JPH0195077A - Printer - Google Patents

Abstract

PURPOSE:To contrive higher operability, by automatically predicting by a printer itself the conditions of rotation of a platen by the operator, and switching a holding current so as to permit a platen knob to be rotated lightly. CONSTITUTION:A driving circuit 34 comprises an exciting circuit 41, a switching circuit 42 for sending a holding current to the circuit 41, a switching-controlling circuit 43 for supplying a control signal SS to the circuit 42, a register 44 and a timer 45. In the switching-controlling circuit 43, two kinds of conditions TA and TC for a switching-ON time T1 with the same period are preliminarily stored. In the case of TA, the holding current IA is largest, whereas in the case of TC, the holding current is sufficiently small. The holding current for a printer is so controlled that a maximum holding current is supplied to a driving motor for a predetermined period of time, e.g., for 2 to several seconds, immediately after a line feeding motor 3 is stopped or immediately after a power supply is switched ON, whereby stepout is prevented from occurring, and that the holding current is reduced to permit easy rotation of a knob 6 of a platen 1 after the predetermined period.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a printer in which a platen is rotationally driven by a pulse motor.

(Prior Art) A platen of a printer that feeds a print medium such as print paper is driven to rotate in synchronization with a printing operation. For example, a pulse motor is used for driving it. Since a pulse motor can rotate a rotor by a certain rotation angle with one pulse, it is often used for conveying objects with high precision due to its good controllability.

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

A printing paper 2 is wound around a platen 1 of this printer, and a line feed motor 3 is provided to carry out so-called line feeding in which the printing paper 2 is conveyed in synchronization with the printing operation. This line feed motor also consists of a pulse motor. The line feed motor is supplied with a line feed code from the host at a predetermined timing to rotate the platen by a rotation angle corresponding to the line feed amount of the printing paper. Based on the specification of this line feed code, the line feed motor rotates the platen 1 via the gear 4, and feeds the printing paper by the specified amount.
transport. Note that during this conveyance, the printing paper is pressed against the platen by the indicator 5.

Further, after the line feed is completed, a constant holding torque is applied to the line feed motor 3. This holding torque is set to a torque sufficient to prevent the printing paper from easily moving due to external force, and a torque that allows the operator to manually feed the printing paper. . In reality, the holding torque is about 115 to 1/10 of the rotational torque when feeding the printing paper by the line feed motor.

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

In the figure, the path line 7 includes a microprocessor 8
, a read-only memory (ROM) 9, a random access memory (RAM) 10, a drive circuit 11, an interface (I/F) control section 12, and a printing section 13.
are connected. The microprocessor 8 is a circuit that performs calculations for controlling this printer. The read-only memory 9 is a memory for storing the operating program and the like. Further, the random access memory 10 is a memory for storing various data necessary for operations such as arithmetic operations. The drive circuit 11 is a circuit that outputs driving pulses to the line feed motor (LF motor) 3. The interface control unit 12 connects an interface connector (I/F connector) from the host side.
Serial data input via 14 is accepted, and
This is a circuit that sends predetermined information to the host side via the interface connector 14. The printing unit 13 is comprised of a print head that performs predetermined printing on print 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, a pulse motor 3 has a pair of excitation coils 1
It consists of a two-phase excitation type pulse motor that rotates the rotor 18 by rotating the vector of the composite magnetic field formed by 6.17. Moreover, although this drive circuit is a well-known circuit,
5 drive circuits 0~4 and 5 resistors R0~
Control signals 80-S4 are supplied via R4% and five NPN transistors T0-T4, and resistors Rs, R
When the switch circuit consisting of PNP transistors T o and T s is on, the excitation coil 16
．． 17 is excited at a predetermined timing, and the rotor 18 rotates.

The control signal SL"S4 is input to the drive circuit K.-4 via the terminals 21 to 24. These signals are rotation control signals that are shifted from each other by π/2.
The control signal S0 input from 0 is intermittently supplied at a predetermined repetition frequency when the motor rotates. If one pulse of this signal S0 is input, the rotor 13 will rotate by π/2. Terminal 25 is a drive circuit K. - This is a terminal that supplies a voltage to pull up the output terminal of 4. Further, the terminal 26 is a circuit that supplies excitation current to the excitation coils 16 and 17 when the transistor T5 is on.

Further, when a predetermined holding current control signal SS is supplied from the terminal 27, the resistor R7 and the diode D. A holding current is supplied to the excitation coil 16.17 via. When the rotor 18 is stopped, any two of the transistors Tl and T4 are on, and this causes the excitation coil 16 to be turned on.
．． A holding current is supplied to 17. Therefore, the rotor 18 is held by 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. The microprocessor 8 then reads this print data, creates a predetermined print signal, and drives the print section 13. When printing for 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 drives the line feed motor 3.
, a control signal s0 (FIG. 3) is supplied for a predetermined period of time.

