JPS6359449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a position detection device, in particular, a position detecting device that detects light from a light source, a light receiver, and an encoder by a signal from a light receiver that receives light from a light source via an encoder while maintaining a constant relative position to the light source. The present invention relates to a position detection device that detects the amount of relative movement of.

Conventionally, such position detection devices have been used to detect, for example, the amount of movement or position of a scanning head of a facsimile machine, the amount of movement of an electronic balance, a rotating drum, etc. Taking a facsimile machine as an example, a fixed linear encoder is placed between a light source and a light receiver that move in synchronization with a scanning head, and the light source and light receiver scan on both sides facing each other. The optical signal obtained during this process is converted into an electrical signal, and the position of the scanning head is detected using this signal. In this case, a slit-shaped linear encoder is used as the encoder. However, the accuracy of such encoder slits is only limited.
It is about 10 lines/mm, and it is difficult to make slits with higher precision.As the slits of the encoder are made finer to increase precision, the optical signal detected and the electricity converted by it are The disadvantage is that the signal becomes very small, making it difficult to accurately detect the position.

SUMMARY OF THE INVENTION Therefore, the present invention has been devised in view of these points, and an object of the present invention is to provide a position detection device capable of accurately detecting a position with a simple configuration.

In order to achieve the above object, the present invention uses a signal from a light receiver that receives light from a light source via an encoder while maintaining a constant relative position to the light source, thereby adjusting the relative position between the light source, the light receiver, and the encoder. In the position detection device for detecting the amount of movement, a plurality of small lenses are periodically arranged on the encoder along the direction of the relative movement, and the light receiver is configured to sequentially receive refracted light from the small lenses. A configuration is adopted in which the relative movement amount is detected based on the incident position of the refracted light on the light receiver, which changes with the relative movement, and is composed of a plurality of light receiving elements arranged in line.

Next, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a light source that moves in synchronization with the scanning head, and is composed of a light emitting element such as a light emitting diode. a light receiver 3 that receives light from the light source 1 while maintaining its relative position to the light source 1;
is arranged, and an encoder 2 is arranged between the light receiver 3 and the light source 1. The light receiver 3 receives light from the light source 1 via the encoder 2. On the surface of the encoder 2 facing the light receiver 3, a plurality of small lenses 2a, 2b, 2c, 2d, . . . are periodically formed to constitute a small lens group.

On the other hand, the light receiver 3 is composed of a plurality of light receiving elements 3 ₁ to 3 _N , and as described later, receives the refracted light from one small lens of the small lens group. Each light receiving element has a refracted light that changes as the light source moves. It receives light sequentially.

Each light receiving element 3 ₁ to 3 _N is connected to a photoelectric conversion element 4 ₁ to 4 _N as shown in FIG. Each photoelectric conversion element 4 is connected to one input of an AND gate 5 ₁ to 5 _N , and the other terminal of the AND gate is connected to the output of each unit 1 to N of a ring counter 6, respectively. The Nth unit of the ring counter 6 is connected to the first unit, and one of the units is preset to "1". The outputs of the AND gates 5 ₁ to 5 _N are connected to an OR gate 7 , and the output of the OR gate 7 is connected to a shift input of a ring counter 6 and also to a counter 8 . This counter 8 is connected to a motor drive circuit 9 and a control circuit 10 for controlling reading or recording.

Next, the operation of the position detection device configured as described above will be explained. Assume now that the encoder 2 is fixed, while the light source 1 and light receiver 3 attached to the scanning head are synchronized and moved in the direction of the arrow to perform scanning. At that time, the course of the light beam emitted from the light source 1 is bent by the encoder 2, and the first
The light enters the second and Nth light receiving elements 3 ₁ to 3 _N in order. Furthermore, if the light source and receiver move, 1,
Light is periodically incident on each light receiving element in accordance with the period of the small lens groups such as 2,...N, 1, 2...N.

This state is illustrated in FIGS. 2A to 2D. That is, when the light source 1 is located at the position A in FIG. 2, for example, the light beam is refracted by the small lens 2c and is incident on the first light receiving element. Next, the light source is shown in Figure 2B.
When the refracted light beam reaches the center of the small lens 2c as shown in FIG.
When the light reaches the middle of c and 2d, it is incident on the Nth light receiving element. Subsequently, as shown in FIG. 2D, the light enters the first light receiving element again through the lens 2d, and this process is repeated periodically. In this case, when the focal length of each lens in the lens array is f, the distance from the focal point to the light receiving element is L, and the shift in the scanning direction of the light emitting element from the lens center is x, then from the center on the light receiving element The deviation y is given by the following formula.

y=x(1+L/f) Here, the magnification rate of minute displacement is (1+L/f) from the above equation. Further, when the aperture of one small lens is a, the required length of the light receiving element group is a(1+L/f).

When this light-receiving element group is composed of N light-receiving elements, the resolution is a/N(1+L/f).

Now, for example, when the light enters the first light receiving element ₃₁ due to the movement of the light source and the light receiver, the photoelectric conversion element ₄₁ is turned on in the circuit shown in FIG. 3, and a high level signal is sent to one input of the AND gate ₅₁ . is applied. If the first unit of ring counter 6 is preset, AND gate 5
₁ is turned on and is input to the counter 8 via the OR gate 7 and is also input to the shift input of the ring counter 6, so that the counter 8 counts one pulse and the second unit of the ring counter 6 is preset. . Next, when light is incident on the light receiving element ₃₂ , the AND gate ₅₂ is turned on, the counter 8 counts pulses, and the third unit of the ring counter 6 is preset. In this way, when light is incident on the light receiving element 3 _N due to the movement of the light source and the light receiver, the AND gate 5 _N is turned on, the Nth pulse is counted by the counter 8, and the ring counter 6 is counted by the first pulse. units are preset. In this way, the counter 8 sequentially selects the light receiving elements 3 ₁ to 3 _N
The motor drive circuit 9 or control circuit 10 is driven according to the counter output. A circuit such as that shown in FIG. 3 is intended to prevent instability in the operation of each light emitting element as it moves from one lens of encoder 2 to the next.

As described above, since the counter 8 receives signals from N light receiving elements and counts them, it can be seen that the position accuracy is N times higher.

In the above embodiment, the encoder is fixed and the light source and light receiver are moved, but the present invention can also be applied to a device in which the light source and light receiver are fixed and the encoder is moved to detect relative movement amount or position. Of course.

As described above, according to the present invention, the amount of relative movement between the light source, the light receiver, and the encoder is detected by the signal from the light receiver that receives light from the light source via the encoder while keeping the relative position with the light source constant. In the position detection device, a plurality of small lenses are periodically arranged on the encoder along the direction of the relative movement, and the plurality of light receivers are arranged so as to sequentially receive refracted light from the small lenses. Since the relative movement amount is detected based on the incident position of the refracted light on the light receiver, which changes with the relative movement, the displacement is detected by the refraction action of the encoder itself. The enlarged, compact, and simple configuration provides the effect that even minute displacements can be detected reliably and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of the device of the present invention, and FIGS. 2A to 2D are explanatory diagrams showing that the refracted rays of the lens change due to the movement of the light source and the light receiver.
FIG. 3 is a block diagram showing a circuit for processing signals from the photoreceiver of FIG. 1. 1... Light source, 2... Encoder, 3... Light receiver, 4... Photoelectric conversion element, 6... Ring counter, 8... Counter, 9... Motor drive circuit, 1
0...Control circuit.

Claims (1)

[Claims] 1. The amount of relative movement between the light source, the light receiver, and the encoder is detected by a signal from a light receiver that receives light from the light source via an encoder while maintaining a constant relative position with the light source. In the position detection device, a plurality of small lenses are periodically arranged on the encoder along the direction of the relative movement, and the plurality of small lenses are arranged so that the light receiver can sequentially receive refracted light from the small lenses. A position detection device comprising a light receiving element and detecting the amount of relative movement based on a position of incidence of the refracted light on the light receiver, which changes with the relative movement.