JP2020106498A - Rotary encoder - Google Patents

Abstract

To heighten detection accuracy up to X-fold and cut back costs by manufacturing at relatively low cost.SOLUTION: Provided is a rotary encoder comprising a rotation input shaft 2 to which the rotation of a detection object is inputted, a pattern rotating disc 3 rotating on the basis of the rotation of the rotation input shaft 2 and having a plurality of first parts Sp to be detected that constitute a repeating pattern Pf in a circumferential direction Ff, and a pattern detection unit 4 including detectors 4a, 4b that detect the repeating pattern Pf. The rotary encoder includes: a base point rotating disc 5 made to rotate by the rotation input shaft 2 and having a second part Sd to be detected that constitutes the base point Do of the circumferential direction Ff; a base point detection unit 6 including a detector 6z that detects the second part Sd to be detected; a speed-increasing mechanism unit 7 for increasing the speed of rotation of the rotation input shaft 2 by a prescribed magnification and outputting the increased speed; a rotation detection shaft 8 made to rotate by the output of the speed-increasing mechanism unit 7; and a pattern rotating disc 3 made to rotate by the rotation detection shaft 8.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rotary encoder suitable for use in detecting a lens position and the like during adjustment of a lens device.

Generally, a lens device used in an optical device such as a camera or a projector has various adjustment mechanisms built therein. Therefore, the outer peripheral surface of the lens barrel is provided with various adjustment rings such as a focus adjustment ring for adjusting the lens position in the optical axis direction, a zooming adjustment ring, and an image plane adjustment ring. The rotational position of each adjustment ring is detected by a rotary encoder which serves as a position detecting means.

Conventionally, as this type of adjustment mechanism (lens device) using a rotary encoder, a focus adjustment device disclosed in Patent Document 1 and an imaging device disclosed in Patent Document 2 are known. The focus adjustment device of the document 1 provides a focus command pulse signal of a rotary encoder for detecting the operation amount of the focus operation knob, a zoom position signal, an iris position signal, and an extender position signal to the focus command signal calculation means. The sensitivity of the focus demand is calculated from these values, and the reciprocal of the value is multiplied by the focus command pulse signal to output the focus command signal to the operation amplification means, and by this operation amplification means, the focus command signal and the focus position detection means A focus control signal that gives a difference of 0 from the output focus position signal is applied to the motor (focus servo means) that drives the focus lens. On the other hand, the image pickup device of Document 2 has a distance detecting means for detecting a distance to a subject (first subject distance) in the automatic mode, and a ring position detecting means for detecting a rotating position of a focus ring operated in the manual mode ( (Rotary solenoid) and conversion means for converting the detection result of the ring position detection means into the distance to the object (second object distance), and the position data relating to the rotation position of the focus ring obtained by the ring position detection means. By giving the focus motor to the CPU, the focus motor is drive-controlled.

By the way, in the adjusting mechanism (lens device) described above, a rotary encoder is used as the position detecting means for detecting the adjustment position. However, this type of rotary encoder (incremental method) is described in Patent Document 3 (optical rotary encoder). As also described, as a basic configuration, a rotatable rotary shaft, a repeating pattern formed by a plurality of slits for rotation detection, which are attached to the rotary shaft and formed at the peripheral end, and It is provided with a rotary slit plate having a slit for zero point detection provided inside, and an optical detecting means for detecting a positional change of the slit due to the rotation of the rotary slit plate.

JP-A-7-301740 JP-A-2007-199551 JP-A-62-232516

However, the conventional rotary encoder including the above-mentioned rotary encoder (Patent Document 3) has the following problems to be solved.

That is, since this type of rotary encoder has a large number of slits formed on the rotary slit plate and detects the position, angle, etc. based on the pulse signal obtained from the optical detection means, etc., it is provided for the rotary encoder to be used. The detection accuracy is determined by the number of slits (slit density) in the rotary slit plate, and the larger the number of slits, the higher the detection accuracy.

