JPS6334032B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric typewriter equipped with a cylindrical platen whose rotation in the circumferential direction is driven by a motor, and its purpose is to improve operability when changing paper. The goal is to improve.

FIG. 1 shows a cylindrical platen 1, with reference numeral 2 an upper paper holder, 3 a lower paper holder, 4 an upper paper holder release lever, and 5 a set sheet of paper. When it becomes necessary to attach or remove the paper 5 in an electric typewriter equipped with such a platen 1, the platen 1 is not necessarily in a position where the paper 5 can be easily attached or detached. Therefore, conventionally,
The operator moves the platen 1 in the axial direction [in the direction of arrow A] and in the circumferential direction [in the direction of arrow B] to a position where the paper 5 can be easily attached and detached, and then
The work of attaching and detaching must be done. At this time, when installing or removing the paper 5 from the platen 1, the platen 1 must be rotated in the circumferential direction by hand, but the holding torque of the motor that drives the rotation in the circumferential direction is generated in the platen 1. Ori,
The platen 1 cannot be rotated by hand while the motor is energized. Therefore, after turning off the power to the motor and turning off the holding torque, the paper 5 is rotated freely by hand to a predetermined position.
After completing the attachment and detachment of the printer, it is necessary to perform a series of operations each time, such as returning the motor to the energized state in preparation for the next printing.

Therefore, the present invention provides a control device that automatically rotates the platen to a predetermined position and automatically turns off the holding torque in the circumferential direction of the platen when a paper replacement instruction is detected. An embodiment of the present invention will be described below with reference to FIG. 2.

Figure 2 is a control circuit diagram of an electric typewriter.
1 is a first motor that drives the rotation of the platen 1 in the circumferential direction, 7 is a second motor that drives the movement of the platen 1 in the axial direction, and 8 is a control device main body that performs printing operations using a microcomputer as the main part. In addition, the first motor 6 or the second motor 7 is driven via the motor control circuit 9 and the motor driver 10 or the motor control circuit 11 and the motor driver 12 in accordance with the line-feeding operation to execute line-feeding and print feeding. . 13 is a first position sensor that detects that the platen 1 is at a predetermined rotational position in the circumferential direction;
14 is a second position sensor that detects that the platen 1 is at a predetermined position within the axial movement range;
A switch circuit 15 is connected in series with the power supply circuit of the first motor 6, and is composed of, for example, a transistor switch. Reference numeral 16 denotes a timer circuit which is instructed to start timing by the control device main body 8, and the output of this timer circuit switches the switch circuit 15 on and off via the switch control circuit 17.

Next, the control device main body 8 includes a timer circuit 16,
The switch circuit 15 through the switch control circuit 17
The explanation will be based on the operation of the control device that controls.

When the control device main body 8 detects that a paper exchange instruction button (not shown) has been operated, the first and second position sensors 1 are activated by the first and second motors 6 and 7.
3 and 14 are driven to the position where the platen 1 is detected, and when it is detected that a circumferential positioning completion signal is issued from the first position sensor 13, the control device main body 8 triggers the timer circuit 16. The timer circuit 16 is provided to provide a time delay until the circumferential inertia of the platen 1 that has rotated to a predetermined position becomes zero. When the timer circuit 16 detects that the predetermined time has elapsed, the switch circuit 15 is turned off. The power supply to the first motor 6 is then turned off, the holding torque in the circumferential direction of the platen is turned off, and the platen 1 can be freely rotated by hand. When this state is reached, the paper 5 is attached and detached by the operator. Note that switch circuit 1 once turned off
5 is then kept in an off state until the control device main body 8 detects some key operation such as line feed or printing operation, and the control device main body 8 moves the platen 1 by the first or second motor 6, 7. When it detects that it has been given instructions that need to drive the
Switch circuit 1 immediately before executing the instructed operation.
5 is returned to the on state, and the instructed operation is executed with the circumferential direction of the platen 1 locked.

With this configuration, the paper exchange instruction button is
With just one operation, the platen 1 moves in the circumferential direction and axial direction to the position defined by the first and second position sensors 13 and 14 where the paper 5 can be easily attached and detached, and at that position, the platen 1 is manually operated. By platen 1
It is now possible to rotate. In addition, if the platen 1 is allowed to move freely in the circumferential direction immediately after completion of driving, the inertia of the circumferential rotation causes the platen 1 to move freely.
However, in the embodiment described above, the holding torque is released by the timer circuit 16 after the circumferential inertia becomes zero, so that the stop position of the platen 1 can be accurately set at the specified position in the circumferential direction. The position may be defined by the first position sensor 13. Moreover, after the paper 5 is attached and detached, the switch circuit 15 can be activated by performing a normal line feeding or printing operation, without having to take the trouble to restore power to the first motor 6 and lock the platen 1 as in the conventional case. is turned on, automatically locking the device.

As described above, according to the electric typewriter of the present invention, when a paper exchange instruction is detected, the platen is rotated to a predetermined paper exchange position by the motor, and the holding torque of the motor is then turned off at a predetermined timing. Because we installed a control device to
When replacing paper, the platen can be easily brought to the specified paper replacement position, and there is no need to perform a switch operation to turn off the power to the motor in order to turn off the holding torque in the circumferential direction. Therefore, the operability during paper exchange is significantly improved and more favorable than in the past.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a conventional platen, and FIG. 2 is a configuration diagram of an embodiment of the electric typewriter of the present invention. DESCRIPTION OF SYMBOLS 1...Platen, 6...First motor, 8...Control device main body, 13...First position sensor, 15...Switch circuit, 16...Timer circuit.

Claims (1)

[Claims] 1. A cylindrical platen with a paper retainer attached to its outer periphery, a motor for rotationally driving the platen, a detection means for detecting when the platen has reached a certain position in the circumferential direction, and a signal for instructing paper replacement. An electric typewriter comprising: a control device that controls the motor when a detection signal is input, stops the motor when a detection signal is output from the detection means, and then releases the holding torque of the motor after a predetermined period of time.