JPS61286173A - Original point setter for type wheel - Google Patents

Abstract

PURPOSE:To enable an original point of a type wheel to be set without using expensivemembers, by a system wherein a non-toothed part of a gear rotated as one body with a type wheel is engaged with a rack to thereby set the original point of the type wheel. CONSTITUTION:When a power source is thrown in under the condition where a type 23a indicating the original point of the type wheel 23 is stopped at an arbitrary position, a carriage 18 is moved leftward, and a gear 24 is rotated counterclockwise in engagement with the rack 26. When the non-toothed part 24a of the gear 24 is engaged to the rack 26, the rotation of the gear 24 is stopped. At this time, the type 23a is located in the vicinity of the uppermost position. The carriage 18 is moved further leftward under this condition, and reaches the original point position set in the vicinity of a frame 11. At this time, the movement of the carriage 18 is stopped, and a stepping motor 21 is excited with respect to a predetermined exciting phase, whereby the type 23a is maintained at the uppermost position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing device using a type wheel, and more particularly to an origin setting device for setting the origin of the type wheel.

[Prior art] A type wheel arranged with a large number of types is rotated by a step motor to select and arrange the desired type at a printing position facing a hammer, and then the type is struck by the hammer onto printing paper on a platen to form the desired type. In a printing device designed to print type, type selection is performed by rotating a type wheel by a predetermined step starting from a fixed origin position. In such a printing device, the origin position of the type wheel is located at an arbitrary location before the power is turned on, and furthermore, when the type wheel is touched by a hand during replacement or the like, its stop position becomes uncertain.

Therefore, it was necessary to set the origin of the type wheel to the printing position when the power was turned on.

Therefore, conventionally, as shown in FIG.
A photointerrupter 3 and a motor 2 are arranged facing each other.
An origin setting device is provided, which includes an origin sensing plate 4 attached to the rear end of the shaft of the motor 2, which passes between the light emitting section 3a and the light receiving section 3b as the motor 2 rotates to block the light emitted by the light emitting section; When the type wheel 1 is rotated when the power is turned on and the origin detection plate 4 blocks the light from the light emitting part 3a, the type wheel 1
The origin position of the type wheel 1 was set by stopping the rotation of the type wheel 1.

[Problems to be Solved by the Invention] In addition to those using the photointerrupter, there are also devices that use an optical encoder as an origin setting device for setting the origin position of the type wheel, but all of these components are expensive. Therefore, the printing device itself has become expensive.

[Object of the Invention] The present invention has been made to solve the problems of conventional origin setting devices. To provide an inexpensive origin setting device capable of setting an origin.

[Means for Solving the Problems] In order to solve the problems of conventional origin setting devices, the present invention provides a step motor that rotationally drives a type wheel on which a large number of type characters are arranged, and a step motor that controls the step motor. A control means for arranging desired type characters at a printing position, a gear that rotates integrally with the type wheel and has a toothless portion in a part thereof, and these type wheels, gears, and a step motor are mounted. , a carriage that moves parallel to the platen, and a rack that is provided outside the printing area and meshes with the gear when the carriage moves outside the printing area.

[Operation] In the present invention, with the above configuration, when the carriage moves outside the printing range and the toothless part of the gear and the rack part are engaged, the control means controls the predetermined excitation phase of the step motor. is energized to place a predetermined type at the printing position, which serves as the origin of the type wheel.

[Example] An example embodying the present invention will be described with reference to FIGS. 1 to 8.

FIG. 1 shows a plan view of this embodiment, in which left and right frames 11
．． A platen 14 is rotatably indicated between the plates 12 and 12 by a support shaft 15, and printing paper can be supported around the outer periphery of the platen 14. The length of the platen 14 is shorter than the length of the support shaft 15, and the platen 14 is mounted to the right of the support shaft 15. A guide shaft 17 is attached between the frames 11 and 12 so as to extend parallel to the platen 14 and the support shaft 15. A carriage 18 is slidably supported on this guide shaft 17, and is driven and controlled by a control circuit 30 via a carriage drive means 19 consisting of a motor (not shown) or the like.

A step motor 21 for character selection is mounted on the carriage 18. The step motor 21 is a PM type or hybrid type step motor having four excitation phases, and rotates intermittently when a force is applied to the shaft 21a in a non-excited state. A type wheel 23 on which a large number of type characters are arranged is attached to the platen side of the shaft 21a of the step motor 21. Also, step motor 2
At the other end of the shaft 21a of No. 1, there is a partially toothless portion 24a.
A gear 24 is attached. This gear 24 is connected to the shaft of the step motor 21 so that when the missing tooth portion 24a is positioned downward as shown in FIGS. 2
It is fixed at 1a. The step motor 21 is driven and controlled by a control circuit 30 via a driver 22.

This drive control method is a method in which two of the four excitation phases of the step motor 21 are excited by sliding one phase at a time. With this excitation method, the stepper motor 21 rotates once in 96 steps corresponding to the 96 characters on the type wheel 23. Therefore, there are 24 printed characters that are selectively arranged at predetermined positions in the same excitation phase, and the interval between the printed characters is 15 degrees. Therefore, when a predetermined excitation phase of the step motor 21 is excited to selectively arrange a predetermined type at a predetermined position, if the angular difference between the position of the type and the predetermined position is within 15 degrees on the left and right sides, the predetermined By energizing the excitation phase of , a predetermined type can be selectively placed at a predetermined position.

