JP2538943B2 - Printer - Google Patents

Description

The present invention relates to a printer in which a platen is rotationally driven by a pulse motor.

(Prior Art) A platen that feeds a printing medium such as a printing sheet of a printer is rotationally driven in synchronization with a printing operation. A pulse motor, for example, is used for the driving. Since the pulse motor can rotate the rotor by a certain rotation angle by one pulse, it is often used for highly accurate conveyance of an object because of its good controllability.

FIG. 2 is an external perspective view of a printer using the pulse motor.

A print sheet 2 is wound around a platen 1 of this printer, and a line feed motor 3 is provided to perform so-called line feed for conveying the print sheet 2 in synchronization with the printing operation. This line feed motor also comprises a pulse motor. A line feed code for rotating the platen by a rotation angle corresponding to the line feed amount of the printing paper is supplied from the host side to the line feed motor at a predetermined timing. The line feed motor rotationally drives the platen 1 via the gear 4 based on the designation of the line feed code, and conveys the printing paper 2 by the designated amount. During the transportation, the printing paper is pressed against the platen by the indicator 5.

After the line feed is completed, a constant holding torque is applied to the line feed motor 3. The holding torque is set to a torque that is sufficient to prevent the printing paper from easily moving due to an external force, and that the operator can manually feed the printing paper. . Actually, the holding torque is
The value is about 1/5 to 1/10 of the rotation torque when the print paper is fed by the line feed motor.

Now, FIG. 3 shows a block diagram of the motor control circuit of such a printer.

In the figure, a bus line 7 includes a microprocessor 8, a read only memory (ROM) 9, a random access memory (RAM) 10, a drive circuit 11, and an interface (I / F) control unit 12. And the printing unit 13 are connected. The microprocessor 8 is a circuit that performs calculations for controlling the printer. The read only memory 9 is a memory for storing the operation program and the like. The random access memory 10 is a memory for storing various data necessary for operations such as calculation. The drive circuit 11 is a circuit that outputs a pulse for driving the line feed motor (LF motor) 3. The interface control unit 12 receives serial data input from the host side via the interface connector (I / F connector) 14 and also receives the interface data.
It is a circuit that sends predetermined information to the host side via 14. The printing unit 13 is a unit that includes a print head that performs predetermined printing on printing paper under the control of the microprocessor 8 and various mechanisms.

FIG. 4 shows a specific wiring diagram of the drive circuit 11 for the line feed motor 3 in the circuit shown in FIG.

In FIG. 4, the pulse motor 3 is a pair of exciting coils.
It consists of a two-phase excitation pulse motor that rotates the rotor 18 by rotating the vector of the composite magnetic field formed by 16 and 17. Although this drive circuit is a well-known circuit, it has five drive circuits K _{0 to} K ₄ and five resistors R _{0 to} R ₄ and 5.
One of the through NPN transistor T ₀ through T _4, the control signal S ₀ to S ₄
Is supplied and the switch circuit consisting of resistors R ₅ and R ₆ and PNP transistors T ₀ and T ₅ is on, the exciting coil
16, 17 are excited at a predetermined timing to rotate the rotor 18.

The control signals S _{1 to} S ₄ are fed to the drive circuit via terminals 21 to 24.
Enter in K _{0 to} K ₄ . These signals are rotation control signals that are deviated from each other by π / 2. Further, the control signal S ₀ input from the terminal 20 is intermittently supplied at a predetermined repetition frequency when the motor is rotating. If one pulse of this signal S ₀ is input, the rotor 13 will rotate by π / 2. Terminal 25 is
This is a terminal that supplies a voltage for pulling up the output terminals of the drive circuits K _{0 to} K ₄ . The terminal 26 is a circuit that supplies an exciting current to the exciting coils 16 and 17 when the transistor T ₅ is on. Also, from the terminal 27 a predetermined holding current control signal
When SS is supplied, via resistor R ₇ and diode D ₀ ,
The holding current is supplied to the exciting coils 16 and 17. During stopping of the rotor 18, any two of the transistors T ₁ ~ transistor T ₄ is is ON, the holding current is supplied thereby to the excitation coil 16 and 17. Therefore, the rotor 18 is held with a constant holding torque.

