JPH10264423A - Thermal recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To erase an image as if it is erased immediately after printing by deciding a situation where the temperature of a thermal recording medium does not lower easily to a level where cloudiness is not fixed immediately and performing the erasing operation a plurality of times. SOLUTION: When a detected temperature is higher than a level for switching the erasing operation, the energy control circuit 24 of a print erase control circuit 16 switches the driving pulse for a thermal print head to an erasing pulse and an applying energy is set to an erasing energy. Energy being applied to the thermal print head is the erasing energy lower than the print energy and a thermal recording medium can not be activated sufficiently by single erasing operation but it is activated by an amount corresponding to the erasing energy. When the detection temperature is higher than an erasing operation switching temperature, erasing operation is performed three times and the thermal recording medium is brought into substantially transparent state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording apparatus which uses a thermoreversible recording material and performs recording and erasing on a recording medium capable of recording and erasing the recording.

[0002]

2. Description of the Related Art Conventionally, when recording or erasing is performed on a thermal recording medium using a thermoreversible recording material, a thermal print head is used as a means for recording by applying heat to the thermal recording medium. As a means for erasing, an apparatus using a heating plate or a heating roller having a built-in heating heater is generally used. Since the magnitude of the thermal energy applied to the thermal recording medium for performing the recording and the magnitude of the thermal energy applied to the thermal recording medium for performing the erasing are different, different thermal applying means are used for the recording and the erasing. A method of using a thermal print head for both recording and erasing is also being studied.

[0003] Recording on a thermal recording medium is performed by clouding a portion corresponding to recording data on the thermal recording medium.
Deletion of a record means that a cloudy portion becomes transparent. In an apparatus that performs both recording and erasing with a thermal print head, if a long time (for example, one week to one month) elapses after the recording is performed, the erasure of the recording is completely completed due to a change in the characteristics of the thermal recording medium. There was a problem that would not be possible. As one solution to this problem, the present applicant has filed a Japanese Patent Application No. 5-197366.
No. 4, so-called pre-printing, in which printing is performed once immediately before erasing a record, was performed, and a method of erasing after activating a thermal recording medium was proposed.

[0004]

However, in the above-described erasing method by pre-printing, it is necessary to perform erasing after sufficiently lowering the temperature of the thermal recording medium after printing. Therefore, it takes time to sufficiently lower the temperature of the thermal recording medium, and the processing time becomes longer. Even if the erasing operation is performed before the temperature of the thermal recording medium is not sufficiently lowered, erasing is not sufficiently performed. Furthermore, when the temperature inside the apparatus is higher than a certain temperature, there is a problem that erasing cannot be performed unless the thermal recording medium is once taken out of the apparatus to lower the temperature of the thermal recording medium.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of recording or recording by applying a printing energy for recording on a thermal recording medium or an erasing energy for erasing the recording by a heating element. In a thermal recording apparatus for erasing data, a temperature detecting means for detecting a temperature near the thermal recording medium and a comparing means for comparing the temperature detected by the temperature detecting means with a predetermined temperature are provided. When erasing is performed, erasing energy is applied to the thermal recording medium a plurality of times by the heating element according to the comparison result of the comparing means.

According to the present invention having the above structure, when erasing a recording on a thermal recording medium, the temperature detecting means detects the temperature near the thermal recording medium, and the detected temperature is compared with the predetermined temperature by the comparing means. Be compared. If the detected temperature is higher than the predetermined temperature, it is determined that sufficient erasing cannot be performed even if pre-printing is performed as it is, and the erasing operation is performed a plurality of times on the thermal recording medium by the heating element. By performing erasing a plurality of times, the thermal recording medium gradually becomes transparent.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a characteristic diagram showing characteristics of the thermal recording medium according to the embodiment of the present invention, and FIGS. 2 to 6 are characteristic diagrams showing characteristics of the thermal recording medium. First, the characteristics of the thermal recording medium will be described with reference to FIGS.

