JPH0226594B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a home position setting device for a carriage in a serial printer, and more particularly to a serial printer in which the carriage is fed horizontally by a stepping motor.

[Conventional technology]

Conventionally, in this type of serial printer,
A carriage carrying a printing device and the like is slidably held on a guide shaft, and the carriage is driven laterally by a stepping motor via a wire rope or the like to print serially. The carriage is moved from a fixed home position set at the start of printer operation to a predetermined position in predetermined steps by driving the stepping motor. Conventionally, in order to set the home position, a Hall element, a magnet, a micro switch, a photo sensor, etc. are used to detect that the carriage has moved to the home position and stop driving the stepping motor. are doing.

[Problem that the invention seeks to solve]

Therefore, the conventional home position setting device is
The various sensors mentioned above and cable wiring for operating them are required, resulting in a complicated structure. Further, there are disadvantages such as the sensor detection ability changes due to temperature changes and the carriage home position changes, and the sensor is prone to failure, and the cost is high.

The purpose of the present invention is to solve the above-mentioned conventional drawbacks and
It is an object of the present invention to provide a carriage home position setting device for a serial printer, which eliminates the need for sensors and can stably set the home position of a carriage at low cost.

[Means for solving problems]

The setting device of the present invention is a serial printer in which a stepping motor drives a carriage slidably held on a guide shaft, and the setting device of the present invention is such that the stepping motor moves the carriage at least over the entire length of the guide shaft. The present invention is characterized in that it includes excitation means that drives the carriage a predetermined number of steps to cause the carriage to collide with a structure provided near one end of the guide shaft, and after the collision, excite the carriage in a fixed manner with a specific excitation phase.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention. That is, the stepping motor 1 is fixed to a frame 2 by suitable means, and a drum 3 having a spiral groove is coaxially fixed to the shaft of the stepping motor 1. Both ends of the wire rope 7 are wound around the spiral groove of the drum 3 a plurality of times in opposite directions, and then each end is latched to the drum 3. And wire rope 7
is guided by a guide pulley 6 and is attached to the carriage 4 with screws 9 via a plate 8 fixed in the middle of the rope.

A long hole is bored in the plate 8, and a screw 9 is inserted into the plate 8.
The mounting position can be adjusted by tightening. The carriage 4 is slidably held by two guide shafts 5 and is movable in the left-right direction (lateral direction) in the figure. The guide shaft 5 is, of course, fixed at both ends to the frame 2, and slides and guides the carriage 4 parallel to a platen (not shown). Then, by driving the stepping motor 1, the drum 3 is
When the carriage 4 rotates, the wire rope 7
can be driven in either left or right direction. Of course, the carriage 4 moves in steps according to the rotation of the stepping motor 1. A stopper 10 is fixed to the left end of the guide shaft 5 in the figure, slightly outside the home position of the carriage 4. It is preferable that the stopper 10 be made of an elastic material such as rubber, from the viewpoint of noise prevention.

The stepping motor of this embodiment has, for example, four phases, and is driven by excitation of two of the four phases,
The rotation angle of one step, that is, the step angle is θ
It is. Fig. 2 is a diagram showing the combination and order of exciting the four phases φ1 to φ4 of the stepping motor. Assuming that the phases φ1 and φ2 are at the rotation angle a when excited, φ2, φ3 By excitation of , b rotates by θ, and by excitation of φ3 and φ4, c becomes,
By excitation of φ4 and φ1, it becomes d. Next, when φ1 and φ2 are excited, the position e is rotated by 4θ from a, and thereafter, the position is sequentially rotated one step at a time from f to i... These rotational positions naturally correspond to the amount of lateral movement of the carriage 4. Therefore, from now on, the above symbols a, b,
c, d... represent the positions of the corresponding carriages 4. In FIG. 2, the excited phases are indicated by ●.

In this embodiment, when initializing the printer, the stepping motor 1 is excited and driven by a drive source (not shown) for a predetermined number of steps required for the carriage 4 to move laterally over its entire length on the guide shaft 5. Therefore, no matter where the carriage 4 is at first, it collides with the stopper 10 and stops, but even after that, the stepping motor 1 continues to be excited, and after the predetermined number of steps, it is finally located at the home position. For example, φ1 and φ2, which are specific excitation phases, are fixedly excited. Such excitation means can be easily realized using a drive source and a simple control circuit (not shown).
Of course, the stepping motor 1 loses synchronization and does not rotate.

However, if the carriage 4 is now stopped at the position indicated by the symbol B in FIG. It is pulled back and stopped. Due to the nature of stepping motors, when phases φ1 and φ2 are excited, the second
Since it can only stop at position a, e, or i shown in the figure, the forced stop position by a stopper etc. is within the range indicated by symbol A in the figure (corresponding to less than 4 times the step angle θ). In this case, it will make a final stop at the position. If the mounting position of the plate 8 is adjusted in advance so that this position e is the desired position, it is possible to set the home position of the carriage 4 at the correct position. If the carriage 4 collides with the stopper 10, there is a risk that the carriage 4 will rebound beyond the above-mentioned range A and the final stop position will be at a, so it is desirable that the stopper 10 be formed of an elastic material such as rubber.
This is desirable from the viewpoint of noise and the like.

The above-mentioned home position setting may be performed, for example, each time printing of each line is started, but this is not desirable in terms of noise and life expectancy. It is easy to make the above settings only when initializing the printer, and thereafter use the stepping motor to control so as not to exceed a predetermined range. That is, in normal printer operation after the home position is once set, the home position is used as the reference point for control, so the stopper is never hit.

It goes without saying that the above-mentioned stepping motor can be constructed in the same manner even if it is a linear stepping motor instead of a rotary stepping motor.

〔Effect of the invention〕

As described above, in the present invention, the stepping motor is driven a predetermined number of steps that the carriage moves at least over the entire length of the guide shaft, and the carriage collides with the stopper to cause the stepping motor to step out of step. The home position of the carriage is set by the self-holding force of the stepping motor through fixed excitation of a specific excitation phase set in advance. Sensors and accompanying wiring and control circuits are not required; simply providing a means for driving a predetermined number of steps or more and fixed excitation of a specific excitation phase is sufficient, and the sensor can be provided at a low cost and can be used to accurately determine the home position. This has the effect of allowing settings to be made. Furthermore, there is no change in the setting position due to temperature fluctuations or the like.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention. Second
The figure is a diagram showing an example of the relationship between the stepping motor excitation phase and position for explaining the operation of the above embodiment. 1...Stepping motor, 2...Frame, 3...
Drum, 4...carriage, 5...guide shaft,
6...Guide pulley, 7...Wire rope, 8...Plate, 9...Screw, 10...Stopper.

Claims (1)

[Scope of Claims] 1. In a serial printer in which a stepping motor drives a carriage slidably held on a guide shaft, the stepping motor moves the carriage at least over its entire length on the guide shaft. A serial printer characterized in that the serial printer is provided with excitation means that drives the carriage a predetermined number of steps to cause the carriage to collide with a structure provided near one end of the guide shaft, and after the collision, excite the carriage in a fixed manner with a specific excitation phase. Carriage home position setting device. 2. A stopper is provided for stopping the carriage slidably held by the guide shaft slightly outside the home position, and the excitation means is configured to control the stepping motor so that the carriage is at least at the guide shaft position only when the power of the printer is turned on. Claim 1, further comprising means for fixedly exciting the stepping motor at a specific excitation phase after causing the carriage to collide with the stopper by driving the stepping motor a predetermined number of steps sufficient to move the stepping motor over its entire length. A carriage home position setting device for a serial printer according to item 1.