medium is printed, while the dots forming the characters, etc. are not printed. The dots forming the blank space are heated to the erasing temperature by the erasing dot heating means and erased. Therefore, when new printing is performed on an old printing area, it is printed as is, and when new printing is performed on a blank area where there is no old printing, new printing is performed,
If there is no new printing in a blank area with no old printing, it remains blank.

The coloring temperature range and color erasing temperature range can be obtained by adjusting the current application time or the current application time and applied voltage applied to the dots.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, but first, the principles of erasing and printing will be explained using FIG. 9 to facilitate understanding of the present invention.

FIGS. 9(a) to 9(d) are thermoreversible characteristic diagrams of a recording medium coated with a thermosensitive agent, where t0 is the color erasing temperature, and Δt0 is the temperature formed around the color erasing temperature t0. t1 is a coloring temperature higher than the coloring temperature band Δt0, and the temperature t1 or higher is the coloring temperature band Δt1.

FIG. 9(a) shows that the recording medium is in the decoloring temperature range Δt.
0 indicates the state when heating deviates, and if nothing has been printed on the recording medium by then, this color erasing temperature range Δ
This indicates that nothing is printed on the recording medium even if it is heated to t0.

[0014] FIG. 9(b) shows that when the print is initially being printed on the recording medium, the printed portion is heated to the decoloring temperature range Δt0, and the print is decolorized (erased). ing.

FIG. 9(c) shows that when nothing is printed on the recording medium at first, the recording medium is heated to the coloring temperature range Δt1 and a new print is made.

FIG. 9(d) shows that when printing is being performed on the recording medium from the beginning, the recording medium is heated to the coloring temperature range Δt1 and printing is performed again.

As is clear from the above, new printing is performed by heating the area to be newly printed to the coloring temperature range Δt1, regardless of the presence or absence of old printing, and at the same time, it is printed by heating the area to be printed to the coloring temperature range Δt1. By heating the part to be printed to the decoloring temperature range Δt0, the part of the new printed part that overlaps with the old printed part maintains the printed state as it is, and when new printing is performed, the blank part is heated to the decoloring temperature range Δt0. Therefore, if old printing exists in that blank area, it will be erased, and if that blank area has been blank from the beginning, it can remain blank. Therefore, the old print is erased at the same time as the new print process.

Next, a first embodiment of the present invention will be explained based on FIG. In the figure, H is a heating element of the thermal head, which is composed of electrical resistors r1 to rn that serve as a heat source for a plurality of dots (n in the illustrated example) installed in a line in the thermal head.

The controller C is mainly composed of a central processing unit (CPU) 3 that performs arithmetic processing based on system data stored in the ROM 1 and print data stored in the RAM 2. is output port 4,
A 2-port RAM 5 and an input port 6 are connected. The output side of the output port 4 is connected to an AND circuit 7 which is manually operated by a clock pulse CP1, and the output side of the AND circuit 7 is connected to an n-ary counter 8 and an N-ary counter 8 for dividing print data line by line. It is connected to a shift register R that records print data for each line. The output side of the n-ary counter 8 is output to the 2-port RAM 5, the input port 6, and the latch L, and the latch L is connected to the shift register R and the driver D that controls the ON/OFF state of energization to each of the electrical resistors r1 to rn. is set between.

Next, control to the dot coloring temperature t1 (coloring temperature band Δt1) and control to the decoloring temperature t0 (coloring temperature band Δt0) will be explained based on the time chart of FIG.

Now, assume that dot data indicating that a certain dot, for example, a dot in which an electric resistor r1 is incorporated, is printed is stored in the shift register R1. As shown in FIG. 2(a), the heating time for one dot is several pulses per interval (TP) of n count pulses (10T in the example shown).
P), the print data is stored as "1" in the first half and "0" in the second half, as shown in FIG. When this is “1”, the driver D1 is an electrical resistor r
1 is energized, and 0 is energized, so that the temperature of the dot is heated as shown in FIG. 2(d). That is, the temperature is gradually increased until the first half reaches "0", and then gradually lowered (cooled) when the second half reaches "0". The shaded area in FIG. 4(d) indicates that the sheet was heated to a coloring temperature range Δt1 exceeding the coloring temperature t1, and the amount of heat necessary for coloring (printing) was obtained. The amount of heat required for this color development is determined by the type of heat-sensitive agent, the magnitude of the applied current, the resistance value of the electrical resistor r1, etc., and can be determined experimentally to obtain a sufficient printing condition. The current application time is adjusted so that the temperature of the dots is cooled to below the coloring temperature t1 in the second half of the process.

