JPH07121605B2 - Automatic print head adjustment mechanism of the printer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a printer device, and is particularly suitable for use in keeping a constant distance between a print head and a print paper regardless of the thickness of the paper. Automatic print head adjustment mechanism for various printers.

[Prior Art] As a conventional technology for keeping the distance between the printing head and the printing paper constant, for example, the technology described in JP-A-59-153131 is known.

In this prior art, first, the stepping motor for driving the print head is driven to move the print head toward the platen side, that is, toward the print paper, and the print head comes into contact with the print paper and cannot move. Even if the motor goes out of step, it is ignored and a certain amount of drive pulse is continuously sent to the stepping motor, and then the stepping motor is driven so that the print head moves away from the platen, and the print head is moved. Is moved by a certain amount to set the distance between the print head and the print paper to a predetermined size.

[Problems to be Solved by the Invention] In the above-mentioned conventional technique, after the printing head comes into contact with the printing paper and the stepping motor for driving the printing head loses step,
Since the advance pulse is continuously sent to the stepping motor, there is a problem in that it takes unnecessary time when adjusting the print head position and noise is generated due to the vibration when the stepping motor is out of step. There is.

An object of the present invention is to solve the above-mentioned problems of the prior art, eliminate wasteful time, and adjust the distance between the print head and the print sheet without noise and vibration, and the print head of the printer. The purpose is to provide an automatic adjustment mechanism.

[Means for Solving the Problems] According to the present invention, the above object is to provide a detection element that generates a pulse in accordance with the movement of a print head while the print head is moving in a direction perpendicular to a print sheet. By detecting the step out of the stepping motor for moving the print head by processing the pulse signal from the detection element, immediately drive the stepping motor in the direction of moving the print head away from the printing paper, and the print head is moved. This is achieved by leaving the print paper a predetermined distance.

[Operation] The printing head can be moved in the vertical direction with respect to the printing paper by the driving stepping motor. Further, a detection element for detecting the movement of the print head is provided, for example, on the stepping motor shaft, and the detection element outputs a pulse signal in accordance with the movement of the print head. When the head is adjusted, the print head is controlled to move in the paper direction, the print head comes into contact with the print paper, and if the stepping motor for moving the print head goes out of step, the pulse width of the pulse signal output from the detection element becomes non-uniform. It changes with respect to a step out. When the control unit processing the pulse signal from the detection element detects a change in the pulse width of this pulse signal, it immediately reverses the stepping motor by a certain amount to move the print head in a direction away from the print sheet, The distance between the print head and the print paper is set to be constant regardless of the thickness of the print paper.

Therefore, according to the present invention, by detecting the step-out of the stepping motor and immediately rotating the stepping motor in the reverse direction, time is wasted and noise is not generated.
The print head can be automatically adjusted.

Even if the two detection elements described above are provided, the same operation as described above can be performed and the same effect can be obtained.

In this case, each of the two detectors outputs, for example, one pulse having a pulse width corresponding to a two-phase advance of the stepping motor at the time of four-phase advance of the stepping motor, and at the same time, detects each of them. The outputs of the detectors are arranged so that a relationship in which the phase is shifted by one phase advance of the stepping motor is established, and these outputs are converted into a binary code. On the other hand, a quaternary counter that changes each time the stepping motor advances by one phase is provided.

The control unit detects the step-out of the stepping motor by monitoring the converted binary code and the output difference of the quaternary counter. That is, the above-mentioned output difference is always given as a constant difference when the stepping motor is out of step, and if the stepping motor is out of step, the output pulse from the detection element stops or Since the timing becomes crazy, it will deviate from a certain value. The control unit detects this, detects stepping out of the stepping motor, and reversely rotates the stepping motor,
The print head can be adjusted to a predetermined distance from the print paper.