Therefore, in order to secure a certain detection accuracy, it is necessary to secure a certain number of slits. In this case, in order to detect the slits with high resolution, highly accurate and expensive optical detection means or magnetic detection means are used. Since a detection means is required, there is a problem that the price of the rotary encoder is eventually increased.

On the other hand, the above-described adjustment mechanism in the lens device requires a plurality of (three) rotary encoders, which causes a non-negligible cost increase in the entire lens device. A rotary volume is also known as a position detecting means that replaces the rotary encoder. Although the rotary volume is advantageous in terms of cost, it is inferior in accuracy to the rotary encoder and is affected by disturbance such as temperature. Since it is easily affected, stability and reliability are difficult.

The present invention aims to provide a rotary encoder that solves the problems existing in such background art.

In order to solve the above-mentioned problems, the rotary encoder 1 according to the present invention rotates on the basis of the rotation of the rotation input shaft 2 into which the rotation of the detection target is input, and the repetitive pattern in the circumferential direction Ff. A rotary encoder provided with a pattern turntable 3 having a plurality of first detected parts Sp... That constitute Pf, and a pattern detection part 4 including at least one detector 4a, 4b for detecting the repeated pattern Pf. There is at least one base rotary disk 5 that is rotated by the rotary input shaft 2 and that has at least one second detected portion Sd that serves as a base point Do in the circumferential direction Ff, and at least one detected target portion Sd. The base point detection unit 6 including the detector 6z, the speed increasing mechanism unit 7 that speeds up and outputs the rotation of the rotation input shaft 2 by a predetermined magnification (X times), and the speed increasing mechanism unit 7 outputs the rotation. The rotation detecting shaft 8 and the pattern turntable 3 rotated by the rotation detecting shaft 8 are provided.

In this case, according to a preferred aspect of the present invention, the pattern detection unit 4 is provided with a pair of pattern detectors 4a and 4b in which the phase Tsp of 1/4 cycle in one cycle Ts of the repeated pattern Pf is arranged differently. it can. Further, the speed increasing mechanism section 7 can be configured by a combination of one or more rotary gears Gi, G11, G12,... On the other hand, the first detected portion (Sp) can be formed by the detected slit portion Sp formed on the pattern rotary disk 3, and the second detected portion (Sd) is formed on the base rotary disk 5. It can be formed by the detection notch Sd or the slit to be detected. Furthermore, the rotation detection shaft 8 can be arranged coaxially with the rotation input shaft 2, and at this time, a space between the rotation detection shaft 8 and the rotation input shaft 2 with respect to the rotation input shaft 2 is set. It is desirable to provide a shaft position holding portion 11 that holds the axis of the rotation detection shaft 8 coaxially. In addition, it is preferable to input the rotational displacement of the lens position adjusting ring 12 (13, 14) in the lens apparatus M to the rotation input shaft 2.

The rotary encoder 1 according to the present invention having such a configuration has the following remarkable effects.

(1) A base rotary disk 5 that has at least one second detected portion Sd that is rotated by the rotary input shaft 2 and that serves as a base point Do in the circumferential direction Ff, and at least one that detects this second detected portion Sd. The base point detection unit 6 including the detector 6z, the speed increasing mechanism unit 7 that speeds up and outputs the rotation of the rotation input shaft 2 by a predetermined magnification (X times), and the speed increasing mechanism unit 7 outputs the rotation. Since the rotation detection shaft 8 and the pattern turntable 3 rotated by the rotation detection shaft 8 are provided, the density of the repetitive pattern Pf on the pattern turntable 3 is substantially changed without changing the shape (precision) of the pattern turntable 3. It is possible to multiply by X times, and the detection accuracy can be dramatically improved. Moreover, it can be easily realized by adding the speed increasing mechanism 7 which can be manufactured at a relatively low cost.

(2) According to a preferred aspect, if the pattern detection unit 4 is provided with the pair of pattern detectors 4a and 4b in which the phase Tsp of 1/4 cycle in one cycle Ts of the repeated pattern Pf is arranged differently, pattern rotation is performed. Similar to the board 3, the pattern detection unit 4 can be implemented without changing the form, so that the intended incremental type rotary encoder can be realized easily and at low cost.

