JPH03231869A - Thermal printer - Google Patents

Abstract

PURPOSE:To prevent occurrence of non-printed area by matching the print operation starting time point of print data through a thermal head with the paper feed starting time point through a pulse motor and matching the print operation ending time point with the paper feed end time point through the pulse motor. CONSTITUTION:When an interface circuit 18 receives print data from a host computor 16, the print data are analyzed and developed in dot image into an image buffer 15 and a print timer is actuated under this state. One step drive is then commanded to a pulse motor 19 through timer interruption control of the print timer while one line of print data are read from the image buffer 15 into a thermal head 21 and an HE signal is turned ON. Consequently, print start timing through the head 21 is matched with the paper feed start timing through the motor 19. Furthermore, print end time point is matched with the paper feed end time point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal printer used as a machine for issuing labels and tags attached to products.

[Prior Art] A thermal printer equipped with a thermal line head suitable for printing bar codes on labels and tags attached to products often uses a step motor as a paper feed motor. In this case, it is impossible to set the paper feed speed to a constant speed at the same time as the paper feed starts, and to immediately stop the motor when the paper feed ends, due to the torque and load of the step motor. The step motor is controlled to gradually increase the speed, then maintain a constant speed, and then gradually decrease the speed when the paper feed ends. The printing operation by the thermal line head is stopped during slow-up when printing is started and during slow-down when printing is stopped, and printing is performed only during constant speed.

However, conventional thermal printers that print only at a paper feed speed or at a constant speed have the following problems. That is, when printing a label as shown in FIG. 11, for example (assuming the label feeding direction is F in the figure) and assuming that the size of the image buffer is approximately 1/2 of the label, first the label is printed. 0~I)/
The label print data up to 2 is developed into the above image buffer and the first printing is performed, and then the fl/
The label print data from 2 to g is expanded to the above image buffer and the second printing is performed.Therefore, printing is not performed during the slow-up at the start of printing and the slow-down at the end of printing. As shown in the figure, the label feed during slowdown in the first printing and the
During the slow-up of the second printing, a non-printing area A occurred approximately in the center of the label that was issued by the label feed. In order to eliminate such problems, it is necessary to equip an image buffer with a size equal to or larger than that of the label, which increases the memory capacity and increases the cost.

Therefore, the invention as claimed in claim 1 provides a thermal printer that prints print data with a larger capacity than the image buffer and does not generate a non-print area even if the printing operation is temporarily interrupted in the middle. That is.

Further, the invention according to claim 2 is capable of printing print data with a capacity larger than that of the image buffer, and even if the printing operation is temporarily interrupted in the middle, a non-print area does not occur, and the print quality is improved. The purpose of the present invention is to provide a thermal printer that can maintain good performance.

[Means for Solving the Problems] The invention according to claim 1 provides an image buffer in which print data is developed, a pulse motor that feeds paper in steps, and print data of the image buffer on the paper that is fed in steps by the pulse motor. In a thermal printer that is equipped with a thermal head for printing output, etc., and controls a step motor to gradually increase the paper feeding speed when paper feeding starts, then control it at a constant speed, and gradually reduce it when paper feeding stops, The time point at which the printing operation of print data starts coincides with the time point when paper feeding by the bell smoke starts, and the time point at which the printing operation ends coincides with the time point at which paper feeding by the pulse motor ends.

The invention according to claim 2, in addition to the invention according to claim 1,
While the paper feeding speed is increasing and decreasing, the amount of power supplied to the thermal head is increased compared to the amount of power supplied when the paper feeding speed is constant.

[Function] In the invention described in claim 1, since the time point at which the thermal head starts printing the print data is made to coincide with the time point at which the pulse motor starts feeding the paper, printing is performed even during slow-up. Furthermore, since the time point at which the printing operation ends coincides with the time point at which paper feeding by the pulse motor ends, printing can be performed even during slowdown.

