Source: http://www.google.com/patents/US4961635?dq=3691140
Timestamp: 2016-05-29 13:57:27
Document Index: 300823646

Matched Legal Cases: ['art 220', 'art 220', 'art 220', 'art 160', 'art 220', 'art 220']

Patent US4961635 - Zoom lens drive mechanism - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA zoom lens drive mechanism which is capable of zooming by moving first and second lens groups with a constant relation being maintained between them and of focusing by moving only the first lens group. A zoom shaft is disposed in parallel with the optical axis of the zoom lens and on the zoom shaft...http://www.google.com/patents/US4961635?utm_source=gb-gplus-sharePatent US4961635 - Zoom lens drive mechanismAdvanced Patent SearchPublication numberUS4961635 APublication typeGrantApplication numberUS 07/398,684Publication dateOct 9, 1990Filing dateAug 25, 1989Priority dateSep 6, 1988Fee statusPaidAlso published asUS5115267Publication number07398684, 398684, US 4961635 A, US 4961635A, US-A-4961635, US4961635 A, US4961635AInventorsShigeru Kondo, Naoki Takatori, Masaaki Morizumi, Shino KanamoriOriginal AssigneeFuji Photo Film Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (19), Classifications (5), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetZoom lens drive mechanism
US 4961635 AAbstract
A zoom lens drive mechanism which is capable of zooming by moving first and second lens groups with a constant relation being maintained between them and of focusing by moving only the first lens group. A zoom shaft is disposed in parallel with the optical axis of the zoom lens and on the zoom shaft there is rotatably disposed a zoom cam ring which includes two cam grooves in the outer periphery thereof. In the zoom shaft there is disposed a first lens group drive means which is free to move in the axial direction of the zoom shaft and in the first lens group drive means there is provided a focus cam ring such that it is free to rotate. Two cam followers respectively provided in the first lens group drive means and in the second lens group are in engagement with the two cam grooves in the zoom cam ring, respectively, and a cam follower provided in the first lens group is in engagement with a cam groove formed in the focus cam ring.
1. A zoom lens drive mechanism comprising:first and second groups of lenses respectively disposed movably in an optical axis direction to form a zoom lens; a zoom shaft disposed in parallel with the optical axis of said zoom lens; a zoom cam ring disposed rotatably on said zoom shaft and including first and second cam grooves in the periphery thereof; a first lens group drive means disposed on said zoom shaft such that it is free to move in the axial direction of said zoom shaft; and, a focus cam means movable in the axial direction of said zoom shaft together with said first lens group and free to move with respect to said first lens group drive means, said focus cam means having a cam groove, wherein two cam followers respectively provided in said first lens group drive means and in said second lens group are respectively brought into engagement with said first and second cam grooves in said zoom cam ring, a cam follower provided in said first lens group is brought into engagement with said cam groove formed in said focus cam means, said zoom cam ring is rotated to thereby move said first and second lens groups in the optical axis direction with a constant relation being maintained therebetween, and said focus cam means is moved to thereby move said first lens group in the optical axis direction. 2. A zoom lens drive mechanism as set forth in claim 1, wherein there is provided an adjustment member for moving said zoom cam ring to an arbitrary position in the axial direction of said zoom shaft.
3. A zoom lens drive mechanism as set forth in claim 2, wherein said cam groove formed in said focus cam means comprises a linear cam groove capable of moving said first lens group beyond a range actually used for focus adjustment.
4. A zoom lens drive mechanism as set forth in claim 1, wherein said first and second lens groups can be freely moved in the optical axis direction by a plurality of guide shafts, respectively, and said first lens group drive means includes a rotation preventive member engageable with one of said plurality of guide shafts to thereby prevent said first lens group drive means from rotating round said zoom shaft.
5. A zoom lens drive mechanism as set forth in claim 4, wherein said rotation preventive member is disposed in the extension direction of said cam follower provided in said first lens group drive means.
6. A zoom lens drive mechanism as set forth in claim 1, wherein there are further provided a zoom drive means for rotating said zoom cam ring electrically and a focus drive means for moving said focus cam means electrically.
7. A zoom lens drive mechanism as set forth in claim 6, wherein there are further provided a finder guided so as to be free to move in a direction where an objective lens moves towards and away from said zoom lens, and a power transmission means for connecting said focus drive means with said objective lens of said finder mechanically and for moving said objective lens of said finder in link with the operation of said focus drive means.
