JPH11105329A - Communication terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a temperature of a print head at a constant level during the printing of data, to prevent the occurrence of variation in a printed image and to obtain a high quality image by a method wherein a preheating time for the print head is controlled in accordance with a detected signal of a temperature detecting means for detecting a temperature of the print head. SOLUTION: A thermistor TH as a temperature detecting means for detecting a temperature of a thermal head H is attached to the thermal head H. An analog temperature signal outputted therefrom is inputted to an energizing control section 5a via an A/D conversion section 5c. The energizing control section 5a looks up a pulse width setting table 5b wherein an ambient temperature, a heating pulse width (heating pulse time) and a preheating width (preheating time) are set in one-to-one correspondence and controls the energizing times (heating pulse width, preheating width) based on the inputted temperature signal. As a result, optimum preheating is always executed so that the temperature of the thermal head H during the printing of the data is maintained at a constant level, then it is possible to prevent the occurrence of variation in the printed image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a communication terminal device in which a print head is preheated while data is being printed.

[0002]

2. Description of the Related Art Conventionally, a communication terminal device such as a facsimile device includes a thermal printer (thermal printer). When heat is applied by a thermal head, received image data or read image data is read. Is printed directly on thermal paper or indirectly printed using an ink ribbon.

FIG. 5 shows an example of a circuit configuration of a thermal head. A plurality of thermal heads H are arranged in a line, each forming a print pixel (in the figure, n1 to n2048).
2048 (A4 size recording width) heating resistors 1
00 and a NAND provided in each heating resistor 100
It includes a gate, a latch circuit 101, and a shift register 102 for storing image data transferred in synchronization with a clock pulse.

Each NAND gate has a shift register 1
02 and an output of the latch circuit 101 connected thereto and predetermined strobe signals ST1 to ST4 (heat pulse) are input. In the figure, each of the strobe signals ST1 to ST4 is input by being divided into four blocks. The strobe signal ST1 is applied to NAND gates corresponding to n1 to n512 of the heating resistor 100, and the strobe signal ST2 is applied to the heating resistor 100. NA corresponding to n513 to n1024
The strobe signal ST3 is supplied to the ND gate by the heating resistor 10
The strobe signal ST4 is supplied to the NAND gate corresponding to n1025 to n1536 of n0 of the heating resistor 100.
The signals are input to NAND gates corresponding to 37 to n2048.

When the image data is serially transferred line by line to the shift register 102 and the latch circuit 101 receives the latch pulse, and then the strobe signals ST1 to ST4 are sequentially sent to the respective NAND gates, the signal becomes N in response.
The AND gate is opened, and the data held in the latch circuit 101 is output. That is, each pixel is printed out according to the data in the shift register 102 at this time.

As described above, the heating of the thermal head H is performed by
This is performed by controlling the heat pulse for each block (in FIG. 5, every four blocks). For example, when the black pixels are continuous (when the black ratio of one line is high).
Means that heat is stored in the thermal head H, the temperature rises,
The print may have uneven shading. To prevent this,
Conventionally, the overall temperature of the thermal head H is detected, and the change in the temperature controls the heat pulse time (heat pulse width). That is, when the temperature of the thermal head H is low, a heat pulse for a long time is applied,
When the temperature of the thermal head H is high, a short-time heat pulse is applied.

In a communication terminal device equipped with this type of thermal head H, for example, when printing facsimile-received image data, the decoding time for each line differs, so that the processing speed of the data to be printed is reduced by the printer. The printer may not be able to keep up with the processing speed, and may enter a print standby state. In this case, when the print standby state is canceled and printing is performed, a sudden rise in temperature is not enough to prevent the temperature of the thermal head H from remaining low. A short width pulse (preheat pulse) is applied.

FIG. 6 is a time chart showing the operation at this time. Here, for simplicity of description, a case is shown in which the plurality of heating resistors 100 of the thermal head H are divided into two blocks and strobe signals ST1 and ST2 are input. Also, here, each time printing of one line is completed, the temperature of the thermal head H is detected, and the heat pulse width (time) of the next line is determined. In other words, the heat pulse width t
1 ′ is converted to a heat pulse width t2 ′ by temperature detection.
And the heat pulse width t3 'is determined by the temperature detection.

During preheating in which the motor for printing is not driven, the preheating (pulse) width tp
Is calculated based on the heat pulse width (here, t2 ') of the last printed line before the standby. For example, the width is １ ／ of the last heat pulse width. However, if the preheat width tp is fixed, the temperature of the thermal head H may become too high or too low depending on the length of the standby time (the number of standby lines) (somewhat). Therefore, it has been considered that the preheat width tp is changed in several stages according to the number of standby lines.

For example, if the last heat pulse width is 2 ms
(Milliseconds), the first 10
The line has a preheat width tp of 1 ms, which is a half of the last heat pulse width, but a line exceeding the preheat width tp is 1/1/1 of the last heat pulse width to prevent the head H from being overheated. The width is changed to 0.25 ms, which is the width of 8.

In the above description, the preheat control when the printer is in the print standby state has been described. However, when the print data of one line is blank, that is, when the print data is an all white line, the same control is performed. Control was not performed.

[0012]

However, in the above-mentioned conventional communication terminal device, the preheating time of the print head is determined by the heat pulse time at the time of printing before the all white line or the last before printing. Therefore, when the standby state is released, the temperature of the print head does not always reach the optimum temperature, and the print density sometimes becomes uneven.

The present invention has been made in view of such circumstances, and a high-quality image can be printed by calculating a preheat time in addition to a heat pulse time based on the temperature of a print head. It is an object to provide a communication terminal device as described above.

[0014]

In order to achieve the above object, a communication terminal device according to a first aspect of the present invention comprises a temperature detecting means for detecting a temperature of a print head, and a temperature detecting means for detecting the temperature of the print head. Control means for controlling the preheating time of the print head according to the temperature. This makes it possible to perform optimal preheating when the data is an all-white line or during data printing standby, and when printing data, the temperature of the print head can be kept constant, resulting in unevenness in the printed image. This does not occur, and a high-quality image can be obtained.

According to a second aspect of the present invention, the temperature detecting means of the first aspect detects the temperature of the print head at predetermined intervals, which are intervals at which data is printed line by line. That is, at a predetermined time interval for printing one line of data, the temperature of the print head is detected each time, and when the data to be printed is ready at that time, the heat pulse time is determined based on the detected temperature. However, if the next print line is an all-white line or if the data to be printed is not ready and a standby state is set, the preheat time is determined based on the detected temperature.

According to a third aspect of the present invention, the temperature detecting means of the first or second aspect is constituted by a thermistor.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the internal configuration of the communication terminal device of the present invention. Here, a configuration example of the facsimile machine F is shown as one of the communication terminal devices, but the present invention is not limited to this, and it is a device that prints data using a print head that generates heat. For example, a personal computer (personal computer) having a thermal printer function and a facsimile communication function may be used.

The signal processing unit 1 is constituted by a CPU or the like, and not only controls each unit of the facsimile apparatus F, but also
It performs processing such as encoding and decoding for facsimile communication. The ROM 2 stores a program for controlling the operation of the facsimile machine F in advance. RAM3
Stores temporary data generated at the time of execution of the process, and also stores a facsimile number (telephone number) of the other party in advance.

The reading section 4 reads an image from a set document and sets it as image data. The recording unit 5 is configured by a thermal printer or the like, and records (prints out) data received from another facsimile machine or the like as image data. The operation unit 6 includes various keys and performs various input settings for the facsimile machine F. Display 7
Is composed of a liquid crystal display device, an LED, and the like, and displays an operation state, an operation procedure, and the like of the facsimile device F.

The modem 8 modulates and demodulates signals for facsimile communication. The line control unit 9 is configured by an NCU or the like, and closes and opens the communication line L (analog line). When a digital line such as an ISDN line is connected, the modem 8 is not provided, and the line control unit 9 is configured by an ISDN interface connected to the DSU. The facsimile apparatus F encodes image data read by the reading unit 4 and transmits the encoded image data through the communication line L.
The basic operation of decoding image data received through the communication line L and printing out the image data from the recording unit 5 is performed.

According to the present invention, in order to keep the temperature of the print head at the time of printing data constant by the recording unit 5, the printing operation is performed when the print data is an all-white line where the print data is blank or during printing standby. The feature is in the control of the preheating of the print head. Therefore, in the present invention, the image data (image data) read by the reading unit 4 is not directly printed from the recording unit 5 without encoding (copy function), but the image data (image data) received through the communication line L is not used. While receiving the encoded data) or temporarily
This is related to the case where the data is stored in the image memory and recorded from the recording unit 5 while sequentially decoding.

FIG. 2 schematically shows the structure of the recording section 5 which is a main part of the present invention. Here, a case is shown in which data is recorded on predetermined recording paper using a thermal head H as a print head. The circuit configuration and basic operation of the thermal head H have already been described with reference to the related art and FIG. Thermal head H
Has a thermistor TH at the center thereof as temperature detecting means for detecting the temperature of the head H, and an analog temperature signal (a signal that decreases as the temperature rises) output from the thermistor TH is A / A. It is converted into a digital temperature signal by the D conversion unit 5c, and is input to the energization control unit 5a constituting the control means of the present invention.

The energization control unit 5a determines in advance the environmental temperature and the heat pulse width (hereinafter also referred to as "heat pulse time").
And the preheat width (hereinafter, also referred to as “preheat time”) with reference to the pulse width setting table 5b set correspondingly, and based on the input temperature signal, the thermal head H
To control the power supply time (heat pulse width, preheat width).

