JP2000296650A - Position detection means - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately record with a long unit or the like by providing a U-shaped sensor for reading a pulse from an encoder fence to detect a position of a print head, and arranging one or above U-shaped holders covering parts of the fence oppositely to the sensor. SOLUTION: An encoder fence is clamped at its one end 4a at a protrusion 5a of a frame 5 with a screw 6 and clamped at a protrusion 5b of the frame 5 with a spring 7 engaged with a hole 4b of the other end with a screw 6. A mounting direction of the fence coincides with an axial direction of a guide shaft 2, namely, a direction A of a main scanning direction. A U-shaped holder 8 is disposed at a center of the direction A of the fence, and fixed to a protrusion 5c of the frame 5 to surround the fence from its lower side. The sensor 3 is mounted to be opposed to the holder 8 through the fence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head position detecting means for an ink jet printer or the like.

[0002]

2. Description of the Related Art Hitherto, a position detecting means comprising an encoder fence and a sensor for reading a pulse from the encoder fence has been used for detecting the position of a print head.

FIG. 6 shows an example of an encoder fence holding structure in such a position detecting means.

In FIG. 1, an end 4a of an encoder fence 4 is fixed to a projection 5a provided on a frame 5 with a screw 6, and the other end of the encoder fence 4 is fixed to a projection 5b of the frame 5. 4 b is locked by a screw 6 via a spring 7.

[0005]

In the conventional structure described above, that is, the encoder fence holding structure in which one end 4a of the encoder fence 4 is fixed and the other end 4b is locked by a spring 7,
If the hand is touched by mistake, there is a problem that the encoder fence 4 comes off from the detection position of the U-shaped sensor 3 surrounding the encoder fence 4.

Further, the pulse print signal from the sensor 3 is disturbed due to the vibration of the encoder fence 4, causing a problem that the print quality is deteriorated. In particular, in the case of a high-resolution machine where the demand for printing accuracy is high, or in the case of an encoder fence for a long machine, the situation is even more so.

As a measure for solving the above problem, a method of attaching the encoder fence to another rigid member so as not to be deformed is considered. However, in this case, the member to which the encoder fence is pasted is likely to be warped or distorted, and it is necessary to maintain the mounting position of the encoder fence with high accuracy, and the mounting operation itself is difficult. For these reasons, there has been a problem that the distance between the sensor and the encoder fence varies and the position is disturbed, thereby deteriorating the print quality.

It is an object of the present invention to improve the above-mentioned drawbacks and to provide an encoder fence holding structure capable of performing high-precision recording even in the case of a high-resolution machine or a long machine.

[0009]

According to a first aspect of the present invention, there is provided an encoder fence having one end fixed and the other end locked by elastic means along a main scanning direction of a print head. A printing apparatus, which is provided so as to cover a part of the encoder fence, and has a U-shaped sensor for reading a pulse from the encoder fence and detecting a position of a print head, facing the U-shaped sensor. And at least one U-shaped holder that covers a part of the encoder fence.

[0010] Preferably, a vertical gap between the U-shaped holder and the encoder fence is smaller than a portion covered by the U-shaped sensor in the vertical direction of the encoder fence.

Further, in order to solve the above-mentioned problem, the U-shaped holder may be provided with a cushioning material for absorbing the vibration of the encoder fence.

Alternatively, a projection is provided on the U-shaped holder, and a hole is provided at a position facing the projection on the encoder fence so that the projection does not come in contact with the encoder fence. May be prevented.

According to the position detecting means having the above structure, even if the encoder fence touches the encoder fence by hand, the encoder fence comes into contact with the U-shaped holder, so that the encoder fence comes out of the U-shaped sensor detection range. It will not be lost.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an outline of an encoder fence holding structure as an example of the present invention.

In FIG. 1, reference numeral 1 denotes a print head of an ink jet system, 2 denotes a guide shaft for holding the print head 1 so as to be movable in an A direction which is a main scanning direction, 3
Is a U-shaped sensor of a transmission optical type. The sensor 3 is mounted on the print head 1 in order to detect the position of the print head 1. The sensor 3 is mounted so as to surround the encoder fence 4 from above.

Here, the encoder fence 4 has its end 4a fixed to the projection 5a of the frame 5 with a screw 6, and the other end of the encoder fence 4 with a spring 7 hooked into the hole 4b.
b is fixed with screws 6. Needless to say, the mounting direction of the encoder fence 4 coincides with the axial direction of the guide shaft 2, that is, the direction A which is the main scanning direction.

The encoder fence 4 is made of a transparent material such as polypropylene, and a reference pitch line 4c for blocking light from the sensor 3 is printed on the end face on the sensor 3 side.

Reference numeral 8 denotes a U-shaped holder, which is located at the center of the encoder fence 4 in the direction A and is fixed to the projection 5c of the frame 5 so as to surround the encoder fence 4 from below. Here, the U-shaped sensor 3 and the U-shaped holder 8 are mounted so as to face each other via the encoder fence 4.

Reference numerals 9 and 10 denote rollers for transporting the sheet 11 in the direction of arrow B.

