JPS6031107A - Auto focus camera - Google Patents

Abstract

PURPOSE:To reduce a probability of an out-of-focus even if a distance measuring error is generated by constituting so that a lens set position is changed by luminance information and distance information of an object to be photographed. CONSTITUTION:A lens set position is selected by a distance zone in which an object to be photographed exists, and a luminance of the object to be photographed. As for long distance lens set positions L1-L3, a hyperfocal distance in each diaphragm is used so that the far point does not exceed the infinity, instead of which the near point is expanded to a short distance side. On the other hand, short distance lens set positions S1-S3 are determined so that the further closest focusing distance can be covered in accordance with an expansion of the near point of the long distance lens set positions L1-L3. In this way, a range shown by two dotted lines can be covered by changing the long distance lens set position in accordance with a luminance of the object to be photographed. Also, a range shown by two full lines can be covered by changing the short distance lens set position in accordance with a luminance of the object to be photographed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photographic film camera and a magnetic camera with a built-in autofocus device, and more specifically to an autofocus camera improved to control the lens set position by combining distance information and brightness information. It is related to.

Autofocus cameras have a built-in distance measuring device that detects the shooting distance to the subject, and when the release button is pressed, the shooting lens starts extending, and the shooting lens advances according to the shooting distance detected by the distance measuring device. The lens is positioned step by step. This positioning is achieved by a locking tooth that moves in conjunction with the photographic lens, and a macnet that is activated by a signal from the distance measuring device.
This is done by a positioning lever that is actuated by this magnet and engages with the locking teeth.

The larger the number of lens set positions, the better the front focus state can be obtained, but in this case, a multi-point distance measuring device is required and the cost increases. recently,
Autofocus cameras are commercially available that control the lens set position using a small amount of distance information, such as two points, by utilizing the depth of field of a photographic lens.

The two-point autofocus device divides the shooting distance into two zones, a near zone and a far zone, determines which zone the subject is in, and sets the lens position according to that zone. The focus is adjusted in two stages, using the depth of field of the photographic lens.

FIG. 1 is a graph showing the range that can be photographed by a two-point autofocus device. Fi18 as a shooting lens
Used F2.8 at 2m, circle of least confusion 0.06
It is possible to photograph the range fl.

When the subject is in the near zone, the taking lens is set to 81m, for example 1.5m, and when the subject is in the far zone, the LLM is set to 81m, for example 1.5m.
．． Set to 0m. When the photographic lens is set at 81 m, the range between the two solid lines is the circle of least confusion 0.06. When the lens is set within Llm, the range between the two dotted lines falls within the circle of least confusion of 0°06n, and both are in almost satisfactory focus.

Generally, most autofocus cameras have a built-in so-called program shutter that changes the aperture and shutter speed depending on the brightness of the subject. In this autofocus camera with a built-in program shutter, the aperture value increases as the subject brightness increases, resulting in a deeper depth of field and a wider photographable range.

However, with the two-point autofocus device mentioned above,
Since the same lens set position is always used regardless of the subject brightness, there are the following disadvantages. The lens set position L1 for the far zone uses the hyperfocal distance at a certain aperture value, for example F5.6, but if the brightness of the subject increases and the aperture is stopped down further, the far point becomes infinite. Spread beyond the distance. However, the area beyond this infinity has no practical meaning, so -
8-' It becomes useless. Furthermore, since the overlap between the close-range photographable range and the long-distance photographable range is narrow, there is a problem in that if a distance measurement error occurs, there is a high probability that the image will be out of focus.

The present invention aims to widen the range of possible shooting force as much as possible. To make it possible to take a clear image over a wide range, to widen the area where 52 adjacent photographable ranges overlap, and to reduce the probability of blurring even if a distance measurement error occurs. The object of the present invention is to provide an autofocus camera that can perform the following functions.

The present invention is characterized in that the lens set position is changed depending on the brightness information and distance information of the subject. For example, when using a two-point distance measuring device, set the lens according to the aperture so that the long distance lens set position is the hyperfocal distance.

The position is shifted to the short distance side, and tft is accordingly shifted to the short distance/set position to the close side to cover the close range.

