JPH07214813A - Thermal printer - Google Patents

Abstract

PURPOSE:To provide a thermal printer capable of effecting a high quality printing at a high speed. CONSTITUTION:Since a motor speed control means 8 controls the operating speed of a motor so as to make the transfer speed of a printing medium high as environmental temperature rises, the printing operation can be effectively performed at a high speed. In addition to the control by the motor speed control means 8, an electricity application control means 10 controls the energizing time of a heating element of a thermal head according to environmental temperature and also a pulse width control means 12 controls the width of the electric pulse applied during the energizing period according to the entire temperature of the thermal head. In this way a fully high quality printing can be effected at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer capable of effectively increasing the printing speed. The present invention also relates to a thermal printer capable of high-speed, high-quality printing.

[0002]

2. Description of the Related Art Thermal printers are widely used for automatic ticket issuing machines installed in train stations, airports, and the like. The thermal printer selectively energizes a plurality of heat-generating elements of a thermal head to generate heat, thereby printing on a paper sheet, that is, a printing medium, which is transferred via a transfer roller or the like driven by a motor. , Dot printing of desired characters and the like is performed. For example, in the case of a thermal printer of the type using an ink ribbon, the ink of the ink ribbon is melt-transferred to the surface of the print medium by the heat generation of the heat generating element, thereby performing dot printing. On the other hand, in the case of a thermal printer of the type that does not use an ink ribbon, the surface of the heat-sensitive printing medium is colored by the heat generated by the heat-generating element, so that dot printing is performed.

Generally, in a thermal printer,
In order to reduce the load on the power source, the plurality of heating elements are operationally divided into two groups.
The two groups are alternately energized and deenergized to share the desired printing.
That is, during printing, as shown in FIG. 5, while the heating elements Ha of one group are in the energization on state for printing a specific dot, the heating elements Hb of the other group are maintained in the energization off state. After that, when the heating element Hb is turned on to print another dot, the heating element Ha is turned off, and so on.

For each heating element Ha, Hb, the time from the time when the heating element is turned on to the time when it is turned on next is such that the dot printing cycle for printing one dot is equal to the energization cycle, and the heating element Ha , Hb is the total time length of the energization on time and the energization off time.

By the way, the quality of printing by such a thermal printer is greatly influenced by the environmental temperature around the printer. Therefore, the environmental temperature is detected successively and the environmental temperature is detected according to the detected environmental temperature. It has been conventionally performed to control the length of the energization on time of the heating element per dot printing cycle.

The control of the energization on time will be described in more detail as follows. In general, as the ambient temperature becomes considerably lower than the normal ambient temperature, the surface temperature of the print medium exposed to the ambient temperature and the substantially whole temperature of the thermal head (hereinafter, simply referred to as the whole head temperature To tell)
Will also be lower. Therefore, if the power-on time of the heat generating element remains the same as that at the time of the normal environmental temperature, it means that ink is formed or color is formed on the print medium (hereinafter, both the ink formation and the color formation are described. (Using the term "coloring") is not enough
Print leakage may occur. So in this case,
Control is performed to make the power-on time of the heating element longer than that at the normal ambient temperature.

On the contrary, when the environmental temperature is considerably higher than the normal environmental temperature, the surface temperature of the print medium and the temperature of the entire head also increase accordingly. For this reason, if the power-on time of the heat generating element remains the same as that at the normal environmental temperature, excessive coloring occurs, and the edges of printed characters and the like spread and become blurred. Therefore, in this case, control is performed so that the energization ON time of the heating element is shorter than that at the normal ambient temperature.

By the way, in the case where such a thermal printer continuously prints on a large number of printing media, the temperature of the entire head rises considerably regardless of the environmental temperature, and the heat-generating element when the energization is off. The temperature will rise. For this reason, if the power-on time of the heating element remains the same as when the temperature of the head is normal as a whole, a situation occurs in which color development becomes excessive, as described above. Therefore,
To solve this, the temperature of the entire head is sequentially detected,
It has been conventionally practiced to control the energization ON time of the heating element according to the detected head overall temperature. That is, when the temperature of the entire head becomes high due to continuous printing or the like, control is performed to shorten the energization ON time of the heating element.

[0009]

However, in the above-mentioned conventional control, since the transfer speed of the print medium by the motor is always constant regardless of the change of the environmental temperature, the printing process is effectively speeded up. could not. Further, in the above-mentioned conventional control, since the energization ON time of the heating element is only controlled based on the detection of only one of the environmental temperature and the entire head temperature, multifaceted and fine print control is possible. It was not possible to print with sufficiently high quality.

The present invention has been made in view of the above points, and it is a first object of the present invention to provide a thermal printer capable of effectively increasing the printing speed.

A second object of the present invention is to provide a thermal printer capable of high-speed printing with sufficiently high quality.

[0012]

In order to achieve the first object, the thermal printer according to the first aspect of the present invention has a plurality of heating elements (H) of a thermal head (H).
A thermal printer that performs desired printing on a print medium (PM) that is transferred to the head (H) through a motor (M) when e) is energized by an electric pulse (P). And an environmental temperature sensor (4) for detecting an environmental temperature around the printer, and a transfer of the print medium (PM) as the environmental temperature detected by the environmental temperature sensor (4) increases. A motor speed control means (8) for controlling the operating speed of the motor (M) according to the environmental temperature detected by the environmental temperature sensor (4) is provided so as to increase the speed.

In order to achieve the above second object, in the thermal printer according to the second aspect of the present invention, a plurality of heat generating elements (He) of the thermal head (H) are energized by electric pulses (P). As a result, the thermal printer performs desired printing on the print medium (PM) transferred to the head (H) via the motor (M), and the environmental temperature around the printer is controlled. An environmental temperature sensor (4) for detecting, a head temperature sensor (5) for detecting the overall head temperature which is a substantially overall temperature in the thermal head (H), and the environmental temperature sensor (4). According to the environmental temperature detected by the environmental temperature sensor (4), the transfer speed of the print medium (PM) increases as the detected environmental temperature increases. Motor speed control means (8) for controlling the operating speed of the motor (M), and the energization ON time of the heat generating element (He) becomes shorter as the detected environmental temperature becomes higher, and the detected environment becomes higher. Depending on the detected ambient temperature, the energization ON time of the heating element (He) becomes longer as the temperature becomes lower,
Energization control means (10) for controlling the energization on time of the heat generating element (He), and the head temperature sensor (5)
As the temperature of the entire head detected by the temperature rises, the heating element (He) is turned on during the energization ON time.
As the width of each electric pulse (P) applied to the head becomes shorter and the detected temperature of the whole head becomes lower, the width of each electric pulse (P) becomes longer so that the whole detected head becomes wider. A pulse width control means (12) for controlling the width of the electric pulse (P) according to the temperature is provided.

[0014]

In the thermal printer according to the first aspect, the motor speed control means (8) includes the print medium (PM) as the environmental temperature detected by the environmental temperature sensor (4) increases. Since the operation speed of the motor (M) is controlled so that the transfer speed of the printer is increased, the printing process can be effectively speeded up.

Further, in the thermal printer according to the second aspect, in addition to the features according to the first aspect,
The energization control means (10) controls the energization on time of the heating element (He) according to the environmental temperature detected by the environmental temperature sensor (4), and the pulse width control means (12) controls the head. The width of the electric pulse (P) is controlled according to the temperature of the entire head detected by the temperature sensor (5). In this way, it is possible to print at high speed and with sufficiently high quality.

[0016]

1 is a block diagram showing the construction of a thermal printer according to an embodiment of the present invention.
For example, it is applied to an automatic ticket issuing machine installed at a train station, an airport, or the like.

