JPH04280215A - Auto focusing camera - Google Patents

Abstract

PURPOSE:To prevent the photographing as a projector window and light receiv ing window for distance measurement are covered with the fingers at the time of using an auto focusing camera of active type. CONSTITUTION:When it is detected that a subject is not situated within a general distance measuring range from the result of the distance measurement by an auto focusing device, the operating state of a scene button 6 which is operated at the time of photographing a subject of point at infinity is confirmed. When the scene button 6 is not operated, an alarm is displayed by a LED 24 or a buzzer 26 to inform a photographer of a distance measurement abnormal state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera with a built-in autofocus device, and more particularly to an autofocus camera that detects an abnormal state of distance measurement and displays a warning.

0002

2. Description of the Related Art Recent compact cameras have built-in active type autofocus devices. In such a camera, for example, when a shutter button is pressed halfway, a light projecting section is driven to project distance measuring light toward a subject. The distance measurement light is reflected by the subject and enters the light receiving unit,
Since the incident position corresponds to the distance to the subject,
A distance signal correlated with the subject distance can be determined based on the photoelectric signal obtained from the light receiving section. When the distance signal is obtained in this way and the shutter button is subsequently fully pressed, the photographic lens moving mechanism is activated to move the photographic lens to a focus position corresponding to the distance signal, and then the shutter is opened and closed.

A known camera is equipped with an infinity setting mechanism for forcibly moving the photographic lens to an infinity focus position by manual operation. As is well known, in the case of active type autofocus cameras, as the distance to the subject increases, the reflected light from the subject that enters the light receiving section becomes weaker, and the photoelectric signal output from the light receiving section is affected by noise. It becomes easier. For this reason, in the past, even if you tried to take a picture of an object at infinity, such as a landscape, the photographic lens might not be moved to the set position at infinity, but by using the above-mentioned infinity set mechanism, This makes it possible to take pictures of subjects such as landscapes in clear focus without being affected by noise.

0004

[Problem to be Solved by the Invention] In order to achieve accurate focusing using such an active type autofocus device, apart from when operating the infinity setting mechanism, it is necessary to correctly direct the distance measuring light from the light emitter to the subject. The premise is that the light will be projected towards. However, some inexperienced photographers sometimes cover the light emitter or light receiver of the autofocus device with their fingers when holding the camera, and in such cases, the photoelectric signal cannot be obtained from the light receiver and the subject becomes Even though the object was close, the photographic lens was set at a position that corresponded to long distance or infinity.

The present invention has been made to solve the above-mentioned problems, and provides an autofocus camera that prevents the user from taking a picture with a finger covering the light emitting part or the light receiving part of the autofocus device. The purpose is to

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a method in which the distance signal obtained from the autofocus device is determined by the distance measurement light from the subject even when the infinity setting mechanism is not operated. When dealing with the case where reflected light cannot be received, a warning can be displayed to the photographer to prompt him to confirm. For this reason, the autofocus camera of the present invention includes an infinity setting mechanism that moves the photographing lens to a focus position relative to infinity, giving priority to the distance signal from the autofocus device by operating the manual setting member; The apparatus includes a warning signal generating means that generates a warning signal by determining that a photoelectric signal is not output from the light receiving part when no operation is detected, and a display that operates to display a warning in response to the generation of the warning signal. .

[0007]

[Embodiment] In FIG. 2 showing the appearance of a camera using the present invention, the front of the camera body includes a photographing lens 2, a finder objective window 3, a light emitting window 4 for distance measurement, a light receiving window 5, and a landscape button 6. is provided. At the back of the light projection window 4, the light projection lens 8 shown in FIG. Shine. On the other hand, at the back of the light receiving window 5 is an IR that cuts visible light and transmits near-infrared light.
A filter 12, a light receiving lens 13, and a semiconductor position detector (hereinafter referred to as PSD) 14 are provided. The optical axes of the light projecting lens 8 and the light receiving lens 13 are parallel to the optical axis of the photographing lens 2, and the ranging light projected onto the subject is reflected by the subject and then passes through the light receiving lens 13 to the PSD 14. incident. The incident position of the ranging light on the PSD 14 differs depending on the distance to the subject, and the PSD 14 outputs a photoelectric signal corresponding to the incident position of the ranging light. When the photoelectric signal obtained in this way is input to the autofocus IC 15, the autofocus IC 15 performs distance measurement calculation using the distance between the optical axes of the light emitting lens 8 and the light receiving lens 13 as a base line length.
A distance signal corresponding to the subject distance is input to the CPU 16. The protrusion 17 in FIG. 2 is provided to prevent the photographer from inadvertently covering the light-receiving window 5 with the fingers of his/her right hand when gripping the camera body. is not necessarily necessary.

