JP2001033682A - Lens-barrel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the complication of a lens-barrel caused by end detection of a telescopic end and a wide angel end in a zoom lens-barrel so as to simplify the end detection. SOLUTION: When front group moving rings are moved with front group rollers engaged with a cam groove 4a by turn of a cam ring 4, and when rear group lens-barrels are moved with rear group rollers engaged with a cam groove 4b, optical-axis-directionally from a telescopic end to a wide-angle end respectively, a recess 10 is provided only in a wide-angle position of the cam ring 4, an end switch 15 having a contact engaged and disengaged with the recess 10 is attached to a flange of a fixed tube, wide angle end sides of the cam grooves 4a, 4b of the cam ring 4 are extended further to be formed turnably upto a lens-barrel storing end, and abutting in cam groove ends of the both rollers is absorbed by a friction mechanism of a turning drive source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel structure, and more particularly to an end detection of a projection lens for a liquid crystal projector and a lens barrel structure related thereto.

[0002]

2. Description of the Related Art Conventionally, many proposals have been made for an edge detection configuration, such as an interchangeable lens and a lens shutter. However, in a projection lens for a liquid crystal projector, recently, there is a demand for miniaturization of the main body of the liquid crystal projector to suppress the entire length of the projection lens. Therefore, in order to suppress the total length of the projection lens, there is a means for further storing the projection lens than the wide end. For this purpose, a lens barrel structure having a detection mechanism at the wide end is required.

[0003]

However, the lens barrel structure is different from the above-mentioned prior art in view of application and accuracy, and the end detection mechanism also takes in signals at the telephoto end and the stowed end in addition to the wide end, thereby increasing complexity. It was the composition which did. As a result, the number of parts increased, and the shape was complicated.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object of the present invention to provide a lens barrel structure having a simple and inexpensive end detection mechanism which is configured to withstand the impact strength of the end at the tele end and the stored end.

[0005]

In order to achieve the above-mentioned object, the present invention provides an end detecting portion of an end detecting mechanism in a lens barrel structure only at a wide end position of a turning member which is turned to a storage position. It is a thing.

[0006]

According to the first aspect of the present invention, the end detecting portion of the end detecting mechanism in the lens barrel structure has only the wide end position, and the tele end and the storage end are mechanical end buttings. With a small number of parts, it is possible to easily and inexpensively obtain a lens barrel having an end detecting means. According to the second aspect of the present invention, since the end detecting portion is configured to detect the concave portion or the convex portion on the rotating member and the electric signal, the end detecting portion can be easily and easily set. According to the third aspect of the present invention, the concave portion on the rotating member has a slope in a certain angle range and has a configuration in which a reciprocating difference is suppressed, so that a required state can be smoothly set at the time of photographing and storing. According to the fourth aspect of the present invention, since the rotary member does not have the notch for the zoom stopper, the lens barrel structure can be manufactured simply and at low cost. According to a fifth aspect of the present invention, since a friction mechanism is provided in the actuator for the abutting of the mechanical end, a lens barrel component can be provided even when a certain load or more is generated at the tele end and the storage end. Will not be damaged.
According to the sixth aspect of the present invention, since the component for the electric signal is set in the fixed portion, the end detecting mechanism can be easily set in the lens barrel.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view of a lens barrel for a liquid crystal projector having a lens barrel structure of the present embodiment, FIG. 2 is an enlarged sectional view of a main part thereof, and FIG. 3 is a developed view of a cam ring and a fixed barrel thereof. In the figure, reference numeral 1 denotes a focus ring, which is directly connected to the front lens barrel 2. A male helicoid 2a having a certain lead is formed on the outer diameter of the front group lens barrel 2, and is helicoidally connected to the female helicoid 3a formed on the inner diameter of the front group moving ring 3. The front group moving ring 3 is fitted on the front part of the inner diameter part of the fixed cylinder 5, and three rollers 7 projecting from the outer diameter part penetrate through the rectilinear grooves 5 a formed in the fixed cylinder 5. It engages with three front group cam grooves 4 a formed on the cam ring 4 fitted on the outer diameter of the fixed cylinder 5. The cam ring 4 is fixed to the fixed cylinder 5
The three rollers 9 projecting from the outer diameter portion on the rear end side engage with the circumferential groove 4c to regulate thrust, and rotate at a fixed position.

Reference numeral 6 denotes a rear lens barrel, which is fitted on the inner diameter of the fixed cylinder 5 and a roller 8 projecting from the outer diameter of the rear cylinder penetrates a straight groove 5a formed in the fixed cylinder 5 to form the cam. It engages with three rear group cam grooves 4b formed on the ring 4. The front group cam groove 4a and the rear group cam groove 4b of the cam ring 4 extend from the telephoto end to the wide end to extend to the lens barrel housing end. Reference numeral 12 denotes a focus key, and a focus gear 13
, And is key-coupled to the focus ring 1 for rotation. The focus gear 1
Reference numeral 3 is fitted to the outer diameter portion of the cam ring 4 so as to rotate at a fixed position, and meshes with an output gear 16a of a focus motor 16, which will be described later, so that electric focusing is possible. Reference numeral 14 denotes a zoom gear, which is attached to the outer diameter portion of the cam ring 4 and has an output gear 1 of a zoom motor 17 described later.
7a and has an electric zoom configuration.