A printing medium PM such as a ticket as in the conventional case
Is transferred relative to the thermal head H via a transfer roller or the like driven by a motor M. Also in this thermal printer, in order to reduce the load on the power source, a plurality of heating elements H of the thermal head H are used.
The operation e is divided into two groups in terms of operation, and the two groups are alternately turned on and off to be shared so that desired printing is performed.

In FIG. 1, a control unit 2 controls the entire thermal printer and is composed of, for example, a microcomputer. The environmental temperature sensor 4 sequentially detects the environmental temperature around the thermal printer, and is provided at a predetermined location separated from the thermal head H. The head temperature sensor 5 sequentially detects the temperature of the entire head of the thermal head H, and the heating element He in the thermal head H is detected.
It is provided at a location adjacent to. The environment temperature sensor 4 and the head temperature sensor 5 may be any temperature sensor such as a thermistor. The analog outputs of the environmental temperature sensor 4 and the head temperature sensor 5 are A /
After being digitally converted through the D converter 6, the data is taken into the control unit 2 as data indicating the current environmental temperature and the current head overall temperature, respectively.

In a predetermined area of the ROM 7, a motor speed table T1, an energization on time table T2 and a pulse width table T3 are prepared. The motor speed table T1 stores appropriate motor speeds for each environmental temperature within a predetermined range. Further, the energization on-time table T2 stores appropriate energization on-time for each environmental temperature within a predetermined range. Further, the pulse width table T3 stores appropriate electric pulse widths for each head overall temperature within a predetermined range. Furthermore, the appropriate motor speed, energization ON time, and electric pulse width are determined based on experiments.

Under the control of the control unit 2, the motor speed control means 8 reads from the motor speed table T1 an appropriate motor speed corresponding to the current environmental temperature detected by the environmental temperature sensor 4, The speed of the motor M is controlled according to the read motor speed, thereby changing the transfer speed of the print medium PM to the thermal head H. By this control, the dot printing cycle of each heating element He can be changed according to the change of the environmental temperature.

That is, when the current environmental temperature is lower than the normal environmental temperature, the speed of the motor M is slowed down so that the dot printing cycle is as shown in FIG. It becomes shorter than that at the normal environmental temperature shown in b). On the contrary, when the current environmental temperature is higher than the normal environmental temperature, the speed of the motor M is increased, so that FIG.
As illustrated in (c) of (1), the dot printing cycle becomes longer, and accordingly, the energization on time TON becomes longer. In this way, when the environmental temperature becomes high, the print medium PM
By increasing the transfer speed of the print medium PM, it is possible to print at a higher speed than in the case where the transfer speed of the print medium PM is always constant regardless of the change in the environmental temperature.

Under the control of the control unit 2, the energization time control means 10 determines, from the energization on time table T2, an appropriate energization on time according to the current environmental temperature detected by the environment temperature sensor 4. The heating elements H that are currently set are read according to the read energization ON time.
It has a function of controlling the power-on time of e.

That is, when the current environmental temperature is lower than the normal environmental temperature, the energization on-time TON of each heating element He is the energization on-time at the normal environmental temperature, as in the example of FIG. It is controlled to be longer than TON. Conversely, when the current environmental temperature is higher than the normal environmental temperature, the energization on-time TON of each heating element He is the energization on-time T at the normal environmental temperature, as in the example of FIG.
It is controlled to be shorter than ON. By such control, each heating element He corresponding to the change of environmental temperature
It is possible to appropriately change the heat generation time of.

As is known, each energization ON time TO
During N, a plurality of electric pulses P for causing the heating element He to generate heat continues to be applied. That is, energization means applying an electric pulse P, and each energization on time T
ON is a time during which the plurality of electric pulses P are continuously applied. Under the control of the control unit 2, the pulse width control means 12 reads from the pulse width table T3 an appropriate electric pulse width according to the current head overall temperature detected by the head temperature sensor 5, It has a function of controlling the width of the electric pulse P applied to each heating element He during the energization ON time according to the width of the read electric pulse.