8. A zoom lens drive mechanism as set forth in claim 6, wherein there are provided a finder having a moving lens movable in the optical axis direction thereof to thereby achieve zooming, and a power transmission means for connecting said zoom drive means and said moving lens of said finder mechanically and for moving said finder moving lens in link with the operation of said zoom drive means.
9. A zoom lens drive mechanism comprising:first and second groups of lenses respectively disposed movably in an optical axis direction to form a zoom lens; a zoom shaft disposed in parallel with the optical axis of said zoom lens; a zoom cam ring disposed rotatably on said zoom shaft and including first and second cam grooves in the periphery thereof, said zoom cam including a hollow portion therein; a first lens group drive means disposed so as to be freely movable in the axial direction of said zoom shaft and also that it advances into said hollow portion in said zoom cam ring normally or when it is moved in the direction of said zoom cam ring; and, a focus cam ring movable in the axial direction of said zoom shaft together with said first lens group, free to rotate with respect to said first lens group drive means, and advanceable into said hollow portion in said zoom cam ring normally or when it is moved in the direction of said zoom cam ring, wherein two cam followers respectively provided in said first lens group drive means and in said second lens group are respectively brought into engagement with said first and second cam grooves in said zoom ring, a cam follower provided in said first lens group is brought into engagement with said cam groove formed in said focus cam ring, said zoom cam ring is rotated to thereby move said first and second lens groups in the optical axis direction with a constant relation being maintained therebetween, and said focus cam ring is rotated to thereby move said first lens group in the optical axis direction. Description
Now, the cam groove 132A formed in the focus cam ring 132 is a groove which is linear with respect to the angle of rotation of the focus cam ring 132. Also, if the range of angle of rotation of the focus cam ring 132 actually used is assumed to be 100�, then the cam groove 132A is formed in the range of 200� including the actually used range of angle of rotation of 100� as well as a further formed angle of 50� and a further rearward angle of 50� with respect to the actually used range of angles of rotation of 100�. The reason why the cam groove 132A is formed substantially exceeding the actually used range of angle of rotation is to perform a zoom adjustment.
Also, the low pass filter 150B is inserted the prism box 150 from behind and is then fixed by a stop plate 150C and two screws 150D. As shown in FIG. 3, the CCD sensor 154 is positioned in a CCD holder 158, and is then fixed by a stop plate 159 having light shield rubber 159A, and after, that the CCD holder 158 is fixed to the rear portion of the prism box 150.
In other words, as shown in FIGS. 11(A) and (B), there is mounted a brush 167 to the rear slide frame 104A, while, in a zoom code plate 168 on which the brush 167 is slidable, there is provided a zoom code which shows the absolute position of the rear slide frame 104A. Therefore, in zooming the zoom lens, if the brush 167 is moved on the zoom code with the movement of the rear slide frame 104A, then there is obtained a code signal (zoom information) which corresponds to the position of movement thereof. The zoom information is used to control an AE system, for example. Also, the zoom code plate 168 is formed with elongated bores 168A, 168A and 168A, which permit the zoom code plate 168 to move in the direction of an optical axis L. And, the zoom code plate 168 is adjusted in position so that desired zoom information can be output, for example, when the zoom lens is moved to the telephoto end, before it is fixed by screws 169, 169.
The bore 183A in the bottom board 183 has a center which is identical with the optical axis of the zoom lens and the diaphragm plate 182 is formed with 5 bores, 182A, 182B, --- at equal pitch intervals. The five bores also face the bore 183A in the bottom board 183 and are different in diameter from one another. And, the iris motor 181 is controlled in accordance with the amount of light received from the object and detected by the AE sensor 156 and it rotates the diaphragm plate 182 so that one of the five bores in the diaphragm 182 can face the bore 183A in the earth plate to thereby obtain a desired amount of incident light. Also, the diaphragm plate 182 is formed with a notch 182C and, by means of the output of a photo interrupter (not shown) to detect the notch 182C, the home position in the automatic exposure control can be detected.
(Barrier Opening/Closing Mechanism
FIG. 15(A) shows the closed state of the barrier. In this state, the energizing force of the tension spring 191 is transmitted to the pin 108A on the barrier 108, the drive plate 192, the pin 192B on the drive plate 192, the torsion spring 195, and the pin 194B on the switch cam 194 in this order, trying to cause the switch cam 194 to rotate in a counter-clockwise direction in FIG. 15(A), but, due to the fact that the drive arm 186 is abutted against the side surface of the switch cam 194, the switch cam 194 is prevented from rotating, whereby the closed state of the barrier can be maintained. Also, in this case, since any desired pressing force from the cam portion 194A of the switch cam 194 is not applied to the lever 196A of the limit switch, the limit switch 196 is OFF.