(3) According to a preferred aspect, if the speed increasing mechanism section 7 is configured by a combination of one or more rotary gears Gi, G11, G12,... It can contribute to facilitation of implementation and cost reduction.

(4) According to a preferred aspect, if the first detected portion (Sp) is formed by the detected slit portion Sp formed on the pattern turntable 3, one plate member is used, and the conventional manufacturing technology level is used. Since it can be easily manufactured, it can contribute to cost reduction of the pattern turntable 3.

(5) According to a preferred aspect, if the second detected portion (Sd) is formed by the detected notch Sd or the detected slit formed on the base-point rotary disc 5, one sheet is formed, like the pattern rotary disc 3. Since the plate member can be easily manufactured by the conventional manufacturing technology, it can contribute to cost reduction of the base rotary disk 5 and further the whole, and can be easily and surely detected by the transmission type optical sensor or the like.

(6) According to a preferred aspect, if the rotation detection shaft 8 is coaxially arranged with respect to the rotation input shaft 2, the swelling of the internal layout due to the addition of the speed increasing mechanism unit 7 can be avoided, so the rotary encoder 1 can be implemented as an optimum form from the viewpoint of downsizing.

(7) According to a preferred aspect, if the shaft position holding unit 11 that holds the rotation detection shaft 8 coaxially with the rotation input shaft 2 is provided between the rotation detection shaft 8 and the rotation input shaft 2, the rotation detection can be performed. Since unnecessary blurring between the shaft 8 and the rotary input shaft 2 can be prevented, it can contribute to improvement and stabilization of detection accuracy.

(8) According to a preferred aspect, if the rotational displacement of the lens position adjusting rings 12 (13, 14) in the lens apparatus M is input to the rotation input shaft 2, the lens position adjusting ring 12 ( Since it can be used to detect the adjustment position of (13, 14), it is possible to contribute to the cost reduction of the entire lens apparatus M while ensuring the detection accuracy required for this detection. That is, backlash that affects detection accuracy occurs due to the addition of the speed-up mechanism unit 7. However, in the case of the lens apparatus M, since the lens adjustment mechanism including the motor, the sensor, the gear, and the like is provided, this adjustment is performed. Backlash of the mechanism becomes dominant. Therefore, for example, by performing backlash control in which the rotary encoder 1 always reads in a constant direction of operation, it is possible to ignore the backlash of the speed increasing mechanism 7 and reduce the overall detection accuracy. Does not occur.

Sectional plan view of a rotary encoder according to a preferred embodiment of the present invention, The configuration diagram of the main part of the rotary encoder seen from the front, A front right perspective view showing the internal structure of the rotary encoder, A front left perspective view showing the internal structure of the rotary encoder, Front view of the pattern turntable used for the rotary encoder A front view of a base rotary disk used for the rotary encoder, A block system diagram of a processing system for processing the output signal of the rotary encoder, Waveform diagram of the output signal of the rotary encoder, An external perspective view of the rotary encoder, Peripheral configuration diagram when the rotary encoder is used in a lens device, Overall appearance diagram when the same rotary encoder is assembled to the lens device,

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the configuration of the rotary encoder 1 according to the present embodiment will be described with reference to FIGS. 1 to 9.

The illustrated rotary encoder 1 includes a casing 21 including a cylindrical casing main body 21m integrally formed with a front end face 21ms and a lid 21r forming a rear end face 21rs closing a rear end opening of the casing main body 21m. .. The casing body 21m and the lid 21r are integrally formed of a rigid material such as a synthetic resin material or a metal material. Further, in the inside of the casing 21, the front inner plate 22 and the rear inner plate 23 are arranged in parallel with a predetermined width apart from the front end face 21ms and the rear end face 21rs, respectively. Note that reference numerals 24 and 25 denote a pair of fixing members that connect the internal plates 22 and 23. Then, the front bearing portion 26 is attached to the center opening portion of the front end face 21ms, and the rear bearing portion 27 is attached to the center opening portion of the rear end face 21rs. Therefore, the front bearing portion 26 and the rear bearing portion 27 are coaxially positioned.