[Embodiment] An embodiment of an automatic print head adjusting mechanism of a printer according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the construction of a first embodiment of the present invention, and FIGS. 2 and 3 are a side view and a front view showing a mechanical portion of a printer device to which the present invention is applied. 1 to 3, 1 is a print head, 2 is a carrier, 3 is an upper guide rail, 4 is a lower guide rail, 5 is a gear, 6 is a pinion, 7 is a slit disk, 8 is a slit detecting element, 9
Is an ink ribbon, 10 is a printing paper, 11 is a platen, 12a is a left side frame, 12b is a right side frame, 13 is an underframe, 14 is a stepping motor, 15 is a stepping motor drive circuit, 16 is a pulse generator, 17, 18 is a pulse width measuring unit, 19 is a step-out control unit, and 20 is a motor rotation command unit.

The printer device to which the present invention is applied is configured as follows, as shown in FIGS.

That is, the under frame 13 includes the left side frame.
12a and the right side frame 12b are fixed, and the upper guide rail 3 is fixed to the upper part thereof. The carrier 2 on which the print head 1 is placed is guided by the upper guide rail 3 and the lower guide rail 4, and can move in the direction indicated by the arrow B in FIG. If the print head 1 is operated in the state shown in the drawing, the printer device shown in the drawing will move to the left side frame 12a.
The ink of the ink ribbon 9 can be transferred to the printing paper 10 on the platen 11 which is rotatably fixed between the right side frame 12b and the right side frame 12b for printing.

The lower guide rail 4 is rotatable with respect to the left side frame 12a and the right side frame 12b, and has a gear 5 attached to its right end. I have a heart. Therefore, when the gear 5 rotates, the carrier 2 and the print head 1 are moved to the arrow A in the figure.
And the distance between the tip of the print head 1 and the platen 11 is changed. The gear 5 is driven by a stepping motor 14 and a pinion 6 attached to the shaft of the motor 14. A slit disk 7 is attached to the shaft of the stepping motor 14 and rotates as the tip of the print head 1 moves. A slit detecting element 8 including a light source and a photodetector is provided on both sides of the slit disk 7, and detects the slit of the rotating slit disk 7 and outputs a pulse signal.

The adjustment of the print head 1 of the printer apparatus configured as described above is performed by the motor rotation command section 20, the pulse generator 16, the stepping motor drive circuit 15, the pulse width measuring sections 17, 18 as shown in FIG. Also, the control unit including the step-out determination unit 19 performs the process as described below.

When adjusting the distance between the print head 1 and the print sheet 10, first, the motor rotation command unit 20 issues a command to move the tip of the print head 1 toward the platen 11, for example, at a predetermined interval. Generated by a phase-advancing pulse signal
Give to 16. Based on this command, the pulse generator 16 outputs a pulse signal for driving the stepping motor, and the stepping motor drive circuit 15 outputs the pulse signal to the stepping motor.
Drive 14 The stepping motor 14 is
The leading end of the printing head 1 is moved in the direction in which it comes into contact with the printing paper 10, and at the same time, the slit disk 7 constituting the detector provided on the motor shaft rotates. Slit detection element 8
In this way, a pulse signal is generated by the slit of the slit disk 7 and is output to the pulse width t _f measuring unit 18. The pulse signal by slit detection has an on / off ratio.
The pulse width t _f is 50%, and the pulse width t _f
Measured by

On the other hand, the pulse interval of the command pulse from the motor rotation command unit 20 is measured by the pulse width t _c measuring unit 17. The pulse interval of this command and the pulse width obtained from the slit disk 7 are substantially the same when the stepping motor 14 is rotating normally without step-out,
The slit width of the slit disk 7 is defined.

The measured values of the pulse widths t _c and t _f measured by the pulse width measuring units 17 and 18 are compared by a subtracter, the difference between them is calculated, and the difference t _d is given to the step-out determining unit 19. The step-out determination unit 19
Determines that the stepping motor 14 has stepped out when the absolute value of t _d exceeds a certain value. That is,
As described above, when the stepping motor 14 is rotating normally without step-out, the pulse interval t _c of the command pulse from the motor drive command unit 20 and the detection pulse output from the slit detection element 8 Since the pulse width t _f is set to be almost the same, the difference t _d becomes zero or a value close to zero. However, if the stepping motor 14 goes out of step, the pulse interval of the command does not change, but the pulse width of the pulse output from the slit detection element 14 changes due to vibration or stop of the motor. Therefore, the absolute value of the difference t _d becomes larger than the predetermined value, and the step-out determination unit 19 determines the stepping motor 14 based on the difference value.
The out-of-step can be detected.