Hereinafter, an embodiment of the present invention will be explained in 4-4 with reference to the drawings. This will be explained in detail.

FIG. 2 shows an embodiment in which the lens set position is changed in six steps using brightness information. In this example, the aperture is set to F5.6 when the subject brightness is below BY 7.5 (corresponding to a light value LV12.5 when using l80100 film), and the light value LV12.5 to 14 is set to F5.6.
．． 5, it is set to Fll, and when the light value L V is 14.5 or more, it is set to F18.5.

According to the 8-step aperture value, the near-distance lens set position has 8 steps of 81-88, and the long-distance lens set position also has 8R steps of Ll-L8. Therefore, depending on the distance zone in which the subject exists and the subject brightness, one of the six lens set positions can be selected.
) is selected.

The lens set position is determined as follows. For the long distance lens set positions L1 to L8, the hyperfocal distance at each aperture is used so that the far point does not exceed infinity, and instead the near point expands toward the near distance side. That is, the lens set position is Ll when the light value is within LV12.5, L2 when the light value is between LV12.5 and LV14, and L8 when the light value is LV14 or more. On the other hand, the short-distance lens set positions 81 to S8 are determined so that they can cover very close distances, depending on the spread of the near point of the short-distance lens set positions Ll-L8. In other words, when the light value is LV12.5 or lower, the lens set position is 81, and between LV12.5 and 14, Fi,
It becomes 82, and becomes 88 for LV14 and above.

As described above, the range shown by the two dotted lines can be covered by changing the long-distance lens set position in eight steps depending on the aperture value, that is, the brightness of the subject. Furthermore, by changing the short-distance lens set position in eight steps depending on the subject brightness, it is possible to cover the range shown by the two solid lines.

8 and 4 show the lens setting mechanism of the present invention. Annular lens 1OF consisting of 4 lens elements
i. It is held in the rotating cylinder 11.

The rotary cylinder 11 is slidably fitted inside the fixed cylinder 12. A cam plate 18 is rotatably attached to the outer periphery of the fixed cylinder 12. When the cam plate 18 rotates together with the bin 14, the rotary cylinder 11 is rotated via the fork part 15 fixed to the rotary cylinder 11. The photographing lens 10 is moved along the optical axis.

-18 is engaged. This positioning lever 18 has a shaft 19
It is pivotally supported by and biased clockwise by a spring 20. In addition, the other end of the positioning lever 18 is equipped with a magnet) 2.
An armature 22, which is held by suction to 1, is fixed.

A locking lever 25 is engaged with an engaging portion 24 of the cam plate 18 . This locking lever 26 is pivotally supported by a shaft 26, and has an armature 27 made of a permanent magnet fixed to one end. This armature 27 is the magnet 2
When the magnet 28 is energized, a repulsive force acts to rotate the locking lever 25 counterclockwise.

7- Rotate until it engages with 17. The rotational position of the cam plate 18 is detected by the pair of brushes 88 and 84 contacting the common contact point 85 and the branch-shaped contact group 86, respectively, and counting the number of the branch-shaped contact group 86.

The aperture drive lever 88 is supported approximately at the center by a shaft 89, and the pin 40 provided at one end is in contact with the aperture cam 41. Furthermore, the pin 42 provided at the other end of the iris drive lever 88 is fitted into the elongated hole 44 of the iris blade 48 . The aperture blades 48 rotate about the shaft 45 to adjust the light passing through the photographic lens IO. In addition, the aperture blade 48
Although only 10,000 of them are shown in the figure, as is well known, the other one is rotatably provided.

When the magnet 28 is energized during focus adjustment, the locking lever 25 is counterclockwise and rotated counterclockwise to be disengaged from the retaining portion 24 . As a result, the cam plate 18 is rotated clockwise by the stored force of the spring 82.

8- The rotation of the cam plate 18 is transmitted to the rotary cylinder 11 via the pin 14 and the fork portion 16. The rotating barrel 11 rotates while holding the photographic lens lO, and the cam groove 47 and the bottle 4
Move forward by combining with 8.