Now, returning to FIG. 3 again, when print data is input from the host side to the interface control unit 12 via the interface connector 14, this print data is stored in the random access memory 10. Then, the microprocessor 8 reads out the print data, creates a predetermined print signal, and drives the printing unit 13. When the printing of one line is completed, the microprocessor 8 supplies a line feed signal to the drive circuit 11. The drive circuit 11 receives the line feed signal and supplies the control signal S ₀ (FIG. 3) to the line feed motor 3 for a predetermined time. As a result, the line feed motor 3 rotates by a predetermined rotation angle.

FIG. 5 is a perspective view showing a speed reduction mechanism of the line feed motor.

In the figure, an idle gear 4a meshes with the output shaft of the line feed motor 3. The idle gear 4a meshes with the platen gear 4b, and the platen gear 4b is directly connected to the shaft 1a of the platen 1.

When the line feed motor 3 is driven by this mechanism, it is decelerated by the idle gear 4a and the platen gear 4b at a predetermined reduction ratio, and the platen 1 is rotated by a predetermined angle.

Next, FIG. 6 shows specific contents of the control signals S _{0 to} S ₄ and the holding current control signal SS input to the circuit described in FIG.

FIG. 6 is a timing chart of the respective control signals.

First, while the line feed motor 3 is stopped, the holding current control signal SS [Fig. 6 (f)] for holding the motor at a predetermined position is supplied. Immediately before the line feed motor rotates, the control signal S ₀ is repeatedly supplied with an appropriate pulse width for settling [FIG. 6 (e)]. In this settling section, an exciting current is supplied to a predetermined exciting coil to adjust the position of the rotor.

Next, when the line feed motor is activated, the rotation control signals S _{1 to} S ₄ are supplied with a shift of π / 2 from each other. In this acceleration section, the signals S _{1 to} S ₄ each have their repetition frequencies increased so as to gradually narrow their pulse widths (FIGS. 6 (a) to 6 (d)).

After that, the line feed motor enters the constant speed section, then enters the deceleration section, and when the line feed of a predetermined rotation is completed, the drive signals S _{1 to} S ₄ are stopped.

Here, the control signal S ₀ is again supplied with a predetermined pulse width (which is wider than the driving state of the motor), and the rotor of the motor is stopped at the target position [Fig. 6 (e)]. After the control signal S ₀ disappears, the control signal SS for supplying the holding current is again supplied to the motor drive circuit [FIG. 6 (f)].

Here, the control signal SS is, for example, as shown in FIG. 6 (g), a signal that is periodically turned on and off with a constant switching cycle, and is in the on state for the time T ₁ as shown in the figure, _This signal is in the off state for ₂ hours. That is, in this ON state, the holding current SS is equal to the resistance shown in FIG.
It is supplied to the exciting coils 16 and 17 via R ₇ and the diode D ₀ . In the off state, an induced current flows. Conventionally, the ratio of the on-state time to the off-state time is fixed to an optimum value, and a predetermined holding current is obtained by this.

(Problems to be Solved by the Invention) By the way, the holding current control signal shown in FIG.
When the ratio of the on-state time in SS increases with respect to the switching cycle, the holding current supplied to the exciting coil effectively increases.

FIG. 7 shows a graph showing the relationship between the switching on time and the holding current.

Generally, if the holding current is large, the motor will not step out, but if the knob is rotated by hand, a large force is required. On the other hand, if the holding current is small, the force for rotating the knob can be light, but the motor easily loses step due to external force.

