JPS62226007A - Position detecting device for printer - Google Patents

Abstract

PURPOSE:To eliminate an error at the time of detecting a position, and to simplify an adjustment of an interval between a magnetic scale and a magnetic sensor, by providing a plane being parallel to the axis center, on the overall length, to one piece of guide shafts, and performing multiple magnetization onto said plane. CONSTITUTION:As for one piece of guide shaft 24 of those which are used by combining >=2 pieces, a magnetic material is baked to its plane part, and by performing magnetization a little to said material, a magnetic scale is formed. Also, a magnetic sensor 27 is attached to a carriage 26, and a degree of parallelization of the surfaces of the scale 28 and the sensor 27 is determined by a minute size tolerance of the shaft 24 and a shaft movably fitting hole of the carriage 26, and a variation of a position signal does not occur in case of a practical use. Also, as for the carriage 26, a groove for attaching the sensor 27 is worked, and on its groove, a surface A of almost the same surface as the scale 28, and a surface B for fixing a surface C of the sensor 27 and holding an interval of the scale 28 and the sensor 27 are provided. Its interval is the same as a step difference of the surfaces A, B, and the accuracy is obtained easily by a machine work. In this way, a position is detected with high accuracy, and also, the adjusting work is simplified.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a printer head position detection device for various printers such as wire tod matrix printers and thermal transfer printers, and in particular to a position detection device that uses a magnetic scale and a magnetic sensor. This relates to a detection device.

[Prior art]

Conventionally, in printer head drive mechanisms, a rotary encoder is installed on the servo motor for head drive to detect the rotation angle of the servo motor to position the printer head. A common method is to perform positioning. FIG. 4 is a schematic perspective view showing the drive mechanism. In this figure, 1 is a print head, 2 is a drive motor, 3 is a rotary encoder, 4 is a drive belt, 5 and 6 are guide shafts, 7 is a print platen, and 8 is a carriage. In the above configuration, the positioning of the print head is performed indirectly via the drive belt by detecting the rotation angle of the motor with a rotary encoder, so that positioning errors are likely to occur due to elongation of the drive belt due to changes over time.

In addition, as a means to compensate for the drawbacks of the indirect positioning device,
Direct printhead positioning devices have been used. Specifically, it is as shown in the schematic perspective view of FIG.

In this figure, 1.2, 4.5, 6□ 7.8 indicate the same items as in Figure 4. A rotary encoder is not attached to the drive motor; instead, a magnetic scale 9 is fixed to a bracket/nod (as shown) mounted on a pedestal, a magnetic sensor 10 is carried on a carriage, and the two are placed facing each other. ing. In this configuration, the print head is positioned by detecting the magnetic signal from the magnetic scale with a magnetic sensor mounted on the carriage and controlling the motor, so that positioning errors due to elongation of the drive heald, etc. do not occur.

However, since the magnetic scale is supported on a stand and the magnetic sensor is supported on a carriage, each of which is supported on separate bases, it is extremely difficult and complicated to set the distance between the magnetic scale and the magnetic sensor with high precision. Adjustment work is required. Furthermore, reducing the difference in the distance when the carriage moves from the right end to the left end similarly requires complicated adjustment work.

Accurately setting the distance between the magnetic scale and the magnetic sensor is the most important point for maintaining stability and accuracy for magnetic encoders.

(Unexamined Japanese Patent Publication No. 6O-206665) [Problems to be Solved by the Invention] In the indirect position detection device using the rotary encoder described above, errors are likely to occur in detecting the position N of the print head.
, Direct position detection devices that use a linear encoder with separate magnetic scale and magnetic sensor have the problem that setting the interval between the magnetic scale and magnetic sensor with high precision requires extremely difficult and complicated adjustment work. have.

The purpose of the present invention is to easily adjust the distance between the magnetic scale and the magnetic sensor without causing errors in position detection.
The object of the present invention is to provide a position detector that can transmit information with high precision.

[Means for solving problems]

The present invention is characterized in that one of the plurality of guide shafts is provided with a plane parallel to the axis along the entire length of the guide shaft, and multipolar magnetization is performed on this plane. .