On the other hand, on the central axis of the casing 21, the rotation input shaft 2 located on the front side and the rotation detection shaft 8 located on the rear side are arranged. Therefore, the rotary input shaft 2 is rotatably supported by the front bearing portion 26, the front side projects forward from the front end face 21 ms, and the rear side penetrates through the center of the front inner plate 22. It projects to the rear of 22. Further, the rotation detecting shaft 8 is rotatably supported by the rear bearing portion 27, and the front side penetrates the center of the rear inner plate 23 and projects to the front of the rear inner plate 23. As a result, the rotation detection shaft 8 is arranged coaxially with the rotation input shaft 2. As a result, it is possible to avoid the swelling of the internal layout that accompanies the addition of the speed increasing mechanism section 7 described later, so that the rotary encoder 1 can be implemented as an optimal form from the viewpoint of downsizing.

Further, a base point rotary disk 5 shown in FIG. 5 is attached to the outer peripheral surface of the rotary input shaft 2. The base rotary disk 5 is manufactured by forming a notch (second detected part) Sd to be detected on the outer circumference of one circular plate made of a rigid material such as a synthetic resin material or a metal material. In this case, as shown in FIG. 5, the notch Sd to be detected is provided by forming an arc portion having a diameter smaller than the diameter of the base point rotary disk 5 over the half circumference of the circular plate on the outer circumference of the base rotary disk 5. be able to. As a result, the base point rotary disk 5 having at least one notch Sd to be detected, which serves as the base point Do in the circumferential direction Ff, is obtained. If such a detected notch (second detected portion) Sd is used, as with the pattern turntable 3 described later, a single plate member can be used to easily manufacture by the conventional manufacturing technology level. There is an advantage that it can contribute to cost reduction of the base point rotary disk 5 and further the entire cost, and can be easily and surely detected by a transmission type optical sensor or the like.

Further, a mounting hole 5c is formed at the center position of the base rotary disk 5, the mounting hole 5c is mounted and fixed to the outer peripheral surface of the cylindrical mounting member 31, and the mounting member 31 is fixed to the rotary input shaft 2. Attach it to the peripheral surface and fix it. As a result, the base rotary disk 5 is located in the space between the front end face 21ms and the front inner plate 22, as shown in FIG.

On the other hand, the pattern turntable 3 shown in FIG. 6 is attached to the outer peripheral surface of the rotation detection shaft 8. The pattern turntable 3 has a plurality of detected slit portions (first detected portions) Sp... directed toward the center on the outer circumference of a circular plate made of a rigid material such as a synthetic resin material or a metal material. And produce. As shown in FIG. 6, the detected slit portions Sp... are formed at regular intervals along the circumferential direction Ff. In the embodiment, an example in which "20" detected slit portions Sp... Are provided is shown. As a result, the pattern turntable 3 having the repeated pattern Pf in the circumferential direction Ff is obtained. If such a detected slit portion (first detected portion) Sp... Is used, it is possible to easily manufacture the pattern turntable 3 with a single plate member according to the conventional manufacturing technology level. Can contribute.

Further, a mounting hole 3c is formed at the center of the pattern turntable 3, and the mounting hole 3c is mounted and fixed to the outer peripheral surface of the cylindrical mounting member 32. Attach it to the peripheral surface and fix it. As a result, the pattern turntable 3 is located in the space between the rear end face 21rs and the rear inner plate 23, as shown in FIG.

Further, since the rear end surface of the rotation input shaft 2 and the front end surface of the rotation detection shaft 8 are coaxially opposed to each other, the bearing recess 29 is formed in the axial direction Fs at the center position of the rear end surface of the rotation input shaft 2. At the same time, the shaft protrusion 30 is formed so as to project in the axial direction Fs at the center position of the front end face of the rotation detection shaft 8, and the shaft protrusion 30 is inserted into the bearing recess 29 for assembly. As a result, the shaft convex portion 30 constitutes the shaft position holding portion 11 which is rotatably held by the bearing concave portion 29. In this way, if the shaft position holding unit 11 that holds the rotation detection shaft 8 coaxially with the rotation input shaft 2 is provided between the rotation detection shaft 8 and the rotation input shaft 2, the rotation detection shaft 8 and the rotation detection shaft 8 can be rotated. Since unnecessary blurring between the input shafts 2 can be prevented, it can contribute to improvement and stabilization of detection accuracy.