Reference numeral 15 denotes an end switch, which is attached by a screw near the rear portion of the outer diameter of the fixed cylinder 5 and whose contact 15a is provided at the rear end of the outer diameter of the cam ring 4 for detecting a wide end position. The edge detection mechanism is configured by engaging and disengaging the U-shaped concave portion 10. Reference numeral 16 denotes a focus motor, and 17 denotes a zoom motor, both of which are held by a base plate 18 attached to the flange portion of the fixed cylinder 5 with screws, and a friction mechanism is disposed forward from respective output gears 16a and 17a. During an excessive load, the output gears 16a and 17a run idle with respect to the output shaft. Reference numeral 11 denotes a stopper pin which limits the margin at the retracted end and the telephoto end.

The operation system of this embodiment having the above configuration will be described with reference to the flowchart of FIG. First, when the power supply of the liquid crystal projector is turned on in step 1, the cooling fan operates in step 2, the operation is ready for operation in step 3, and the process proceeds to step 4. In step 4, the zoom switch is turned on, the zoom motor 17 is driven, the cam ring 4 rotates from the storage end to the wide end via the zoom gear 14, and the front group cam groove 4a and the rear group cam groove 4b are lifted. The zoom drive of the front group lens and the rear group lens is performed, and the process proceeds to step S5.

In step 5, the end switch 15 detects whether the cam ring 5 has rotated to the wide end. If the wide end is not detected, the process proceeds to step 6, and if it is detected (ON), the process proceeds to step 7. . In step 7, the zoom drive is temporarily stopped by the ON signal of the end switch 15, but when the ON signal is reset on the circuit, the zoom drive becomes possible again, and the optimal screen size is selected between tele and wide. After the screen size is set, the process proceeds to step 8.

In step 8, the switch of the focus motor 16 is turned on, the focus ring 1 is rotated via the focus gear 13 and the focus key 12, and the process proceeds to step 9. In step 9, the front lens barrel 2 is moved in the optical axis direction by helicoid coupling with the front group moving ring 3 due to the rotation of the focus ring 1, and the focusing is performed. If so, return to step 8. In step 10, image projection starts and projection is performed, and when projection ends in step 11, step 1
In step 13, the cooling fan is turned off, and in step 13, the zoom position at an arbitrary position is driven to the storage end.
To turn off the power and end a series of operations.

In this embodiment, the end detecting portion of the cam ring 4 is formed in the concave portion 10. However, the end detecting portion is formed in a hemispherical convex portion, and is turned on when the contact 15a of the end switch 15 rides on the convex portion. It goes without saying that it may be configured.

[0014]

As described above, according to the first aspect of the present invention, the end detecting portion of the end detecting mechanism in the lens barrel structure has only the wide end position, and the tele end and the storage end are mechanical end buttings. With this arrangement, it is possible to easily and inexpensively obtain a lens barrel having end detecting means with a reduced number of parts. According to the second aspect of the present invention, since the end detecting portion is configured to detect the concave portion or the convex portion on the rotating member and the electric signal, the end detecting portion can be easily and easily set. According to the third aspect of the present invention, the concave portion on the rotating member has a slope in a certain angle range and has a configuration in which a reciprocating difference is suppressed, so that a required state can be smoothly set at the time of photographing and storing. According to the fourth aspect of the present invention, since the rotary member does not have the notch for the zoom stopper, the lens barrel structure can be manufactured simply and at low cost. According to a fifth aspect of the present invention, since a friction mechanism is provided in the actuator for the abutting of the mechanical end, a lens barrel component can be provided even when a certain load or more is generated at the tele end and the storage end. Will not be damaged. According to the sixth aspect of the present invention, since the component for the electric signal is set in the fixed portion, the end detection mechanism can be easily and easily set in the lens barrel.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a lens barrel having a lens barrel structure according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part thereof.

FIG. 3 is a development view of the cam ring and the fixed cylinder.

FIG. 4 is a flowchart illustrating the operation system.

[Explanation of symbols]

1. Front lens barrel, 2. Focus ring, 3. Front group moving ring, 4. Cam ring, 5. Fixed cylinder, 6. Rear group lens barrel, 7. Front group roller, 8 ..Roller group rollers, 9 ... Thrust rollers, 10 ... End detection recesses, 11 ... Stopper pins, 12 Focus keys, 13 Focus gears, 14 Zoom gears, 15 End switches, 16.
・ Focus motor, 17 ・ ・ Zoom motor, 18 ・ ・
Ground plate.

Claims (6)

[Claims] 1. A lens barrel structure wherein an end detection portion of an end detection mechanism is provided only at a wide end position, and a tele end and a storage end are abutting mechanical ends. 2. The lens barrel structure according to claim 1, wherein said end detecting portion is configured to detect a concave portion or a convex portion on said rotating member by an electric signal. 3. The lens barrel structure according to claim 2, wherein the concave portion on the rotating member has an inclination in a certain angle range to reduce a reciprocating difference. 4. The lens barrel structure according to claim 2, wherein said rotary member has no notch for a zoom stopper. 5. The lens barrel structure according to claim 1, wherein a friction mechanism is provided in the actuator for abutting the mechanical end. 6. The lens barrel structure according to claim 2, wherein a component for an electric signal is set on a fixed portion.