JPS5918230B2 - Serial printer - drive unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving device for a serial printer such as a dot printer or an inkjet printer that prints on a recording medium using a print head that moves opposite to the recording medium.

5 Conventionally, some serial printers of this type use a pulse motor or a servo motor as a motor for moving and driving a print head.

However, printers using the above-mentioned pulse motor have the disadvantage that, due to the nature of the pulse motor, rotational irregularities are large and print shapes are poor. In addition, in order to eliminate the influence of the inertia load of the print head movement, measures such as gradually changing the rotational speed of the motor when the print head starts and stops moving are taken, which is not suitable for high-speed printing. The printer No. 25 using the servo motor had the drawback that the servo motor itself was expensive and its control circuit was complicated, making the printer expensive. To eliminate these drawbacks, there is a motor 30 using an induction motor or a DC motor.

Such devices usually include, for example, an electromagnetic clutch in the rotation transmission system that transmits the rotation of the motor to move the print head, and the clutch sets the direction of movement of the print head and controls the movement and stop of the print head. However, this type of device had the following 35 drawbacks. In other words, the above-mentioned motor is generally constantly rotating, and this rotation is stopped by an electromagnetic clutch to control the movement of the print head, so when the print head starts or stops moving, it generates a very large impact. A force is applied to the rotational transmission system. For this reason, it has been difficult to design the rotation transmission system, and it has been difficult to ensure sufficient durability. Moreover, since the motor is constantly rotating,
The motor makes noise even when not printing, and the power consumption of the motor increases, making it unreasonable and uneconomical. The present invention has been made in consideration of these circumstances, and its purpose is to provide a serial printer drive device that can smoothly start and stop the movement of the printing head, and that is simple in configuration and inexpensive. It is about providing.

Hereinafter, details of the present invention will be explained with reference to the drawings showing one embodiment.

FIG. 1 is a schematic configuration diagram, and numeral 1 denotes a movable carriage on which a printing head is attached, and is movably provided on guide rails 2a and 2b.

The printing head is provided to face the recording surface of recording paper 3 as a recording medium, and the recording paper 3 is sequentially fed out by a paper feed roller (not shown). The movable carriage 1 is connected to a wire 4, and the wire 4 is wound around a freewheel 5, and is wound and unwound. This pulley 5 is rotationally driven by an induction motor 6 via a speed reduction mechanism consisting of a worm gear 7 and a worm wheel 8. Further, at both ends of the guide rail 2a, there are provided position detectors 9 and 10, such as photocouplers, for setting the printing range on the recording paper 3 by the print head, that is, detecting the movement limit position. The printing head is moved by the motor 6 within a range set by the position detectors 9 and 10, so that predetermined printing can be performed on the recording paper 3. Incidentally, a driving current is supplied to the induction motor 6 by a circuit configured as shown in FIG.

That is, the current supplied from the AC commercial power source 11 via the power switch 12 is selectively switched and controlled by a charging/discharging circuit consisting of a capacitor 13 and a diode 14 connected in series, as well as relays 15 and 16, which will be described later. It is supplied to the induction motor 6 via the polarity changeover switches 15a, 15b and the brake changeover switch 16a. The switches 15a and 15b are used to change the polarity of the current supplied to the motor 6, and 17 in Figure J is a phase advance capacitor.

The energization circuit of the induction motor 6 configured as described above is controlled by the control circuit shown in FIG. be done.

