JP3029334B2 - Temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for a system using a thermal head as a main heat source.

[0002]

2. Description of the Related Art In an apparatus equipped with a thermal printer using a thermal head (such as a facsimile), a thermal printer is used to control the printing energy of the thermal head to print at a uniform density and to prevent bleeding. It is necessary to prevent the temperature of the head from excessively rising. At the same time, it is necessary to prevent the temperature of the entire system from excessively rising. For this reason, in order to monitor the temperature of the thermal head, for example, there is an apparatus in which a thermistor as a temperature detecting element is attached to the thermal head. In this apparatus, printing is interrupted as soon as the temperature exceeds a set value in order to prevent the temperature of the entire system from rising excessively or at the end of printing of the page being printed. In order to make the density uniform, it is common practice to reduce the printing energy in accordance with the temperature detected by the thermistor. Further, there is also an apparatus which does not monitor the temperature of the thermal head itself, determines the number of continuous copies at the time of continuous copying, and provides a rest time to keep the temperature constant when the number of copies is reached.

[0003]

SUMMARY OF THE INVENTION A thermal printer having a thermal head includes a unit having a lower upper limit temperature (a magneto-optical read / write) than the thermal head in the same housing.
In a temperature control system that stops printing when the temperature detection value of the thermal head exceeds a set value when stored together with a write device (MO), recordable compact disc (CD-R), etc. There is a temperature difference between the temperature of the unit and the unit with the lower maximum temperature that exists in the same housing of the system.If only the temperature of the thermal head is used, the temperature of that unit becomes too high, and an excessive cooling capacity is required. And may be. Also,
Taking this into consideration, if a certain non-printing determination line is mechanically set to the temperature of the thermal head based on the temperature of the unit, it is possible that printing is frequently stopped. Also, in a facsimile machine equipped with a thermal head, if the printing is stopped due to a rise in temperature during reception and the line is disconnected, the printable determination line and the print unavailable determination line are the same. If the print job is re-transmitted from the printer, the temperature of the thermal head immediately rises, so that printing cannot be performed again and a line disconnection occurs. In this case, either the case where the communication ends in the middle of one document or the case where the communication ends with only the one sheet. In the method in which the number of continuous copies is limited, even if the temperature has not risen in the all-white copy, a rest time is meaninglessly inserted. In addition, the print density may be significantly reduced during continuous reception.

An object of the present invention is to provide a system in which a thermal printer having a thermal head is housed together with a unit having an upper limit temperature lower than that of the thermal head in the same housing, in which printing energy control of the thermal head and temperature in the system are controlled. An object of the present invention is to provide a system that balances control.

[0005]

In order to solve this problem, a temperature control apparatus according to the present invention includes a thermal printer having a thermal head and a unit having an upper limit temperature lower than that of the thermal head in the same housing. In the system, the elapsed time measuring means for measuring the elapsed time from the end of the previous printing by the thermal head to the start of the current printing, a temperature detecting element for measuring the current temperature of the thermal head, and the elapsed time measuring means. For each elapsed time, a table in which the temperature of the thermal head is associated with the temperature of the unit, storage means for storing a print disable determination line corresponding to the upper limit temperature of the unit, and the elapsed time measuring means Above time read from the table corresponding to the measured elapsed time and the temperature measured by the temperature sensing element The temperature of the knit, characterized in that it comprises a control means for stopping printing when exceeding the upper limit temperature of the unit. Preferably, the apparatus further comprises storage means for storing the temperature of the thermal head at the time of completion of the previous printing, wherein the control means measures the value stored in the storage means, the current temperature of the thermal head, and the elapsed time measuring means. An amount representing the degree of heat dissipation is calculated from the elapsed time and the printout determination line for the unit is determined from the calculated value. Also, preferably, resumes printable printing after printing discontinuation by the control means the temperature T _p
Is provided by the user.

[0006]