The means for detecting the temperature of the thermal head H is not limited to the thermistor TH having a negative temperature characteristic, and a plurality of temperature detecting means such as thermistor TH may be provided, and the average value thereof may be used. , Etc., a more accurate temperature may be detected. Further, the power supply control unit 5a may calculate the power supply time from the environmental temperature by using a calculation formula set in advance in a ROM or the like without referring to the pulse width setting table 5b configured by a RAM or the like.

Furthermore, here, the energization control unit 5a, the pulse width setting table 5b, and the A / D conversion unit 5c have been described as belonging to the recording unit 5, but the energization control units 5a and A / D
The function of the D conversion unit 5c may be executed by the signal processing unit 1 and the pulse width setting table 5b may be provided in the RAM 3. As described above, according to the present invention, the preheat time is controlled in addition to the heat pulse time according to the temperature of the thermal head H detected by the thermistor TH. The temperature of the head H can be kept constant. That is, when the temperature of the thermal head H is relatively low, preheating is performed for a relatively long time, and when the temperature of the thermal head H is relatively high, preheating is performed for a relatively short time. This makes it possible to obtain a high-quality image without causing unevenness in the printed image.

FIG. 3 is a time chart showing the above operation. Here, in order to simplify the explanation as in FIG. 6, a case is shown in which the plurality of heating resistors of the thermal head H are divided into two blocks and strobe signals ST1 and ST2 are input (see FIG. 5). . Here, 1
The temperature of the thermal head H is detected by the thermistor TH at intervals of a predetermined time for printing image data for each line. That is, each time the thermal head H is printed at a predetermined interval for printing one line of data (an interval indicated by a broken line in the drawing).
When the data of the line to be printed is available at that time, the heat pulse time is determined on the basis of the detected temperature. At some point, or when it takes time to decode the received data, and when the data of the line to be printed is not available and the apparatus enters a standby state, the preheating time is determined based on the detected temperature.

In the figure, the heat pulse width t1 is detected by the temperature detection, the heat pulse width t2 is detected by the temperature detection,
The heat pulse width t6 is determined by detecting the temperature.
Further, during the preheating in which the motor for printing is not driven, the preheating width t3 is determined by detecting the temperature, the preheating width t4 is determined by detecting the temperature, and the preheating width t5 is determined by detecting the temperature.

As described above, the preheat widths t3, t4, t4 are variably set according to the temperature at that time for each line processing.
If 5 is determined, the temperature of the thermal head H when printing data after standby release may become too high or low depending on the number of standby lines (standby time). Therefore, the temperature of the head H can be set to an optimum temperature.

FIG. 4 is a flowchart showing the above operation (S
100 to S108). Note that here, 1
Energization control unit 5a for a predetermined time for printing line data
The operation of FIG. If the printer is in an operable state, the voltage of the thermistor TH is detected, and the voltage is held as the environmental temperature (S100, S101). Here, if the data of the line to be printed is complete and there is a print request and the previous line is not being printed, the heat pulse width is determined and this heat pulse is output to perform printing (S102).
To S105). On the other hand, since the print data is an all white line or the data is not aligned, there is no print request, and unless the heat pulse is being output (during the previous line printing), the preheat width is determined and this preheat is output (S106 to S106). S1
08).

[0030]

As can be understood from the above description, in the communication terminal device according to the first aspect of the present invention, depending on the temperature of the print head, during the data printing standby or when the print data is all white lines. Since the preheating time at a certain time is controlled, the temperature of the print head when printing data can be optimized. Therefore, a printed image is not uneven, and a high-quality image can be obtained.

According to the second aspect, the temperature of the print head is detected at intervals of printing data for each line, so that fine preheating control can be performed. According to the third aspect, since the temperature of the print head is detected by the thermistor, appropriate preheating control can be realized with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of a communication terminal device according to the present invention.

FIG. 2 is a diagram illustrating an example of a main configuration of a recording unit.

FIG. 3 is a time chart showing an example of a basic operation of the communication terminal device of the present invention.

FIG. 4 is a flowchart illustrating an example of a basic operation of the communication terminal device of the present invention.

FIG. 5 is a circuit diagram showing an example of a configuration of a thermal head.

FIG. 6 is a time chart showing an operation of a conventional communication terminal device.

[Description of Signs] F: Facsimile machine 1: Signal processing unit 5: Recording unit 5a: Power supply control unit H: Thermal head TH: Thermistor t1, t2, t6 ... Heat pulse width t3, t4, t5 ... preheat width

Claims (3)

[Claims] A communication terminal device for printing data at a predetermined time interval line by line, preheating the print head while waiting for data printing, and keeping the temperature of the print head constant when printing data. A communication terminal device, comprising: a temperature detecting unit for detecting a temperature of the print head; and a control unit for controlling a preheating time of the print head in accordance with the temperature detected by the temperature detecting unit. 2. The temperature detecting means according to claim 1, wherein said temperature detecting means comprises:
The communication terminal device according to claim 1, wherein a temperature of the print head is detected. 3. The communication terminal device according to claim 1, wherein said temperature detecting means comprises a thermistor.