JPH05109216A - Position control device - Google Patents

Abstract

PURPOSE:To reduce the cost by greatly reducing the number of optical sensors, to speedily perform an abnormality detection and an abnormality processing and to prevent the generation of defects such as a collision. CONSTITUTION:A section 2 to be detected which has the length corresponding to a traveling section S of a head unit 5 is provided to this device and unit patterns C1... and D1... whose detection signals detected by an optical sensor 3 are set '0' and '1' respectively are provided alternately and repeatedly in the longitudinal direction of the section 2. Furthermore, the length of unit pattern in a front pattern region Af and a rear pattern region Ar which is devided by home position Ph is set different from each other and an end section pattern Es of '1' that is longer than the unit pattern C1... on one part of the front end or the rear end in the section 2, is provided. Moreover, an end section pattern Ee of '0' that is longer than unit pattern C1..., is provided on the other part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control device suitable for use in an image scanner or the like for controlling the position of a movable part such as a head unit by detecting a detected part with an optical sensor.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional position control device 30 used in an image scanner or the like.

In FIG. 4, Mo is an image scanner, which comprises a platen glass 31 on which a document Wo is set, and a head unit 32 arranged below the platen glass 31. The head unit 32 is guided by the rails 33, and is moved in the left-right direction in the drawing along the lower surface of the platen glass 31 by a drive device 36 including a drive motor 34, a transmission belt 35, and the like. Further, the head unit 32 includes an image sensor 37 and a rod lens array 38.

On the other hand, 30 is a position control device. The position control device 30 is a control position such as a home position Ph located at the center of the platen glass 31 and a start position P located at one end of the platen glass 31.
s and the position of the head unit 32 at the end position Pe located at the other end of the platen glass 31 are detected and the position control of the head unit 32 is performed, and the transmission is provided at each position Ph, Ps, Pe. Type optical sensors 41h, 41s, 41e and head unit 3
2 is attached to the shutter plate 40 and an optical sensor 41.
The controller 42 is provided with which the detection signals of h, 41s and 41e are input and which outputs a control signal to the drive motor 34.

Therefore, in the reading mode, after the head unit 32 set at the home position Ph moves to one end (start position Ps) of the platen glass 31, the other end (end position Pe) is moved along the lower surface of the platen glass 31. ) And then returned to the home position Ph again. At this time, the head unit 32
Moves to the respective positions Ps, Pe, Ph, the shutter plate 40 puts the optical sensors 41s, 41e, 41h into the light-shielded state, and the position of the head unit 32 is detected, and the position control is performed based on the detected position. .. When the head unit 32 moves along the lower surface of the platen glass 31, it scans the original Wo set on the platen glass 31 to read an image.

[0006]

However, the above-described conventional position control device 30 has the positions P for position control.
Since the optical sensors 41s, 41e, and 41h must be provided for each of s, Pe, and Ph, the position Ps for position control is set.
The number of optical sensors 41s is required according to the number of ..., There is a problem that the cost is increased. Further, when the head unit 32 stops due to an external force applied during movement, or when the head unit 32 finally stops at a midway position other than the control position, the position of the head unit 32 becomes unknown, and therefore an abnormal operation state is detected. Alternatively, there is a problem that it takes time for abnormal processing such as position correction and that the head unit 32 collides with the drive motor 34 and the pulley of the drive device 36, and other parts such as the chassis.

The present invention solves the problems existing in the prior art as described above, and achieves cost reduction by drastically reducing the number of optical sensors, and at the same time, performs abnormality detection and abnormality processing promptly and causes collision. An object of the present invention is to provide a position control device that can prevent the adverse effects such as the above.

[0008]

According to the present invention, a detected portion 2 is detected by an optical sensor 3 and a movable portion 4, for example, a head unit 5 provided with an image sensor 6 in an image scanner M (or facing a head unit). When configuring the position control device 1 for controlling the position of the platen glass 7), in particular, the detected portion 2 having a length corresponding to the movement section S of the head unit 5 is provided, and the optical sensor is provided in the longitudinal direction of the detected portion 2. The unit pattern C1, C2, C3 ..., D1, D2, D3 ... In which the detection signal detected by 3 is "0" or "1" is alternately and repeatedly provided, and the front pattern area Af is divided by the home position Ph. The unit patterns in the rear pattern region Ar are provided with different lengths, and the unit patterns C2 and D2 are provided at one of the front end and the rear end of the detected portion 2. Remote end pattern Es of long "1"
And an end pattern Ee of “0” longer than the unit patterns C1 and D1 is provided on the other side.

