JPH04314560A - Driving circuit of printer - Google Patents

Abstract

PURPOSE:To control the printing timing of a printing part, easily confirm the operating condition of a protective circuit for monitoring ribbon feed control and lighten processing loads on CPU including software. CONSTITUTION:Data DETA and triger Tr are produced by CPU 2 and the data is sent through an output control buffer 3 into an impact driving part 4 in order for a predetermined printing function to be performed. The triger Tr of the CPU 2 is sent through a protective circuit 5 retained by CR time constant into the output control buffer 3 and a motor controller 7. Since the motor controller 7 controls ribbon feed synchronously with the impact driving part 4 based on an output Q from the protective circuit 5, the operating condition of the protective circuit 5 can be confirmed by the ribbon feeding condition.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer drive circuit for controlling printing by a printer.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional printer driving circuit. The printer is provided with the illustrated drive circuit 30, and the drive circuit 30 controls the drive of the printing section. When the printer is a wire dot type printer, the control contents of the printing section are dot impact timing control and ribbon feeding control.

The port A output (DATA output) of the CPU 32 outputs data corresponding to the dot via the output control buffer 33 to the impact driving section 34 provided for each wire dot. This output control buffer 33 is provided with a timing circuit 35 that defines the output timing of the data via port B. This timing circuit 35 is composed of a multivibrator, and is activated by a trigger from port B that is output at the same timing as the output from port A, and after a predetermined time (corresponding to approximately the impact time) according to a CR constant, the control terminal of the output control buffer 33 is activated. By giving an operation stop output to
This is to obtain the N/OFF output timing. As a result, the output control buffer 33 causes a high current to flow to the impact drive section 34 in an extremely short period of time, and the impact drive section 34 records dots on the recording paper.

[0004] Furthermore, the operation timing of the motor driver 38 is controlled by the port C output of the CPU 32 via the motor controller 37, and ribbon feeding is controlled.

[0005]

However, if the conventional timing circuit 35 malfunctions for some reason, current continues to flow through the impact drive section 34, resulting in burnout of the coil. Further, when checking the operation of the multivibrator constituting the timing circuit 35, special work is required, such as waveform observation. In addition, since the output time is controlled from port A and port B, which are separate ports, port A
If port B remains output and the output of the timing circuit 35 is not turned off, there is a risk that a similar problem will occur.

[0006] Regarding the control of ribbon feeding, since the ribbon feeding is controlled in synchronization with the timing of dot impact by the port A output,
Control is mainly dependent on the PU port C output, and the amount of software has increased.

[0007] As another conventional example, data specifying the ON time of the dot impact is sent from the port A output, and in response to the simultaneously output port B output, a protection circuit (the above-mentioned timing circuit 3
5, but with a different CR constant), and this protection circuit forcibly turns off data transmission after the ON time elapses, but this protection circuit 35 is separate from port A. The protection circuit operation can be easily checked because it is established based on the port B output of the system, and because the port A output does not work during normal conditions and is only intended to protect when an abnormality occurs. There wasn't.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to easily check the operating state of a protection circuit that monitors dot impact timing control and ribbon feed control, which are controls of a printing unit. It is an object of the present invention to provide a protection circuit for a printer that can reduce the burden on the CPU side including software.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the printer protection circuit of the present invention includes a CPU 2 that outputs data DATA corresponding to each dot and a trigger Tr synchronized with the output of the data DATA; The data DATA
The trigger Tr
In a printer drive circuit comprising an output control buffer 3 that controls the output of data DATA based on
A protection circuit 5 receives the output of the trigger Tr, holds it with a time constant CR of a predetermined time, and outputs a signal Q to the output control buffer 3; The present invention is characterized in that it is equipped with a motor controller 7 that feeds out the ribbon in synchronization with the present invention.

0010

[Operation] The data DATA generated by CPU2 is
The signal is outputted to the impact drive section 4 at a predetermined timing under the control of the output control buffer 3 which receives the trigger Tr of the PU2. The output control buffer 3 outputs data DATA based on the output of the protection circuit 5 which is held for the period of the trigger Tr. The output Q of the protection circuit 5 is input to the motor controller 7, and the motor controller 7 controls ribbon feeding at a timing synchronized with the impact drive unit 4.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a printer drive circuit according to the present invention, and FIG. 2 is a timing chart showing each signal of the drive circuit. The printer is provided with the illustrated drive circuit 1, and the drive circuit 1 controls the drive of the printing section. It is assumed that this printer is a wire dot type printer. The port A output of the CPU 2 is transmitted via the output control buffer 3 to the impact drive unit 4 provided for each wire dot pin (recorder) as shown in FIG. 2(a).
Data DATA corresponding to the dot is output.