In FIG. 2, the horizontal axis represents temperature, and the vertical axis represents the density of the thermal recording medium. When recording is performed by making the transparent thermal recording medium cloudy, the printing temperature Tp is changed from the room temperature Tu to the printing temperature Tp.
Until it reaches room temperature Tu again,
The thermal recording medium becomes cloudy. As shown in FIG. 2, E-C-D-F-F
The route is followed in the order of -GHA. Here, if the heating temperature is equal to or higher than the cloudiness start temperature Tps, the thermal recording medium starts clouding, but it is necessary to heat to the cloudiness saturation temperature Tpl in order to obtain a sufficient print density. Further, in order to fix the clouded portion after heating, the clouded fixing temperature Tf
It is necessary to lower the temperature of the thermal recording medium to below.

Next, when the turbid thermal recording medium is made transparent, that is, when erasing is performed, the thermal recording medium is heated from the room temperature Tu to the erasing temperature Te. As shown in FIG. 2, AB
The route is followed in the order of -C-D-E. As a result, the thermal recording medium becomes transparent, and maintains the transparent state under a temperature environment lower than that. Here, if the heating temperature is equal to or higher than the clearing start temperature Tes, the thermal recording medium starts to be transparent.
It is necessary to heat from e to a temperature lower than the cloudiness onset temperature Tps.

When erasing is performed after printing (especially immediately after), the medium must be heated to the printing temperature Tp, then lowered to at least the opaque fixing temperature Tf, and then heated to the erasing temperature Te. This is due to the characteristic (hysteresis characteristic) of the thermal recording medium. As shown in FIG. 3, when the temperature of the thermal recording medium after heating has decreased only to a temperature higher than the opaque fixing temperature Tf, the erasing temperature Te. Even if heated up, it becomes cloudy again. This is shown in FIG. 3, where E-CD-F-G-H-α-H-
The route is followed in the order of H'-HA. This is the reason why the temperature of the heat recording medium after heating must be lowered to the opaque fixing temperature Tf or lower.

When printing is performed after erasing, printing is possible by heating to the printing temperature Tp irrespective of the temperature of the thermal recording medium after erasing, and after heating, it becomes cloudy below the cloudy fixing temperature Tf. When both printing and erasing are performed using only a thermal print head, the thermal recording medium has a characteristic that its characteristics change with the passage of time after printing. This will be described with reference to FIG.

In FIG. 4, the horizontal axis represents thermal energy applied to the thermal recording medium, and the vertical axis represents the density of the thermal recording medium. The magnitude of the thermal energy increases toward the right side of the figure. First, the relationship between FIG. 4 and FIG. 2 will be described. FIG.
Then, as the energy applied to the thermal print head as the heating element is increased, the heating temperature transmitted to the thermal recording medium increases, and when the energy E1 is applied, the temperature transmitted to the thermal recording medium reaches the erasing temperature Te, When E2 is applied, the temperature transmitted to the thermal recording medium reaches the printing temperature Tp.

When the energy applied to the thermal print head is gradually increased using a cloudy thermal recording medium, the cloudiness starts to disappear when the applied energy reaches E3. The temperature transmitted to the thermal recording medium at this time corresponds to the erasing start temperature Tes shown in FIG. 2, and erasing starts but is not yet sufficient. The temperature transmitted to the thermal recording medium when the applied energy is between E4 and E5 corresponds to a temperature from the transparent saturation temperature Tel to a temperature lower than the turbidity onset temperature Tps, and can be sufficiently erased to the transparent saturation density.

When the applied energy is further increased, cloudiness starts, and when energy of E2 or higher is applied, a temperature higher than the cloudiness saturation temperature Tpl is transmitted to the thermal recording medium, and printing can be performed with cloudiness saturation density. This is shown in FIG.
The route is followed in the order of -O.

When the same energy is applied to a transparent thermal recording medium, the applied energy is equal to the erasing energy E.
When the value is 1 or less, the density of the thermal recording medium does not change, and when higher energy is applied, the characteristics are almost the same as those when the cloudy thermal recording medium is used. If this is shown in FIG. 4, it will be a route that follows ENO. The characteristic shown by the solid line in FIG. 4 is the characteristic when printing and erasing are performed without time after printing (after white turbidity fixing).