In the past, in order to obtain this holding torque sufficiently, the switching on time TB was set so that the holding current IB shown in this graph could be obtained. However, with this setting, the deviation of the printing paper is unlikely to occur, but the knob of the platen is heavy and there is a problem in its operability.

The present invention has been made in view of the above points, and an object of the present invention is to provide a printer excellent in operability when an operator tries to rotate a knob of a platen.

(Means for Solving Problems) A printer according to the present invention includes a motor that feeds a print medium after a medium feed switch is pressed and after a printing operation based on input data ends, and a drive circuit that controls the rotation of the motor. In the printer having the following, the drive circuit sets the holding current to be supplied to the motor after the print medium is fed, based on the holding unit that stores the holding current information and the holding current information stored in the storing unit. A first control circuit that has a switching control circuit that outputs a control signal to be performed and a timer circuit that measures the time during which the control signal is output, and the holding current information stored in the storage means sets the holding torque of the motor high. And a second command value for setting the motor holding torque to be lower than the holding torque set by the first command value. The control signal is a first control signal output based on the first command value stored in the storage means, and a second control signal output based on the second command value stored in the storage means. The timer circuit starts clocking after the print medium is fed by pressing the medium feed switch or after the print medium is fed by the printing operation based on the input data, and is switched after a predetermined time. The switching control circuit outputs a timing signal for switching the control signal of the control circuit, and the switching control circuit is configured to selectively switch at least two of the control signals. After the printing medium is fed by the printing operation based on the above, the output of the first control signal is maintained and output from the timer circuit. The control signal is switched to the second control signal based on the generated timing signal, and is switched to the first control signal again before the printing medium is fed after the medium feed switch is pressed or before the printing operation is started based on the input data. It is what

(Operation) The above device does not fix the holding current to a constant value as in the conventional case, but uses the first control signal for setting the holding torque of the motor high and the holding torque of the motor by the first control signal. By having at least two control signals of the second control signal set lower than the set holding torque, and selectively switching the at least two control signals, the setting of the holding current supplied to the motor can be changed. That is, when the operator wants to rotate the knob of the platen, the holding torque is selected low, and in other cases, the holding torque is selected higher. As a result, the deviation of the printing paper is prevented and the operability is improved.

(Embodiment) FIG. 1 is a block diagram of a motor control circuit of a printer of the present invention.

This circuit uses a common bus line 32, a microprocessor
31 and read only memory 32 and random access memory
The memory 33, the drive circuit 34, the interface control unit 35, and the printing unit 36 are connected to each other. The line feed motor 3 is connected to the drive circuit 34, and the interface connector 38 is connected to the interface controller 35.

The configuration and operation of each of these blocks are almost the same as those described in FIG. Therefore, the description of the overlapping portions will be omitted, but the drive circuit 34 of the printer of the present invention is characterized.

The drive circuit 34 includes an excitation circuit 41 having substantially the same configuration as the drive circuit shown in FIG. 4, a switching circuit 42 that sends a holding current to the excitation circuit 41, and a switching circuit 42 that supplies a control signal SS to the switching circuit 42. Control circuit 43 and register
It is composed of 44 and a timer 45.

FIG. 8 shows a concrete connection example of the switching circuit 42.

The switching circuit 42 is composed of a PNP transistor T _S , a resistor R _S connected between its emitter bases, and a diode D _S connected to its connector. Also, PNP
A power supply 46 for exciting the exciting circuit 41 is connected to the emitter of the transistor T _S. The exciting circuit 41 is connected to the cathode of the diode D _S. The switching control circuit 42 is connected to the base of the transistor T _S.

 The control circuit having the above configuration operates as follows.

In FIG. 1, the data input / output and printing operations are shown in FIG.
The holding current is supplied to the line feed motor 3 as follows, although it is similar to the one described in the figure.

First, the microprocessor 31
For example, 5-bit holding current information is input. In response to this, the switching control circuit 43 sets a predetermined switching cycle (T ₁₊ + T ₂ ) as shown in FIG.

The switching control circuit 43 is preset with two or more kinds of switching conditions in the same cycle. For example, in this embodiment, two kinds of conditions are set for the switching on time T ₁ shown in FIG. 7, that is, TA and TC.

The holding current IA is the largest when the switching on time is TA, and the holding current is sufficiently small when the switching on time is TA. When the switching control circuit 43 applies the control signal SS as shown in FIG. 6 (g) to the base of the transistor T _S shown in FIG. 8, the transistor T _S is turned on for T ₁ hours and turned off for T ₂ hours. This on / off operation is repeated. This will power
An exciting voltage is intermittently applied from 46 to the exciting circuit 41 through the diode D _S , and the exciting current has an average value.

In the present invention, the switching on time is switched according to the operating conditions of the printer.

FIG. 9 shows a timing chart of control signals of the drive circuit of the present invention.

In the figure, control signals S ₁ to
The control signal S ₀ supplied to S ₄ and the excitation circuit is exactly the same as that already described in FIG.

Here, the holding current control signal SS is supplied while the motor is stopped, but the basic signal content is also the same as that shown in FIG. 6 (g).

Here, in this printer, the effective holding current is changed as shown in FIG. 9 (g). That is, the holding current is set to the maximum value IA during the period from settling to acceleration, constant speed, deceleration, and settling, and the holding current is set to the predetermined time t while the line feed motor is stopped.
During this period, set the maximum value to IA, and then set to IC. Then, when the driving of the line feed motor is started again, the holding current is returned to the maximum value IA.

The timer 45 shown in FIG. 1 is provided to measure the timing for switching the holding current, that is, the time t for maintaining the holding current at the maximum value.

FIG. 10 is a flowchart showing the operation of the printer of the present invention shown in the timing chart of FIG.

First, when the power of the printer is turned on, the switching time is set to TA, that is, the holding current becomes the maximum value IA (step S1). Next, if print data is not stored in the receive buffer, the timer starts (step
S2). Then, it is judged whether or not data has arrived in the reception buffer (step S3). LF or FF by panel switch
When is pressed (step S4), the switching time is set to TA and the holding current is maximized (step S5). When the LF or FF is not pressed by the switch, the time-out of the timer is monitored (step S6). If not, the process returns to step S3. If the time is out, the switching time is set to the minimum value of the TC holding current (step S7). In this state, the operator can easily turn the knob of the platen in order to insert the printing paper or the like.
After this, the process returns to step S3 again, and it is monitored whether the reception buffer data has come and whether there is LF and FF from the switch. When it is determined that data has arrived in the reception buffer (step S3), the switching time is switched to TA (step S3).
S5). In this case, the holding current has the maximum value IA. Then, thereafter, printing, LF (line feed), or FF (page feed) processing is performed (step S8). In this case, the holding current is at the maximum value, and step-out due to external force is unlikely to occur. During these processes, it is always determined whether the receive buffer is empty (step S9).

Then, the reception buffer becomes empty, and it is further determined whether or not printing, line feeding, and FF are all completed (step S10), and when these are completed, the process returns to step S1 again.

If the holding current of the printer is controlled by the above procedure, immediately after the line feed motor is stopped or the power is turned on, for a fixed time, for example, 2 seconds to several seconds,
While the maximum holding current is supplied to the drive motor to prevent step-out, after that, the knob of the platen can be easily turned. Then, at the time of driving the line feed motor, the holding current is selected to the maximum value to prevent step-out.

 The present invention is not limited to the above embodiments.

The holding current can be switched in several stages by further adding various conditions. Further, although a control signal for turning on / off at a constant switching cycle is used for switching the exciting current, even if the exciting voltage itself is directly increased / decreased or the switching cycle is changed, the effective exciting current It can be switched.

