JP4849505B2 - Position detection apparatus and optical apparatus having the position detection apparatus - Google Patents

Description

  The present invention relates to a position detection device and an optical device having the position detection device, and in particular, position detection in which light from a light projecting element is reflected by a detection member provided on a moving member and detected by a light receiving element. It relates to the device.

  Conventionally, as a device for detecting the position of a moving member, for example, as shown in FIG. 6, infrared light from a light projecting element provided on a fixed portion is reflected by a detection member provided on the moving member and detected by a light receiving element. By doing so, a position detection device that performs position detection is known. In FIG. 6, 101 is a sensor in which a light projecting element 101a and a light receiving element 101b are integrated on one chip, and 102 is a scale made of transparent glass. The infrared light from the light projecting element 101a is reflected by the reflecting portion 102a on the bottom surface of the scale 102 and enters the light receiving element 101b. Here, as shown in FIG. 6, the reflecting portion 102 a is configured in a shape in which planes with an angle slightly wider than 90 ° are arranged in a mountain shape and arranged in a moving direction at a predetermined interval, Molded on the surface with a replica layer. The angle is set so that the infrared light from the light projecting element is reflected by each chevron plane and all guided to the light receiving element. The reflectors 102a are continuously arranged at equal pitches in the movement direction, and the intensity of the light amount is repeated in a substantially sine wave shape according to the movement amount, and the movement amount is detected by counting the wave number.

Conventionally, a plate spring, an adhesive, or the like has been used as means for fixing the optical component such as the scale described above to the holding member.
In addition, in the case of using such an adhesive, since the adhesive adheres to the reflecting surface by the wraparound of the adhesive, a groove is provided around the fixed portion of the optical component as in Patent Document 1, for example, or Patent Document 2 In order to prevent the adhesive from adhering to the reflective surface and to prevent the optical properties from being impaired, a groove for storing excess adhesive as described above is provided.
JP 2003-185898 A JP 2001-255441 A

However, in the case of the leaf spring of the conventional example, the number of parts is increased or a space for the spring is required.
Further, in the case where an adhesive is used as in Patent Document 1 and Patent Document 2 of the above-described conventional example, a stable light amount can be obtained simply by providing a groove around the fixed portion or a groove in which excess adhesive is accumulated. Above is not always enough.
In particular, the position where the light from the light projecting means is reflected by the reflecting portion of the detection member provided on the movable support member, and the output of the reflected light is detected by the light receiving means to detect the movement position of the support member. In a detection device or the like, there is a possibility that light reflected by the holding member that holds the detection member may enter the light receiving element, which is affected by the light quantity stability.

  In view of the above problems, the present invention provides a position detection device that can hold an optical component with a simple configuration without being affected by optical performance, and an optical device having the position detection device. It is intended to do.

In order to achieve the above object, the present invention provides a position detection device configured as follows and an optical device having the position detection device.
That is, the position detection device of the present invention includes a light projecting unit and a light receiving unit, a reflecting unit, and a support member that moves while supporting the reflecting unit, and reflects light from the projecting unit by the reflecting unit. In the position detection device that receives the reflected light by the light receiving means and detects the movement position of the support member based on the output from the light receiving means,
The support member is formed with a plane portion spaced apart from the reflecting means by a predetermined distance within the light incident range to the reflecting means, on the side opposite to the light incident side of the reflecting means, and to the reflecting means. A fixing portion for fixing the reflecting means is formed outside the light incident range, and the fixing portion includes a mating portion for holding the reflecting means, and the support spaced apart from the mating portion. A concave portion to which an adhesive is applied at an end surface portion of the member; and a non-contact portion formed with a predetermined gap between the reflection portion and the flat portion of the support member between the joint portion and the concave portion. It is characterized by having .
The optical device of the present invention is characterized by having the above-described position detection device.

  According to the present invention, it is possible to realize a position detection device capable of reliably holding an optical component with a simple configuration and without being affected by optical performance, and an optical device having the position detection device. it can.

With the above configuration, the object of the present invention can be achieved. However, in the embodiment of the present invention, the configuration can be specifically configured as follows.
The position detection device according to the present embodiment includes a detection member made of a light-transmitting material on which a reflection portion that reflects light from the light projecting unit is formed, and a support member that holds the detection member and is movable in a predetermined direction. The light reflected by the reflecting portion of the detection member is converted into an electrical signal by the light receiving means, so that the relative position of the support member and the light receiving means is detected.
In the support member, a flat surface portion that maintains a certain distance from the reflecting portion is formed on the opposite side of the light incident side of the reflecting portion within a range in which light is incident on the detecting member.
Further, the support member is formed on an end portion of the support member that is spaced apart from the mating portion that holds the detection member outside the range in which the light to the detection member is incident. A concave portion to which the adhesive is applied, and a non-contact portion formed with a predetermined gap between the mating portion and the detection member and the flat portion of the support member between the concave portions, respectively. It has been.