A signal from the step-out determination unit 19 indicating whether or not the stepping motor 14 is out-of-step is given to the motor rotation command unit 20, and the motor rotation command unit 20 outputs the signal while the stepping motor 14 is out of step. , Outputs a command to move the tip of the print head 1 toward the platen 11. When the step-out determination section 19 detects that the stepping motor 14 has stepped out, the motor rotation command section 20 determines that the front end of the print head 1 has come into contact with the surface of the print sheet 10 via the ink ribbon 9. In order to move the print head 1 away from the platen 11 by a certain amount, the stepping motor 14 is instructed to rotate in the opposite direction by a certain amount.

By performing the above-described operation, the first embodiment of the present invention sets the distance between the tip of the printing head 1 and the upper surface of the printing paper 10 constant regardless of the thickness of the printing paper 10. Since the stepping motor 14 goes out of step immediately after the stepping motor 14, it is possible to eliminate unnecessary time for adjusting the print head, and the stepping motor 14 goes out of step with noise. , It is possible to prevent the occurrence of vibration.

In the above-described first embodiment of the present invention, the pulse width measuring unit
17 is a stepping motor 14 from the motor rotation command unit 20.
Is measuring the interval t _c of the advance pulse for the control of
The interval t _c of the advance pulse is predetermined when the advance pulse of a constant frequency is supplied to the stepping motor to rotate the stepping motor by self-starting, and since it is constant, it is not necessary to measure this interval. In the present invention, the pulse width measuring unit 17
Instead of the above, even if a functional unit capable of directly outputting the above-mentioned interval t _c is provided, the same operation as described above can be performed, and the same effect can be obtained.

Further, the present invention is measured by the pulse width measuring unit 18,
Even if a holding unit for holding the measured value of the pulse immediately before the detection pulse from the slit detecting element 8 is provided instead of the pulse width measuring unit 17, the stepping motor out-of-step is detected in the same manner as described above. It is possible to operate the same as in the first embodiment of the present invention and to obtain the same effect.

FIG. 4 is a block diagram showing the configuration of the second embodiment of the present invention, FIG. 5 is a diagram showing the configuration of the printer mechanism portion, FIG. 6 is a diagram showing the output waveforms of two slit detecting elements, and FIG. The figure shows a Gray code / binary code conversion circuit.
FIG. 9 is a diagram for explaining the operation of the circuit of FIG. 7, and FIG. 9 is a diagram showing output waveforms of the two slit detection elements when the motor is out of synchronization. In FIGS. 4 and 5, 8a is an A-phase slit detecting element, 8b is a B-phase slit detecting element, 21 is a quaternary counter,
Reference numeral 22 denotes a Gray code / binary code conversion unit, and other symbols are the same as those in FIGS. 1 to 3.

In the second embodiment of the present invention, the printer mechanism section is the fifth embodiment.
This is different from the first embodiment of the present invention in that the portion shown in the figure, that is, the slit detecting element is composed of the A-phase slit detecting element 8a and the B-phase slit detecting element 8b. As shown in FIG. 6, these A-phase and B-phase slit detecting elements 8a, 8b are both "1" output and "0" for two steps while the stepping motor 14 is advanced by four steps. "It produces an output, and further the B-phase slit detection element 8b
The output of the A-phase slit detecting element 8a is arranged so as to have a phase delay of 90 ° with respect to the output of. This allows
When the stepping motor 14 is operating normally without stepping out, the output from the A-phase or B-phase slit detection element changes each time the stepping motor 14 advances by one step. . The outputs from both detection elements 8a and 8b (hereinafter referred to as A-phase output and B-phase output) are given to a Gray code / binary code conversion circuit as shown in FIG. This Gray code / binary code conversion circuit operates according to the truth value as shown in FIG.
The binary code according to the combination of the phase output and the B phase output is output. That is, this binary code is a signal that changes by "1" every time the stepping motor 14 advances by one step.