Directly under the rotational position of the cam plate 18, a pair of brushes 88°84
It is detected by counting the pulses generated from the Then, when the cam plate 18 rotates to a position corresponding to a predetermined lens setting position, the magnet 21 is turned off.
Then, the positioning lever 18 engages with one of the locking teeth 17.

When the photographic lens lO is set in a predetermined lens cellar 111, the aperture drive lever 88 rotated by the aperture cam 41 rotates the aperture blades 48 to adjust the aperture value.

After the focus adjustment and setting of the aperture υ described above, the shutter 49 opens. During the opening of the shutter 49, light passing through the opening formed by the diaphragm blades 48 enters the film. As is well known, the cam plate 18 is rotated counterclockwise in conjunction with the winding operation and returned to the locked state by the locking lever 25. In this embodiment, the aperture is controlled in conjunction with the cam plate 18, but since the aperture value is adjusted in four stages depending on the brightness of the subject, the aperture value can be set electrically as in the past. A programmable shutter can be used.

FIG. 5 shows an example of the electric circuit of the present invention. Clock circuit 5 (ld, when the release button is pressed,
A clock pulse is generated and sent to AND circuit 51 and transistors 62 and 6B.

A near-infrared light emitting diode 54 is connected to this transistor 52.
is connected and emits blinking near-infrared light. This near-infrared light beam is turned into a spot light by a lens 65 and travels toward the subject.

The near-infrared light, which is adjusted so that its diameter does not expand, illuminates a part of the object to be ranged. The near-infrared light reflected by this object passes through a lens 56 and enters two photodiodes 57 and 58. Here, the outputs of these photodiodes 57 and 58 are the same when the object is present at the boundary point, and when the object is present in the near zone or far zone, the output of one is higher than the other. It is arranged like this.

The output signals of the photodiodes 57 and 58 are input to a comparator 69 and compared there.

When the subject is in the far zone, the output of the photodiode 68 is higher than the output of the photodiode 57, so the output of the comparator 69 is at a low level (hereinafter referred to as rLJ). When the subject is within the close range zone, the photodiode 57
Since the output of the comparator 59 becomes higher, the output of the comparator 59 becomes a high level (hereinafter referred to as "H").

When the output of the comparator 69 is "H", a signal differentiated by the capacitor 60 and the resistor 61 is sent to the %51 0 times. Since this AND circuit 51 is opened and closed by clock pulses from a clock circuit 60, it is not affected by external light such as a warning light.
2 and set this. Therefore, when the object is in the short distance zone yGC, the output terminal Q of the flip-flop 6211- is rHJ, and when the object is in the far distance zone, it is "
L”.

As described above, when the release button is pressed, the distance measuring device energizes the magnet 28 to allow the rotation of the cam plate 18, and also irradiates the subject with near-infrared pulsed light, and uses the reflected light to generate two Performs point distance measurement. When the object is present in the long distance zone, the inverter 64 opens AND circuits 65 to 68, and when the object is present in the short distance zone, the AND circuits 69 to 72 are opened.

A light receiving element 75/Ii for measuring subject brightness is connected in series with a resistor 76, and the voltage at a connection point 77 is input to comparators 78-80.

These comparators 78 to 80 have reference voltages of different levels input to their east input terminals.
It can be determined whether the original price is higher than eight levels. Note that the variable resistor 8I is for setting the film sensitivity.

The output signals of the comparators 78 to 80 are passed through inverters 82 to 84 and directly to an AND circuit 85.
~88, and these circuit elements allow the light values to be classified into 4R levels as shown in Table 1.

[As can be seen from the first fi, the output terminal of any one of the four AND circuits 85 to 88 becomes "
-H”. The output signals of these AND circuits 85 to 88 are sent to the long distance AND circuits 65 to 68 and the short distance AN
The signals are sent to D circuits 69 to 72, respectively. AND these
The circuits 65 to 72U are for combining the light values and distance information of the 49th floor and dividing them into the states of the 8R floor.