The position detectors 9 and 10 each include a light emitting diode 20.
and a photocoupler consisting of a phototransistor 21, and a photocoupler consisting of a light emitting diode 22 and a phototransistor 23, and when the movable carriage 1 reaches a predetermined position, each photocoupler (position detector) 9, 10 The lights 9a and 10a are blocked respectively. Output terminal (emitter) of the phototransistor 21
The signal output from the circuit is supplied to the base of a transistor 24 as a waveform shaping circuit. This transistor 2
The emitter of No. 4 is grounded, and the collector is connected to the power supply via a load resistor 25. The output (collector) of this transistor 24 is connected to one input terminal of an AND gate circuit 26, and an inverter circuit 27 and a resistor 2
8a and an integrating circuit consisting of a capacitor 28b are connected in series to the other input terminal of the gate circuit 26. Further, a signal outputted from the output end (emitter) of the phototransistor 23 is supplied to the base of a transistor 29 serving as a waveform shaping circuit. The emitter of this transistor 29 is grounded, and the collector is connected to a power supply via a load resistor 30. The output (collector) of this transistor 29 is an AND gate circuit 31
is connected to one input terminal of the inverter circuit 3.
2, a resistor 33a, and a capacitor 33b. The outputs of this gate circuit 31 and the gate circuit 26 are supplied to an OR circuit 34, and the logical sum is taken and inputted to a timer 35. A resistor 36 and a capacitor 37 connected to this timer 35 are used to set the operating time of the timer 35, for example, 100m.
It is set to sec. The output of this timer 35 is supplied to a transistor 36 that drives the relay 16 mentioned above, and is also supplied to a trigger terminal T of a D-type flip-flop FF 39 via an OR circuit 38.
The circuit consisting of the relay 16 and transistor 36 forms a first switch drive circuit. A signal is supplied to the data terminal D of the FF 39 from the inverter circuits 2 and 7, and the state is set based on the supplied signal. The relay 15 is controlled by the transistor 40 which is driven by the state setting of the FF 39. has been done. The circuit consisting of the relay 15 and the transistor 40 forms a second switch 1 drive circuit. Further, a signal is supplied to the OR circuit 38 from a charging/discharging circuit including a resistor 42 and a capacitor 43 via an inverter circuit 41. Hereinafter, the operation of the device configured as described above will be explained with reference to the operational waveform diagram shown in FIG. 4.

By turning on the power switch 12 at time T1, the capacitor 43 is charged via the resistor 42 as shown in FIG. 4a. The charging voltage of this capacitor 43 is detected by the inverter circuit 41.
At time T2 when the threshold voltage of 1 is exceeded, the inverter circuit 4
1 inverts its output as shown in FIG. 4b. Thus, the inverter circuit 41 outputs a HIGH level signal for time (T1 to T2) as an all clear signal 7. At this time, when the print head, that is, the movable carriage 1 is within its moving range, the light beams 9a and 10 of the detectors 9 and 10 are
A is not shielded from light by the town moving carriage 1.
Therefore, both transistors 24 and 29 are in the ON state,
Its output is at LOW level. The inverter circuit 27 which inputs this LOW level signal gives a HIGH level signal to the FF 39, and the FF 39 receives the input from the inverter circuit 27 at the rise of the signal supplied from the inverter circuit 41 (time T1). The signal is read and the FF 39 is set at the falling edge (time T2). Therefore F
F39 outputs a HIGH level signal from time T2, as shown in FIG. 4c, and turns transistor 40 ON. Due to the ON state of this transistor 40, the relay 15
Switches 15a and 15b, which are driven and controlled by the relay 15, supply reverse current to the motor 6. This reverse current causes the motor 6 to rotate in the reverse direction, winding the wire 4 around the pulley 5 and moving the movable carriage 1 toward the detector 9. Further, at this time, the capacitor 13 is charged with a DC charge via the diode 14. Due to the reverse rotation of the motor 6, the movable carriage 1 moves to the detector 9.
When the movable carriage 1 reaches the mounting position at time T3, the movable carriage 1 blocks the light 9a from the detector 9.

The phototransistor 21 detects this light blocking and stops supplying current to the transistor 24. By stopping the current supply, the transistor 24 becomes OFF, and its output is inverted to the HIGH level as shown in FIG. 4d. Inverter circuit 27 that receives this HIGH level signal as input
As shown in FIG. 4e, the output is inverted and a LOW level signal is output. The signal outputted from the inverter circuit 27 is supplied to the gate circuit 26 as a signal waveform as shown in FIG. This gate circuit has a threshold level (indicated by a chain line in the figure), and detects a signal below the threshold level as a LOW level, and a signal above the threshold level as a HIGH level. Therefore, the gate circuit 26 calculates the AND of the respective signals of FIG. 4 d and FIG.
A HIGH level signal is output for the time (T3 to T4) as shown in FIG. This HIGH level signal is sent to the OR circuit 34.
The timer 35 outputs a HIGH level signal for 100 msec from time T3 to time T5 as shown in FIG. 4h. This timer 3
The HIGH level signal from 5 causes transistor 36 to go to 0.
Set to N state and activate relay 16. The switch 16 is switched for a period of time (T3 to T5) by the operation of the relay 16, and the current supply from the power source 11 to the motor 6 is stopped, and the DC charge charged in the capacitor 13 is supplied to the motor 6. . An eddy current is generated in the armature of the motor 6 by the DC charge, that is, the DC current supplied from the capacitor 13, and the rotation of the motor 6 is braked. Thus, the rotation of the motor 6 is immediately stopped, and the movement of the movable carriage 1 is stopped. In addition, the timer 35
The signal output from the FF 39 is supplied to the FF 39 via the OR circuit 38.

Therefore, the FF 39 reads the LOW level signal of the inverter circuit 27 shown in FIG. Set the LOW level signal. With this setting, the FF 39 changes its output to the LOW level from time T5, as shown in FIG. 4c, and turns off the transistor 40. Due to the OFF state of the transistor 40, the relay 15 is de-energized and the connections of the switches 15a and 15b are switched. This switch 15a
, 15b, a positive current is supplied to the motor 6, and the motor 6 rotates in the forward direction, moving the movable carriage 1 toward the detector 10. During this movement, a predetermined signal (not shown) is applied to the print head, and the print head prints on the recording paper 3. In this way, the recording paper 3 is printed by the print head.
When the movable carriage 1 reaches the mounting position of the detector 10 at time T6, the movable carriage 1 blocks the light 10a of the detector 10.

At this time, the movable carriage 1 in the detector 9
The transistor 24 is 0N.
in a state. As the light 10a is blocked by the movable carriage 1, the phototransistor 23 becomes 0FF, and the current supply to the transistor 29 is stopped. By stopping the current supply, the transistor 29 becomes OFF, and its output becomes a HIGH level signal as shown in FIG. 4.
This HIGH level signal is inverted by the inverter circuit 32 as shown in FIG. 4j, and further converted into a waveform as shown in FIG. supplied to
This gate circuit 31 operates in the same manner as the gate circuit 26, and as shown in FIG.
Outputs a GH level signal. This HIG[-1 level signal is supplied to the timer 35 via the OR circuit 34, and the timer 35 operates in the same manner as at time T3. Therefore, transistor 36 is at 0 during time (T6-T8).
The state becomes N, and the rotation of the motor 6 is braked. Also time (
During the period from T6 to T8), the signal output from the timer 36 is supplied to the FF 39 via the OR circuit 38, and the HIGH level signal output from the inverter circuit 27 is read at the rising edge of time T6, At the time of falling, the above-mentioned HIGH level state is set. With this setting, the transistor 40 becomes ON again, causing the motor 6 to rotate in the reverse direction using the relay 15, and the movable carriage 1 is returned to the original mounting position of the detector 9. Of course, printing is also performed when returning. Thereafter, the above operation is repeated, and the movable carriage 1 reciprocates between the detectors 9 and 10, and performs predetermined printing on the recording paper 3 that is sequentially fed out as the movable carriage 1 moves back and forth.

According to the device configured as described above, the printing head (movable carriage 1) can be smoothly moved by rotating the motor 6 in the forward or reverse direction, and this movement can be made extremely smooth by applying a direct current to the motor 6. It can be stopped.

Therefore, compared to a system in which the rotational force of the motor is transmitted via an electromagnetic clutch, there is no need to apply sudden force to the motor, print head, or rotational transmission system, which simplifies the design and improves durability. can be measured. Furthermore, the inertia of the print head can be reduced, and the print head moves at a constant speed within a short time after the print head starts moving, and stops within a short time after the start of braking. Therefore, it can be widely applied to the above-mentioned dot printers, jet printers, etc., and the characteristics of conventional devices can be improved. For example, in a dot printer that prints with a 5 x 7 dot matrix, the distance between each dot is usually set to 2.54/6, and in a dot printer that prints with a 7 x 9 dot matrix, the distance between each dot is set to 2.54/6. The distance between the dots is 2.54/
It is set to 12mm. In such devices, the print head must move at a constant speed, and if it takes a long time from the start of movement until the print head reaches a constant speed, dots may be printed overlapping each other, or the distance between each dot may be It becomes shorter. In other words, the dot matrix forming one character becomes so-called smeared, resulting in poor print shape. In this respect, according to the present apparatus, as described above, the printing head can be moved at a constant speed in a short period of time, so that good printing can be obtained. Further, as described above, since the movement inertia is small, less braking energy is required to be applied to the motor 6, and since the motor 6 is not constantly rotated, noise caused by the motor 6 can be reduced. Furthermore, since the capacitor's charge is used for the braking cape, the configuration is simple. Furthermore, since the induction motor 6 is used, the print head can be moved at a constant speed without using an electromagnetic clutch or the like, and there is almost no variation in the moving speed due to uneven rotation compared to a conventional pulse motor. It does not require an expensive and complicated configuration unlike those using servo motors, and has the advantage of being able to sufficiently move the print head at high speeds. The print head may not only move linearly on the guide rails 2a and 2b by the wire 4, but may also move in an arcuate manner, for example, in a concave manner with respect to the supplied recording paper 3. Various types of recording paper 3 can be used depending on the purpose, such as plain paper, heat-sensitive recording paper, and discharge rupture recording paper.

Furthermore, not only the detectors 9 and 10 for detecting the position of the print head but also a proximity switch such as a reed switch or a micro switch may be used. Further, although an induction motor is used in the above embodiment, a DC motor may also be used. According to the present invention, the print head is moved by a motor via a movement transmission system, the movement limit position of the print head is detected by a pair of position detectors, and a timer is operated by the position detection output of the position detector. The control selector switch is switched for a certain period of time using the time count operation output of the timer, and the motor is braked for a certain period of time with the charge of the capacitor that has been charged in advance during the operation period of the motor, and the motor is controlled to stop. Since the polarity changeover switch is changed at the timing when the time count operation output stops to change the polarity of the supply to the motor, the printing head can start and stop moving smoothly.
Furthermore, it is possible to provide a serial printer drive device that has a simple configuration and is inexpensive.

[Brief explanation of the drawing]

The figure shows one embodiment of the present invention, and FIG. 1 is a schematic diagram;
Figure 2 is a motor current circuit diagram, Figure 3 is a control circuit configuration diagram,
(Figure 4 is an operating waveform diagram. 1... Movable carriage (print head), 3...
... Recording paper, 6 ... Induction motor, 9, 10 ... Detector, 13 ... Capacitor (DC charge charging), 15a, 15b ... ...
Switch (current polarity switching), 16a...Switch (braking means).

Claims (1)

[Claims] 1. A recording medium, a print head that faces the recording surface of this recording medium and is movable in the print recording direction of the recording surface, a motor that moves this print head via a movement transmission system, and the above-mentioned print head. a pair of position detectors for detecting the limit position of movement of the head relative to the recording medium; a capacitor connected to a power source via a diode; and a capacitor connected in series between the power source and the motor to supply current to the motor. a polarity changeover switch for changing the polarity of the motor, a braking control changeover switch for selectively connecting the motor to both ends of the power supply or capacitor via the polarity changeover switch, and a position detection output from the pair of position detectors. One timer that responds and counts for a certain period of time,
A first switch drive circuit that connects the motor to the capacitor by switching the braking control switch for a certain period of time in response to the time count operation output of the timer; A serial printer drive device comprising: a second switch drive circuit that operates one flip-flop to latch one of the outputs of the two position detectors, and switches the polarity changeover switch.