As shown in FIG. 1, the scenery button 6 is connected to an infinity set signal generating circuit 18. The infinity set signal generation circuit 18 inputs an infinity signal to the CPU 16 when the scenery button 6 is pressed. CPU1
6 determines the moving position of the photographing lens 2 based on either the distance signal inputted from the autofocus IC 15 or the above-mentioned infinity signal, and controls the lens moving circuit 19 to move the photographing lens 2 to that position. A lens set motor 20 is driven by this lens moving circuit 19,
The photographing lens 2 is set at a movement position determined by the CPU 16. As will be described in detail later, both the distance signal from the autofocus IC 15 and the infinity signal from the infinity set signal generation circuit 18 are sent to the CPU 16.
, the CPU 16 gives priority to the infinity signal, thereby moving the photographing lens 2 to a position where it can focus on an object at infinity.

The release signal generating circuit 22 inputs a half-press signal to the CPU 16 when the shutter button 10 is pressed halfway, and a full-press signal when the shutter button 10 is pressed fully. The CPU 16 receives these half-press signals and full-press signals and controls execution of the photographing sequence including the lens movement process described above. The LED driver 23 receives a warning signal from the CPU 16 and drives a warning LED 24 provided in the finder objective window 3. Similarly, the buzzer driver 25 drives a buzzer 26 built into the back cover of the camera, for example, in response to a warning signal from the CPU 16. The shutter device 27 is composed of, for example, a program shutter, and opens and closes in response to an exposure signal from the CPU 16. Of course, the CPU 16 controls the operation of the shutter device 27 to achieve appropriate exposure according to the film sensitivity and subject brightness.

The operation of the camera will be further explained with reference to the flowchart of FIG. When the shutter button 10 is pressed halfway and a halfway press signal is input to the CPU 16, the CPU 16 sends a distance measurement command to the autofocus IC 15. Autofocus IC15 is
Upon receiving the distance measurement command, the IRED 9 is turned on and distance measurement light is emitted toward the subject. When the subject is within the normal distance measurement range of about 1m to 8m, a sufficient amount of distance measurement light is returned to the PSD14, so the autofocus IC
15 performs distance measurement calculation based on the photoelectric signal from the PSD 14, and calculates a distance signal having a predetermined value. The value of this distance signal is temporarily stored in the working RAM in the CPU 16, and when the shutter button 10 is fully pressed, the lens moving circuit 19 is driven in accordance with the value of the distance signal, and the photographing lens 2 is moved to the lens set. It is moved by the motor 20 to a position corresponding to the value of the distance signal. The movement completion signal is C
When fed back to the PU 16, the CPU 16 opens and closes the shutter device 27, thereby taking a picture.

On the other hand, even if distance measurement is performed by the operation of the autofocus IC 15, for example, if the subject is located at a distance of 10 meters or more and the distance measurement light does not reach there,
Even if it reaches the distance measuring light reflected there, if it is too weak to be detected by the PSD 14, the PSD 14 will no longer output a photoelectric signal. PS even if distance measurement is performed
When a photoelectric signal is not obtained from D14, autofocus IC 15 inputs to CPU 16 a normal range outside signal indicating that the subject is located outside the normal distance measurement range based on the photoelectric signal from PSD 14. When receiving a signal outside the normal range from the autofocus IC15, the CPU1
Reference numeral 6 refers to whether or not the landscape button 6 is being pressed at the time when the shutter button 10 is pressed halfway, that is, whether or not the infinity set signal is being input from the infinity set signal generation circuit 18. When it is confirmed that the infinity set signal has been input, the normal photographing sequence continues, and when the shutter button 10 is subsequently pressed fully, the photographing lens 2 moves to a position where it can focus at infinity. Then, the photo is taken.