That is, when the current head overall temperature is lower than the normal head overall temperature, as illustrated in FIG. 3A, the width W of the electric pulse P for each heating element He is as shown in FIG. ) It is controlled so as to be longer than the width W of the electric pulse P at the normal head overall temperature shown in FIG. vice versa,
When the current current head overall temperature is higher than the normal head overall temperature, as illustrated in FIG. 4C, the width W of the electric pulse P for each heating element He is equal to the electric current at the normal head overall temperature. It is controlled to be shorter than the width W of the pulse P. By controlling the width W of this electric pulse P,
Each heating element H corresponding to the change in the temperature of the entire head
It is possible to control the heat storage amount of e.

According to this embodiment, when the energization time control means 10 shortens the energization on-time TON as described above, the energization on-time TON is shortened.
It is also possible to perform control for shortening the power-off time while considering the current environmental temperature. In this way, the printing process can be speeded up more effectively. Incidentally, in the related art, even if the control for shortening the energization on-time TON in each printing cycle is performed as described above, the energization off-time is maintained at the same length as the normal time, and therefore each dot is The printing cycle is not shortened so much. Therefore, the above-mentioned conventional control cannot satisfy the user's demand for speeding up the printing process as much as possible.

FIG. 4 is a flow chart showing the procedure of print control executed in the thermal printer having the above-mentioned configuration.

For example, when a staff member turns on a predetermined print start switch (not shown), the environmental temperature sensor 4 causes
An analog output signal indicating the current environmental temperature is generated (step ST1). This analog output signal is A /
Digitally converted by the D converter 6 (step ST
2) After that, as data showing the current environmental temperature,
It is stored in a register (not shown) of the control unit 2.

Next, the control unit 2 refers to the motor speed table T1 based on the current environmental temperature stored in the register to check whether the currently set rotation speed of the motor M is appropriate. It is determined whether or not (step ST3). When the determination result in step ST3 is YES, the process further proceeds to step ST4. However, if the decision result in the step ST3 is NO, the motor speed control means 8 executes the motor speed control subroutine of the step ST5. That is, in this motor speed control subroutine, the proper motor speed corresponding to the current environmental temperature is read from the motor speed table T1, and the currently set read motor speed is changed to the read motor speed. When such a motor speed control subroutine is performed, the result of the determination in step ST3 is YES, so the process proceeds to step ST4.

In step ST4, the control section 2 refers to the energization on time table T2 to refer to the energization on time TON of each heating element He currently set.
Is determined to be appropriate. If the decision result in the step ST4 is YES, the process advances to a step ST6.
However, if the decision result in the step ST4 is NO, the energization time control means 10 executes the energization on-time control subroutine of the step ST7. That is, in this energization on-time control subroutine, the appropriate energization on-time TON corresponding to the current environmental temperature is read from the energization on-time table T2, and the energization on-time of each heating element He that is currently set is Change to the read power-on time. When such an energization ON time control subroutine is performed, the determination result of step ST4 is YE.
Since S, the process proceeds to step ST6.

In step ST6, the head temperature sensor 5
This produces an analog output signal indicating the current overall head temperature. This analog output signal is digitally converted by the A / D converter 6 (step ST
8) Then, the data is stored in a register (not shown) of the control unit 2 as data indicating the current head overall temperature.

At the next step ST9, the control section 2 refers to the pulse width table T3 based on the current head overall temperature stored in the register,
It is determined whether or not the width W of the electric pulse P for each heating element He that is currently set is appropriate. If the decision result in the step ST9 is YES, the energization ON time TON, the motor speed and the width W of the electric pulse P are set.
Since all are appropriate, the actual printing process is started (step ST11). But step S
When the determination result of T9 is NO, the pulse width control means 12 performs the pulse width control subroutine of step ST10. That is, in this pulse width control subroutine, an appropriate pulse width corresponding to the current head overall temperature is read from the pulse width table T3, and the width W of the electric pulse P for each heating element He that is currently set is Change to the proper pulse width read. When such a pulse width control subroutine is performed, the determination result in step ST9 is YES, so that the actual printing process is started in step ST11.