Furthermore, a protection circuit 5 is provided between the port B output of the CPU 2 and the output control buffer 3 for regulating the output timing of the data. This protection circuit 5
is a NAN between port B output and output control buffer 3.
A D circuit 5a is provided. Also, port B output and N
A time constant circuit 5b is further provided between the AND circuits 5a. The time constant circuit 5b is turned ON by the trigger Tr of the port B shown in FIG. 2(b), which is output at the same timing as the port A output, and the
R time constant for a predetermined time (corresponding to impact protection time) T1
A Q output that turns OFF after the lapse of time is output to the NAND circuit 5a. Therefore, the output of the NAND circuit 5a is
It becomes ON state at the timing of output, remains ON state during the trigger Tr of port B, and outputs Q to output control buffer 3.
Output. Note that the output is inverted by the NAND circuit 5a. As a result, the output control buffer 3 outputs data output data to the impact driving section 4 during the period of this Tr shown in FIG. 2(b), and performs various print recordings on the recording paper. At this time, even if the output of the trigger Tr of port B is output for an abnormally long period, the output of the NAND 5a is always turned off after the predetermined time T1 has elapsed due to the output of the time constant circuit 5b, and the coil of the impact drive unit 4a is Acts as burnout protection.

The output of the time constant circuit 5b is sent to an OR circuit 6.
The signal is input to the motor controller 7 via. A ribbon motor clock signal CLK shown in FIG. 2(d) is input to this motor controller 7. Then, the motor controller 7 outputs a control signal CTL in which CLK is synchronized with the output of the time constant circuit 5b as shown in FIG. 2(e) to the motor driver 8 to control ribbon feeding.

[0014] As a result, based on CLK of a constant period,
Since the configuration is such that the ribbon feeding is controlled using the output of the time constant circuit 5b, the ribbon feeding is performed in synchronization with the timing of impact. Therefore, the operating state of the time constant circuit 5b can be confirmed simply by visually monitoring the ribbon feeding state. Incidentally, the CR constant of the time constant circuit 5b is set to a time necessary for feeding a predetermined ribbon and sufficiently short to protect the coil of the impact drive section 4 from burnout. Ribbon feeding control does not entirely depend on the CPU 2, and as described above, it is configured to also function as impact control, and there is no need to provide a special port, reducing the burden on the CPU 2 and software. Can be done.

In FIG. 1, a predetermined time is set at the input of the OR circuit 6 by a capacitor C2 and a resistor R2, and a ribbon winding section 9 is configured by a diode 9a and a Schmitt inverter 9b for preventing chattering. may be provided. By setting the CR time constant to the time required to wind up slack in the ribbon, the ribbon winding section 9 can prevent staining of the recording paper due to slack in the ribbon when the power is turned on.

In the above embodiment, the output control buffer 3
Although the configuration was such that a wire dot type impact drive unit 4 was arranged at the rear stage, instead of this impact drive unit 4,
The present invention can also be applied to a thermal transfer type thermal head, in which case the heating time for the thermal head can be controlled in the same manner as in the above embodiment, and similar effects can be obtained.

[0017]

[Effects of the Invention] According to the printer drive circuit of the present invention,
The printing time of the printing section is monitored by a protection circuit, and
Since the configuration is such that the ribbon is fed using the output of this protection circuit, the printing control state of the printing section can be easily determined by visually observing the state of ribbon feeding. Further, since there is no need to provide special software and an independent port for ribbon feeding control as in the past, the burden on the CPU including software can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a drive circuit of a printer according to the present invention.

FIG. 2 is a timing chart of signals of each component of the drive circuit.

FIG. 3 is a block diagram showing a drive circuit of a conventional printer.

[Explanation of symbols]

2... CPU, 3... Output control buffer, 4... Impact drive section, 5... Protection circuit, 5a... NAND circuit, 5b... Time constant circuit, 6... OR circuit, 7... Motor controller, 8...
Motor driver, 9... Ribbon winding section.

Claims (1)

[Claims] Claim 1: Data (DATA) corresponding to each dot.
), and a CPU (2) that outputs a trigger (Tr) synchronized with the output of the data (DATA);
An impact drive unit (4) having a recorder that performs printing on recording paper based on A), the CPU, and the impact drive unit are provided on the data (DATA) line between the CPU and the impact drive unit, and based on the trigger (Tr). , and an output control buffer (3) for controlling the output of data (DATA), which receives the output of the trigger (Tr) and holds it for a predetermined time constant (CR). a protection circuit (5) that outputs a signal (Q) to the output control buffer (3), and an output (Q) of the protection circuit (5) is input;
A printer drive circuit comprising: a motor controller (7) that feeds out a ribbon in synchronization with the time constant (CR).