Therefore, the central angle of the toothless portion 24a of the gear 24 is 15 degrees at most.

A rack 26 having teeth provided at equal intervals on its upper surface is fixed to the left frame 11. This rack 26 has a length at least equal to the circumference of the gear 24, and is located toward the left from the printing start position. When the carriage 18 moves further to the left than the left end of the platen 14, the gear 24 and the rack 26 mesh with each other.

Furthermore, a carriage origin detection mechanism 34 composed of a microswitch or the like is attached to the left frame 11. The carriage origin detection mechanism 34 is connected to the left frame 1.
It is detected that the carriage 18 has moved to the carriage origin set near 1, and a signal indicating this is output to the control circuit 30.

As shown in FIG. 2, the control circuit 3o is connected with a keyboard 32, a driver 22 for the step motor 21, a carriage drive means 19, a carriage origin detection mechanism 34, and the like. The control circuit 30 then controls the type wheel 2
A program for controlling the operation of the entire printing device, such as the relative position of each type with respect to the origin of No. 3, is stored, and each member is driven and controlled based on the program.

The operation of this embodiment configured as above will be explained.

Before the power is turned on to the printing device, as shown in FIG. 3, the type 23a indicating the origin of the type wheel 23 is stopped at an arbitrary position. When the power is turned on from this state, the control circuit 30 does not excite the step motor 21.
The carriage 18 is moved to the third position via the carriage drive means 19.
Move to the left in the diagram. Carriage 18 is platen 1
4, the gear 24 and the rack 26 mesh with each other as shown in FIG. As the carriage 18 is moved to the left in FIG.
1 is in a de-energized state, -car 24 is in the rack 26
It rotates counterclockwise in the same figure while engaging with the Accordingly, the shaft 21a of the step motor 21 and the type wheel 23
also rotates counterclockwise in the same figure. And carriage 1
8 continues to move to the left, and as shown in FIG.
When the toothless portion 24a of No. 4 engages with the rack 26, the gear 24
The rotation in the counterclockwise direction is stopped, and accordingly, the rotation of the shaft 21a of the step motor 21 and the type wheel 23 is also stopped. At this time, the type 23 indicating the origin of the type wheel 23
a is placed near the uppermost position as shown in FIG.

In this state, the carriage 1B is further moved to the left, and the carriage 18 is set near the frame 11 on the left side.
reaches the origin position. The carriage origin detection mechanism 34 detects that the carriage 18 has reached the origin position, and outputs a signal indicating this to the control circuit 30. The control circuit 3o is
Immediately upon receiving this signal, the carriage drive means stops the movement of the carriage 18 to the left as shown in FIG. 6, and the driver 22 excites a predetermined excitation phase of the step motor 21. Due to this excitation, the printed characters 23a located near the uppermost position are maintained at the uppermost position as shown in FIG. In FIGS. 5 and 6, even if the type 23a indicating the origin of the type wheel 23 is placed at a position slightly shifted from the uppermost position, the displacement is corrected by excitation of a predetermined excitation phase, and the As shown in FIG. 7, the printed characters 23a are placed and held at the uppermost position.

Thereafter, the control circuit 30 moves the carriage 18 to the right in FIG.
Place it at the print start position shown in the figure.

In this position, the type wheel 23 faces the printing paper which is supported around the platen 14. And the keyboard 32
Based on the input signal, the control circuit 30 rotates the step motor 21 by a predetermined amount via the driver 22 to place the desired type at the uppermost position and perform a printing operation.

Note that the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit thereof. For example, as long as the toothless portion 24a of the gear 24 and the rack 26 are engaged, a predetermined excitation phase of the step motor 21 may be excited at any position on the rack 26.

[Effects of the Invention] As described above, the type wheel origin setting device according to the present invention can eliminate the need for a gear wheel that rotates integrally with the type wheel without using expensive components such as a photointerrupter or an optical encoder. The origin of the type wheel can be set by energizing a predetermined excitation phase of the step motor while the teeth are engaged with a rack provided outside the printing range. Printing equipment can be provided.

[Brief explanation of the drawing]

1 to 8 show a type wheel origin setting device according to the present invention, FIG. 1 is a plan view, FIG. 2 is an electrical block diagram, FIGS. 3 to 8 are enlarged views of main parts, and FIG. The figure is a partially enlarged perspective view of a conventional example. In the figure, 14 is a platen, 21 is a step motor, 23 is a type wheel, 24 is a gear, 24a is a toothless portion, 26 is a rack, and 30 is a control circuit (control means).

Claims (1)

[Claims] A type wheel (23) in which a large number of type characters are arranged, and a step motor (2) that rotationally drives the type wheel (23).
1); a control means (30) for controlling the step motor (21) to position desired characters in the type wheel (23) at a printing position; , a gear (24) having a toothless part (24a) in a part thereof, the type wheel (23), the gear (24), and the step motor (21) are mounted, and are mounted against the platen (14). a carriage (18) that moves in parallel with the printing area; and a rack part (26) that is provided outside the printing area and meshes with the gear (24) when the carriage (18) moves outside the printing area. , in a state in which the toothless portion (24a) of the gear (24) and the rack portion (26) are engaged, the control means (30) controls the step motor (2).
1) A type wheel origin setting device characterized in that a predetermined excitation phase of 1) is excited to place a predetermined type character at a printing position and set the origin of the type wheel (23).