JPS649948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printing device in which printing is performed while the printing head is moved by a heating element placed on the printing head.

Conventional thermal printing devices supply power to a heating element placed on the print head at regular intervals.
Since printing is performed by running the print head, a trailing phenomenon occurs in the print due to the running characteristics of the print head.

Hereinafter, the trailing phenomenon of printing will be briefly explained using the time chart shown in FIG.

Figure 1a shows the running speed when the printing head is fed intermittently, and the shaded area in Figure 1a shows the power supply time to the heating element placed on the printing head. . As is clear from Figure 1a, power is always supplied to the heating elements for a fixed period of time regardless of changes in the running speed of the print head. The length of the dot becomes longer as the running speed of the print head increases, and such trailing phenomenon in the print becomes extremely difficult to read, which has been considered a bigger problem than in the past.

In view of the above drawbacks, the present invention provides a thermal printing device which aims to improve the quality of printing by controlling the power supply time to the heating element according to the moving distance of the printing head.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a thermal printing device according to an embodiment of the present invention.

In FIG. 2, reference numeral 1 denotes a heating element that generates heat when supplied with electric power to print on printing paper, and is placed on a printing head (not shown). A motor 2 is a drive source for a carriage (not shown) for moving the print head, and is controlled by a motor drive circuit 3. 4 is a pulse generator that outputs a pulse signal according to the number of rotations of the motor 2; A counter 5 sends out a print start signal and a print end signal based on the number of pulse signals from the pulse generator 4. A latch circuit 6 opens the gate circuit 7 in response to a print start signal sent from the counter 5, and closes the gate circuit 7 in response to a print end signal. 8
is a print control circuit which controls the motor drive circuit 3 and sequentially outputs print pattern signals to the gate circuit 7 via the latch circuit 9 using the print start signal sent from the counter 5 as a timing signal.

The operation of the thermal printing device configured as described above will be described below.

First, the carriage is moved by the drive of the motor 2, and as the carriage moves, the print head on which the heating element 1 is placed starts to move.

On the other hand, the pulse generator 4 sends a pulse signal to the counter 5 in accordance with the number of rotations of the motor 2.
The counter 5 counts the pulse signals sent from the pulse generator 4, and generates a print start signal when it counts a specific number of pulse signals, and generates a print end signal when it counts a specific number of pulse signals thereafter. . That is, depending on the number of pulse signals sent from the pulse generator 4, a print start signal and a print end signal are alternately generated.

The print start signal and print end signal are sent to the latch circuit 6, and the print pattern signal is sent from the print control circuit 8 to the heating element 1 via the latch circuit 9 in response to the print start signal and print end signal. is gated by the gate circuit 7. That is, the travel distance of the print head is detected by the pulse generator 4 and the counter 5, and a print start signal is sent from the counter 5 when the print head reaches a first predetermined position at which to start generating heat to the heating element 1. is input to the latch circuit 6, and the latch circuit 6 controls the gate circuit 7 with the print start signal, thereby sending a print pattern signal from the print control circuit 8 to the heating element 1 via the latch circuit 9 and the gate circuit 7. do. On the other hand, when the print head reaches a second predetermined position at which the heating element 1 should end, a print end signal sent from the counter 5 is input to the latch circuit 6, and the latch circuit 6 is gated by the print end signal. By controlling the circuit 7 and gating the print pattern signal sent from the print control circuit 8 to the heating element 1 via the latch circuit 9 with the gate circuit 7, even if the running speed of the print head changes, the printing can be continued. Since printing is performed by generating heat depending on the travel distance of the head, it is possible to prevent the trailing phenomenon.

A more detailed explanation will be given below with reference to FIG.

In Fig. 3, Fig. 3a shows the running speed of the printing head when it is fed intermittently, Fig. 3b shows the pulse signal of the pulse generator, and Fig. 3c shows the counter 5.
3d is a print end signal sent from the counter 5. FIG.

As is clear from FIG. 2A, first, the driving speed of the print head increases in a curved manner as the motor 2 is driven. In response to the running of the print head, the pulse generator 4 generates a pulse signal as shown in FIG. 4b.
The counter 5 counts the pulse signals, generates a print start signal at time _T1 as shown in FIG. 4c, and opens the gate circuit 7 via the latch circuit 6.

When the gate circuit 7 is opened, a print pattern signal sent from the print control circuit 8 causes the heating element 1 to generate heat via the latch circuit 9.

On the other hand, after counting a certain number of pulse signals, the counter 5 generates a print end signal at time _T2 , closes the gate circuit via the latch circuit 6, and gates the print pattern signal sent from the print control circuit 8. .

Thereafter, in the same way, a print start signal is generated at T ₃ , T ₅ , T ₇ , and T ₉ to open the gate circuit 7, while the time
By generating a print end signal at T ₄ , T ₆ , T ₈ , and T ₁₀ and gating the print pattern signal sent through the gate circuit 7, the speed distance of the print head increases or decreases in a curved manner. However, by supplying power to the heating element 1 at a specific position on the printing paper, it is possible to perform printing by heat generation on the printing paper at regular intervals.

As described above, according to this embodiment, the pulse generator 4 generates a pulse signal in accordance with the rotation of the motor 2 that drives the print head on which the heating element 1 is placed.
and a counter 5 that counts the pulse signal by a specific number and generates a print start signal and a print end signal.
By providing a gate circuit 7 that gates the power supplied from the print control circuit 8 to the heating element 1 in response to the print start signal or print end signal sent from the counter 5, the travel distance of the print head changes in a curved manner. Printing can be performed at equal intervals even when printing is performed, and the trailing phenomenon of printing can be prevented.

As described above, the present invention provides a traveling distance detecting means for calculating the traveling distance of the printing head from the driving means for driving the printing head on which the heating element is mounted, and transmitting a printing control signal in accordance with the traveling distance of the printing head. and gate means for gating the electric power supplied to the heating element in response to the printing control signal sent from the running distance detecting means, thereby preventing the trailing phenomenon of printing that has conventionally occurred. can be produced, and its industrial value is great.

[Brief explanation of drawings]

FIG. 1 is a time chart showing the characteristics of a conventional thermal printing device, FIG. 2 is a block diagram of a thermal printing device according to an embodiment of the present invention, and FIG. 3 is a time chart showing the same characteristics. 1... Heat generating element, 2... Motor, 4... Pulse generator, 5... Counter, 7... Gate circuit.

Claims (1)

[Claims] 1. A heating element placed on the print head, a motor that drives the print head, a pulse generator that outputs a pulse signal according to the number of rotations of this motor, and a print start signal and print signal that input this pulse signal. A thermal printing device comprising: a counter that sends out an end signal; and gate means that gates the power supplied to the heating element in response to a print start signal and a print end signal from the counter.