In the second aspect of the invention, the amount of power supplied to the thermal head is increased during printing during slow-up and slow-down compared to when printing is performed during constant speed. During slow-up and slow-down, the period of one line becomes longer, so the heat accumulation in the thermal head is reduced compared to when the speed is constant. Therefore, by increasing the amount of power supplied during slow-up and slow-down compared to that during constant speed, good quality printing can be obtained even during slow-up and slow-down.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a thermal printer. In the figure, 10 is a CPU as the main body of the control unit.
(Central processing unit), which includes various arithmetic circuits, memory control circuits, etc., and controls each part according to a preset program. And this CPU10 has an address bus.

A program ROM 12 in which program data is set, a character ROM 13 in which character generator data is set, via a path line 11 such as a data bus,
A work RAM 14 used for various calculations, an image buffer 15 for expanding print data, and an interface circuit 1 for receiving print data and various commands sent from the host computer 16 through a transmission line 17.
8. A motor driver 20 that drives and controls a four-phase pulse motor 19 as a paper feed motor, and a thermal line head ( A head driver 22 for controlling energization of the thermal head (hereinafter abbreviated as a thermal head) 21, a two-channel timer circuit 23, and the like are connected.

Here, in the timer circuit 23, one channel is used as a print timer that determines the print cycle of one line,
The other channel is used as a head OFF timer that determines the energization time of the thermal head 21 for one printing.

When the power is turned on, the CPU 10 performs a second program based on the program data in the program ROM 12.
Execute the main routine shown in the figure.

That is, when the power is turned on, the work RAM 14,
Initialization such as clearing the image buffer 15 is performed. Thereafter, the interface circuit 18 waits for print data to be received from the host computer 16. and,
If the print data is received, the character ROM13
The print data is analyzed using character generator data, etc., and the print data is drawn in the image buffer 15 as a dot image. Next, the timer time setting process of the print timer shown in FIG. 3 is executed. That is, C
PU10 determines whether the pulse motor 19 is slowing up when starting paper feeding, slowing down when stopping paper feeding, or at a constant speed after starting paper feeding. In the case of constant speed, a preset constant printing time at constant speed is set as the timer time of the head OFF timer in the timer circuit 23. On the other hand, when slowing up or slowing down, the printing time is determined by the current number of steps of the pulse motor 19 (longer than the fixed time at constant speed, and gradually shortens during slowing down). ) is set as the timer time of the print timer.

After setting this timer time, the printing timer is started and the printing data reception standby state is returned.

On the other hand, when the above print timer times out, the CPU
1 executes the timer interrupt routine shown in FIG.

That is, when the chain side loading routine is started, the data developed in the image buffer 15 is read line by line and outputted to the head driver 22 as head data. At the same time, the HE double signal to the head driver 22 is turned on.

As a result, the thermal head 21 is energized with a predetermined voltage. Also, the pulse motor 1 is connected to the motor driver 20.
9, one-step drive is commanded.

Next, a timer time setting process for the head OFF timer shown in FIG. 5 is executed. That is, the CPU 10 determines whether the pulse motor 19 is in slow amplification mode when starting paper feeding, slowing down when paper feeding is stopped, or constant speed after paper feeding is started. And when at constant speed,
A preset constant enable time at constant speed is set as the timer time of the head OFF timer in the timer circuit 23. On the other hand, in the case of slowing down or slowing down, the enable time is set according to the current number of steps of the pulse motor 19 (if the time is longer than the constant time at constant speed, and the time is slowing down) The timer time of the head OFF timer is set as the timer time of the head OFF timer.

After setting this timer time, proceed to the above and start the SOTO OFF timer.

Thereafter, it is determined whether all lines of print data in the image buffer 15 have been printed. If printing has not yet been completed, the printing timer is restarted and the process returns to the main routine. On the other hand, when printing is completed, the print timer is stopped and the process returns to the main routine.

On the other hand, if the above head OFF timer times up,
CPU 1 executes the timer interrupt routine shown in FIG. That is, the HE multiplier signal to the head driver 22 is turned off and the process returns to the main routine.

In this embodiment configured as described above, when print data sent from the host computer 16 is received by the interface circuit 18, the received data is analyzed and developed in the image buffer 15 as a dot image. Under this condition, the print timer is started, and the pulse motor 19 is controlled by the timer interrupt control of this print timer.
One step driving is commanded, one line of print data read from the image buffer 15 is output to the thermal head 21, and the HE multiplier signal is turned on. That is, the timing at which printing is started by the thermal head 21 and the timing at which paper feeding is started by the pulse motor 19 coincide.

