JPH10138572A - Thermal printing equipment - Google Patents

Abstract

(57) [Problem] To reduce the processing speed and minimize the power supply and cost in an apparatus for printing with a plurality of thermal heads. SOLUTION: The printing speed is controlled by shifting the driving timing of the thermal heads 1 and 2, and the maximum value of the driving current (total current) is suppressed low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printing apparatus for printing on a medium using a thermal head, and more particularly to a thermal ticket printer, a color printer, and the like for printing on a medium using a plurality of thermal heads.

[0002]

2. Description of the Related Art In order to drive a thermal head, a large-capacity power supply is required, and the power supply becomes large, which is one of the factors that hinder the miniaturization of the apparatus. As described in Japanese Patent Application Laid-Open No. 3-142257, as a method of reducing the power of the thermal head, a method of dividing a thermal head heating element into a plurality of blocks and controlling the drive timing between the blocks by the number of black pixels. Has been proposed. Further, as described in JP-A-8-20136, a method has been proposed in which the printing speed is controlled by the character size to be printed to reduce the power. However, when printing is performed by driving a plurality of thermal heads, the peak current value becomes a plurality of times as large as when one thermal head is driven. For example, as shown in FIG. 2, when printing is performed on a medium by simultaneously driving two thermal heads (thermal heads 1 and 2), the peak current value (overall current) is doubled, and a power supply having a large current capacity is used. is required. The prior art did not consider this point.

[0003]

SUMMARY OF THE INVENTION In an apparatus for printing on a medium by using a plurality of thermal heads, the apparatus can be downsized.
In order to improve the processing speed, it is necessary to make the interval between the thermal heads as narrow as possible and to shorten the transport path length. For example, when the interval between two thermal heads is smaller than the length of the medium, after printing with one thermal head, return the medium such as a ticket to the upstream, transport it again, and print with the other thermal head. Processing speed decreases. Also,
In order to print simultaneously without shifting the drive timings of a plurality of thermal heads, it is necessary to increase the allowable amount of the power supply, which hinders downsizing of the apparatus. An object of the present invention is to reduce the size of a printing mechanism by arranging a plurality of thermal heads at a narrow interval, and to reduce the transport time by driving a plurality of thermal heads for printing. It is an object of the present invention to provide a small-sized, high-speed thermal printing apparatus by increasing the processing speed and shifting the drive timing of the thermal head to lower the maximum value of the drive current, thereby reducing the size of the power supply.

[0004]

In order to achieve the above object, the present invention provides a plurality of thermal heads (1, 2 in FIG. 1).
Transport means such as transport rollers (10 and 11 in FIG. 1);
The present invention is applied to a thermal printing apparatus including means (not shown) for driving them, a power supply (not shown), and a control unit (not shown) for controlling the drive timing of the thermal head and the transporting means. , Reduce the interval between thermal heads, drive multiple thermal heads for printing, and
By shifting the drive timing of the thermal head,
It is characterized in that the power supply is miniaturized to constitute a thermal printing apparatus for small-sized and high-speed printing. More specifically, after turning off the drive current of one thermal head, control is performed so as to turn on the drive current of the next one thermal head (see FIG. 4), or printing of one dot line. The cycle is set to be at least twice the drive current pulse width of one thermal head, and the medium transport speed is made to correspond to the printing cycle (see FIG. 5). Further, when printing is performed by driving N thermal heads, the printing cycle of one dot line is set to be at least N times the driving current pulse width of one thermal head,
By setting the medium conveyance speed to correspond to the printing cycle, the overall maximum current can be suppressed to the same level as when one thermal head is driven (see FIG. 6). Head drive current pulse width N /
(N-1) times to 2 times, the conveyance speed of the medium is made to correspond to the printing cycle, and the reduction in the processing capacity is minimized.
For example, the overall maximum current is suppressed (see FIG. 7).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing the thermal printing apparatus of the present embodiment. First, the configuration will be described. Platen rollers 3 and 4 facing the thermal heads 1 and 2, and transport rollers 10 and 11 for transporting the medium 7, the transfer paper 5 passing between the thermal head 1 and the platen roller 3, and the thermal head 2 and the platen roller 4, And 6. The platen rollers 3, 4 and the transport rollers 10, 11 are driven to rotate by a motor (not shown). Also, transfer paper 5,
6 is wound by a motor (not shown) in synchronization with the conveyance of the medium 7. The sensor 12 detects the leading end of the medium 7 and triggers driving of the thermal heads 1 and 2. Also,
For example, by using a black ribbon for the transfer paper 5 and a red ribbon for the transfer paper 6, two-color printing of black and red can be performed. Next, the operation will be described. When the medium 7 is transported between the thermal head 1 and the platen roller 3 by the transport roller 10, the thermal head 1 is driven to melt the ink of the transfer paper 5 and transfer the ink onto the medium 7 to perform printing. When the medium 7 is transported between the thermal head 2 and the platen 4, the thermal head 2 is further driven to perform printing on the medium. A current for driving the thermal head and the motor is supplied from a power source (not shown). The driving of the transport path and the thermal head is controlled by a control unit (not shown) at a timing described later.