Here, the change in the characteristics of the thermal recording medium due to the elapsed time after the printing will be described. If the energy applied to the thermal print head is increased for about one week to one month after printing, the change in print density is due to In contrast to the characteristics indicated by the solid line, the thermal recording medium that has passed for a considerable time after printing shows the characteristics indicated by the one-dot chain line, and the medium that has passed the time shows the characteristics indicated by the two-dot chain line. The longer the time elapses, the higher the applied energy at which erasing is started.

Therefore, the applied energy at the time of erasing is E
When it is set to 1, a change in this characteristic of the thermal recording medium may cause a case where sufficient erasure cannot be performed or a case where the data cannot be erased substantially.

When the thermal print head is used as an erasing means, the characteristic with respect to the temperature when erasing the thermal recording medium in the cloudy state shown in FIG. 2 becomes longer as shown in FIG. Indeed, the erase start temperature Tes changes to Tes' (characteristic indicated by a dashed line), and furthermore Te.
It is considered that the temperature at which erasing becomes possible changes so as to move to a higher temperature side so as to change to s "(characteristic indicated by a two-dot chain line). For example, when the temperature of the thermal recording medium is changed to the characteristic indicated by the two-dot chain line in FIG. The recording medium is not sufficiently transparent,
It becomes translucent. This is shown in FIG.
The route is followed in the order of −E ″.

Next, the thermal recording apparatus according to the present embodiment will be described. FIG. 7 is a schematic configuration diagram illustrating the thermal recording apparatus according to the embodiment, and FIG. 8 is a block diagram illustrating a control unit of the thermal recording apparatus according to the embodiment.

In FIG. 7, the thermal recording apparatus 1 is provided with a medium insertion port 2 and a transport path 3, and transport rollers 4 and 5, a thermal print head 6 and a platen roller 7 are arranged along the transport path 3. ing. The transport rollers 4 and 5 are driven by a motor (not shown) as a drive source, and
Is transported along the transport path 3. The thermal print head 6 includes a thermal recording medium 8 and a platen roller 7.
Heat energy is applied to a desired position of the medium 8 while traveling between the two. Thus, printing or erasing is performed.

In FIG. 8, the control unit 10 of the thermal recording apparatus 1
Is provided with a CPU 11 for controlling the overall operation of the apparatus 1. The host interface 12, the ROM 13, the RAM 14, the motor control circuit 15, and the print erasure control circuit 16 are connected to the CPU 11. The host interface 12 is connected to a host device and controls communication with the host device. The ROM 13 stores a firmware program of the CPU 11 and the like. The RAM 14 temporarily stores print data or erase data. The motor control circuit 15 is connected to the print erasing device mechanism 17 and controls the driving of a motor provided in the mechanism 17. The thermal print head 6 is provided in the print erasing mechanism 17. The print erasure control circuit 16 drives and controls the thermal print head 6 in the print erasure device mechanism 17.

FIG. 9 is a detailed block diagram showing the print erasure control circuit 16. In FIG. 9, the print erasure control circuit 16
Is provided with a print data line memory 21 and an erase data line memory 22. The print data line memory 21 temporarily stores print data for one dot line in dot units. The erase data line memory 22 temporarily stores a portion that needs to be erased in dot units.

The data in the print data line memory 21 and the data in the erase data line memory 22 are both output as serial data to the print / erase data switching circuit 23.
The print / erase data switching circuit 23 selects either the input print data or the erase data, and sends them to the thermal print head 6 at the time of printing or erasing, respectively.

The print erasure control circuit 16 is also provided with an energy control circuit 24 and an A / D converter 25. The energy control circuit 24 is a circuit for controlling the driving energy of the thermal print head 6 during printing and erasing. The A / D converter 25 includes the device mechanism 17
A temperature detection signal from a temperature detection sensor 26 provided therein is input as an analog signal. The analog signal is converted into a digital signal and then transmitted to the CPU 11. The temperature detection sensor 26 is configured by a thermistor or the like, and detects a temperature near the thermal recording medium 8. The above print erase control circuit 16
Each circuit in is controlled by the CPU 11.