The second embodiment of the present invention is to detect the step-out of the stepping motor by the binary code based on the pulse signals obtained from the two slit detecting elements 8a and 8b as described above. However, instead of the pulse width measuring units 17 and 18 in the first embodiment, as shown in FIG.
Binary counter 21 and Gray code / binary code converter
22 differs from the first embodiment in that it is provided with 22, but the other parts are configured in the same manner and operate as described below.

When adjusting the distance between the print head 1 and the print sheet 10, first, the motor circuit command unit 20 issues a command to move the front end of the print head 1 toward the platen 11, and the pulse generation unit.
The operation until 16 rotates the stepping motor 14 via the stepping motor drive circuit 15, moves the print head 1 and rotates the slit disk is completely the same as that of the first embodiment of the present invention described above. The same is done.

When the stepping motor 14 rotates to move the print head 1, the A-phase and B-phase slit detecting elements 8a and 8b are
The slits of the slit disk 7 generate the A-phase output and the B-phase output as shown in FIG. 6 and send them to the Gray code / binary code conversion section 22. The Gray code / binary code conversion unit 22 includes the conversion circuit as shown in FIG. 7 described above, and outputs a binary code corresponding to the combination of the A phase output and the B phase output.

On the other hand, the command pulse from the motor rotation command section 20 is input to the quaternary counter 21, and the quaternary counter 21 periodically outputs a 2-bit binary code. The binary code from the quaternary counter 21 and the binary code from the Gray code / binary code conversion unit 22 are compared by a subtractor, the difference is calculated, and the difference is input to the step-out determination unit 19. To be done. The step-out determination section 19 determines whether or not the stepping motor 14 has stepped out based on this difference, and notifies the motor rotation command section 20 of the determination result.

When the stepping motor 14 is rotating normally without step-out, the motor 14 synchronizes with the command pulse from the motor rotation command section 20 to advance the phase by one step, and the gray code binary The output signal of the code 22 changes with each step advance of the stepping motor 14, and the output of the quaternary counter also changes with each step advance of the stepping motor 14. Therefore, the difference between the output of the Gray code / binary code conversion unit 22 and the output of the quaternary counter 21 is always a constant value when the stepping motor 14 is not out of step. However, when the stepping motor 14 goes out of step, the output of the quaternary counter does not change from the normal state, but the output pulses from the A-phase and B-phase slit detecting elements 8a and 8b are, for example, the ninth pulse. As shown in the figure, the disorder occurs, and therefore, the order of outputs of the Gray code / binary code conversion unit 22 is changed, or the change timing is deviated. Therefore, the difference described above changes due to the step-out of the stepping motor 14. That is, the step-out determination unit 19 detects whether or not the stepping motor 14 is out of step by determining whether or not the difference between the output of the Gray code / binary code conversion unit 22 and the output of the quaternary counter changes. The motor rotation command unit 20 that receives the detection result can perform the process after the step-out detection as in the case of the first embodiment of the present invention described above.

According to the second embodiment of the present invention as described above, the same effect as that of the first embodiment of the present invention can be obtained.

In the above-described two embodiments of the present invention, the stepping motor 14 may be a known two-phase excitation drive type. The arrangement of the A-phase and B-phase slit detecting elements in the second embodiment of the present invention is not limited to the example shown in the figure, and the output pulse of the stepping motor 14 when it is rotating without step-out occurs. May have any arrangement as long as the relationship shown in FIG. 6 can be obtained.

Further, in the above-described first and second embodiments of the present invention, the slit disk 7 may be provided with a slit printed on a transparent plate such as glass or acrylic, which constitutes a drive mechanism of the print head. Alternatively, the teeth of the gear 5 may be used. Further, the slit disk 7 may be a rotating magnet and the slit detecting element may be a magnetic sensor.