On the other hand, a detector 6z using a transmissive optical sensor having a light emitting portion 6zs and a light receiving portion 6zr is attached to the front inner plate 22, as shown in FIGS. The detector 6z constitutes the base point detection unit 6. In this case, as shown in FIG. 3, the detector 6z is arranged so as to sandwich the rotation locus of the detected cutout portion (second detected portion) Sd of the base rotary disk 5 by the light emitting portion 6zs and the light receiving portion 6zr. Set up. As a result, the detector 6z can detect the notch Sd to be detected. Therefore, when the base rotary disk 5 rotates, the detector 6z outputs the pulse detection signal Pz shown in FIG. 8C. The pulse detection signal Pz is a pulse signal related to the Z phase output from the incremental rotary encoder.

Further, as shown in FIGS. 2 to 4 and 6, detectors 4a and 4b are attached to the rear inner plate 23. The detectors 4a and 4b constitute a pattern detection unit 4 that detects the repeated pattern Pf formed on the pattern turntable 3. For one of the detectors 4a (the same applies to the other detector 4b), the same transmissive optical sensor as the above-described detector 6z can be used. That is, it has the light emitting portion 4as and the light receiving portion 4ar, and detects the rotation locus of the detected slit portion (first detected portion) Sp of the pattern turntable 3 so as to be sandwiched by the light emitting portion 4as and the light receiving portion 4ar. Arrange the container 4a. As a result, the detector 4a can detect the detected slit portions Sp... Therefore, when the pattern turntable 3 rotates, the detector 4a outputs a pulse detection signal Pa shown in FIG. 8A. The pulse detection signal Pa is a pulse signal related to the A phase output from the incremental type rotary encoder.

Further, as shown in FIGS. 4 and 6, the other detector 4b is arranged such that the phase Tsp of 1/4 cycle in one cycle Ts of the repeating pattern Pf is different from that of the one detector 4a. .. Except for this point, the arrangement of the other detector 4b is the same as that of the one detector 4a. As a result, the detector 4b can detect the detected slit portions Sp... In which the phase Tsp of 1/4 cycle is deviated. Therefore, when the pattern turntable 3 rotates, the detector 4b can detect the detected slit portions Sp. The pulse detection signal Pb shown in FIG. The pulse detection signal Pb is a pulse signal relating to the B phase output from the incremental rotary encoder.

In this way, if the pattern detection unit 4 is provided with the pair of pattern detectors 4a and 4b in which the phase Tsp of the 1/4 cycle in the 1 cycle Ts of the repetitive pattern Pf is arranged differently, the same as the pattern turntable 3 In addition, since the pattern detection unit 4 can be implemented without changing the form, the intended incremental type rotary encoder can be easily realized at low cost.

FIG. 7 shows a block system diagram of a processing system for processing the respective detection signals obtained from the detectors 4a, 4b and 6z. Reference numeral 41 denotes a processing unit having various arithmetic processing functions, and the input side of the processing unit 41 is shown in FIGS. 8A, 8B, and 8C obtained from the detectors 4a, 4b, and 6z. The pulse detection signals Pa, Pb, Pz are given. The processing unit 41 performs arithmetic processing of each detection signal Pa, Pb, Pz corresponding to the incremental type rotary encoder, and the output side of the processing unit 41 has a movement amount (rotation amount) corresponding to the rotation input of the rotation input shaft 2. A data Dm relating to (amount), data Dx relating to rotational position/rotation angle, data Dv relating to rotational speed, and data Df relating to rotational direction are obtained.