Here, a method of controlling the driving energy of the thermal print head 6 will be described with reference to FIG.
FIG. 10 is an explanatory view showing a thermal print head drive pulse. FIG. 10A shows a print pulse.
(B) shows an erase pulse. Control of driving energy
This is performed by keeping the drive voltage of the thermal print head 6 constant and changing the drive pulse width. FIG. 10 (A),
In (B), the horizontal axis indicates time, and the vertical axis indicates drive voltage. In the drawing, t1 and t2 indicate the drive pulse width, and the area of the hatched portion is proportional to the magnitude of the applied energy. Regarding the relationship between the print pulse and the erase pulse, the print pulse width t1
> Erase pulse width t2, and the print energy is larger than the erase energy. Changing the drive pulse width can be easily performed by firmware incorporated in the CPU 11. Needless to say, the control of the driving energy may be performed by changing the magnitude of the voltage.

Next, the operation of the embodiment will be described mainly with reference to the flowchart shown in FIG. FIG. 11 is a flowchart showing the operation of the embodiment. First, the thermal recording apparatus 1 is in a state of waiting for the insertion of the thermal recording medium 8, and when the thermal recording medium 8 is inserted into the medium insertion slot 2 of the thermal recording apparatus 1, the insertion is detected by an insertion detection sensor (not shown). (Step 1). Accordingly, the CPU 11 notifies the host device of the insertion of the medium 8 via the host interface 12, controls the motor control circuit 15, drives the transport roller 4, and draws the thermal recording medium 8 into the transport path 3 ( Step 2).

In step 3, the CPU 11 determines whether the command from the higher-level device is an erase command (command for performing an erase operation). If the command is an erase command, the CPU 11 proceeds to step 4. If the instruction is other than the erase command,
The process shifts to a process according to the instruction, but is not directly related to the present embodiment, and thus the description is omitted.

In step 4, the detected temperature θ in the vicinity of the thermal recording medium 8 detected by the temperature detection sensor 26 is converted into a digital signal by the A / D converter 25, and is taken into the CPU 11. Next, the CPU 11 compares the acquired detected temperature θ with the erasing process switching temperature θa (step 5). The erasing process switching temperature θa is the opaque fixing temperature T shown in FIG.
f, and the time required for the temperature of the thermal recording medium 8 to fall below the cloudy fixing temperature Tf does not significantly affect the entire erasing processing time. .

As a result of the comparison, when the detected temperature θ is smaller than the erasing process switching temperature θa, the driving pulse for driving the thermal print head 6 by the energy control circuit 24 of the print erasing control circuit 16 is shown in FIG. A printing pulse is set, and the energy applied to the thermal print head 6 is set to the printing energy "E2" shown in FIG. 4 (step 6).

Next, at step 7, the CPU 11 drives the motor of the device mechanism 17 via the motor control circuit 15,
The transport rollers 4 and 5 are rotated to transfer the thermal recording medium 8 to the transport path 3.
Along the forward (FWD) direction. The forward direction refers to a direction in which the transport path 3 in the thermal recording apparatus 1 moves rightward from the insertion port 2 in FIG.
The reverse direction is called a reverse (REV) direction.

The thermal recording medium 8 is a thermal print head 6
Is moved to the position, the CPU 11 drives the thermal print head 6 to heat the portion of the thermal recording medium 8 to be erased. The energy applied at this time is the printing energy "E2" (step 8). As a result, the portion of the thermal recording medium 8 to be erased is in a printed state, the thermal recording medium 8 is activated, and has the characteristic shown by the solid line in FIG. In the present embodiment, the portion to be erased is the entire printing surface of the thermal recording medium 8, but it is not necessarily required to be the entire surface. When the printing of the portion of the thermal recording medium 8 to be erased in Step 8 is completed, the motor of the device mechanism unit 17 is stopped, the conveying rollers 4 and 5 are stopped, and the conveyance of the medium 8 is stopped (Step 9).