[ _Function ] Temperature T _{8 of the} unit having the upper limit temperature T _8limit
And the detected temperature T ₀ of the temperature detecting element is the elapsed time t ₀
Is experimentally obtained in advance as a function of and stored in the storage means as a table. Unit upper limit temperature T
_The print disable determination line T _limit corresponding to 8 _{limit is set} to the state (the elapsed time t from the end of the previous print to the start of the current print).
_By appropriately changing the value according to ( ₀ ), printing is not frequently stopped. That is, the temperature T ₈ of the unit _having the lower upper limit temperature T _8limit is estimated from the current detected temperature T ₀ of the thermal head, and control is performed so as not to exceed the upper limit temperature of this unit. In this way, using a single temperature sensing element attached to the thermal head, the print energy control of the thermal head and the temperature control within the system are practically sufficiently assured, and a uniform density is assured by the thermal head. It also protects other units inside. Preferably, an amount ((T ₁ −T ₀ ) / t ₀ in the embodiment) representing the degree of heat radiation is calculated in consideration of the temperature T ₁ at the end of the previous printing, and based on this amount, the printing failure determination line T _{The limit} is determined with higher accuracy. Further, it is possible to set user printable line T _p for printing resumed by setting means.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a printer according to an embodiment of the present invention. In one housing (1), a thermal head (2), a platen roller (4), a motor (5) as a driving unit, a power supply (6), a thermal paper (7), and a magneto-optical read / write device (MO). (8) is equipped. The image data is stored in the magneto-optical read / write device (8). The thermal paper (7) is supplied onto a platen (4) by a motor (5), and image data is printed by a thermal head (2). In this device, the main heat source is the thermal head (2). The magneto-optical read / write device (8) is a unit having a low maximum temperature and is housed in the same housing (1) as the thermal head (2), so that it is indirectly heated by the thermal head (2). In the thermal head (2),
A thermistor (3) as a temperature detecting element is attached.
The density of the output image of the thermal head (2) is made constant based on the temperature detected by the thermistor (3). further,
It is necessary to prevent the temperature of the magneto-optical read / write device (MO) (8), which is a unit having a low upper limit temperature, from rising too much by printing on the thermal head (2), which is a main heat source. To limit the temperature rise due to the thermal head (2), a magneto-optical read / write device (MO)
It is most reliable to attach a thermistor to (8), but a thermistor, an A / D converter, and the like are separately required, which increases the cost. In this embodiment, practically sufficient temperature control is guaranteed by one thermistor (3) attached to the thermal head (2).

FIG. 2 shows a block diagram of the control circuit. C
The PU (11) is a microprocessor that performs temperature control. When the CPU (11) sends a strobe signal (printing trigger) to the thermal head (2) via the strobe control port (12), the analog output of the thermistor (3) detects the temperature from an A / D converter or the like. The signal is converted into a digital signal in the circuit (13),
Input to (11). R connected to CPU (11)
The AM (14) stores elapsed time information (t ₀ ) described later, a print disable determination line T _limit and a print enable determination line T _p . The ROM (15) which is connected to the CPU (11), the table and the upper limit temperature T _8Limit detection for each elapsed time t ₀ the temperature T ₀ and the estimated temperature T ₈ is stored. Furthermore, the operation unit (16), when the user sets the printable judgment line T _p, and sends a setting signal to the CPU (11). The elapsed time t ₀ described later is measured using a timer by software.

In the ROM (15), a relationship between T ₀ and T ₈ and a T _8limit as shown in the graph of FIG. 3 are stored as a table corresponding to each elapsed time t ₀ . So, CP
U (11) corresponds to the ROM (1) corresponding to the elapsed time t _0.
Select a table from 5). Then, in order to determine whether or not printing is possible, the temperature T ₀ is determined by the thermistor (3) during printing.
Is detected, and T estimated from the table from the ROM (15) is used.
Compare ₈ with _T8limit . If the temperature exceeds the upper limit, printing is stopped. Thus, the temperature rise of the unit (8) is also prevented by using the thermistor for making the print density of the thermal printer uniform. After printing stop and decreases the detection temperature T ₀ further reaches the printable judgment line T _p, printing is resumed. At the time of printing is completed or when the printing stop, for the measurement of elapsed time t ₀ from the previous printing is completed, the timer starts operating.

FIG. 4 shows the temperature T ₀ of the thermal head (2).
When the temperature T ₈ of the unit (8) indicates the status of the temperature control as a function of time. Printing is initiated after t ₀ elapsed from the previous printing is completed. With the start of printing, the temperature T ₀ of the thermal head (2) rises. From the elapsed time t _{0, a} table is selected from the ROM (15), and an estimated value T ₈ of the temperature of the unit (8) is obtained. The temperature T ₈ is also increased along with the print start. (The pattern of the temperature rise changes depending on the elapsed time t _0. ) In the case of FIG. 4, when the temperature T _{0 of the} thermal head reaches the print disable determination line T _limit , printing is stopped. At this time, the temperature of the unit (8) has not yet reached the upper limit temperature _T8limit . After the printing is stopped, the temperature T ₀ of the thermal head (2) decreases. After printing discontinued, the temperature T ₀ of the thermal head (2) reaches a printable judgment line T _p, printing is resumed. At this time, the elapsed time t ₀ from the previous stop of printing is obtained, and from this, T ₈ is obtained from the table newly selected in the ROM (15). When the detected temperature T ₀ reaches the print-impossible determination line T _limit again, printing is stopped again.

By the way, among the upper limit values of the temperature control, the print disable determination line T _limit is determined by the system, but the print enable determination line T _p can be set arbitrarily. Printable line T _p is, if you set too low, to time to resume printing is applied, is set too high, frequently printing is stopped. It is better to leave the trade-off between the time until reprinting becomes possible and the number of continuously printable sheets at the time of reprinting to the preference of the user. Therefore, in this embodiment, the user operates the operation unit (16), and to set the printable judgment line T _p.