Guide shafts are usually used in combination of two or more, but by making one of them double as a magnetic scale and also attaching a magnetic sensor to the carriage, it is possible to control the relative position of the magnetic scale and magnetic sensor, especially the parallelism of their surfaces. is determined by the dimensional tolerance between the guide shirt) and the guide shaft fitting hole of the carriage, which is 10 to 20 μm.
is within the range of With the above-mentioned difference in parallelism, fluctuations in the position signal do not occur in practice, and stable position control can be performed.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is a perspective view of the main parts of a printer head according to the present invention. 21 is the print head, 22 is the transverse feed motor, and 23 is the drive belt with a pulley on the opposite side of the motor.
(When shown) 24 and 25 are guide shirts!・Both sides are fixed to the pedestal (as shown). 26 is a carriage node, 27 is a magnetic sensor attached to the carriage, and 28 is a guide shaft 24.
29 is a printing platen, which is also rotatably fixed at both ends to a pedestal (as shown).

In this embodiment, a magnetic paint is baked onto the flat surface of the guide shaft 24 and subjected to slight magnetization to form a magnetic scale.

Figure 2 shows the print head, carriage, guide shaft,
FIG. 2 is an explanatory diagram showing a mutual arrangement relationship between a magnetic scale and a magnetic sensor. The carriage 26 has a guide shaft 2
4 and a groove for attaching the magnetic sensor 27 are machined. The groove has two planes, an A plane and an 8 plane,
The A side is machined to have dimensions that are approximately on the same plane as the magnetic scale 28.

The 8th surface is for holding the magnetic scale 28 and the magnetic sensor 27 at a predetermined interval, and the 0th surface of the magnetic sensor is pressed against this and fixed. Here, the interval between the magnetic scale and the magnetic sensor is the same as the step size between the A side and the B side, and the interval accuracy is the same as the step size accuracy. It is easy to reduce the dimensional accuracy of the step to 1/100 m or less by machining, and there are situations where the interval accuracy must also be adjusted.
Can be easily maintained at 100 mm or less. Also, the accuracy of the spacing between the magnetic scale and the magnetic sensor when the carriage moves from the left end to the right end in Figure 1 is determined by the accuracy of the alignment of the guide shaft with the hole in the carriage, and this is also 1/100.
It is easy to make it smaller than a dragon, and there is no need for any adjustment during assembly.

FIG. 3 shows another embodiment of forming a magnetic scale.

(a) is the side where a parallel part is formed by grinding parallel to the axis of the guide shaft 24, a groove is machined in the longitudinal direction, and a plastic magnet 29 is embedded in this groove to form a magnetic scale; (b) This is an example in which the guide shaft 24 is made of an iron-chromium-cobalt alloy and is directly used as a magnetic scale.

〔Effect of the invention〕

According to the present invention, errors that occur in an indirect position detection device using a servo motor with a rotary encoder can be prevented, and compared to a direct position detection device in which a magnetic scale and a magnetic sensor are installed separately, the magnetic scale and the magnetic sensor are installed separately. The accuracy of the sensor spacing is improved, allowing highly accurate position detection and simplifying adjustment work.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a printer head according to the present invention, FIG. 2 is a perspective view of main parts according to the present invention, FIG. 3 is another embodiment of the present invention, and FIG. 4 is a conventional printer head. FIG. 5 is a perspective view showing another conventional printer head. 1.21...Print head, 24.25...Guide shaft, 27...Magnetic sensor, 28...Magnetic scale. Figure 2 Figure 3 (G) (b)

Claims (2)

[Claims] (1) A platen, a carriage on which a print head is mounted, a drive section that fixes a loop-shaped drive belt to the carriage and moves the carriage via the drive belt by rotation of a drive motor, and a drive unit that is fitted to the carrier. A printer consisting of a guide section that guides the carriage in a predetermined direction using a plurality of guide shafts, and a position detection device that stops the carriage at a predetermined position using a magnetic scale and a magnetic sensor or a servo motor with a rotary encoder. A position detection device for a printer characterized in that one of the shafts is also used as a magnetic scale. (2) The printer according to claim 1, wherein the guide shaft has one plane parallel to the axis over its entire length, and a magnetic scale is provided on this plane. position detection device