As described above, according to the present invention, when the print head is adjusted, the stepping motor can be driven to rotate in the reverse direction immediately after the print head comes into contact with the print sheet. It is possible to eliminate waste and to prevent noise and vibration caused by step-out.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention, FIGS. 2 and 3 are side and front views showing a mechanical portion of a printer to which the present invention is applied, and FIG. A block diagram showing the configuration of the second embodiment of the present invention, FIG. 5 is a diagram showing the configuration of the printer mechanism section, FIG. 6 is a diagram showing output waveforms of two slit detecting elements, and FIG. 7 is a gray code. A diagram showing a binary code conversion circuit, FIG. 8 is a diagram for explaining the operation of the circuit of FIG. 7, and FIG. 9 is a diagram showing output waveforms of two slit detection elements when the motor is out of synchronization. 1 ... Printing head, 2 ... Carrier, 3 ... Upper support rail, 4 ... Lower support rail, 5 ... Gear, 6 ...
Pinion, 7 ... slit disk, 8, 8a, 8b ... slit detection element, 9 ... ink ribbon, 10 ... printing paper,
11 …… Platen, 12a, 12b …… Left and right side frames, 13 …… Underframe, 14 …… Stepping motor, 15 …… Stepping motor drive circuit, 16 …… Pulse generator, 17,18 …… Pulse width measuring unit, 19 ... step-out determination unit, 20 ... motor rotation command unit, 21 ... quaternary counter, 22
...... Gray code / binary code converter.

Claims (7)

[Claims] 1. A printer in which a printing paper is mounted on a platen and printing is performed on the printing paper while moving the printing head in the platen axis direction, the stepping motor moving the printing head in a direction perpendicular to the printing paper. The stepping motor starts to step out due to the detection element for detecting the pulse generated with the movement of the print head and the print head being controlled to move in the platen direction from the initial position and contacting the print sheet. Out-of-step detection means for detecting that the step-out detection means, the change in the pulse width of the pulse detected by the detection element, and the pulse interval of the advance pulse for controlling the drive of the stepping motor A stepping motor step-out is detected by detecting it based on the difference between the pulse width detected by the detection element and the pulse width, After out detection of the stepping motor by the detection means, an automatic adjustment mechanism of the print head of the printer, characterized in that to move away the print head from a certain amount platen. 2. A printer in which a printing paper is mounted on a platen, and printing is performed on the printing paper while moving the printing head in the platen axis direction, a stepping motor for moving the printing head in a direction perpendicular to the printing paper. , Two detection elements for detecting a pulse generated with the movement of the print head as a pulse having a duty of 50% each time the stepping motor advances by four phases and shifting the phases by 90 ° from each other. Detecting that the stepping motor has begun to step out by detecting that the mutual relationship between the pulses detected by the two detection elements does not change in synchronization with the advance pulse that controls the driving of the stepping motor. Adjusting step means, and moving the print head in a direction away from the platen by a certain amount after detecting step-out of the stepping motor. Automatic print head adjustment mechanism for printers. 3. The detection by the out-of-step detecting means that the mutual relationship between the pulses detected by the two detecting elements does not change in synchronization with the phase advance pulse is detected by the two detecting elements. 7. The method according to claim 1, wherein the pulse is generated based on a difference between a binary code obtained by converting the pulse with a Gray code / Pinary code converting means and a binary code obtained by encoding the advance pulse with a quaternary counter. An automatic adjustment mechanism for the print head of the printer according to item 2. 4. The device according to claim 1, wherein the detection element is an element for detecting a slit of a slit disk provided on the shaft of the stepping motor.
An automatic adjusting mechanism for a print head of the printer according to the item 2 or 3. 5. The automatic adjusting mechanism for a print head of a printer according to claim 4, wherein the slit disk has a slit printed on a transparent plate such as glass or acrylic. 6. The automatic adjusting mechanism for a print head of a printer according to claim 4, wherein a gear for driving the print head is used in place of the slit disk, and its teeth are used in place of the slit. 7. The automatic adjustment of a print head of a printer according to claim 1, 2 or 3, wherein said detection element is an element for detecting a change in magnetic flux due to a rotating magnet. mechanism.