FIG. 2 is a sectional view showing details of the positional relationship among the encoder fence 4, the sensor 3 and the holder 8 in FIG.

The sensor 3 is provided with a light emitting section 3a and a light receiving section 3b. When the print head 1 is moved in the direction of arrow A by moving means such as a motor (not shown), the sensor 3 Sensing the line 4c,
The print signal is transmitted to the print head 1 to perform printing at a predetermined position. A detailed description of the printing operation is omitted.

Here, the encoder fence 4 and the sensor 3
And the holder 8 are not in contact with each other, and since the encoder fence 4 is mounted straight by the spring 7 as described above, the distance between the sensor 3 and the encoder fence 4 is always kept constant. As a result, the sensor 3 can accurately detect the reference pitch line 4c on the encoder fence 4.

In the direction in which the sensor 3 and the holder 8 face each other, the gap g1 between the holder 8 and the encoder fence 4 is smaller than the height (covered portion) g2 of the sensor 3 on the encoder fence 4 (g1 <g1). g2) Yes. Therefore, even if the hand accidentally touches the encoder fence 4 when not printing or the like and the encoder fence 4 is pushed down as shown in FIG. The problem of coming off is eliminated.

Further, from the state where the encoder fence 4 of FIG.
Needless to say, by removing the external force applied to the encoder fence 4 in FIG. 2 by the restoring force of the spring 7.

FIG. 4 is a sectional view showing the details of the positional relationship among the encoder fence 4, the sensor 3, and the holder 8, which is another example of the present invention.

In the figure, the holder 8 is provided with a cushioning material 12 for absorbing the vibration of the encoder fence 4.
The cushioning material 12 is desirably soft enough to not impair the linearity of the encoder fence 4, for example, a sponge having a low hardness. According to this configuration, the vibration of the encoder fence 4 caused by the movement of the print head 1 can be suppressed, and stable print quality can be obtained even in the case of a high-resolution machine or a long machine in which the encoder fence 4 is long. It is.

FIG. 5 is a sectional view showing the details of the positional relationship among the encoder fence 4, the sensor 3, and the holder 8, which is another example of the present invention.

In the example shown in FIG. 5, a pin 8a which is a projection is provided on the holder 8 and the pin 8 of the encoder fence 4 is provided.
A hole 4d, which is larger than the pin 8a, is provided at a position opposite to the hole a. According to this configuration, the encoder fence 4 can be prevented from coming off the holder 8.

In the above description, only one holder 8 is provided, but a plurality of holders 8 may be provided.

[0031]

As described above, according to the present invention, one end of the encoder fence is fixed and the other end is locked by a spring. The encoder fence can be held straight without bending without touching the encoder fence without touching the encoder fence even if an external force is applied to the encoder fence. However, since the encoder fence abuts on the holder, the encoder fence does not come off from the sensor.

Further, since the holder is provided with a cushioning material for absorbing the vibration of the encoder fence, the sensor can read the signal of the encoder fence stably and maintain high print quality.

Furthermore, since the holder is provided with a projection which does not contact the hole of the encoder fence, it is possible to prevent the encoder fence from coming off the holder.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an encoder fence holding structure as an example of the present invention.

FIG. 2 is a partial sectional view showing details of FIG. 1;

FIG. 3 is a partial sectional view showing details of FIG. 1;

FIG. 4 is a partial sectional view showing another example of the present invention.

FIG. 5 is a partial sectional view showing another example of the present invention.

FIG. 6 is a perspective view showing a conventional encoder fence holding structure.

[Explanation of symbols]

1 is a print head, 2 is a guide shaft, 3 is a sensor, 4 is an encoder fence, 5 is a frame, 6 is a screw, 7 is a spring, 8 is a holder, 9 and 10 are rollers,
Reference numeral 11 denotes a sheet, and 12 denotes a cushioning material.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masato Katada 1060 Takeda, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Naoto Ueda 1060 Takeda Hitachinaka City, Ibaraki Prefecture F-term in Hitachi Koki Engineering Co., Ltd (Reference) 2C480 CA01 CA31 CA49 CB35 CB40 EC04

Claims (4)

[Claims] 1. An encoder fence having one end fixed and the other end locked by elastic means along a main scanning direction of a print head, and disposed so as to cover a part of the encoder fence. A printing apparatus comprising a U-shaped sensor that reads a pulse from the encoder fence and detects a position of a print head, wherein the U-shaped sensor faces the U-shaped sensor and covers a part of the encoder fence. Position detecting means for a printing apparatus, wherein at least one holder is provided. 2. The position detecting means of a printing apparatus according to claim 1, wherein a vertical gap between said U-shaped holder and said encoder fence is provided by said U-shaped sensor in a vertical direction of said encoder fence. A position detecting means of the printing apparatus, wherein the position detecting means is smaller than a portion to be covered. 3. The position detecting means according to claim 1, wherein said U-shaped holder is provided with a cushioning material for absorbing vibration of said encoder fence. 4. A projection is provided on the U-shaped holder, and a hole is provided at a position of the encoder fence facing the projection so that the projection does not come into contact with the encoder fence. 4. A position detecting means for a printing apparatus according to claim 1, wherein said position detecting means prevents the position from being detected.