(Effects of the Invention) In the printer of the present invention described above, the timer circuit measures the time for supplying a high holding current to the motor. A high holding current is set immediately after feeding the medium after the printing operation, and a low holding current is set after the lapse of a predetermined time.Before the printing medium feed or before the printing operation by pressing the medium feed switch even if the low holding current is set Can be set again to a high holding current. Therefore, a high holding current can be supplied not only before and after the printing operation but also before and after the printing medium feed by pressing the medium feed switch, and a low holding current can be supplied after a lapse of a predetermined time, and the holding current is always supplied to the motor. Therefore, it is possible to prevent out-of-step of the motor due to vibration of the printer or external force, and to perform reliable printing without misalignment of the printing paper. In particular, in a printer that performs high-speed printing, residual vibration after printing continues for a predetermined time, and the holding torque of the motor can be set high during this predetermined time, so it is a printer that performs high-speed printing. However, it is possible to prevent the deviation of the printing paper. Also, when the operator turns the platen knob, the holding current is already automatically set to a low value, so the knob can be turned with a small force, and the holding current is not cut off. Even if it is turned, the excitation phase of the motor can be maintained in a stable state. Further, since the printer automatically switches the holding current setting, the operator does not accidentally switch the holding current setting.
The holding current can always be set optimally, and both reliable printing and improved operability can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a motor control circuit of a printer according to the present invention, FIG. 2 is an external perspective view of a commonly used printer, FIG. 3 is a block diagram of a motor control circuit of a conventional printer, and FIG. Explanatory diagram of a conventional printer drive circuit,
FIG. 5 is a perspective view of the deceleration mechanism of this motor, FIG. 6 is a timing chart of control signals of a conventional drive circuit, FIG. 7 is a graph showing the relationship between its switching on time and holding current, and FIG. FIG. 9 is a specific wiring diagram of the switching circuit of the printer of the present invention, FIG. 9 is a timing chart of control signals of the drive circuit, and FIG. 10 is a flowchart of the operation of the printer of the present invention. 1 ... Platen, 2 ... Printing paper, 3 ... Motor, 34 ...
… Drive circuit, 41 …… Excitation circuit, 42 …… Switching circuit, 43 …… Switching control circuit.

Continuation of the front page (56) References JP-A-56-120376 (JP, A) JP-A-59-7069 (JP, A) JP-A-56-162999 (JP, A) Actual development Sho-56-32999 (JP , U) Actual Development Sho 61-170552 (JP, U) Japanese Patent Publication 2-58114 (JP, B2) Japanese Patent Publication 51-30641 (JP, B2)

Claims (1)

(57) [Claims] 1. A printer having a motor for feeding a print medium after a medium feed switch is pressed or after a printing operation based on input data is completed, and a drive circuit for controlling the rotation of the motor. Means for storing holding current information,
A switching control circuit for outputting a control signal for setting a holding current to be supplied to the motor after feeding the print medium based on the holding current information stored in the storage means, and outputting the control signal. Holding current information stored in the storage means includes a first command value for setting a high holding torque of the motor and a first command for holding torque of the motor. Having at least two command values of a second command value to be set lower than the holding torque set by the value, and the control signal is a first control signal output based on the first command value, The timer circuit has at least two signals of a second control signal that is output based on the second command value, and the timer circuit outputs the print medium after the medium feed switch is pressed or is input. After feeding the print medium by the printing operation based on the data, timing is started, and after a predetermined time, a timing signal for switching the control signal of the switching control circuit is output, and the switching control circuit includes at least two of the above. A control signal is selectively switched, and after the print medium is fed after the medium feed switch is pressed or after the print medium is fed by the printing operation based on the input data, the output of the first control signal is maintained. The first control signal is switched to the second control signal based on the timing signal output from the timer circuit, and the first control signal is output again before the print medium is fed after the medium feed switch is pressed or before the print operation is started based on the input data. A printer characterized in that the control signal is switched to.