On the other hand, the speed increasing mechanism 7 is arranged in the space between the front inner plate 22 and the rear inner plate 23. The speed increasing mechanism 7 has a function of increasing the speed of the rotation of the rotation input shaft 2 by a predetermined magnification (X times) and outputting the speed, and rotating the rotation detecting shaft 8 by this output. Therefore, the speed increasing mechanism 7 can be configured by a combination of one or more rotary gears Gi, G11, G12,... Specifically, as shown in FIGS. 1 and 2, an input gear Gi fixed to the outer circumference of the rotary input shaft 2, a first gear G11 meshing with the input gear Gi, and a second gear integrated with the first gear G11. A gear G12, a third gear G21 meshing with the second gear G12, a fourth gear G22 integral with the third gear G21, an output gear Go fixed to the outer periphery of the rotation detection shaft 8 and meshing with the fourth gear G22. The first gear G11 and the second gear G12 are rotatably supported by the shaft 35 provided between the front inner plate 22 and the rear inner plate 23, and the third gear G21 and the fourth gear G22 are The shaft 36 is rotatably supported by a shaft 36 provided between the front inner plate 22 and the rear inner plate 23. As described above, if the speed increasing mechanism 7 is composed of a combination of one or more rotary gears Gi, G11, G12,..., Go, it can be composed of a combination of general-purpose parts, so that the implementation is easy and the cost is low. Can contribute to

In the case of the speed increasing mechanism section 7 illustrated, the number of teeth of the pattern turntable 3 (the number of detected slit sections Sp...) Is “20”, and therefore the resolution is 20×4=80. If the gear ratio is set to 40, the total resolution is 80×40=“3200”. Note that FIG. 9 shows an external configuration of the rotary encoder 1. In FIG. 9, 51z is a connection terminal of the detector 6z, 51a is a connection terminal of the detector 4a, and 51b is a connection terminal of the detector 4b, which are exposed to the outside through the casing body 21m.

By the way, with the addition of the speed increasing mechanism section 7, backlash that affects the detection accuracy occurs. However, in the case of the lens apparatus M, the adjustment mechanism of the lens including the motor, the sensor, the gear, and the like is provided, and thus this adjustment Backlash of the mechanism becomes dominant. Therefore, for example, by performing backlash control in which the rotary encoder 1 always reads in a constant direction of operation, it is possible to ignore the backlash of the speed increasing mechanism 7 and reduce the overall detection accuracy. Does not occur.

Therefore, according to the rotary encoder 1 according to the present embodiment, as a basic configuration, the rotation input shaft 2 into which the rotation of the detection target is input, the rotation input shaft 2 rotates based on the rotation of the rotation input shaft 2, and A pattern turntable 3 having a plurality of first detected parts Sp... Which form a repeated pattern Pf in the circumferential direction Ff, and a pattern detection part 4 including at least one detector 4a, 4b for detecting the repeated pattern Pf. A rotary encoder provided, which has at least one second detected portion Sd which is rotated by the rotation input shaft 2 and serves as a reference point Do in the circumferential direction Ff, and the second detected portion Sd. A base point detection unit 6 including at least one detector 6z for detecting the speed, a speed increasing mechanism unit 7 for speeding up and outputting the rotation of the rotation input shaft 2 by a predetermined magnification (X times), and the speed increasing mechanism unit. Since the rotation detection shaft 8 which rotates by the output of 7 and the pattern turntable 3 which turns by this rotation detection shaft 8 are provided, the pattern turntable 3 can be repeatedly used without changing the shape (precision) of the pattern turntable 3. The density of the pattern Pf can be substantially multiplied by X, and the detection accuracy can be dramatically improved. Moreover, it can be easily realized by adding the speed increasing mechanism 7 which can be manufactured at a relatively low cost.

Next, a method of using the rotary encoder 1 according to this embodiment will be described with reference to FIGS. 10 and 11.

FIG. 11 shows the appearance of the lens device M mounted on the projector 100. The lens device M includes a focus adjusting mechanism, a zoom adjusting mechanism, and an image plane adjusting mechanism, and on the outer peripheral surface of the lens barrel Mc, a focus adjusting ring 12 for operating the focus adjusting mechanism and a zooming for operating the zoom adjusting mechanism. An adjustment ring 13 and an image plane adjustment ring 14 for operating the image plane adjustment mechanism are provided. The adjustment rings 12, 13, 14 are rotatably mounted over a predetermined range, and rack portions 12s, 13s, 14s are formed on the outer peripheral surfaces of the adjustment rings 12, 13, 14 respectively.