On the other hand, the print data in the image buffer 15 is sequentially read line by line, and when all the data has been read out, the print timer is stopped. As a result, the one-step drive command to the pulse motor 19 is no longer issued, and the output of print data to the thermal head 21 and the HE multiple signal ON operation are no longer performed. That is, the timing at which printing by the thermal head 21 ends coincides with the timing at which paper feeding by the pulse motor 19 ends.

Incidentally, the timer time of the print timer is set to gradually become shorter from the start to several steps. As a result, the pulse motor 19 gradually rotates at high speed and slows down (time tO to tl in FIG. 7). Therefore, as described above, since the timing at which printing starts coincides with the timing at which paper feeding starts, printing is performed even during slow-up.

Thereafter, the timer time of the print timer is controlled to be constant at a predetermined value. As a result, the pulse motor 19 is operated at a high speed and at a constant speed (times t1 to t2 in FIG. 7). At this time, printing is performed line by line by the thermal head 21, as in the conventional case.

Thereafter, the timer time of the print timer is set so that the timer time is gradually increased by several steps until it stops. As a result, the pulse motor 19 gradually rotates at a low speed and slows down (times t2 to t3 in FIG. 7). Therefore, as described above, since the timing at which printing ends coincides with the timing at which paper feeding ends, printing is performed even during slowdown.

Also, before, l? lE HE signal on time is head OF
Controlled by F timer. That is, the head OFF timer is started in response to the HE double signal ON output, and the above H is started by interrupt control of this head OFF timer.
E times signal is turned off. Here, it goes without saying that the timer time of the head OFF timer is set shorter than the timer time of the print timer at the same time. Moreover, the above head O
The timer time of the FF timer is set to be gradually shortened while the pulse motor 19 is slowing up, set to a predetermined constant value while the pulse motor 19 is at a constant speed, and set to be gradually lengthened while the pulse motor 19 is slowing down. Therefore, the HE multiple signal on time is the 7th
As shown in the figure, the time during slow-up and slow-down is longer than during constant speed.

In general, the period of one line during slow-up and slow-down is longer than that during constant speed, so if printing is performed during slow-up or slow-down, the heat accumulation in the thermal head 21 will be reduced and printing will be possible. quality deteriorates. To prevent this, the amount of power supplied to the thermal head 21 may be increased. In this embodiment, the amount of power supplied to the thermal head 21 is increased by making the ON time of the HE double signal longer during slow-up and slow-down than during constant speed.
There is no risk of print quality deterioration during slow-up or slow-down.

As described above, according to this embodiment, the print data developed in the image buffer 15 is printed even when the pulse motor 19 is slowing up and slowing down.
Even if the print data is larger than the capacity of the image buffer 15, a non-print area A as shown in FIG. 12 will not occur. In other words, even an image buffer smaller than print data can be handled, so memory capacity can be reduced and costs can be reduced.

Further, since the amount of power supplied to the thermal head 21 during printing during slow-up and slow-down is increased, it is possible to prevent problems such as deterioration of print quality.

In the above embodiment, printing quality is ensured by increasing the amount of power supplied to the thermal head by making the ON time of the HE double signal longer during slow-up and slow-down than during constant speed. Alternatively, printing quality can be ensured by increasing the amount of power supplied by increasing the voltage applied to the thermal head 21 during speed-up and slow-down compared to during constant speed.

An example in this case will be described below. It should be noted that the block configuration and the main routine of CPU10 after power-on are the same as those in the previous embodiment, so a description thereof will be omitted here.