Although the above embodiment was carried out on an automatic ticket issuing machine installed in a train station, an airport, etc., of course, the present invention may be carried out for other purposes.

[0034]

As described above, in the thermal printer according to the present invention, the motor speed control means controls the operating speed of the motor so that the transfer speed of the print medium becomes faster as the environmental temperature becomes higher. Since it is controlled, the excellent effect that the printing process can be effectively speeded up is achieved.

Further, in the thermal printer according to the present invention, in addition to the control by the motor speed control means, the energization control means controls the energization on time of the heat generating element according to the environmental temperature, and the pulse is applied. Width control means
The width of the electric pulse is controlled according to the temperature of the entire head. In this way, the effect that high-quality printing can be performed at high speed is also achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a thermal printer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the control performed by the motor speed control means and the energization time control means of FIG.

FIG. 3 is a diagram illustrating control performed by a pulse width control unit in FIG.

FIG. 4 is a flowchart showing a procedure of print control executed in the embodiment.

[Explanation of symbols]

 H thermal head He heating element M motor 4 environment temperature sensor 5 head temperature sensor 8 motor speed control means 10 energization control means 12 pulse width control means

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[Procedure amendment]

[Submission date] June 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a thermal printer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating control performed by a motor control unit and an energization time control unit of FIG.

FIG. 3 is a diagram illustrating the control performed by the pulse control means in FIG.

FIG. 4 is a flowchart showing a procedure of print control executed in the embodiment.

FIG. 5 shows a printing cycle of a conventional heating element.
It is a time chart .

[Explanation of Codes] H thermal head He heating element M motor 4 environment temperature sensor 5 head temperature sensor 8 motor speed control means 10 energization control means 12 pulse width control means

Claims (3)

[Claims] 1. A plurality of heating elements (He) of a thermal head (H) are energized by an electric pulse (P) to be transferred to the head (H) via a motor (M). A thermal printer for performing desired printing on a print medium (PM), the environmental temperature sensor (4) for detecting an environmental temperature around the printer, and the environmental temperature sensor (4). The operating speed of the motor (M) is controlled according to the environmental temperature detected by the environmental temperature sensor (4) so that the transfer speed of the print medium (PM) increases as the environmental temperature rises. A thermal printer comprising a motor speed control means (8). 2. A plurality of heat generating elements (He) of a thermal head (H) are energized by electric pulses (P) to be transferred to the head (H) via a motor (M). A thermal printer for performing desired printing on a print medium (PM), comprising: an environmental temperature sensor (4) for detecting an environmental temperature around the printer; and a substantially entire thermal head (H). A head temperature sensor (5) for detecting the temperature of the entire head, which is a temperature, and a transfer speed of the print medium (PM) increases as the environmental temperature detected by the environmental temperature sensor (4) increases. A motor speed control means (8) for controlling the operating speed of the motor (M) according to the environmental temperature detected by the environmental temperature sensor (4); The detection is performed such that the energization on time of the heat generating element (He) becomes shorter as the temperature rises, and the energization on time of the heat generating element (He) becomes longer as the detected environmental temperature becomes lower. With the energization control means (10) for controlling the energization ON time of the heat generating element (He) according to the ambient temperature, and with the increase in the overall head temperature detected by the head temperature sensor (5), The width of each electric pulse (P) applied to the heating element (He) during the energization ON time becomes shorter, and the detected overall head temperature becomes lower. In order to increase the width, depending on the detected overall head temperature,
The thermal printer according to claim 1, further comprising pulse width control means (12) for controlling a width of the electric pulse (P). 3. The plurality of heat generating elements (He) are operationally divided into two groups, and the two groups are alternately energized and deenergized to alternately share the printing operation. And the energization control means (10) is configured to perform the heating element (He).
3. The thermal printer according to claim 2, wherein the energization on time is controlled to be shortened, the energization off time is controlled to be shortened accordingly.