Next, the CPU 11 executes the print erasure control circuit 16.
The drive pulse for driving the thermal print head 6 is changed to the erase pulse shown in FIG. 10B by the energy control circuit 24, and the energy applied to the thermal print head 6 is set to the erase energy "E1" shown in FIG. Step 10). Next, the motor in the device mechanism 17 is driven by the motor control circuit 15 to
Is rotated in the reverse direction. Thereby, the thermal recording medium 8
Travels on the transport path 3 in the reverse direction (step 1).
1).

Next, the erasing energy "E1" is applied to the thermal print head 6 to erase the portion of the thermal recording medium 8 to be erased (step 12). The thermal recording medium 8 has characteristics immediately after printing by pre-printing, and a portion to be erased can be completely erased. The erased thermal recording medium 8 is
The paper is ejected from the medium insertion slot 2 by the transport rollers 4 and 5 (step 13), and the erasing operation is completed.

If the detected temperature θ is higher than the erasing process switching temperature θa in step 5, the print erasure control circuit 1
The drive pulse for driving the thermal print head 6 is changed to the erase pulse shown in FIG. 10B by the energy control circuit 24, and the energy applied to the thermal print head 6 is set to the erase energy "E1" shown in FIG. (Step 20).

Next, the motor of the device mechanism 17 is driven by the motor control circuit 15 to rotate the transport rollers 4 and 5,
The thermal recording medium 8 is transported along the transport path 3 in the forward direction (step 21). When the thermal recording medium 8 is conveyed to the position of the thermal print head 6, the CPU 11 drives the thermal print head 8 to heat a portion of the thermal recording medium 8 to be erased. In the present embodiment, the portion to be erased is the entire printing surface. The energy applied at this time is the erasing energy “E1” (step 22).
When the elapsed time after printing is long, the thermal recording medium 8 cannot be sufficiently erased by only one erasing operation. However, when the thermal recording medium 8 is heated to the erasing temperature Te by this one erasing operation, As shown in FIG. 6, even if the elapsed time after printing is long, the printing density is somewhat reduced. 6 shows a route that follows the sequence of ABJE ". Since the energy applied to the thermal print head 6 is the erasing energy" E1 ", it is lower than the printing energy.
Although the thermal recording medium 8 cannot be sufficiently activated by one erasing operation, activation for the erasing energy is performed.

When the erasing operation of the portion of the thermal recording medium 8 to be erased in step 22 is completed, the motor of the device mechanism 17 is stopped, the transport rollers 4 and 5 are stopped, and the medium 8
Is stopped (step 23). Next, the energy applied to the thermal print head 6 is set to the erase energy “E1” shown in FIG. 4 by the energy control circuit 24 of the print erase control circuit 16 (step 24), and the transport rollers 4 and 5 are rotated. The thermal recording medium 8 is transported in the reverse direction along the transport path 3 (Step 25).

The thermal recording medium 8 is a thermal print head 6
The CPU 11 drives the thermal print head 8 to heat the portion of the thermal recording medium 8 to be erased. The energy applied at this time is the erasing energy “E1” (step 26). Due to this erasure, activation of the thermal recording medium 8 proceeds a little further, and the print density further decreases as shown in FIG. This is shown in FIG.
When the erasing operation is completed, the transport rollers 4 and 5 are stopped, and the transport of the medium 8 is stopped (step 27).

Next, from step 20 to step 22 described above.
The operation up to is repeated. That is, in step 28, the energy applied to the thermal print head 6 is set to the erasing energy "E1". In step 29, the thermal recording medium 8 is transported in the forward direction. E "is applied. FIG. 1 shows the change of the thermal recording medium 8 due to the step 30, E'-LE.
In the order of

As described above, when the detected temperature θ is higher than the erasing processing switching temperature θa, the erasing operation is performed three times. As shown by, it becomes almost transparent. This change is shown in FIG. 1, and ABJE ″ -KE′-L
The route is followed in the order of -E. The number of erasing operations depends on the characteristics of the thermal recording medium 8 and the characteristics of the apparatus (for example, the medium conveyance speed).
Not limited to times. The thermal recording medium 8 which has completed the three erasing operations is discharged from the apparatus from the insertion opening 2 by the transport roller 4 (step 31), and a series of erasing operations is completed.