[0012] Furthermore, when the infinity set signal is not input while the out-of-normal-range signal is input from the autofocus IC 15, the CPU 16 drives each of the LED driver 23 and the buzzer driver 25. The LED 24 lights up in the viewfinder, and the buzzer 26 sounds to display a warning. This process is recommended to use the landscape button 6 when shooting landscapes, where the subject distance is infinite or 10 meters or more, to avoid the negative effects of noise. At the same time, even if the protrusion 17 shown in FIG. 2 is provided, it is effective in preventing the photographer from taking a picture while covering the light receiving window 5 of the autofocus device with his/her gripped finger.

[0013] Assuming that you press the landscape button 6 to take a picture when the subject is at infinity, the landscape button 6
The fact that a signal outside the normal range is being output from the autofocus IC 15 when is not pressed means that the PSD 14
This indicates that an appropriate photoelectric signal is not being output from the camera, and there is a high possibility that the photographer's finger is resting on the light projecting window 4 or the light receiving window 5. Therefore, in such a case, a warning display is displayed to notify the photographer of the abnormality as described above, and an NG flag is set to prohibit the shutter release in the same state as shown in the flowchart of Fig. 3. . When the NG flag is set, even if the shutter button 10 is fully pressed, the photographing lens 2 cannot be moved or the shutter device 2 cannot be moved.
7 is not opened or closed, it is possible to prevent photographing with incorrect distance measurement.

The present invention has been explained above according to the illustrated embodiments, but in carrying out the present invention,
An operation signal caused by pressing the landscape button 6 is input to both the autofocus IC 15 and the CPU 16, and when the operation signal is input to the autofocus IC 15, an infinite distance signal is sent from the autofocus IC 15 to the CPU 16 without performing distance measurement. The configuration may be such that the user inputs the following information. In this case as well, the CPU 16 determines whether there is an abnormality in distance measurement based on whether or not an operation signal is input from the landscape button 6 when receiving the infinite distance signal, as in the above embodiment. moreover,
It is also possible to determine that the distance measurement is abnormal when a photoelectric output of a predetermined level or higher is not obtained from the PSD 14 while the landscape button 6 is not operated. Note that there is a possibility that the distance measurement light does not enter the PSD 14 because the distance to the subject is too short, but even in such a case, it is possible to detect a distance measurement abnormality with the configuration described above.

[0015]

[Effects of the Invention] As described above, according to the autofocus camera of the present invention, when the autofocus device cannot receive the reflected distance measurement light and cannot perform normal distance measurement, the infinity setting mechanism is activated. The system checks whether the manual operation member for activation is being operated, and displays a warning when the manual operation member is not operated. This eliminates the inconvenience of performing distance measurement with the lens covered and adjusting the focus using the inaccurate distance signal obtained as a result.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the configuration of a camera embodying the present invention.

FIG. 2 is an external view of a camera using the present invention.

FIG. 3 is a flowchart representing processing performed in a camera using the present invention.

[Explanation of symbols]

2 Photography lens 4 Floodlight window 5 Light receiving window 6 Scenery button 15 Autofocus IC 16 CPU

Claims (2)

[Claims] [Claim 1] Distance measuring light is projected toward the subject, the distance measuring light reflected by the subject is received, a distance signal corresponding to the distance to the subject is detected, and the photographing lens is adjusted according to the distance signal. In an autofocus camera, the autofocus camera is equipped with an autofocus device that moves the lens to an infinity position, and an infinity setting mechanism that moves the photographic lens to a focus position at infinity in priority to the autofocus device by operating a manual setting member. If the distance signal detected by the autofocus device corresponds to a signal when no distance measuring light is received and the manual setting member is not operated, a warning is displayed. Autofocus camera. 2. A light projecting section that projects distance measuring light toward a subject; a light receiving section that receives the ranging light reflected from the subject and outputs a photoelectric signal; a distance measurement calculation unit that calculates a distance signal corresponding to the distance to the camera; a lens movement mechanism that moves the photographing lens to a focus position corresponding to the distance signal; and a lens movement mechanism that detects the operation of the manual setting member and detects the an infinity setting mechanism that moves the photographing lens to a focus position relative to infinity with priority over the distance signal calculated by 1. An autofocus camera comprising: warning signal generating means for generating a warning signal; and a display device for displaying a warning in response to the generation of the warning signal.