JPH0213165Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a position detection device for a printing unit in a serial printer used as an output device of an information processing device. It is possible to accurately and reliably detect whether or not the printing unit has returned to the left end without being affected by paper dust or the like.

FIG. 1 is a plan view showing an outline of a conventional serial printer, and FIG. 2 is a front perspective view of a print head. A printing paper 2 is wound around the platen 1, and a printing unit consisting of a printing head 5 mounted on a carrier 6 is supported by a guide shaft 3 with a feed screw and a guide shaft 4 arranged parallel to the platen 1. ing. The guide shaft 3 with a feed screw is rotationally driven by a space motor 8 via a timing belt 7, so that the print head 5 is transported in the space direction shown by arrows a ₁ and a ₂ .

At the tip of the print head 5, as shown in FIG. 2, vertical lines of wires W ₁ , W _{2 ,} . While space feeding at a predetermined speed, at each time t ₁ , t ₂ ... at a constant cycle,
By selectively driving and protruding the wires W ₁ , W ₂ . . . using magnets built into the head 5, the paper 2
For example, a character such as "A" is printed on the top by a combination of dots 9, . . . .

By the way, there is no problem if the medium to be printed on is thin such as continuous paper 2 or a single sheet, but
In the case of a thick bankbook 10 as shown in the figure, it is necessary to increase the distance between the printing head 5 and the platen 1. For this purpose, conventionally, as shown in FIG. 3, the guide shaft 4 is rotatable around the guide shaft 3 with a feed screw, and when printing on a thick soot body 10, a carrier 6 is attached to the guide shaft 4. is rotated in the direction of arrow _a3 , and the printing head 5 is moved back to the position shown by the solid line. Although this retraction is necessary during printing operations and reversing operations, it is especially necessary when attaching and detaching the medium 10.

However, if the carrier 6 is made rotatable around the guide shaft 3 in this way, it can be detected that the carrier 6 has arrived at the left end, which is the home position, or that the carrier 6 has passed a specific position on the way. Special measures are required to detect the position. That is, normally, a detector 11 consisting of a light emitting element and a light receiving element is arranged at the left end position of the apparatus as shown in FIG. The left end is detected by the plate 13 arriving and blocking the light emitted from the light emitting element from being received by the light receiving element.

When the carrier 6 rotates around the guide shaft 3, the shielding plate 13 also rotates together with the carrier 6, so even if the shielding plate 13 rotates, the shielding plate 13 does not close to the slit 1.
It is necessary to make the width of the slit 12 sufficiently wide so that it can fit into the slit 2. However, in this case, the detection by the detector 11 is hindered, and the detection accuracy is reduced. Therefore, the width of the slit 12 of the detector 11 is reduced by attaching the shielding plate 13 to the carrier 6 near the guide shaft 3 with a feed screw, which rotates only a small amount. 3 is located directly below the print medium, so
Paper dust generated from the print medium is likely to accumulate on the light emitting surface and light receiving surface of the detector 11, requiring frequent cleaning of the detector, making handling inconvenient for the user.

The purpose of the present invention is to solve such problems in conventional position detection devices.To achieve this purpose, the present invention has developed a printing unit having a carrier 6 on which a print head 5 is mounted.
By printing on the printing medium on the platen while moving along the guide shaft 4, and by rotating the printing unit around the other guide shaft 3,
In a printer configured such that the print head 5 is retracted from the platen, a detected member, that is, a shielding plate 14 is provided separately from the carrier 6, and the detected member 14 is connected to the guide shaft 4. It is guided so that it can move in parallel directions.

In addition, in the middle of the path of the printing unit, the detection target member 14 is placed in the middle of the path of the printing unit so that the printing unit comes into contact with the detection target member 14 and moves the detection target member 14 to the detection position. Member 14
Part 20 of the figure is prominent.

A detector 11 is provided to detect the detected member 14 when the detected member 14 arrives at the detection position.

