JPS6026034B2 - Print control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for shifting a print head using a pulse motor.

As seen in serial printers, when the print head is shifted by a pulse motor, simply driving the pulse motor step by step causes residual vibration, and it takes time for the print head to stop at a new digit position.

Therefore, in order to prevent this residual vibration, the characteristics of the pulse motor are used to apply braking torque to the motor by switching the excitation phase to the motor during step rotation of the pulse motor. However, conventionally, the timing of applying such braking torque is fixed, and therefore, if uneven rotation of the pulse motor occurs due to frictional resistance of the print head movement system consisting of the pulse motor, print head, pulley, wire, etc. The timing of the braking torque is no longer appropriate, and residual vibrations are not effectively suppressed.

The present invention aims to eliminate the above-mentioned drawbacks by applying braking torque at a timing that corresponds to the rotational state of the pulse motor.The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows an embodiment of the control device, in which 1 is a four-phase pulse motor, 2 is a drive pulley directly connected to the motor, 3 is an idle pulley, 4 is a wire stretched between both pulleys 2 and 3, and 5 is a print head connected to the wire and shifted from left to right in the figure each time the pulse motor 1 rotates one step forward.

Note that the print head is composed of, for example, a thermal print head. 6 is forward rotation pulse MFP or reverse rotation pulse MB
This is a drive signal generation circuit that takes P as an input and generates four-phase excitation signals PHI to PH4 for the pulse motor.When one normal rotation pulse MFP is input, this circuit
The pulse motor 1 should be rotated one step forward (the phase relationship of the excitation signal is advanced, and when one reverse pulse MBP is inputted, the pulse motor 1 should be rotated one step in the reverse direction) (the phase relationship of the excitation signal is retracted).

Reference numeral 7 denotes a drive circuit for receiving the excitation signals PHI to PH4 and causing current to flow through each excitation winding of the pulse motor, and this circuit is connected in series to each of the excitation windings, for example, and is controlled by each of the excitation signals. It consists of switching transistors.

Reference numeral 8 denotes a timing detector, which is directly connected to the pulse motor 1, and includes a slit disk 1 having slits 9, 9, . . . corresponding to the step angle of the motor on its periphery.
0, and a photointerrupter 11 consisting of a pair of light sources and a light-receiving element, which are arranged on both sides of the circumference of the disk.

Thus, the timing detector 8 generates a detection signal SLP-W in response to one step rotation of the pulse motor 1. Note that this correspondence relationship is set so that the detection signal SLP-W is generated before the rotor of the pulse motor 1 reaches the next step position. 12 is a stop signal generation circuit, and this circuit includes first and second inverters 13 and 14 connected in series.
, a first monostable multi 15, and a first differentiating circuit 16, the detection signal SLP-m is waveform-shaped by the first and second inverters 13 and 14, and then converted into a reverse pulse MBP.
The signal enters the drive signal generation circuit 6 and triggers the first monostable multi 15.

The trailing edge of the output of the first monostable multi 15 is differentiated by the first differentiating circuit 16, and the output passes through the OR gate 17 to the normal rotation pulse M'
P and enters the drive signal generation circuit 6. 18 and 19 are a second monostable multi and a second differentiator, respectively. The second monostable multi 18 is triggered by the start pulse SP, and its output is differentiated at its trailing edge by the second differentiator 19, and then passed through the OR gate 17. It becomes a normal rotation pulse MFP and enters the drive signal generation circuit 6.

Next, the operation of the above device will be explained with reference to the signal waveform diagram in FIG.

Start pulse SP that commands the print head 5 to start printing
When , the second monostable multi 18 generates an output 6S2 for a certain period of time.

If the print head 5 is a thermal print head, character heat is generated in the print head 5 during the period of output SS2, and printing is executed in that digit. When the output of the second monostable multi 18 disappears, an output is generated from the second differentiating circuit 19, so that the drive signal generating circuit 6 receives the normal rotation pulse MF.
P enters.

The drive signal generation circuit 6 and the drive circuit 7 are normal rotation pulse MFPs.
Then, move pulse motor 1 toward the next step position.
Rotate the step. Immediately before the pulse motor 1 reaches the next step position, the timing detector 8 generates a detection signal SLP-m, and this signal immediately generates a reverse rotation pulse M.
It becomes BP.

Therefore, the drive signal generation circuit 6 and the drive circuit 7 receive the reverse rotation pulse MBP and retract the excitation phase of the pulse motor 1 by one step, thereby applying a braking torque to the pulse motor 1. After the above-mentioned reverse rotation pulse MBP is generated, an output SSI is generated from the first monostable multi 15 for a certain period of time, and when the output SSI disappears, a forward rotation pulse MFP is generated via the first differentiating circuit 16 and the OR gate 17, and therefore, this pulse MFP is generated. At this point, the braking torque is released. (b) The duration of the output SSI of the first monostable multi 15 is set so that the braking torque is applied to the extent necessary and sufficient to stop the pulse motor 1 at the new step position. will stop at a new digit without residual vibration. As is clear from the above description, according to the present invention, when the print head is moved by a pulse motor, the timing of applying braking torque to the pulse motor to prevent residual vibration during digit movement is fixed as in the conventional method. Instead, the braking torque is set according to the rotation of the pulse motor, so even if the rotation of the pulse motor is uneven, the braking torque is always applied at the appropriate timing, making it possible to effectively suppress residual vibration. When adjusting the torque timing, it is only necessary to adjust the timing detector (in the embodiment, adjust the relative position between the photointerrupter 11 and the stop IJ socket disc 8), so the adjustment work is also easy. Become.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram for explaining the operation of the embodiment. 1.../gus motor, 5...print head, 8...timing detector, 12...
Stop signal generation circuit. Figure 2 of the ship

Claims (1)

[Claims] 1. A control device for shifting a print head by a pulse motor, which comprises: a drive signal generation circuit that inputs a forward rotation pulse or a reverse rotation pulse to generate a forward rotation or reverse rotation drive signal for the pulse motor; and a stop signal generation circuit that generates first and second signals at different times based on the detection force of the detector, and a stop signal generation circuit that generates a first signal and a second signal at different times based on the detection force of the detector, A print control device characterized in that the subsequently generated first and second signals are input to the drive signal generation circuit as the reverse rotation pulse and the forward rotation pulse, respectively, to stop the print head without residual vibration. .