JPS60129717A - Motor-driven variable focus camera - Google Patents

Abstract

PURPOSE:To shorten the time required for focus switching and attain high-accuracy focusing by forming different-pitch grooves which are used for focusing at the time of long focal length and short focal length and for focus switching in a shaft having a feed groove. CONSTITUTION:The cam groove formed in the driving shaft 7 is variable at three positions; and a part C is where an engaging pin 6 moves during the focus switching of a lens barrel, and parts B and A are where the engaging pin 6 moves at the time of short focal length and long focal length respectively. When a motor 9 reverses in the opposite direction of an arrow to reverse the shaft 7, a lens barrel earth plate 2 moves in the opposite direction (backward) of an arrow and the motor 9 is powered off at a break of a pattern detected by a contact piece 23, thereby holding the lens barrel base plate 2 at the position. When the motor 9 is powered on again to rotate normally, the lens barrel base plate 2 enters B and moves. Simultaneously, a specific numbers of pulses are counted by contact pieces 15a and 15b which contact a rotating pulse disk and then the motor 9 is powered off to stop the base plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides at least two
The present invention relates to a so-called variable focus camera capable of switching to different focal lengths, and particularly to a motor-driven variable focus camera in which switching of its optical system is controlled by a motor.

FIG. 1 shows a drive mechanism according to a conventional example of a so-called motor-driven variable focus camera that can take two or more focal lengths by switching the photographing optical system. This is characterized by the ability to perform both focusing and focal length switching using a single motor without having to rely on manual operations, making it easy to take pictures.

However, in this conventional example, since the lens barrel base plate M for focusing and J/0 point distance switching is always driven at the same pitch by rotating the drive bar R, there are the following problems. Ta. That is, tJJ of point distance
Since the moving distance of (drive for switching) -R is relatively long, it takes a long time to switch between II and IJ.On the other hand, if you make the drive (drive) faster, the switching time can be shortened, but it is difficult to achieve focusing accuracy.

In addition, the rotation angle detection pattern (pattern of pulse plate S-J) that detects the speed of movement of the drive Tsuk-R through the amount of rotation of the drive motor is used for each focal point in a bifocal switching camera with long focal length and short focal length, for example. It is necessary to provide a rotation angle detection pattern for each distance, and accordingly, multiple sets of number detection contacts T, etc. are also required, which complicates the overall structure.

The present invention has been made in order to eliminate the drawbacks of the conventional examples described above, and each has a long focal length with a different pitch;
A drive shaft for a lens barrel having a first feed groove used for focusing at l1, a second feed groove used for focusing at short f and r point distances, and a third feed groove used for focal length switching. The objective is to provide a motor-driven variable focus camera with

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic oblique view of a motor-driven variable focus camera showing one embodiment of the present invention, and FIG. 3 is a schematic side view thereof. In the figure, ■ is the main lens and the lens barrel base plate 2
is maintained. A support bar 3 is fixed to the lens barrel base plate 2, and both ends of the support bar 3 are fitted and held by a front plate 4 and a rear plate 5.

This allows the support bar 3 to slide in the front-rear direction between the front plate 4 and the rear plate 5.

Reference numeral 6 designates an engagement pin with a smooth end that is attached to the lens barrel base plate 2 and engages with a cam groove of a drive shaft 7, which will be described later. 7 is a drive shaft provided with a single cam groove, and the pitch of the cam groove is variable at eight locations. That is, the details are shown in FIG. 3. Section 0 is the longest pitch of movement of the engagement pin 7 when switching the focal point of the lens barrel, and section B is the part where the engagement pin 7 moves during short focal length focusing. Part A, which is the shortest pitch of movement, is a part where the pitch at which the engagement bin moves during focusing at long focal length is longer than part B in proportion to the amount of movement t. A gear 8 is fixed to the rearmost end of the drive shaft 7, and is connected to a pinion IO of a motor 9. The gear 8 is also connected to a reduction gear l], , 12.18, and a pulse plate 14 having a conductive pattern of 4'+'1'i is fixed on the reduction gear 13. The pulse plate 14 has a contact piece 15.
a and 15b are in contact with each other, and when the pulse plate rotates, pulses corresponding to each pattern can be counted.

1 (5 is the sub-lens and is held in the holder 17. It is fixed to the boulder 17) (-18 is both of them!'r
:1, : are fitted and held by the lens barrel base plate 2 and the holding plate 19, so the sub lens 16 can be rotated about the bar 18, and is urged in the direction of opening by the pi-19. ing. A cam protrusion 20 is recessed in the rear plate 5, and when its tapered part 20a contacts the holder 17, the holder 1.7 is rotated in the counterclockwise direction against the pins 19, and the secondary Lens i LS is moved back from the photographing optical axis. Contact pieces 21, 22 and 28 are fixed to the lens barrel base plate 2 and slide on the pattern substrate 24. The front plate 4 is fixed to the rear plate 5 with screws 25, and the rear plate 5 is fixed to a camera body (not shown).

Next, the operation of the motor-driven variable focus camera according to the embodiment of the present invention will be explained. Photographing using only the main lens 1 will be referred to as standard photography, and photography using a combined optical system of the main lens 1 and auxiliary lens 16, in which the auxiliary lens 16 is arranged on the optical axis, will be referred to as telephoto photography.

In the case of standard photography, the motor 9 reverses in the direction opposite to the direction of the arrow, causing the drive shaft \7 to reverse in the direction opposite to the direction of the arrow. As a result, the lens barrel base plate 2 moves in the direction opposite to the direction of the arrow toward the rear of the camera using the support bar 3 as a guide. In the case of telephoto shooting, motor 9 moves 1 in the direction of the arrow.
Rotate E to rotate the drive shaft 7 forward in the direction of the arrow. As a result, the lens barrel base plate 2 moves in the front direction of the camera as indicated by the arrow D in the figure.

First, the case of standard shooting will be explained. Telephoto (not shown)
When the standard changeover switch (hereinafter abbreviated as TW changeover switch) is set to the standard side, the motor 9 rotates in reverse, causing the gear 8 to reverse, so that the drive shaft 7 starts reverse rotation. As a result, the lens barrel base plate 2 moves along the cam groove C portion using the support bar 3 as a guide, and moves toward the rear of the camera, and when the pattern detected by the contact piece 23 falls or falls, the power to the motor 9 is also cut off. The lens barrel base plate 2 is held in that position by leaning down (
initial position setting during standard shooting). When a release operation is performed in this state, the distance to the subject is measured by an AF mechanism (not shown) and distance information is obtained. Thereafter, the motor 9 is energized again to rotate in the forward direction. As a result, the drive shaft 7 also rotates iE, enters the cam groove 8 portion using the support bar 8 as a guide, and moves the lens barrel base plate 2 forward. The pulse plate 14 also rotates as the motor rotates 90 times, but when a predetermined number of pulses corresponding to the above-mentioned distance information is counted by the contact pieces J, 5a and the contact piece 15b, the power to the motor 9 is turned off, and therefore the mirror Tube base plate 2
．． The extension also stops and focusing ends. Thereafter, the shutter is opened and closed, and exposure control is completed.

Next, the case where the TW changeover switch is switched to the telephoto side will be explained. When the T-W selector switch is set to the telephoto side, the motor 2 rotates in the normal direction and the drive shaft 7 rotates in the normal direction, so the lens barrel base plate 2 moves along the long pitch cam groove C using the support bar 3 as a guide, and the camera move forward. Contact piece 2
When the pattern detected by (1) and 2z is interrupted, the power to the motor 9 is cut off, so the movement stops, and the lens barrel base plate 2 is held at that position (initial position setting during telephoto shooting). At this time, the holder 17 of the sub-lens 16 and the cam protrusion 20 of the rear plate 5 are no longer in contact with each other, so that the sub-lens 16 is placed on the photographing optical axis. When the release operation is performed in this state, the motor 9
is rotated in the normal direction, and the lens barrel base plate 2 enters the cam groove A portion and begins to move forward. At the same time, the contact pieces 15a and 15b detect the pattern on the pulse plate and count the number of pulses. When a predetermined number of pulses have been counted, the power to the motor 9 is turned off to stop extending the lens barrel base plate 2, thereby completing focusing.

FIG. 4 is a circuit diagram for controlling the operation of the optical system drive motor according to the embodiment of the present invention. Further, FIG. 5 is a detailed view of the patterned substrate 24 shown in FIG. 2, and these will be explained below. In the figure, the same parts as in FIGS. 2 and 3 are indicated by the same symbols, and 5O is a power supply. 52a, 5
2b is a normally open switch that turns off at the first stroke of the release operation, and is linked to r4-i, and 58a, 53b
is the switch that turns on during the second stroke, and this is also ′
They are linked to each other. 54a and 54b are T-W changeover switches that are linked to each other, and when they are in contact with the A side and D side in the figure, when they are being read, they are connected to the telephoto side (T side), and also to the B side and B side. This is the case when the time is set to the standard side (W side). Suin? 21.22 and 2:3 are respectively the second
It is the contact piece in the figure, and terminal 1 in the figure? 'ljA, B, C, D
, E respectively indicate the patterns shown in FIG. The W thin string flash position and the T thin string/η position shown in FIG. 5 are the positions where the focus position of the photographing optical system is placed at the super/force position, and correspond to the above-mentioned initial position setting. . That is, it shows the position where the lens barrel base plate 2 is always placed when it is set to the standard shooting preparation state and the telephoto shooting preparation state, respectively.

Next, when focusing is started by the release operation, the shooting preparation state is at the W-thin string (to) position or the T-thin string ■
The lens barrel base plate 2 holding the photographing optical system can be moved by a stroke P and a stroke Q, respectively.

The stroke Q on the T side is exactly twice as long as the stroke P on the W side.
This is because it is assumed that the amount of protrusion of the optical system required for focusing from ■ to close up is exactly twice the amount required for side photography. In other words, W-side photography uses an optical system consisting only of the main lens, while T-side photography uses an optical system composed of a main lens and a secondary lens, so the focal length on the T side is longer than on the W side. In the embodiment, it is assumed that the ratio of the amount of protrusion associated with this is doubled. The pattern of the pulse plate for detecting the extended position of the photographic lens during focusing is shown in detail in FIG. Drive shaft 7
Since the pitch of the cam portions of the A section and B section is set to match the feeding moon of the T side and W side, focusing is possible at the same rotation angle on both the T and W sides. Therefore, the pattern should be -, and the range from ~ far to close is 6.
Since we are assuming a divided case, pattern 14a has 6
The book is illustrated. Therefore, during focusing on the W side, when the photographic lens is driven from the far side to the close side, the pulse plate 14 rotates exactly one degree and produces six pieces (7) / (
Similarly, during focusing on the T side, the pulse plate 14 rotates once and counts six pulses.

Returning to FIG. 4, the explanation of the operation will be continued. T-side shooting mode (IIF
In the i state, the switches 21 and 22 are not connected to either terminal C or B. When the release operation is performed in this state, the switches 52a and 52L+ are turned off by the first stroke of the release, and the distance to the subject is detected by the AF mechanism (not shown), and then the switch 53a and 52L+ are turned off by the second stroke. 531)
Since is turned on, the AF control circuit 51 is activated. This AF
The control circuit 51 stops the focusing drive of the photographic lens when the pulse plate 14 counts the number of pulses corresponding to the ranging information obtained in the first stroke of the lens, and moves the photographic lens to a predetermined position. This is a circuit that maintains the motor current and generates an off signal to turn on the motor. When focusing drive is started, the switch 21 is connected to the terminal C side, and the switch 22 is connected to the terminal B side. After the focusing is completed and the subsequent exposure control is completed, the switches 58a, 53b are activated by the return of the release operation.
is turned off, and then switches 52a and 52b are turned back on. As a result, a voltage in the reverse direction is applied to the motor 9, and the photographing lens moves backward. switches 21 and 22
When the motor 9 is not connected to either terminal C or B, the power to the motor 9 is turned off. That is, the photographing lens returns to the T-side superflash position.

W (T-W selector switch 5 in 1111 shooting preparation state)
4a and 541] are connected to the terminals E and B side,
Switch 2: is in the off state. When a release operation is performed in this state, the AF control circuit 51 is activated and focusing is performed in the same manner as described above. When focusing starts, the switch 23 returns to the on state,
When the switches 52a and 52b return to the on state with the return of the release operation, since the switch 22 is connected to the B side, a voltage in the reverse direction is still applied to the motor 9 ((14) The shadow lens moves backward.W When the motor returns to the super ■ position on the side, the switch 23 is turned off and the power to the motor 9 is also turned off, so that the motor stops at that position.

In the embodiment, the lens barrel is moved by rotating the drive shaft, but instead of the drive shaft, the lens barrel may be moved by rotating an engaging member that engages with the drive shaft.

As explained above, according to the present invention, in a mechanism that moves a lens barrel forward and backward by constant rotation of a single drive shaft to perform focusing and focal length switching, the pitch of the portion of the drive shaft used for focusing at a long focal point is By setting the pitch of the part used for focusing during short focal length and the pitch of the part used during focus switching appropriately, the time required for switching the corner point with the longest stroke can be shortened, and high-precision focusing can be achieved. It becomes possible. Therefore, since focus switching is performed quickly, it is less likely that a photo opportunity will be missed.

Further, since focusing at short and long focal lengths can be performed using a set of pulse plate and contact piece, the mechanism can be simplified.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a drive mechanism of a motor-driven variable focus camera according to a conventional example, FIG. 2 is a schematic perspective view of a drive mechanism of a motor-driven variable focus camera according to an embodiment of the present invention, and FIG. 2 is a partially detailed view of the mechanism, FIG. 4 is a circuit diagram for controlling the operation of the optical system drive motor according to the embodiment of the present invention, and FIG. 5 is an enlarged view of the patterned board shown in FIG. FIG. 6 is an enlarged view of the pulse plate shown in FIG. 2. ■・・・・・・・・・・・・Main lens, 21M・・・・
... Lens tube base plate. 3......Support bar, 4...
・・・・・・Front base plate. 5・・・・・・・・・Rear base plate, 6・・・・・・・・・
...Engagement bin. ? , R... Drive shaft, 8...
・・・・・・Gear. 11-1B... Reduction gear, 14. S...
...Pulse board. 15 a + 15 b + T... contact piece, 16...
・・・・・・Secondary lens. 17・・・・・・・・・Holder, 18・・・・・・・・・
·bar. 19・・・・・・・・・Spring, 20・・・・・・・・・
・Cam protrusion. 21-23... contact piece, 24......
・Pattern board. 25・・・・・・・・・Bis, 51・・・・・・・・・
・AF control circuit. 52a, 52b, 53a, 53b ---release switch. 15a, 54b...T-W changeover switch. 4th evil figure 5th figure 6th figure

Claims (3)

[Claims] (1) It is equipped with a shaft having a feed groove and an engaging part 4A that engages with the feed groove, and a motor rotates either the shaft or the engaging part (A) to move the lens barrel back and forth, and adjust the focal length. In a motor-driven variable focus camera with a three-point mechanism, the axes are long bars with mutually different pitches, ←point pressure i'ilU
1ljj focusing, a second feeding groove used for focusing at short focal lengths, and an eighth feeding groove used for focal length switching. (Principal point camera. (2) The ratio of the pitch of the first feed groove used for focusing at long focal lengths 11, 1j and the pitch of the second feed groove used for focusing at short focal lengths is determined by the amount of extension of the long focal length lens and the pitch of the second feed groove used for focusing at short focal lengths. 2. A variable focus camera driven by a variable focus lens according to claim 1, wherein the ratio is a ratio of the amount of lens extension of the focal point. (3) The variable motor drive according to claim 2, characterized in that the pitch of the eighth feed groove used when switching the focal length is larger than the pitch of both the first and second feed grooves. focus camera.