On the other hand, at other positions on the outer peripheral surface of the lens barrel Mc, a focus drive unit 61 for rotationally displacing the focus adjustment ring 12, a zooming drive unit 62 for rotationally displacing the zooming adjustment ring 13, and an image plane adjustment ring 14 are provided. An image plane drive unit 63 for rotational displacement is provided, and each drive unit 61, 62, 63 is attached to an assembly plate unit Ms integrally provided on the outer peripheral surface of the lens barrel Mc. In this case, the focus driving unit 61, the zooming driving unit 62, and the image plane driving unit 63 have the same basic configuration, although the details such as the layout are different.

FIG. 10 shows the focus drive unit 61 extracted. The focus drive section 61 includes a rotation drive section 71 attached to a predetermined position of the assembly plate section Ms. Further, the rotation drive section 71 decelerates the rotation of the motor section 72 and the drive section of the motor section 72. A reduction gear unit portion 74 for rotating 73 is provided. The drive gear 73 meshes with the rack portion 12s formed on the outer peripheral surface of the focus adjustment ring 12.

Further, the rotary encoder 1 according to the present embodiment is mounted at a position adjacent to the rotary drive unit 71 in the assembly plate Ms, and the driven gear 75 is mounted on the tip end side of the rotary input shaft 2 of the rotary encoder 1. .. Then, the driven gear 75 is meshed with the rack portion 12s of the focus adjustment ring 12. As a result, when the motor section 72 rotates, this rotation output is decelerated by the reduction gear unit section 74, and the driven gear 75 rotates at a low speed. As a result, the focus adjustment ring 12 meshed with the driven gear 75 is rotationally displaced, and the position of the focus adjustment system lens is adjusted through the focus adjustment mechanism not shown in the figure. On the other hand, the rotational displacement of the focus adjustment ring 12 is transmitted to the rotary input shaft 2 via the driven gear 75, and the rotary encoder 1 according to the present embodiment rotates the focus adjustment ring 12 at the rotational position (rotation angle) and rotation. The moving direction is detected.

By the way, when the rotary encoder 1 is configured as a conventional rotary encoder, that is, when the rotary encoder without the speed increasing mechanism 7 is configured, one rotation of the rotation input shaft 21 is detected as a “20” pulse. It That is, one rotation of the pattern turntable 3 is detected. On the other hand, in the rotary encoder 1 according to the present embodiment including the speed increasing mechanism section 7, the "3200" pulse described above is detected by one rotation of the rotation input shaft 21. That is, 3200/20=160 times (X times) pulses are detected, and the detection accuracy can be dramatically improved.

As described above, the backlash that occurs due to the addition of the speed increasing mechanism section 7 affects the detection accuracy, but the magnification of the speed increasing mechanism section 7 that can ensure the detection accuracy required by the lens apparatus M is set. Since the selection can be made, the optimum rotary encoder 1 matching the lens device M can be constructed. In particular, in the case of the lens device M, as described above, each drive unit 61 is provided with the reduction gear unit unit 74, so that the backlash generated by the speed increasing mechanism unit 7 is caused in the reduction gear unit unit 74. It suffices to ensure detection accuracy that takes into account the backlash that occurs.

In this way, if the rotational displacement of the lens position adjusting rings 12 (13, 14) in the lens apparatus M is input to the rotary input shaft 2 of the rotary encoder 1 according to the present embodiment, the lens position Since it can be used for detecting the adjustment position of the adjustment ring 12 (13, 14), it is possible to contribute to the cost reduction of the entire lens apparatus M while ensuring the detection accuracy required for this detection. Therefore, it is possible to construct a practical rotary encoder 1 that matches the lens device M.

Although the preferred embodiments have been described in detail above, the present invention is not limited to such embodiments, and the details of the configuration, shape, material, quantity, numerical values, etc. do not depart from the gist of the present invention. The range can be changed, added, or deleted arbitrarily.