In this embodiment, the CPU 10 is configured to execute the timer interrupt routine shown in FIG. 8 when the print timer started in the main routine times up. That is, when the sedative routine is started, the data developed in the image buffer 15 is read line by line and output to the head driver 22 as head data. Next, the head applied voltage setting process shown in FIG. 9 is executed. In other words, CPU10 is pulse motor 1
9, it is determined whether the speed is slowing up when starting paper feeding, slowing down when stopping paper feeding, or at constant speed after starting up paper feeding. In the case of constant speed, a preset constant applied voltage at constant speed is set. On the other hand, during slow-up or slow-down, the applied voltage according to the current number of steps of the pulse motor 19 (higher voltage than the constant applied voltage during constant speed, and gradually increases during slow-up) (It is set so that it becomes lower, and it is set to gradually increase during suf-down.)

After setting the head applied voltage, the HE multiplier signal to the head driver 22 is turned on. As a result, the thermal head 21 is energized at the set voltage. It also instructs the motor driver 20 to drive the pulse motor 19 in one step. At the same time, a head OFF timer is started. Thereafter, it is determined whether all lines of print data in the image buffer 15 have been printed. If printing has not yet been completed, the printing timer is restarted and the process returns to the main routine. On the other hand, when printing is completed, the print timer is stopped and the process returns to the main routine.

Incidentally, when the head OFF timer times out, the HE multiplier signal to the head driver 22 is turned off as in the previous embodiment, and the process returns to the main routine.

With this configuration, as shown in FIG. 10, the voltage applied to the thermal head 21 gradually decreases during slow-up of the pulse motor 19 (times tO to tl), and decreases during constant speed (times t1 to t2). ) is stable at the lowest value and gradually increases during slowdown (times t2 to t3). That is, during slow-up and slow-down, the voltage applied to the thermal head 21 is higher than that during constant speed, so the amount of power supplied to the thermal head 21 is increased, and the print quality is prevented from deteriorating.

[Effects of the Invention] According to the present invention configured as described above, the following effects can be achieved.

According to the invention as set forth in claim 1, there is provided a thermal printer that does not generate a non-print area even when printing data with a larger capacity than the image buffer and the printing operation is temporarily interrupted in the middle. can.

According to the invention set forth in claim 2, even when printing data with a larger capacity than the image buffer and the printing operation is temporarily interrupted in the middle, a non-printing area does not occur and the printing quality is improved. We can provide a thermal printer that can maintain the

[Brief explanation of drawings]

1 to 7 are diagrams showing an embodiment of the present invention, in which FIG. 1 is a block diagram of the overall configuration, FIG. 2 is a flowchart showing the main routine, and FIG. 3 is a timer timer of the print timer. Flowchart showing the setting process; FIG. 4 is a flowchart showing the print timer interrupt routine; FIG. 5 is a flowchart showing the head OFF timer time setting process; FIG. 6 is a flowchart showing the head OFF timer interrupt routine; FIG. 8 is a timing diagram of drive signals and HE multiplier signals for the pulse motor, FIGS. 8 to 10 are diagrams showing other embodiments of the present invention, FIG. 8 is a flowchart showing a print timer interrupt routine, and FIG. 10 is a flowchart showing the setting process of the head applied voltage, FIG. 10 is a timing diagram of the drive signal for the pulse motor and the HE double signal, FIG. 11 is a diagram showing an example of a printed label, and FIG. 12 is a diagram showing a label where a non-printing area has occurred. It is a figure which shows the printing example of. 10...CPU, 15...Image buffer, 19
... Pulse motor, 21 ... Thermal head, 23
...Timer circuit.

Claims (2)

[Claims] (1) Equipped with an image buffer in which print data is developed, a pulse motor that feeds paper step by step, a thermal head that prints out the print data of the image buffer on the paper that is step fed by this pulse motor, etc.
In a thermal printer that controls the step motor so that the paper feeding speed is gradually increased when starting paper feeding, then controlled at a constant speed, and gradually decreased when paper feeding is stopped, the time point at which printing operation of print data by the thermal head starts. The thermal printer is characterized in that: coincides with a time point at which paper feeding by the pulse motor starts, and a time point at which printing operation ends coincides with a time point at which paper feeding by the pulse motor ends. (2) The thermal printer according to claim 1, wherein while the paper feed speed is increasing or decreasing, the amount of power supplied to the thermal head is increased compared to the amount of power supplied when the paper feed speed is constant.