On the other hand, if the print data of the dots in which the electric resistor r1 is incorporated is blank, the driver D1 is turned on.
As shown in the figure (e), the pulse width TP becomes a ratio of 1 to 4, and the average current flowing through the electric resistor r1 becomes 1/4 compared to the time of coloring described above. Same figure (
Therefore, the amount of heat generated by the electrical resistor r1 exhibits a temperature curve that moves up and down around the decoloring temperature t0, as shown in (g) of the same figure, and the average amount of heat generated by this heating is Temperature band Δt for erasing the dots in which resistor r1 is incorporated
Heat to 0.

As described above, according to the apparatus of this embodiment, the printable coloring temperature range Δt1 can be adjusted by adjusting the time period of the current applied to each of the electrical resistors r1 to rn incorporated in the dot. and erasable temperature range Δt0
Therefore, when performing new printing, if each dot is heated to either the coloring temperature band Δt1 or the color erasing temperature band Δt0, new printing can be performed while erasing the old printing. be able to. Therefore, the printing processing time is short, and when the device of this embodiment is incorporated into station service equipment such as an automatic ticket gate, it is possible to improve customer service efficiency.

FIG. 3 shows a second embodiment of the present invention, which differs from the first embodiment in that the voltage applied to each of the electrical resistors r1 to rn is changed to the coloring voltage V1. A decoloring voltage V0, which is smaller than the coloring voltage V1, is prepared, and these voltages are applied to each electric current through a switching circuit S driven by a flip-flop (F/F) circuit F controlled by a controller C. The voltage is applied selectively to the resistors r1 to rn.

FIG. 4 is a time chart of the device of this embodiment, and FIG. 4(a) shows n count pulses.
In addition, the same figure (b) shows the power supply voltage supplied to each electric resistor r1 to rn, and the coloring voltage V by the F/F circuit F is shown.
1 and the decoloring voltage V0 are alternately supplied. Now, when the dot in which the electric resistor r1 is incorporated is in the printing state, the same figure (c) and the same figure (d)
As shown in , the voltage and current at the time of coloring are electric resistor r1
The amount of heat applied to the predetermined coloring temperature range Δt1 (the same figure (
(See the shaded part in d)) is obtained.

On the other hand, when the dot in which the electrical resistor r1 is installed is blank, the decoloring voltage and current are applied to the electrical resistor r1, as shown in FIGS. The amount of heat in the predetermined color erasing temperature range Δt0 is obtained.

In the apparatus of this embodiment, the coloring temperature band Δ
Since a power supply for obtaining t1 and the color erasing temperature band Δt0 is separately prepared, the temperature rise width in one pulse width TP for erasing can be reduced, and therefore the temperature fluctuation range Δt1 within one dot can be reduced, so color erasing can be performed. Performance can be improved.

FIGS. 5 to 7 show third and fourth embodiments of the present invention, which are intended to improve the decoloring performance compared to the first and second embodiments. 1st and 2nd above
In the embodiment, the smaller the energization pulse width TP, the more precise control can be performed in small increments (the width of Δt0 is small). By the way, in the first and second embodiments described above, since the energization time was controlled by exchanging the data of the shift register R and latch L multiple times within one dot, the pulse width TP
The lower limit of is determined by the speed of the shift register, the control speed of the CPU, etc., and control in smaller increments is not possible. Therefore, in the third and fourth embodiments, the energization control within one dot is performed using a gate inserted between the latch L and the driver D, and the pulse width TP is created without changing the data of the shift register R and the latch L. This is intended to be carried out at high speed using the clock CP2 or the like.

FIG. 5 shows a third embodiment, which is an improvement on the first embodiment. The difference lies in the use of a gate circuit G provided between the latch L and the driver D, CP2 for creating a color erasing energization pulse, and CP3 for creating a coloring energization pulse.

OO30 The gate circuit G is provided corresponding to each of the electrical resistors r1 to rn, and the chain line in FIG.
1 shows details of the gate circuit G1 corresponding to No. 1. Gate circuit G1 is an AND circuit 1 of the output of latch L1 and CP3.
0, a negation 13 of latch L1, an AND circuit 12 of CP2, and an OR circuit 11 whose inputs are the outputs of both AND circuits.

In the above configuration, the dot in which the electric resistor r1 is incorporated is in the printed state (latch L1 output is "1")
), as shown in FIGS. 6(c) and (d),
A coloring current is applied to the electric resistor r1, and a heat amount (the shaded area in FIG. 12C) in a predetermined coloring temperature range Δt1 is obtained.

On the other hand, when the dot in which the electric resistor r1 is incorporated is blank (the output of the latch L1 is "0"),
As shown in FIGS. 6(e) and 6(f), a decoloring current is applied to the electrical resistor r1 to achieve a predetermined decoloring temperature range Δt.
0 amount of heat is obtained.