The apparatus of this embodiment is a printer equipped with a thermal head. Similarly, in the case of a facsimile apparatus equipped with a thermal head, printing is interrupted due to a rise in temperature during reception and the line is disconnected. There is. Further, even if the transmission sender again, when the temperature T ₈ of the unit (8) having an upper limit temperature is not very lowered, sometimes middle line will be cut again. When printable judgment line T _p is set too low, to take time to receive resume, if too high a transmitting side transmits a plurality of originals, printing many times it is aborted and need to resend many times Come out. Therefore, in this case as well, the trade-off between the time until re-reception is possible and the number of continuously receivable images at the time of re-reception is left to the preference of the user, and the usability is better.

FIG. 5 shows a flow of print control of the CPU (11). When a print trigger indicating the start of printing is received (YES in S1), the temperature T ₀ of the thermal head (2) is measured by the thermistor (3) (S2), and the elapsed time t ₀ from the previous printing is obtained by a timer ( S3), based on the elapsed time t ₀ select a table from the ROM (15), reads the upper limit temperature T _8Limit unit (8) (S4). In addition,
The elapsed time t ₀ is obtained by a timer by software. Next, from the temperature T ₀ detected by the thermistor (3), the temperature T _{8 of the} unit (8) is obtained from the selected table.
Is read (S5). Next, if T ₀ (T ₈ ) is lower than the print _failure determination line T _limit (upper limit T _8limit ) (S6).
YES), print is permitted, and one page is printed (S
7). If the printing is not completed (N in S8)
O), the temperature T ₀ of the thermal head (2) is determined (S
9) Return to S5 and continue printing. If the printing is completed (YES in S8), the timer for the elapsed time is operated (S8).
10), end. If it is determined in S6 that printing is not possible (NO in S6), printing is stopped (S11) and a timer for measuring elapsed time is started (S12). Then, the temperature T ₀ of the thermistor (3) is measured (S13). After waiting for the measured temperature T ₀ to reach the printable temperature T _p (YES in S14), the process returns to S2 and printing is resumed.

Further, preferably, the thermistor temperature T ₁ at the end of printing of the previous page is stored in the RAM (14), and at the start of printing, the thermistor temperature T at the present time (at the start of printing) is set.
₀ and from the elapsed time t ₀ Metropolitan from after the completion of all of the pages printed (T ₁ -T ₀₎
/ T ₀ is calculated. This value is an amount indicating the heat radiation state of the system itself. Therefore, the larger the (T ₁ −T ₀ ) / t ₀ , the higher the non-printable determination line T _limit is set, and (T ₁
The smaller the _{value of} −T ₀ ) / t ₀ , the lower the print disable determination line T _limit . This enables highly accurate control. In this case, (T ₁ −T ₀ ) / t is stored in the ROM (15).
A table of T ₀ -T ₈ and a print disable determination line T _limit are stored using ₀ as a parameter.

[0015]

According to the present invention, a configuration is realized in which the temperature rise of the unit having the lower upper limit temperature is suppressed by changing the print non-determination line according to the situation, and the printing is not frequently stopped. This ensures uniform density by the thermal head and also protects another unit in the same housing. In addition, since the non-printable determination line is set based on the information of the previous elapsed time and the current thermistor temperature, highly accurate control is possible. Furthermore, when the print-impossible determination line is set in consideration of the temperature at the end of the previous time, more accurate control can be performed. Further, since the user can set the printability determination line, the user can select a trade-off between the time until re-reception is possible and the continuously receivable number of sheets at the time of re-reception.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit.

FIG. 3 is a diagram showing a relationship between a detected temperature T ₀ and a unit temperature T ₈ .

FIG. 4 is a diagram showing a temperature control situation.

FIG. 5 is a flowchart of print control.

[Explanation of symbols]

2: thermal head, 3: thermistor, 8: unit having an upper limit temperature, 11: CPU, 15: RO
M, 16 ... RAM.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B41J 2/365 B41J 2/375 G05D 23/19 G06K 15/10

Claims (3)

(57) [Claims] In a system in which a thermal printer having a thermal head and a unit having an upper limit temperature lower than the upper limit temperature of the thermal head are housed in the same casing, a method from the end of previous printing by the thermal head to the start of present printing is provided. Elapsed time measuring means for measuring the elapsed time, a temperature detecting element for measuring the current temperature of the thermal head, and correspondence between the temperature of the thermal head and the temperature of the above unit for each elapsed time measured by the elapsed time measuring means. The table and the storage means for storing a print non-determination line corresponding to the upper limit temperature of the unit, the elapsed time measured by the elapsed time measuring means,
Temperature control means for stopping printing when the temperature of the unit read from the table corresponding to the temperature measured by the temperature detecting element exceeds the upper limit temperature of the unit. apparatus. 2. The temperature control device according to claim 1, further comprising a storage unit configured to store a temperature of the thermal head at the time of previous printing completion, wherein the control unit stores a temperature of the thermal head at the time of previous printing completion and a temperature of the thermal head. A system which calculates a quantity indicating a degree of heat radiation from a current temperature and an elapsed time measured by the elapsed time measuring means, and determines a print disable determination line for the unit from the calculated value. 3. The temperature control device according to claim 1, further comprising setting means for allowing a user to set a printable temperature at which printing is restarted after printing is stopped by the control means.