The output terminals of the AND circuits 65 to 72 are connected to eight AND circuits.
Connected to the input terminals of circuits 90 to 97, respectively,
It is determined whether the contents match the contents of the decimal counter 100, and when they match, the output terminal of the □R circuit 101 becomes "
H”. The output signal of this OR circuit 101 is inputted to the pace of the transistor 10B via the inverter 102, and when the output signal of the OR circuit 101 becomes "H", the transistor 108 is turned off. The counter 100
counts the pulses output from the inverter 104 each time the brush 84 contacts the branch-like contact 86.

When the release button 2B is pressed, two-point distance measurement and four-level light value measurement are performed as described above, and depending on the combination, one of the output terminals of AND circuits 6.5 to 72 is selected. becomes "H". On the other hand, due to the rotation of the cam plate,
As the brushes 88, 84 move, the number of branch contacts is counted by a decimal counter 100. In this decimal counter 100, for example, when four pulses are input, only the fourth terminal becomes rHJ, and when five pulses are input, only the fifth terminal becomes rHJ. And example i! AND circuit 6
1 when only the output terminal of 8 is rHJ, and AN when the decimal counter 100 counts 4 pulses.
The output terminal of the D circuit 98 becomes "H". At this time, since the transistor 108 is reversed from ON to OFF, the positioning lever 18 engages with the fourth locking tooth to prevent rotation of the cam plate 18 and set the photographing lens 10 at a predetermined position.

Table 2 11 Focal length (f) 82. I has an aperture F value of 2.8
This figure shows an example of the lens set position when using the photographic lens. In this embodiment, the lens set position in the near zone is kept constant, but it may be changed as described above. Also, since LVlo is 5 or less, strobe photography is used, so the lens set position for the long distance zone is moved to the front. Furthermore, the aperture value is changed between the near zone and far zone,
Parts list m control is performed.

15- Although the above embodiment uses a two-point distance measuring device, it may be an eight-point distance measuring device or the like. Further, although the lens set position has eight steps, it may be four steps or 10 RPi cape.

According to the present invention having the above configuration, by combining distance information and brightness information, the lens set position tit can be controlled in multiple stages even though the distance measuring device has a small number of steps. Therefore, the depth of field can be effectively used to greatly expand the photographable range. Furthermore, since the present invention widens the overlap between two adjacent photographable ranges, it is possible to reduce the probability of blurring even if a distance measurement error occurs.

[Brief explanation of drawings]

FIG. 1 is a graph showing the photographable range when using a conventional two-point distance measuring device in which the lens set position is kept constant regardless of subject brightness. FIG. 2 is a graph showing the photographable range of the present invention when the lens set position is changed depending on the brightness of the subject. FIG. 8 is a front view showing the lens setting mechanism of the present invention in which the lens setting position can be changed in eight stages. FIG. 4 is a sectional view showing the lens moving mechanism. FIG. 5 is a circuit diagram showing the electrical configuration of the present invention. lO... Photographing lens] l... Rotating barrel 12... Fixed barrel 18... Cam plate 17... Locking tooth 18... Positioning lever 21...! Magnet 25 eQ locking lever 289...Magnet 88 84@-@Brush 85 86,...Contact 88@...! Aperture drive lever 419 @ Droplet aperture cam 48 / Middle aperture blade 50 ... ◆ Clock circuit 54 ** Near-infrared light emitting diode 57.58 / 9 Photo diode 59 / 9 Comparator 75 @ ... Light-receiving element 78 ~ go@e@comparator 18-1 Fiction ≧ CSJ call Law-hatred

Claims (3)

[Claims] (1) A lens set that combines a distance measurement section that measures the shooting distance of a subject and outputs distance information, a photometry section that measures the brightness of the subject and outputs brightness information, and the distance information and brightness information. The camera is characterized by comprising a signal processing section that outputs a position signal, a lens set section that positions the photographing lens according to the lens set position signal, and an aperture that controls an aperture value according to the luminance information. Autofocus camera. (2) The distance measuring unit divides the photographing distance into two zones, a short distance zone and a long distance zone, and detects in which zone the subject is present. The autofocus camera described in item 1. (3) The autofocus camera according to claim 2, wherein the aperture is linked to a lens set section.