  According to the present embodiment, with the above configuration, it is possible to provide a compact position detection device with a simple configuration without requiring new parts for holding the detection member. In addition, the configuration of the non-contact part can prevent the adhesive from wrapping around, and the light reflected from the holding part can be received by having a flat surface that keeps the distance from the detection member constant within the light incident range. It is possible to prevent the amount of light from becoming unstable by reaching the means. Thereby, a highly accurate position detecting device can be realized.

Examples of the present invention will be described below. In this embodiment, the present invention is applied to constitute a zoom lens barrel.
FIG. 1 is a sectional view of a zoom lens barrel in the present embodiment.
In FIG. 1, 1 is a first group barrel, 2 is a fixed barrel, 3 is a second group barrel, and 4 is a fourth group barrel.
The first group barrel 1 holds a first group lens L1 which is a fixed lens, and is fixed to the fixed barrel 2 with screws.
The second group barrel 3 holds a second group lens L2 that performs zooming, and is held movably in the optical axis direction. The guide means in the optical axis direction is constituted by a guide bar and a sleeve similar to the later-described fourth group lens barrel, and the drive means is driven by a known stepping motor or the like.

The third lens group L3 is a fixed lens and is held by the fixed lens barrel 2.
The fourth group barrel 4 holds the focus lens L4 and performs focusing by moving in the optical axis direction.
Reference numeral 5 denotes a CCD holder, which holds a low-pass filter (not shown) and a CCD as an image sensor, and is fixed to the fixed barrel 2 with screws. Reference numeral 6 denotes an aperture unit, which is inserted from the upper side of the lens barrel and fixed with screws (not shown).
Reference numeral 7 denotes a sensor including a light projecting element, a light receiving element, and a circuit that converts it into an electrical signal according to the amount of light received, and is attached so that the light projecting element and the light receiving element are positioned in the opening 2 a provided in the fixed barrel 2. It has been.
The sensor 7 is mounted on the substrate 7a and is fixed to the fixed barrel 2 together with the substrate 7a with screws 7b. Reference numeral 8 denotes a scale that reflects infrared light from the light projecting element of the sensor 7, and is adhered and fixed to the fourth group barrel 4.

FIG. 2 is a perspective view of a fourth group barrel holding a scale 8 which is position detecting means in this embodiment, and FIG. 3 is an exploded perspective view of the fourth group barrel of FIG.
In these figures, the fourth group lens barrel 4 has a sleeve 4a, and is held movably in the optical axis direction by passing through a guide bar 9 held at one end by the fixed lens barrel 2 and at the other end by the CCD holder 5. ing. Further, on the opposite side across the optical axis, similarly, a guide bar 10 held by the fixed barrel 2 and the CCD holder 5 is engaged with the U-shaped groove 4b to prevent rotation.

Next, the drive mechanism of the fourth group barrel 4 will be described with reference to FIG.
Reference numeral 11 denotes a coil which is engaged with the holding frame portion 4c of the fourth group barrel and fixed with an adhesive. A magnet 12 is magnetized in two poles in the optical axis direction and is fixedly held on the inner wall of the fixed barrel 2 while being attracted by a magnetic force to a yoke 13 made of an iron plate. Therefore, a moving coil type actuator is configured by arranging a coil in the magnetic field generated by the magnet 12 and flowing a current. The coil wiring is drawn out of the lens barrel by a flexible printed circuit board (not shown) so as not to hinder the movement of the fourth group lens barrel 4, and is connected to the control circuit. The scale 8 for position detection is engaged with the scale holding portion 4d of the fourth group barrel 4 and fixed with an adhesive.

Next, the scale holding structure in this embodiment will be described.
FIG. 4 is a detailed view of the scale holding portion, FIG. 4 (a) is a view seen from the upper surface of the scale, FIG. 4 (b) is a cross-sectional view taken along the line A-A, and FIG. It is an arrow view.
FIG. 5 is an exploded perspective view of the scale holding unit.
Two holding portions 4e in the form of ribs are formed in the holding portion 4d of the scale 8. The side surface portion of the rib-shaped joint portion 4e is mated with the side surface of the scale 8, and the bottom surface portion of the rib-shaped joint portion 4e is in contact with the reflecting surface 8a.
Reference numeral 4f denotes an end surface of the holding portion 4d, and the end surface 4f of the holding portion is joined to the end surface in the optical axis direction of the scale 8, and the scale 8 is positioned by the rib-like fitting portion 4e and the end surface 4f of the holding portion. Is done.