Next, the driving timing of the thermal heads 1 and 2 will be described. FIG. 3 shows a drive current to the thermal head when printing is performed by a single thermal head 1 or 2 in the present embodiment. An electric current is supplied during the pulse energizing time t for each period T, and during this period, the medium 7 is conveyed by one dot line length to continuously print on the medium 7. In this embodiment, the drive timing of the thermal head 1 and the thermal head 2 is changed as shown in FIG.
Is continuously controlled to turn on the current. According to this method, the current capacity of the power supply can be suppressed without increasing the overall maximum current value (total current), so that the power supply can be downsized. On the other hand, in the example shown in FIG. 2 as a conventional technique, since the current is simultaneously supplied to the thermal heads 1 and 2, the total maximum current value is doubled and a power supply having a large current capacity is required. Further, the control unit of the present embodiment detects the drive energizing time of the thermal heads 1 and 2 before starting printing. As a result, when the non-energizing time is shorter than the energizing time of the thermal head, as shown in FIG.
The cycle is made longer than twice the energizing time, and the drive timing of the thermal heads 1 and 2 is controlled to be shifted in the same manner as described above. According to this method, the maximum current value (total current) can be kept low, and the power supply can be downsized. At this time, the motor is controlled so as to change the medium transport speed in accordance with the cycle.

Next, the drive timing when three thermal heads are used will be described. FIG. 6 is a diagram showing a method for driving a thermal head according to the second embodiment of the present invention. The thermal printing apparatus according to the present embodiment has the third printing apparatus shown in FIG.
And the driving current at the time of printing by a single head is as shown in FIG. In this embodiment, as shown in FIG. 6, the cycle is controlled to be three times or more the energizing time, and the drive timings of the three thermal heads 1 to 3 are controlled to be shifted. According to this method, the maximum current value (total current) can be suppressed to the same level as when one thermal head is driven, and the power supply can be downsized. At this time, the motor is controlled so as to change the medium transport speed in accordance with the cycle.

FIG. 7 shows a method for driving a thermal head according to a third embodiment of the present invention. The thermal printing apparatus according to the present embodiment has a configuration in which the third thermal head 3 is added to FIG. 1, and the driving current when printing with a single head is as shown in FIG. In the present embodiment, as shown in FIG. 7, the cycle is controlled to be 1.5 times or more the energizing time and the drive timings of the three thermal heads are shifted. In this case, the power supply is larger than in each of the above embodiments, but the maximum current value (total current) can be suppressed to twice that of driving one thermal head. Further, the motor is controlled so that the medium transport speed is changed in accordance with the cycle. According to this method, it is possible to reduce the size of the power supply while minimizing a decrease in processing capacity. Even when printing with four or more thermal heads, as described above, by changing the cycle in accordance with the energization time, the number of thermal heads, and the capacity of the power supply, a decrease in processing capacity is minimized. It is possible to reduce the size of the power supply while keeping it to a minimum. For example, when driving N thermal heads, the cycle of one dot line is set to N / (N-1) of the energizing time of one thermal head.
More than double.

When driving N thermal heads, the printing cycle of one dot line is set to {N / (N-1)} times or more of the driving current pulse width of one thermal head, A specific example of a method for setting the medium conveyance speed so as to correspond to the printing cycle is shown in a table.

[Table 1] This shows the relationship between the printing cycle and the processing speed.
In the table, the printing cycle for one thermal head and the processing speed at that time are "1". The values on the left indicate the case where the processing speed is increased, and the values in the parentheses on the right indicate the case where the power supply capacity is reduced. The upper part of the method according to the present invention represents a case where the power supply is reduced when the printing cycle is at least twice or more, and the lower part represents a case where the processing speed is to be increased even if the power supply is slightly increased. In addition, according to the method of the present invention, it is possible to cope with the case where the same type of thermal head has individuality and energization time is different. That is, when printing is performed simultaneously with N thermal heads, the printing cycle of one dot line is set to be equal to or more than the sum of the drive current pulse widths of the n (n = 2 to N) thermal heads, and The transport speed corresponds to the printing cycle.

[0010]

According to the present invention, when printing is performed by driving a plurality of thermal heads, a reduction in processing capacity can be minimized and the maximum current can be reduced as a whole, so that the power supply can be reduced in size and cost. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a side view of a thermal printing apparatus showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating respective drive currents and an entire drive current when two thermal heads are simultaneously driven by a conventional control method.

FIG. 3 is a diagram illustrating a drive current to the thermal head when printing is performed by a single thermal head.

FIG. 4 is a diagram illustrating a method of driving the thermal head according to the first embodiment of the present invention, wherein drive currents when two thermal heads are shifted in drive timing;
FIG. 4 is a diagram showing the entire drive current.

FIG. 5 is a diagram illustrating a driving method of the thermal head according to the first embodiment of the present invention, and is a diagram illustrating a case where the energizing time is longer than the non-energizing time.

FIG. 6 is a diagram illustrating a method of driving a thermal head according to a second embodiment of the present invention, and is a diagram illustrating a case where printing is performed with three thermal heads.

FIG. 7 is a diagram illustrating a method of driving a thermal head according to a third embodiment of the present invention, and is a diagram illustrating a case where printing is performed with three thermal heads.

[Explanation of symbols]

1,2 ... thermal head, 3,4 ... platen roller,
5, 6: transfer paper, 7: medium, 10, 11, transport roller,
12: sensor.

Claims (3)

[Claims] A plurality of thermal heads for performing printing on the medium; a driving unit configured to drive the thermal head and the transporting unit; and a power supply, and configured to drive the plurality of thermal heads. 1. A thermal printing apparatus for performing printing on a medium by using a thermal printer, comprising: a control unit that controls printing so as to shift the drive timing of a plurality of thermal heads. 2. The method according to claim 1, wherein when shifting the drive timings of the plurality of thermal heads, the control means controls to turn off the drive current of one thermal head and then turn on the drive current of the next thermal head. The thermal printing apparatus according to claim 1, further comprising: 3. When driving N (N ≧ 2) thermal heads, the printing cycle of one dot line is {N / (N−1)} times or more the driving current pulse width of one thermal head. 3. The thermal printing apparatus according to claim 1, further comprising control means for setting the medium conveyance speed so as to correspond to the printing cycle.