FIG. 7 shows a device according to a fourth embodiment of the present invention, which is an improvement on the second embodiment described above, and differs from the second embodiment in that the latch L and Between the drivers D, the F/F circuit F selects the coloring voltage V1, and 1
The output of the AND circuit 9 that is output when the clock pulse CP3 that divides the dot into two is ON, the output when the F/F circuit F selects the decoloring voltage V0, and the inverter 13 that inverts the output of the latch L. A gate circuit G driven by an output AND circuit 12 is provided.

[0034] The gate circuit G includes each electric resistor r1 to rn.
The area within the chain line in FIG. 7 shows the details of the gate circuit G1 corresponding to the electric resistor r1. The gate circuit G1 has an AND circuit 10 whose inputs are the output of the AND circuit 9 and the output of the latch L1, an output of an inverter 13 that inverts the output of the latch L1, and an F/F circuit F that selects the erasing voltage V0. an AND circuit 12 whose input is the output of , and an OR circuit 1 whose input is the output of both AND circuits
It is composed of 1.

In the above configuration, when the dot in which the electric resistor r1 is incorporated is in a printing state, the coloring voltage and current are applied to the electric resistor r1 as shown in FIGS. is applied to obtain the amount of heat in the predetermined coloring temperature range Δt1 (the shaded area in FIG. 3(d)).

On the other hand, when the dot in which the electrical resistor r1 is installed is blank, the decoloring voltage and current are applied to the electrical resistor r1, as shown in FIGS. The amount of heat in the predetermined color erasing temperature range Δt0 is obtained.

In the apparatus of this embodiment, the pulse width TP can be shortened regardless of the processing capacity of the shift register L and the CPU, so that the accuracy of printing processing can be further improved.

Although the four embodiments have been shown above, the first and second embodiments cannot perform small-scale control, but
It has the advantage that it can be controlled by software using U and is highly flexible.

The third and fourth embodiments are based on the first and second embodiments described above.
Since it includes the circuit of the embodiment, it is possible to bring in control by the CPU. That is, it is possible to perform rough control within one dot using data sent from the CPU to the shift register/latch while performing small-scale control using the gate circuit. This can be used, for example, when it is desired to change the energization rate to compensate for changes in environmental temperature.

Further, in the first and second embodiments, one type of energization pattern for color development and one type for decolorization are shown, but the present invention is not limited to this, and various patterns can be considered. Also,
It is also possible to use a combination of multiple patterns for more accurate temperature control.

[0041] In the above-mentioned embodiments, it was explained that color development was performed at a high temperature and decolorization was performed at a lower temperature.
Even in the opposite case, the present invention can be achieved by reversing color development/decolorization.

[0042]

Effects of the Invention According to the apparatus of the present invention, printing can be achieved by adjusting the energizing time of the current applied to each electrical resistor incorporated in the dot, or by adjusting the energizing time and the applied voltage. Since it is possible to obtain a possible coloring temperature range and a color erasing temperature range, when printing a new mark, each dot can be printed by heating it to either the coloring temperature range or the erasing temperature range. , it is possible to perform new printing while erasing old printing. Therefore, the printing processing time is short, and when the device of this embodiment is incorporated into station service equipment such as an automatic ticket gate, it is possible to improve customer service efficiency.

[Brief explanation of the drawing]

FIG. 1 is an electrical configuration diagram of a device according to a first embodiment of the present invention.

FIG. 2 is a time chart related to the device of the first embodiment.

FIG. 3 is an electrical configuration diagram of a second embodiment device.

FIG. 4 is a time chart related to the device of the second embodiment.

FIG. 5 is an electrical configuration diagram of a third embodiment device.

FIG. 6 is a time chart related to the third embodiment device.

FIG. 7 is an electrical configuration diagram of a third embodiment device.

FIG. 8 is a time chart related to devices of the fourth and fifth embodiments.

FIG. 9 is an explanatory diagram for explaining the principle of printing and erasing.

[Explanation of symbols]

C Control section R Shift register L latch D Driver r1~rn　Electric resistor

Claims (3)

[Claims] 1. A recording medium coated with a heat-sensitive agent that develops color when heated to a predetermined coloring temperature range and decolors when heated to a predetermined decoloring temperature range different from the coloring temperature range, In a thermal printing device that prints with a thermal head having a large number of dots arranged in a row, a colored dot heating means heats the dots forming the print out of the dots to the above coloring temperature range, and dots other than the dots forming the print. a color erasing dot heating means for heating the dots to the color erasing temperature range. 2. The thermal printing apparatus according to claim 1, wherein the color forming dot heating means and the color erasing dot heating means obtain a coloring temperature range and a color erasing temperature range, respectively, depending on the duration of current applied to the dots. 3. The thermosensitive device according to claim 1, wherein the color forming dot heating means and the color erasing dot heating means obtain a coloring temperature range and a color erasing temperature range, respectively, depending on the energization time and applied voltage applied to the dots. Printing device.