In addition, an adhesive ditch 4g is provided on an end surface portion in the optical axis direction of the holding portion 4d spaced apart from the fitting portion 4e, and the scale 8 is fixed by applying an adhesive 14 to this space. The cross-sectional area of the adhesive groove 4g is set to be smaller than the cross-sectional area of the scale 8, and by surrounding the adhesive groove 4g with a joint portion, the gap through which the adhesive flows is eliminated, and the adhesive is bonded to the adhesive groove 4g. I try to keep it inside.
However, since the adhesive enters a slight gap by capillarity, the plane of the scale 8 and the holding portion 4d between the fitting portion 4e and the bonding groove 4g is prevented so that the wrapped adhesive does not advance any further. A non-contact groove 4h is formed with a predetermined interval between the two portions. As a result, even if there is some variation in the amount of adhesive applied, it is possible to prevent the adhesive from wrapping around and easily manage the amount of adhesive applied.

A range CC in FIG. 4 indicates a range in which infrared light from the light projecting element is incident while the fourth group barrel 4 is moving.
The rib 4e and the non-contact groove 4h are outside the range of C-C and do not affect the reflected light of the scale.
Reference numeral 4j denotes a flat surface portion on which the holding portion 4d is formed. The flat surface portion 4j is formed of a flat surface having a certain distance from the reflecting surface 8a of the scale within the range of CC.
Since light that has passed through the reflective surface of the scale may be reflected by the scale holder and enter the light receiving element, if there are irregularities in the vicinity of the reflective surface, the amount of light incident on the light receiving element will become unstable, resulting in incorrect position detection. There are things to do.
In the present embodiment, a uniform flat surface is provided in the vicinity of the reflecting surface 8a so that a uniform amount of light is incident within the moving range even if there is reflected light from the holding unit. This realizes highly accurate position detection.

  In the present embodiment, the reflecting surface 8a is configured as an assembly in which the reflecting portion and the transmitting portion are arranged at a fine pitch, and as a result, a substantially sine wave-shaped output is output to the light receiving element as the fourth group barrel 4 moves. appear. Another light receiving element is arranged at a position shifted by a quarter pitch from the pitch of the reflecting part, and the moving direction is determined by signals from the two light receiving elements, and the amount of movement can be detected by counting the number of waves. Is. The absolute position is controlled so as to set the initial position by performing the reset operation by placing the fourth group lens barrel 4 against the mechanical end. Therefore, although the moving coil is used as the driving means in the present embodiment, the same effect can be obtained even when driven by another DC motor, ultrasonic motor or the like. In the above embodiment, the position detection of the zoom lens barrel has been described. However, the present invention is not limited to such a zoom lens barrel, and can be suitably applied to other optical devices.

1 is a cross-sectional view illustrating a configuration of a zoom lens barrel in an embodiment of the present invention. The perspective view of the 4th group barrel which hold | maintained the scale which is a position detection means in the Example of this invention. FIG. 3 is an exploded perspective view of the fourth group barrel in FIG. 2. It is a figure explaining the scale holding | maintenance part in the Example of this invention, (a) is the figure seen from the scale upper surface, (b) is AA sectional drawing, (c) is an arrow view from B direction. The disassembled perspective view of the scale holding | maintenance part in the Example of this invention. The figure explaining the structure of the position detection apparatus in a prior art example.

Explanation of symbols

4: Four-group lens barrel (support member)
4d: Holding portion 4e: Rib-shaped fitting portion 4f: End surface 4g of holding portion: Adhesive groove 4h: Non-contact groove 4j: Flat portion 7: Sensor (light projecting means, light receiving means)
8: Scale (detection member)

Claims (5)

A light projecting unit and a light receiving unit; a reflecting unit; and a support member that moves while supporting the reflecting unit. The light from the light projecting unit is reflected by the reflecting unit, and the reflected light is reflected by the light receiving unit. In a position detection device that receives light and detects a movement position of the support member based on an output from the light receiving means,
The support member is formed with a plane portion spaced apart from the reflecting means by a predetermined distance within the light incident range to the reflecting means, on the side opposite to the light incident side of the reflecting means, and to the reflecting means. of outside light incidence range, and the fixed portion is formed for fixing the reflecting means,
The fixing portion includes a mating portion that holds the reflecting means, a concave portion to which an adhesive is applied at an end surface portion of the support member spaced from the mating portion, and a gap between the mating portion and the concave portion. A position detecting device comprising: a non-contact portion formed at a predetermined interval between the reflecting means and the flat portion of the support member . The cross-sectional area of the recesses the adhesive is applied, the position detection apparatus according to claim 1, characterized in that it is set smaller than the sectional area of said reflecting means. Said support member, the position detecting device according to claim 1 or claim 2, characterized in that a barrel that holds the lens. The position detection apparatus according to claim 3 , wherein the lens barrel is a lens barrel that holds a focus lens. Optical apparatus characterized by having a position detecting device according to any one of claims 1-4.

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