Next, an embodiment of the position detection device according to the present invention will be described. FIG. 5 is a perspective view showing the position detection device, and parts corresponding to those in FIGS. 1 to 4 are designated by the same reference numerals. In the case of the present invention, numeral 14 is a shielding plate, which is separate from the carrier 6. The guide shaft 1 is attached to the sliding portions 15, 15 of this shielding plate 14.
6 is inserted and slides along the guide shaft 16. On the other hand, a guide plate 18 having a slit 17 in a direction parallel to the guide shafts 3, 4, 16 is provided, and the shielding plate 1
4 is arranged to move within the slit 17, thereby preventing the shielding plate 14 from rotating about the guide shaft 16 and becoming unstable. When detecting the left end, this shielding plate 14 is arranged between the left end and the carrier 6, and a return spring 19 is provided to pull the shielding plate 14 toward the carrier 6, so that the carrier 6 is near the left end. When the carrier 6 comes to the left end, the side wall 62 of the sliding portion 61 of the carrier 6 comes into contact with the receiving portion 20 of the shielding plate 14 to press and move the shielding plate 14 toward the left end. Therefore, as shown in FIG. 6, when the carrier 6 moves from the right end side to the left end side, the shielding plate 14 is pushed by the sliding part 61 of the carrier 6 and separated from the stopper 21, and when it reaches the left end. , the shielding plate 14 enters the slit 12 of the detector 11 disposed at the left end, and left end detection is performed. When the carrier 6 starts moving to the right after the left end is detected, the shielding plate 14 is also pulled by the return spring 19 and returns following the carrier 6. However, in the case of left end detection, it is sufficient for the shielding plate 14 to move only near the left end, so only the carrier 6 is moved from the left end to the right end, and the shielding plate 14 is moved only near the left end. At the right end of the slit 17, there is a stopper 21.
is provided to prevent the shielding plate 14 from moving further to the right.

When detecting the light end, the detector 11 is placed on the light end side, the shield plate 14 is placed near the light end, and the return spring 19
It is only necessary to set the positional relationship such that the shielding plate 14 is pulled toward the left end side. It is also possible to detect the position of the carrier 6 between the right end and the left end.

In the configuration of the illustrated example, even if the carrier 6 rotates in the direction of arrow _a3 , the shielding plate 14 does not rotate, and the receiving part 20 of the shielding plate 14 contacts the sliding part side wall 62 of the carrier 6. Even if the sliding part side wall 62 is in sliding contact with the receiving part 20. Therefore, the shielding plate 14 does not rotate, but only moves linearly in the moving direction of the carrier 6 while being guided by the slit 17, and the slit 12 of the detector 11 can be reliably moved without widening the width of the slit 12. Go inside and
The arrival of the shielding plate 14 can be accurately detected.

As is clear from the above illustrated examples, according to the present invention, when the carrier constituting the printing unit moves parallel to the guide shaft, the carrier moves in the same direction, but the printing unit does not move backward. Therefore, when rotating around the guide shaft, a shielding plate, that is, a member to be detected, is provided so that the printing unit is not affected by the rotational movement of the printing unit, and a straight line of the member to be detected is provided. It is provided with guide means for allowing only directional movement. Therefore, when a thick object such as a bankbook is used as a recording medium, even if the carrier rotates around the guide shaft together with the print head, the member to be detected for left end detection does not rotate. Since the detector is simply pushed by the carrier and moves linearly in the same direction as the carrier, unlike the conventional configuration in which the detected member also rotates, the detection accuracy may be reduced due to the wider slit width of the detector. Since the detector is placed near the guide shaft where paper dust tends to accumulate, problems such as the detector being easily soiled by paper dust are solved, and the position can be detected accurately without being affected by paper dust.

[Brief explanation of the drawing]

Figure 1 is a plan view showing an outline of a normal serial printer, Figure 2 is a front perspective view of the print head, and Figure 3 is a front perspective view of the print head.
4 is a perspective view of a conventional position detection device for a printing unit, and FIGS. 5 and 6 are views showing embodiments of a position detection device for a printing unit according to the present invention. FIG. 5 is a perspective view, and FIG. 6 is a rear view. In the figure, 3 is a guide shaft with a feed screw;
4 and 16 are guide shafts, 5 is a print head, 6 is a carrier, 10 is a thick recording medium, 11 is a detector, 1
2 is a slit, 14 is a shielding plate, 17 is a guide slit, 20 is a receiving portion, and 21 is a stopper.

Claims (1)

[Claims for Utility Model Registration] A printing unit having a carrier on which a printing head is mounted prints on a printing medium on a platen while moving along a guide shaft, and the printing unit moves along another guide shaft. A printer configured such that the print head retreats from the platen by rotating about the center, the printer having a detected member separate from the carrier;
The member to be detected is guided so as to be movable in a direction parallel to the guide shaft, and the printing unit comes into contact with the member to be detected during the movement of the printing unit, and the member to be detected is moved to the detection position. A part of the detected member protrudes in the middle of the path of the printing unit so that the detected member can be moved to a detection position, and when the detected member reaches a detection position, a detector for detecting the detected member is activated. A printing unit position detection device comprising: