JPS60217321A - Automatic focus camera - Google Patents

Abstract

PURPOSE:To execute easily focusing by turning a means for supporting a projecting means used for measuring a distance, and a photodetecting means for outputting a signal corresponding to an incident position of a reflected luminous flux from an object to be photographed, by a release operation, and moving continuously a distance measuring range. CONSTITUTION:A luminous flux of a distance measuring use projecting means 1 is converged by a lens 2, reflected by a focus target 6, passes through a lens 4, made incident to a photodetector 3 for outputting signals 3a, 3b corresponding to the incident position, and a distance is derived from the signals 3a, 3b. The projecting and photodetecting means are supported by an AF earth plate 11 turning round a shaft 12. When a release operation is executed, a hook 19 is detached, and the AF earth plate 11 is turned counterclockwise by a spring 13. The focus target 6 is moved to the left by turning of the earth plate 11, and while it moves to a position of 6', a distance is derived plural times by an operating part which is not shown in the figure, and focusing is executed automatically to the shortest distance. In such a way, in whatever position of a picture a main object to be photographed is placed, the focus is matched automatically and correctly to the main object to be photographed.

Description

[Detailed description of the invention] The present invention relates to autofocus cameras.

With conventional autofocus cameras, the distance measurement range (hereinafter referred to as the focus target) was extremely limited relative to the shooting screen, so the object to be photographed was placed at a predetermined position on the shooting screen. Otherwise, there was an inconvenience that it would not be possible to take a photograph with the object in focus. Generally, conventional autofocus cameras only focus on the center of the shooting screen, so the subject can
If there are people lining up, there is a risk that the photographic lens will be focused at infinity.

On the other hand, due to these circumstances, autofocus cameras with a so-called prefocus function have been proposed, but in such cameras, the object to be photographed is set within the focus target and the distance measurement operation is performed. After that, it is necessary to move the camera to the desired screen and perform the photographing operation, which has the drawback of complicating the operation.

The present invention has been developed in view of the above circumstances, and its purpose is to eliminate the need for the above-mentioned complicated operations and to allow the object to be photographed to be attached to the photographing lens no matter where the object is located on the photographic screen. The objective is to provide an autofocus camera that can focus on

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

FIG. 1 shows an example of an autofocus camera of the present invention.
In this figure, l is a light emitting element, 2 is a projection lens for projecting the luminous flux generated by the light emitting element 1 onto a part of the photographing screen,
Reference numeral 3 denotes a light-receiving element whose output ratio from terminals 3a and 3b changes depending on the incident position of the light beam, and 4 a light-receiving element for guiding the projected light beam reflected by an object within the photographic screen to the light-receiving element 3. These lenses are fixed to the AF main plate 11 in the state shown in the figure, and constitute a well-known object distance detection optical system based on the baseline long-distance type distance measurement principle. In addition, in this embodiment, i RED is used as the light emitting element 1, and the light receiving element 3 is used as the light emitting element 1.
A PSD (semiconductor device detector) is used for each.

5 is the main subject located within the shooting screen, 6 is the floodlight lens 2
The range (focus target) on which the light beam from the lens is projected, and 7 is the photographing range of a photographing lens (not shown).

Reference numeral 12 denotes a support shaft provided so as to be perpendicular to the optical axis 0 of the photographing lens (not shown). It is possible to continuously move the determined focus target 6 along the horizontal direction (arrow direction) of the photographing screen.

The focus target 6 is moved from one end of the photographing range 7 to the other end according to the rotation of the AF base plate 11.

13 is a spring that biases the AF main plate 11 in the counterclockwise direction; 14;
is a pin for regulating the rotation of the AF main plate 11 in the counterclockwise direction, and when the focus target 6 moves to the position 6', it comes into contact with the AP main plate 11 to stop the rotation of the AF main plate. Reference numeral 15 denotes a governor gear in which a gear 15a and a roughening wheel 15b are integrally formed coaxially. I'm having fun with lla. Further, the roughening wheel 15b engages with a pallet wheel 17 that is swingably supported on a shaft 18. These constitute a governor mechanism for adjusting the rotational speed of the AF main plate 11.

19 is a release lever, and the protruding end 11b of the AF main plate 11
The AF base plate 11 is held in the illustrated position by being locked with the claw 19a. This release lever 19 is rotatably supported by a shaft 20 and biased counterclockwise by a spring 21, but in the illustrated state, one side thereof is attached to the pin 22.
Rotation by the spring 21 is restricted by being in contact with the spring 21 . The release lever 19 is rotated clockwise in response to the camera release operation, and the release lever 19 is rotated clockwise in response to the release operation of the camera.
Release the locking by 9a. As a result, the AF main plate 11
starts rotating counterclockwise and moves the focus target 6. During this time, an object distance detection circuit, which will be described later, repeats a distance measurement operation based on the output of the PSD 3 at a constant timing. For example, as shown in FIG. 2, if the distance measurement operation is performed when the focus target 6 coincides with the main subject 5, the distance to the main subject 5 will be determined regardless of the position of the main subject 5 on the shooting screen. Information will be obtained. Note that while the AF main plate 11 is rotating, distance information is detected at a constant timing, so the focus target 6 is 6'.
Although multiple distance information can be obtained before moving to the position,
In this embodiment, as will be described later, a distance indicating the closest distance is selected as distance information for adjusting the focus of a photographic lens (not shown). After the rotation of the AF base plate 11 is completed, focus adjustment of the photographic lens is performed based on the selected distance information, and photographing operation of the camera is performed. Also,
Charging of the AF base plate 11 to its initial position is performed in accordance with the winding operation of the camera.

In addition, Sl indicates that the AF main plate 11 is in a counterclockwise direction from the illustrated position.
The object distance detection circuit starts the distance measuring operation by turning off the switch St, which is turned off when the rotation of the object starts.

FIG. 3 shows an outline of the object distance detection circuit, and in this figure, 1 is the above-mentioned light emitting element (iRED), 3 is the above-mentioned light receiving element (PSD), and 31 is the above-mentioned light receiving element (PSD). Driver circuit that drives i RED 1, 4 is PSD
The output of signal line 40.41 (40,
41) is (1, 1) as the detected object distance changes from extremely close to infinity.

It is designed to change in four stages: 8 (1, O), (0, 1), (0, 0). 34 is a selection for selecting distance measurement data to be used for adjusting the focus of the photographic lens from among a plurality of distance measurement data generated on the signal lines 40 and 41 at regular intervals while the AF main plate 11 is rotating. circuit, 33 is i
A signal for controlling the light emission timing of RED 1 is output to the driver circuit 31 via the signal line 35, and distance measurement data generated on the signal lines 40 and 41 is output to the selection circuit 3.
This is a control circuit that outputs a signal for controlling the timing at which data is stored in the selection circuit 34 to the selection circuit 34 via signal lines 36, 37, 38, and 39. Note that the driver circuit 31 outputs 1RED1 while a high level signal is generated on the signal line 31.
to emit light. 'The configuration of the control circuit 33 is shown in FIG.

In this figure, Sl is the above-mentioned switch, and AF main plate 1
It is turned off by the start of rotation in step 1. 21 is a resistor whose one end is connected between the installed switch Sl and the power supply Vcc;
43 is a 6-bit binary counter, the reset input R of which is connected to the switch S1 via the inverter 42. The clock pulse CP is input to the binary counter 43 via the AND gate 45, and the output of the AND gate 45 is connected to the Q6 output of the binary counter 43 via the inverter 44. 46 is Ql of counter 43, Q2. AND gate with each output of Q3 connected, 47.48 is Q4 of counter 43
, an inverter connected to each of the Q5 outputs, 49,
50, 51.52, the output is signal line 3B, 37, 38
．． 39, and AND gate 49 is connected to AND gate 46. The outputs of inverters 47, 48 are connected to AND gate 50, and AND gate 46. Counter 43 Q4. Each output of the inverter 48 is connected to the AND gate 51, the AND gate 46, the inverter 47 . Each output of Q5 of the counter 43 is connected to the AND gate 52, and the AND gates 46 . The outputs of Q4 and Q5 of the counter 43 are connected. Also, Q3 of the counter 43 is connected to the signal line 35.
Output is connected.

In this configuration, before scanning of the focus target 6 is started, the switch St is turned on by the AF main plate 11, so the output of the inverter 42 is at a high level.

Therefore, at this time, the counter 43 is in a reset state, and all outputs of Ql-Q6 are at low level. Note that the low level of the Q6 output causes the output of the inverter 44 to go high, so during this time, the clock pulse CP is output from the AND gate 45, but the counter 23 is reset by the high level output of the inverter 42. Therefore, the count does not advance. After that, when the AF main plate 11 starts rotating in response to the camera release operation and scanning of the focus target 6 starts, the switch S1 is turned off, so the inverter 42
The input of is pulled up to the power supply Vcc by the resistor 21,
Its output is inverted to low level. As a result, the reset of the counter 43 is released and the count of clock pulses CP from the AND gate 45 is started. The signal changes as shown in the timing chart of FIG. 6 until it becomes low level. In addition, the time it takes for Q6 output to reach high level is AF main plate 1.
This is equal to the time required for the focus target 6 to be scanned from one end of the photographing screen to the other end by one rotation. Moreover, the signal lines 35 to 39 are connected to the sixth
The signals shown in the timing chart shown in the figure are generated. That is, while the focus target 6 is being scanned, four high-level pulse signals are sent to the signal line 35 at a constant period.
At the same time, a high-level pulse signal is generated on the signal lines 36 to 39 once while a high-level pulse signal is generated on the signal line 35.

Next, FIG. 5 shows the configuration of the selection circuit 34 for selecting distance measurement data indicating the closest distance from among a plurality of distance measurement data obtained in response to scanning of the focus target 6. In this figure, 60.61 and 62.63 are shift registers that perform parallel-in/serial-out operations, and each DI and D2 are connected to signal lines 41 and 40, respectively, and the P input changes from high level to low level. The distance measurement data generated on the signal lines 40 and 41 when the signal is reversed is stored. Since each P input of the shift registers 60 to 63 is connected to each of the signal lines 36 to 39, each shift register 60 to 63 has an i RED
The distance measurement data generated on the signal lines 40 and 41 when the signal line 1 is turned on corresponds to the scanning of the focus target 6, and is sequentially stored starting from i. That is, the shift register 60 contains the distance measurement data immediately after the start of scanning of the focus target 6, the shift register 61 contains the distance measurement data when the focus target 6 has been scanned by a predetermined amount, and the shift register 62 contains the distance measurement data when the focus target 6 is scanned by a predetermined amount. The distance measurement data obtained when the focus target 6 is further scanned is stored in the shift register 63, and the distance measurement data immediately before the scanning of the focus target 6 is completed is stored. Note that the registers 60 to 63 are used to transfer stored ranging data from the Q output in response to clock input.

Tl-Tl1 in FIG. 5 is a timing signal output from a timing circuit (not shown), and a timing chart of the reference clock pulse and each of the timing signals T1 to Tll is shown in FIG. 64.degree.65.66.67 are AND gates which sequentially output the distance measurement data stored in the registers 60 to 63 through the OR gate 68 when the timing signals T1 to T4 become high level.

69.71 is a 2-bit shift register that takes in distance measurement data from the D input according to the clock input, and the 2-bit outputs Ql and Q2 are the digital comparator 7.
Connected to 0. The digital comparator 70 compares the data input from the shift register 69 and the data input from the shift register 71, and
If the data from 1 is A and the data from the shift register 70 is B, then when the condition A<B is satisfied, A<B.
Sets the output of the terminal to high level. A D-type flip-flop 72 stores the A<B terminal output of the digital comparator 70.

73 and 74 are AND gates, and 75 is an OR gate, which constitute a select gate for the D input of the shift register 71. When the Q output of the flip-flop 72 is at a high level, the distance measurement data transferred from the shift register 69 is input to the shift register 71, and when the Q output is at a high level, the distance measurement data in the shift register 71 is input to the shift register 71 again. Let them input. Note that all the shift registers 60 to 63, 69, and 71 and the flip-flop 72 are reset by a power-up clear circuit (not shown) at the start of scanning of the focus target 6.

With this configuration, the distance measurement data sequentially input from the shift registers 60 to 63 to the shift register 69 is compared with the distance measurement data of the shift register 71, and only when the distance measurement data of the shift register 69 is large, the distance measurement data of the shift register 69 is inputted sequentially to the shift register 69. The distance measurement data of the shift register 71 is transferred to the shift register 71, and the distance measurement data of the shift register 71 is held at other times. Therefore, at the end of the timing chart of FIG.
1 stores the largest distance measurement data among the distance measurement data stored in the shift registers 60 to 63, that is, the distance measurement data indicating the closest distance. The camera then adjusts the focus of the photographic lens based on the distance measurement data stored in the shift register 71.

As described in detail above, according to the present invention, the object distance detection operation of an autofocus camera can be performed over a wide range from one end of the photographing screen to the other end, so that it is possible to detect the object distance regardless of the position of the subject on the photographing screen. It is also possible to take pictures with the subject in focus. Further, no complicated operations are required for this purpose.

Incidentally, on the Kinotsu flow side, an example in which distance measurement data is taken from four points has been shown, but it goes without saying that any number of distance measurement data may be taken.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 are plan views showing an embodiment of the automatic focusing camera of the present invention, FIG. 3 is a circuit diagram showing an outline of the object distance detection circuit of the present embodiment, and FIG. Figure 4 is a circuit diagram showing the configuration of the control circuit, Figure 5 is a circuit diagram showing the configuration of the selection circuit, Figure 6 is a timing chart of signals in the control circuit, and Figure 7 is a timing chart of signals in the selection circuit. . 1------One light emitting element (iRED), 2---One light emitting lens, 3---One light receiving element (PSD), 4------
-Receiving lens, 11----- AF main plate, 19--
---Release lever 131-----driver circuit, 32-per-11 calculation circuit, 33-----1 control circuit,
34-Selection circuit. Figure 1

Claims (1)

[Claims] A light projecting means for emitting a light beam, a light receiving means for guiding the light beam reflected by an object from the light projecting means and outputting a signal according to the incident position of the light beam, and supporting the light projecting/receiving means. An autofocus camera comprising: a support means; and a drive means for continuously displacing a distance measurement range from one end of a shooting screen to the other end by rotating the support means in response to a release operation.