From this state, if the drive arm 186 is rotated counter-clockwise to a position shown in FIG. 16(A), then the barrier 108 is rotated clockwise due to the energizing force of the tension spring 191 to a half open state. Also, if the drive arm 186 is further rotated clockwise to a position shown in FIG. 16(B), then the barrier 108 is further rotated clockwise to a fully open state. In the respective states shown in FIGS. 16 (A) and (B), since the lever 196A of the limit switch 196 is pressed by the cam portion 194A of the switch cam 194, the limit switch 196 is ON.
In other words, responsive to the rotation of the iris motor 181 for opening the barrier 108 from the barrier closed state shown in FIG. 15 (A) to the barrier open state shown in FIG. 16(B), the diaphragm plate 182 has been rotated by 2 rotations or so. And, for example, a position where the diaphragm plate 182 is rotated by three rotations is considered as a home position, and, by controlling the further rotations of the diaphragm plate 182 thereafter, the exposure control is carried out. The above-mentioned home position is detected according to the time when detection signals are output three times from a photo interrupter to detect the notch 182C formed in the diaphragm plate 182, after the output of the above-mentioned limit switch 196 rises from OFF to ON. The control on the rotational movement of the diaphragm plate 182 is performed by applying the number of drive pulses corresponding to the exposure control to the iris motor (pulse motor) 181 from the time of detection of the above-mentioned home position.
In FIG. 17, there are provided on a carrier plate 202 three pins 202A, 202B and 202C over which an F cam 204, an F cam follower 206 and an AF connecting lever part 220 are freely rotatably fitted respectively. And, in order to prevent the latter three members from slipping off out of place, a stop member 208 is fixed to the carrier plate 202 by screws 210 and 210. Between the AF connecting lever part 220 and stop member 208 there is interposed a torsion spring 212 and the AF connecting lever part 220 is energized in the direction of an arrow A by this torsion spring 212.
Now, there is provided a gear 204A in the F cam 204 and the gear 204, as shown in FIG. 1, intermeshes with a gear 166 provided on the zoom connecting shaft 164 of the zoom drive part 160. Also, the F cam follower 206 has a lower end 206A in sliding contact with the cam surface of the F cam 204 and the upper end 206B of the F cam follower 206 is in engagement with the lower end 216A of the F intermediate lever 216. For this reason, when the F cam 204 is rotated in link with the zoom drive operation, then the F intermediate lever 216 is rotated by means of the F cam follower 206.
Now, description will be given here of the abovementioned AF connecting lever part 220 in more detail.
In FIG. 19, there is shown an exploded perspective view of the finder case section 200B. In particular, in this figure, there is provided a finder case 230 and, in the two sides of the finder case 230, there are stored the abovementioned projection lens 250 and light receiving lens 252, respectively. In rear of the projection lens 250, there is disposed a projection frame base 254 on which an infrared ray diode (not shown) is placed, and in rear of the light receiving lens 252, there are disposed two silicone photo diodes (SPD) and the like (which are not shown). That is, the distance measuring means provided in the finder case section 200B employs an active type of trigonometrical measurement, in which an infrared ray of light is projected from the infrared ray diode onto an object and the infrared ray reflected by the object is then directed onto the two SPDs, so that a distance to the object can be measured by means of a ratio of the outputs of the two SPDs.
The objective lens 232 is guided by its moving frame 232A in such a manner that it is freely movable in a direction (a vertical direction) perpendicular to the optical axis of the finder, and in the moving frame 232A there is disposed a moving frame spring 232B which is used to energize the objective lens 232 downwardly.
The moving lens 234 is guided movably in the finder optical axis direction by its moving frame 234A, moving frame stopper 234B and the like. On the lower surface of the moving frame 234A, there is provided a pin with which is engaged an elongated bore 240A formed in a frame lever 240. Also, the base end portion of the frame lever 240 is fixed to the rotary shaft portion of a lens lever 242 and further the lens lever 242 is energized in the direction of an arrow A by means of a tension spring 244.
Also, when the zoom lens is in focus for an infinite distance, then the objective lens 232 is pushed up to the upper-most end against the energizing force of the moving frame spring 232B by the AF connecting lever part 220 and, as the zoom lens is focused in closer ranges, the objective lens 232 is lowered down accordingly.
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