[0009]

According to the position control device 1 of the present invention, the optical sensor 3 (single sensor) moves along the detected portion 2 by the movement of the head unit 5 which constitutes the movable portion 4. The optical sensor 3 moves to sequentially detect the unit patterns C1 ..., D1. At this time, the unit patterns C1 ... and D1 ... of the front pattern area Af and the rear pattern area Ar before and after the home position Ph have different lengths, so that the length of "0" or "1" is detected. Thus, it is possible to detect the relative position of the head unit 5 with respect to the home position Ph, that is, whether the head unit 5 is located within the front pattern area Af or the back pattern area Ar.

Therefore, for example, even when the head unit 5 is finally stopped at a position other than the control position such as the home position Ph due to an external force applied during movement,
Since the relative position of the head unit 5 with respect to the home position Ph can be detected, the home position Ph
Can be returned to. Further, whether or not the movement is normally performed can be easily monitored by the detected detection signal (pulse signal).

On the other hand, one end pattern Es of "1" longer than the unit patterns C2 and D2 is provided at one of the front end and the rear end of the detected portion 2, and the other end is provided with the unit patterns C1 and D1.
Since the end portion pattern Ee of “0” longer than that is provided, the start position Ps and the end position Pe can be detected as the absolute positions by the optical sensor 3, particularly the single optical sensor 3, and the pattern areas Af and Ar can be detected. The home position Ph can be detected as an absolute position by the change in the pattern length at the boundary.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, a schematic structure of the image scanner M will be described with reference to FIGS.

Reference numeral 7 is a platen glass on which a document W is set. Below this, a head unit 5 (movable part 4) which moves along the lower surface of the platen glass 7 is arranged. The head unit 5 incorporates an image sensor 6 and a rod lens array 12 which are elongated in the left-right direction.

The head unit 5 is guided by a pair of left and right rails 13, 13 and the drive unit 1
4 is moved (intermittent movement) in the front-back direction (left-right direction in FIG. 1). The drive device 14 includes a drive motor (stepping motor) 15, a drive pulley 16 rotated by the drive motor 15, an idle pulley 17 disposed at a position separated from the drive pulley 16, and a drive pulley 16 between the drive pulley 16 and the idle pulley 17. A transmission belt (timing belt) 18 is provided, which is arranged along the front-back direction of the platen glass 7 and fixed to the head unit 5.

Next, the configuration of the position control device 1 according to the present invention will be described with reference to FIGS. 1 and 2.

The position control device 1 comprises a transmissive optical sensor 3 comprising a light emitting portion 3a and a light receiving portion 3b which are separated from each other, and the optical sensor 3 is fixed to the lower end of the head unit 5. Further, the detection target portion 2 located between the light emitting portion 3a and the light receiving portion 3b is provided,
The detected portion 2 is arranged along the lower surface of the platen glass 7. On the other hand, 20 is a controller, which receives the detection signal of the optical sensor 3 and outputs a control signal for controlling the operation of the drive motor 15.

As the detected portion 2, a pattern plate 21 having a length corresponding to the moving section S of the head unit 5 is used. The pattern plate 21 has an optical sensor 3 on its upper half.
The unit patterns C1, C2, C3 ..., D1, D2, D3 ... whose detection signals detected by the above are “0” or “1”.
Are alternately and repeatedly formed along the longitudinal direction. As a result, the pattern plate 21 is formed in a comb shape whose upper half is uneven. Therefore, the optical sensor 3 is in a light-shielded state at the positions of the unit patterns C1, C3, ... Which are convex portions, detect “0”, and the unit patterns C2, C4 ,.
At the position of, the light is transmitted and "1" is detected. The center of the movement section S, that is, the center of the pattern plate 21 is the home position Ph, and the sections before and after this are divided into the front pattern area Af and the rear pattern area Ar, and the unit pattern C1 in each area Af and Ar. ,
C2, C3 ... And D1, D2, D3 ... Are "0" and "1"
The length of each is different. Specifically, the length of "1" (concave portion) in the front pattern area Af is shortened and the length of "0" (convex portion) is increased, and the length of "1" (concave portion) in the rear pattern area Ar is reduced. Increase the length and shorten the length of "0" (projection).

On the other hand, the front end of the pattern plate 21 is provided with an end pattern Es of "1" which is longer than the unit patterns C2 and D2, and the rear end thereof has the unit patterns C1 and D2.
An end pattern Ee of “0” longer than 1 is provided. The end pattern Es is used to detect the start position Ps, and the end pattern Ee is used to detect the end position Pe.

Next, the overall operation of the image scanner M including the function of the position control device 1 will be described with reference to FIGS.

The head unit 5 in the reading mode moves according to the arrow line X shown in FIG. First, the transmission belt 18 is moved forward by the forward rotation operation of the drive motor 15, whereby the head unit 5 moves forward. At this time, since the optical sensor 3 sequentially detects the unit patterns C8, C7, C6 ... In the front pattern area Af, the number of each pattern, the temporal length, etc. are monitored to detect the inside of the front pattern area Af. Can be detected and whether or not it is moving normally can be detected. Such detection is performed in the other pattern area A.
The same can be done for r.

When the optical sensor 3 reaches the start position Ps, "1", which is longer than the unit patterns C2 and D2, is detected, and the controller 20 causes the drive motor 15 to rotate in reverse (point 3a in FIG. 3). As a result, the head unit 5 moves from one end to the other end along the lower surface of the platen glass 7. At this time, the head unit 5
Scans the document W set on the platen glass 7 to read an image. When the head unit 5 reaches the end position Pe, which is the other end of the platen glass 7, “0”, which is longer than the unit patterns C1 and D1, is detected. Therefore, the controller 20 causes the drive motor 15 to rotate normally. (Fig. 3b point). As a result, the head unit 5 moves forward, and when the unit pattern C8 of "1" having a different length is detected (point in FIG. 3c), the head unit 5 is moved backward by a preset retreat amount H and stopped ( Figure 3Ph
point). This stop position becomes the home position Ph.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, the light sensor may be reflective, in which case
The unit pattern can be displayed in black and white. Further, although the form in which the head unit side is moved is illustrated, the form in which the platen glass side is moved may be adopted. Further, the positions of the optical sensor and the detected portion may be replaced. Other details, configuration, shape,
The quantity and the like can be arbitrarily changed without departing from the scope of the present invention.

[0024]

As described above, according to the present invention, the detected portion having a length corresponding to the moving section of the movable portion is provided, and the detection signal detected by the optical sensor in the longitudinal direction of the detected portion is "0" or " 1 "unit patterns are alternately and repeatedly provided, and the lengths of the unit patterns in the front pattern region and the rear pattern region divided by the home position are different from each other, and one of the front end and the rear end of the detected portion is provided. Since the end pattern of "1" longer than the unit pattern is provided and the end pattern of "0" longer than the unit pattern is provided on the other side, the following remarkable effects are obtained.

Since a single optical sensor is sufficient, the cost can be reduced by a large reduction in the number of optical sensors.

Since the relative position of the movable portion with respect to the home position can always be detected, abnormality detection such as an operating state and abnormality processing such as position correction can be performed promptly, and absolute positions at the front and rear ends can be continuously detected. Therefore, it is possible to prevent an adverse effect such as a collision caused by the position of the movable portion being unknown.

Since all the detection signals detected from the optical sensor are binary information of “0” and “1”, the configuration of the control system can be simplified and the operation can be ensured.

[Brief description of drawings]

FIG. 1 is a schematic side configuration diagram of an image scanner including a position control device according to the present invention,

FIG. 2 is a schematic front configuration diagram of the image scanner,

FIG. 3 is an operation explanatory view of the position control device,

FIG. 4 is a schematic configuration diagram of an image scanner including a position control device according to a conventional technique,

[Explanation of symbols]

 1 Position Control Device 2 Detected Part 3 Optical Sensor 4 Movable Part 5 Head Unit 6 Image Sensor 7 Platen Glass Af Front Pattern Area Ar Post Pattern Area C1 ... Unit Pattern D1 ... Unit Pattern Es Edge Pattern Ee Edge Pattern M Image Scanner Ph Home Position S Moving Section

Claims (2)

[Claims] 1. A position control device for controlling the position of a movable part by detecting the detected part with an optical sensor, the detected part having a length corresponding to a moving section of the movable part is provided, and a longitudinal direction of the detected part. The unit pattern in which the detection signal detected by the optical sensor is "0" or "1" is alternately repeated, and the lengths of the unit patterns in the front pattern region and the rear pattern region divided by the home position are made different from each other. In addition, an end pattern of "1" longer than the unit pattern is provided on one of the front end and the rear end of the detected portion, and an end pattern of "0" longer than the unit pattern is provided on the other end. Position control device characterized by. 2. The position control device according to claim 1, wherein the movable portion is a head unit equipped with an image sensor in an image scanner or a platen glass facing the head unit.