For example, the speed increasing mechanism 7 is shown to be configured by a combination of one or more rotary gears Gi, G11, G12... Go, but depending on the application, it may be configured by a belt transmission method such as a timing belt. Is also possible. Further, although the first detected portion (Sp) is shown to be constituted by the detected slit portion Sp formed on the pattern turntable 3, it may be constituted by another detected portion such as printing a monochrome pattern. It does not exclude. Further, the second detected portion (Sd) is shown to be constituted by the detected cutout portion Sd formed in the base rotary disk 5, but other detected portions such as formation of the detected slit portion or printing of a black-and-white pattern is performed. It does not exclude the case where the detection unit is used. On the other hand, the rotation detection shaft 8 is preferably arranged coaxially with the rotation input shaft 2, but may be arranged non-coaxially. Further, whether or not the axial position holding portion 11 is provided is arbitrary and is not an essential component. On the other hand, although the case where the two detectors 4a and 4b are used as the pattern detection unit 4 is shown, one detector 4a may be used when other means for detecting the rotation direction is used. , An average value may be used by three or more detectors 4a. Also, an example using one second detected portion Sd has been shown, but the case of using two or more second detected portions Sd... Is not excluded. Therefore, the base point detection unit 6 may include two or more detectors 6z... Which detect the second detected parts Sd.

INDUSTRIAL APPLICABILITY The rotary encoder according to the present invention can be used in various fields including the exemplified lens device and for detecting displacement, position, angle, speed, direction and the like.

1: rotary encoder, 2: rotary input shaft, 3: pattern rotary disc, 4: pattern detector, 4a: detector, 4b: detector, 5: base rotary disc, 6: speed increasing mechanism, 7: rotation detection Axis, 8: Base point detection unit, 6z: Detector, 11: Axial position holding unit, 12 (13, 14): Lens position adjustment ring, Ff: Circumferential direction, Pf: Repeated pattern, Sp...: First detected object Part (detected slit part), Sd: second detected part (detected cutout part), Do: base point, Ts: 1 cycle of the repeating pattern, Tsp: 1/4 cycle of 1 cycle of the repeating pattern, Gi: rotation Gear, G11: rotary gear, G12...: rotary gear, Go: rotary gear, M: lens device

Claims (8)

A rotation input shaft to which the rotation of the detection target is input, a pattern turntable having a plurality of first detected portions that rotate based on the rotation of the rotation input shaft, and form a repetitive pattern in the circumferential direction, and this repetitive pattern Is a rotary encoder comprising a pattern detection unit including at least one detector for detecting, a base point having at least one second detected portion which is rotated by the rotation input shaft and serves as a circumferential base point. A rotating disk, a base point detecting section including at least one detector for detecting the second detected section, a speed increasing mechanism section for speeding up and outputting the rotation of the rotation input shaft by a predetermined magnification, and the speed increasing mechanism section. A rotary encoder comprising: a rotation detection shaft that is rotated by the output of the speed mechanism unit; and the pattern turntable that is rotated by the rotation detection shaft. The rotary encoder according to claim 1, wherein the pattern detection unit includes a pair of pattern detectors arranged such that a phase of a quarter cycle in one cycle of the repeating pattern is different. The rotary encoder according to claim 1, wherein the speed increasing mechanism is configured by a combination of one or more rotary gears. The rotary encoder according to claim 1, wherein the first detected portion is formed by a slit portion formed on the pattern rotary disk. The rotary encoder according to claim 1, wherein the second detected portion is formed by a notch portion or a slit portion formed on the base-point rotary disk. The rotary encoder according to claim 1, wherein the rotation detection shaft is arranged coaxially with the rotation input shaft. 7. An axis position holding unit that holds the axis of the rotation detection shaft coaxially with the axis of the rotation input shaft is provided between the rotation detection shaft and the rotation input shaft. Rotary encoder. The rotary encoder according to claim 1, wherein a rotational displacement of a lens position adjusting ring in the lens device is input to the rotation input shaft.

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