As a result, the line feed motor 3 rotates by a predetermined rotation angle.

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

In the figure, an idle gear 4a is meshed with the output shaft of the infeed motor 3. This idle gear 4a
is engaged with platen gear 4b, and platen gear 4
b is directly connected to the shaft 1a of the platen 1.

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

Next, according to FIG. 6, the control signals 80 to S4 and the holding current control signal SS input to the circuit explained in FIG.
Indicates the specific content.

FIG. 6 is a timing chart of each control signal.

First, while the line feed motor 3 is stopped, a 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, a control signal So is repeatedly supplied with an appropriate pulse width to perform settling [FIG. 6(e)].

During this settling period, an exciting current is supplied to a predetermined exciting coil to adjust the position of the rotor.

Next, when the line feed motor is started, rotation control signals 81 to S4 are supplied with a shift of π/2 from each other. In this acceleration section, each signal S I"" S 4
The repetition frequency is increased so as to gradually narrow the pulse width [Fig. 6(a,) to (d)].

After that, the line feed motor enters the constant speed section, then enters the deceleration section, and when the line feed of the predetermined rotation is finished,
Drive signals 81 to S4 are stopped.

Here, the control signal S is applied again. is 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 this control signal S0 disappears, the control signal S for supplying the holding current again
S is supplied to the motor drive circuit [FIG. 6(f)].

Here, this control signal SS is, for example, a signal that is turned on and off periodically according to a certain switching period, as shown in FIG. This is a signal that is in a time off state. That is, in this on state, the holding current SS flows through the excitation coil 16. through the resistor R7 and the diode Do shown in FIG.
17. In the off state, an induced current flows. Conventionally, the ratio of the on-state to off-state times was fixed at an optimal value, thereby obtaining a predetermined holding current. .

(Problems to be Solved by the Invention) By the way, the holding current control signal S shown in FIG. 6(g)
If the proportion of on-state time in S increases with respect to its switching period, the holding current supplied to the excitation coil effectively increases.

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

In general, if the holding current is large, the motor will not step out, but if you try to rotate the knob by hand, a large amount of force will be required. On the other hand, if the holding current is small, the force required to rotate the knob is light, but the motor is likely to lose synchronization due to external force.

Conventionally, in order to obtain a sufficient holding torque, the switching on time TB was set so as to obtain the holding current IB shown in this graph. However, with this setting, although misalignment of the printing paper is less likely to occur, the platen knob is heavy and has a problem in operability.

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

(Means for Solving the Problems) The printer of the present invention includes a platen that feeds a print medium, a motor that rotationally drives this platen in synchronization with printing operation, and a drive circuit that controls the rotation of this motor. The motor is a multiphase excitation pulse motor that rotates a rotor by rotating a vector of a composite magnetic field formed by a plurality of excitation coils, and the drive circuit is configured to control each excitation when the motor is stationary. It has a switching circuit that periodically controls on/off the holding current supplied to the coil, and this switching circuit controls the ratio of the time when the holding current is turned on and the time when the holding current is turned off during one cycle. The present invention is characterized in that it is configured to selectively switch between two or more types.

(Function) The above device does not fix the holding current at a constant value as in the past, but instead sets two or more ratios of the holding current on time and off time, and selectively switches between these settings. . That is, when the operator intends to rotate the platen knob, a low holding torque is selected, and in other cases, a high holding torque is selected. This prevents the printing paper from shifting and improves operability.

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

This circuit has a configuration in which a microprocessor 31, a read-only memory 32, a random access memory 33, a drive circuit 34, an interface control section 35, and a printing section 36 are connected to a common path line 32. The line feed motor 3 is connected to the drive circuit 34, and the interface connector 3 is connected to the interface control unit 35.
8 are connected.

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

This drive circuit 34 includes an excitation circuit 41 having almost the same configuration as the drive circuit shown in FIG.
A switching control circuit 43 that supplies a control signal SS to
, a register 44 and a timer 45.

FIG. 8 shows a specific example of wiring of this switching circuit 42.

The switching circuit 42 includes a PNP transistor Ts,
It consists of a resistor Rs connected between its emitter and base, and a diode Ds connected to its connector.

Further, a power source 46 for exciting the excitation circuit 41 is connected to the emitter of the PNP transistor T8. An excitation circuit 41 is connected to the cathode of the diode Ds. Further, a switching control circuit 42 is connected to the base of the transistor Ts.

The control circuit having the above configuration operates as follows.

In FIG. 1, data input/output and printing operations are similar to those described in FIG. 3, but the supply of holding current to the line feed motor 3 is performed as follows.

First, the microprocessor 31 inputs, for example, 5-bit holding current information to the register 44. In response to this, the switching control circuit 43 sets a predetermined switching period (TI or +T2) as shown in FIG.