The present invention is not limited to the above embodiment. For example, when printing is performed after erasing, the printing operation may be performed simultaneously with the erasing operation. If printing is to be performed and the erasing operation is to be performed a plurality of times, the printing operation is performed simultaneously with the last erasing operation. When erasing and printing are performed simultaneously, of the heating elements of the thermal print head 6, the printing energy "E2" is applied to the element for printing, and the erasing energy "E1" is applied to the element for erasing. By performing the erasing and printing processes in this manner, the number of movements of the thermal recording medium 8 is reduced, and the overall processing time is shortened.

Further, a cooling fan is provided in the thermal recording device 1, a printing operation (pre-printing) before erasure is performed on the thermal recording medium 8, and then the cooling fan is driven to drive the thermal recording medium 8.
May be cooled. By providing the cooling fan in this manner, the time required for the temperature of the thermal recording medium 8 to drop below the cloudy fixing temperature Tf is reduced, and the erasing processing time is reduced.

When a cooling fan is provided, the CPU 11 and the ROM 13 execute a firmware program shown in FIG.
By controlling the cooling fan to be driven only during the processing from step 6 to step 12 shown in FIG. 1, unnecessary power consumption can be omitted.

[0043]

As described in detail above, according to the present invention, a means for detecting the temperature near the thermal recording medium is provided, and the temperature detected by the detecting means is used when erasing the thermal recording medium. Therefore, if the temperature of the thermal recording medium does not immediately fall below the temperature at which the white turbidity is fixed or the temperature of the thermal recording medium does not easily decrease even if pre-printing is performed. Multiple times to activate changes in characteristics due to the elapsed time after printing, enabling erasure similar to erasing immediately after printing, and erasing records on thermal recording media without prolonging processing time. It can be carried out.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing characteristics of a thermal recording medium according to an embodiment.

FIG. 2 is a characteristic diagram showing characteristics of a thermal recording medium.

FIG. 3 is a characteristic diagram showing characteristics of a thermal recording medium.

FIG. 4 is a characteristic diagram showing characteristics of a thermal recording medium.

FIG. 5 is a characteristic diagram showing characteristics of a thermal recording medium.

FIG. 6 is a characteristic diagram showing characteristics of a thermal recording medium.

FIG. 7 is a schematic configuration diagram illustrating a thermal recording device according to an embodiment.

FIG. 8 is a block diagram illustrating a control unit of the thermal recording apparatus.

FIG. 9 is a detailed block diagram showing a print erasure control circuit.

FIG. 10 is an explanatory diagram showing a thermal print head drive pulse.

FIG. 11 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal recording device 6 Thermal head 8 Thermal recording medium 11 CPU 16 Print erasure control circuit 26 Medium detection sensor

Claims (4)

[Claims] 1. A thermal recording apparatus for recording or erasing a recording by applying a printing energy for recording on a thermal recording medium or an erasing energy for erasing the recording by a heating element, comprising: And a comparing means for comparing the temperature detected by the temperature detecting means with a predetermined temperature, and when erasing the recording on the thermal recording medium, according to the comparison result of the comparing means, A thermal recording apparatus, wherein erasing energy is applied to a thermal recording medium a plurality of times by the heating element. 2. When the temperature detected by the temperature detecting means is lower than the predetermined temperature as a result of the comparison by the comparing means, the heating element applies a printing energy higher than the erasing energy before applying the erasing energy. 2. The thermal recording apparatus according to claim 1, wherein when the temperature detected by the temperature detecting unit is higher than the predetermined temperature, the heating element applies the erasing energy a plurality of times. 3. The thermal recording apparatus according to claim 1, wherein the heating element applies the erasing energy to the entire recording surface of the thermal recording medium in the plurality of erasing energy applications. 4. A thermal recording apparatus for recording or erasing a recording by applying printing energy for recording on a thermal recording medium or erasing energy for erasing the recording by a heating element, wherein the thermal recording medium is cooled. A cooling means is provided, and when erasing a record, the heating element applies the printing energy to the thermal recording medium, then cools the thermal recording medium by the cooling means, and then applies erasing energy. Thermal recording device.