Note that two or more types of switching conditions are set in advance in the switching control circuit 43 at the same period. For example, in this embodiment, two types of conditions are set for the switching on time T1 shown in FIG. 7: TA and TC.

When the switching on time is TA, the holding current IA is the largest, and when the switching on time is TC, the holding current is sufficiently small. The switching control circuit 43 transmits the control signal SS as shown in FIG. 6(g) to the transistor T8 shown in FIG.
When the voltage is applied to the base of the transistor Ts, the transistor Ts repeats an on-off operation of being turned on for a time T1 and then turned on for a time T2. As a result, an excitation voltage is intermittently applied from the power supply 46 to the excitation circuit 41 through the diode Ds, and the excitation current becomes its average value.

In the present invention, the switching-on time is changed depending on 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 81 to 81 supplied to each excitation coil
The control signal S0 supplied to S4 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, and the basic signal content is the same as that shown in FIG. 6(g).

In this printer, the effective holding current is
It is changed as shown in figure (g).

That is, the holding current is set to the maximum value IA while the line feed motor is settling, accelerating, constant speed, decelerating, and settling, and while the line feed motor is stopped, the holding current is set for a predetermined time t. , set to the maximum value IA, then I
Set to C. When the line feed motor starts driving 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 shows a flow chart of the operation of the printer of the present invention shown in the timing chart of FIG.

First, when the printer is powered on, the switching time is set to TA, that is, the holding current becomes the maximum value IA (step Sl). Next, if no print data is stored in the reception buffer, a timer is started (step S2). Then, it is determined whether data has arrived in the reception buffer (step S3). L by panel switch
When F or FF is pressed (step S4), the switching time is set to TA and the holding current is maximized (step S5). When LF or FF is not pressed by the switch, monitor the timer timeout (
Step S6). If there is no timeout, step S3
Return to If timeout, switching time T
The C holding current is set to the minimum value (step S7). In this state, the operator can easily turn the platen knob to insert printing paper or the like. Next step is step S again
Returning to step 3, it monitors whether the receive buffer data has arrived and whether there are LPs and FFs 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 S5). In this case, the holding current becomes the maximum value IA. Thereafter, printing, LF (line feed), or FF (page feed) processing is performed (step S8). In this case, the holding current is at its maximum value and step-out due to external force is less likely to occur. It is determined whether or not the receiving buffer is empty during these processes (step S9).

Then, the reception buffer becomes empty, and it is further determined whether printing, line feed, and FF are all completed (step 510), and when these are completed, the process returns to step S1.

If you control the printer's holding current using the steps above,
Immediately after the line feed motor stops or the power is turned on, the maximum holding current is supplied to the drive motor for a certain period of time, for example 2 seconds to several seconds, to prevent step-out. It can be made easier. When driving the line feed motor,
Select the holding current to the maximum value to prevent tax adjustment.

The present invention is not limited to the above embodiments.

It is also possible to switch the holding current in several stages by taking various conditions into account. Also, when switching the excitation current, the ON/OFF state is turned on at a constant switching period.
Although a control signal to turn off is used, effective switching of the excitation current is also possible by directly increasing or decreasing the excitation voltage itself or by varying the switching period.

(Effects of the Invention) The printer of the present invention as described above automatically predicts the conditions under which the operator rotates the platen knob, and at that time switches the holding current so as to lighten the platen knob. On the other hand, in order to prevent tax adjustments, the holding current can be kept large during printing control, making it possible to achieve both reliable printing and improved operability.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the motor control circuit of the printer of the present invention, Fig. 2 is an external perspective view of a commonly used printer, Fig. 3 is a block diagram of the motor control circuit of a conventional printer, and Fig. 4 is a block diagram of the motor control circuit of the printer of the present invention. An explanatory diagram of a conventional printer drive circuit,
Fig. 5 is a perspective view of the speed reduction mechanism of this motor, Fig. 6 is a timing chart of control signals of the conventional drive circuit, Fig. 7 is a graph showing the relationship between switching on time and holding current, and Fig. 8 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. 1o is a flowchart of the operation of the printer of the present invention. DESCRIPTION OF SYMBOLS 1...Platen, 2...Print paper, 3...Motor, 34...Drive circuit, 41...Excitation circuit, 42...
- Switching circuit, 43... Switching control circuit. Patent Applicant: Oki Electric Industry Co., Ltd. Figure 7 is a graph showing the relationship between the holding current.

Claims (1)

[Claims] Consisting of a platen that feeds a print medium, a motor that rotationally drives the platen in synchronization with the printing operation, and a drive circuit that controls the rotation of the motor, the motor having a plurality of excitation coils. A multiphase excitation type pulse motor that rotates a rotor by rotating a vector of a composite magnetic field formed by The switching circuit is configured to selectively switch between two or more types of ratios of the time during which the holding current is turned on and the time during which the holding current is turned off during one cycle. A printer characterized in that: