JPH03188311A - Range finding device - Google Patents

Abstract

PURPOSE:To reduce power consumption and cost by detecting the change of the center-of-gravity position output of a photodetector appearing when an object enters a focus area and starting the detection of focus matching due to an active system to perform waylay-photographing. CONSTITUTION:When a waylaying mode is set by a mode selector 17, a sequence control circuit 16 drives a processing circuit 15 to detect the present center-of-gravity position of a PSD photodetector 14 and the detection value Xi thereof is obtained. Subsequently, this center-of-gravity detection operation is performed at an equal time interval to obtain a detection value Xk. The value of ¦Xi-Xk¦ is successively compared with a predetermined value and, when said value exceeds a definite value, it is judged that an object 10 enters a focus area and a light emitting signal is applied to a light emitting element in a focus matching sequence. Whereupon, light is projected on the object 10 from the light emitting element 12 through a projection lens 11 and the reflected light is incident on the PSD photodetector 14 through a light detecting lens 13 to perform the detection of focus matching.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is applicable to a distance detection device, more specifically an automatic focusing camera, when a moving subject enters a preset image frame. The present invention relates to a distance detection device for automatically detecting this distance and releasing the shirt.

[Prior Art] In automatic focusing cameras, the following two methods have been conventionally employed as means for detecting the distance to a subject. That is, i) project a beam spot light such as infrared light toward the subject, and use the reflected light as a PS.
A pair of light receiving elements such as D (position detection elements) receive light to obtain a subject distance signal.The so-called active method II) Reflected light from a subject in natural light is received by a charge accumulation type image sensor, and the sensor This is a so-called passive method in which the amount of defocus of the photographic lens is calculated based on the accumulated charge transferred during the process.

To take a photo of a subject using an autofocus (AF) camera that uses these distance detection methods, first, move the photographing lens to the position where the subject you want to photograph is expected to appear. Adjust the distance adjustment ring, then when the subject appears, activate the AF function,
The shirt release mechanism was made to work immediately when the focus signal was output.

[Problems to be Solved by the Invention] By the way, when trying to perform the above-mentioned Ambush Photography using the above-mentioned active method, it is necessary to continuously project an infrared light beam spot until the subject appears, which requires consumption. The disadvantage is that the current is large, which wastes the power supply battery and is not practical.

On the other hand, when performing similar wait-and-focus photography using the passive method described above, the COD integration and defocus calculation 9 focus evaluation can be repeated, so the advantage is that the current consumption is lower compared to the active method. There is. Therefore, the passive method is advantageous for waiting shots.
Active methods were considered unsuitable.

However, from a user's standpoint, it is desirable that an AF camera that uses an active method be able to perform standby shooting with low current consumption, similar to an AP camera that uses a passive method.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a distance detection device that enables low current consumption and low current consumption even in an AF camera employing an active distance measuring device.

[Means and effects for solving the problems] As shown in a conceptual diagram in FIG. 1, the distance detecting device according to the present invention includes a light projecting means 1 that projects light toward a predetermined range of the photographic field of view; Light receiving means 2 that receives reflected light of the projected light and other natural light within the predetermined range and outputs a light reception signal.
and a control means 3 that controls the light projecting means and the light receiving means, processes the light reception signal, and outputs a signal corresponding to the distance to the object within the predetermined range, The light receiving signal of the light receiving means 2 is such that the center of gravity output is constant when the situation within the above predetermined range does not change, the center of gravity output changes when the situation changes, and when this change exceeds a certain amount, the center of gravity output is constant. , the control means 3 causes the light projection means 1 to project light.

That is, the control means 3 controls the light projecting means 1. Light receiving means 2
The light receiving means 2 is composed of a processing circuit 4 which controls the operation of the light receiving means 2 and processes the light reception signal of the light receiving means 2, and a sequence control circuit 5 which sequence controls the overall operation. When there is no change, the center of gravity output is constant, and when the situation within the focus area changes, the center of gravity value changes. When this amount of change exceeds a certain value, the processing circuit 4 sends a light projection signal to the light projection means 1, and the light reception means 2 receives the reflected light from the subject,
The received light signal is processed by the processing circuit 4 and the focused position is sent to the sequence control circuit 5.

[Example] The present invention will be explained below with reference to illustrated embodiments.

FIG. 2 is a configuration diagram of a distance detection device showing a first embodiment of the present invention. A light projecting device that projects light toward a predetermined range of the photographic field of view includes a light projecting lens 11 and a light emitting element 12 consisting of an LED. Projects a luminous flux of It also includes a light-receiving lens 13 that collects the reflected light flux and other natural light from the same area as the area where the light is projected from the light projector, and a light-receiving element 14 that includes a PSD that receives the focused light. The light receiving element 14 outputs the received light signal to the processing circuit 15. The light receiving device and the light projecting device are driven by the processing circuit 15 at appropriate times.

The processing circuit 15 constitutes a control means together with the sequence control circuit 16, and exchanges information signals with the control circuit 16. Further, each mode is set in the sequence control circuit 16 by a mode select 17, and the mode select 17 sends set current mode information to the sequence control circuit 16. The sequence control circuit 16 thereby drives the processing circuit 15 and causes the light emitting element 12 to emit light when a focused point is detected. The processing circuit 15 then detects the center of gravity and sends the center of gravity information to the sequence control circuit 16. In addition, in the waiting mode, the center of gravity is detected by the light receiving element 14 at equal time intervals, and when the detected value changes by a certain value or more, a focused point detection operation is performed.

FIGS. 3(a) to 3(d) show changes in the center of gravity of the light receiving element 14 configured as a PSD in the waiting mode. That is, as shown in FIG. 3(a), when the subject 10 being photographed is not within the focus area 19 within the viewfinder field of view 18, the position of the center of gravity of the PSD is as shown in FIG. 3(c). As shown in the figure, it is located towards the center or to the left.

When the subject 10 enters the focus area 19 as shown in FIG. 3(b), the center of gravity of the PSD is located at the center of the V as shown in FIG. 3(d). Therefore, the in-focus point detection operation is performed by detecting this change in the center of gravity position.

FIG. 4 shows the flow of the operation of the distance detecting device in the waiting mode. When performing a cover shot, first, the mode select 17 is set to the cover mode. Then, the sequence control circuit 16 drives the processing circuit 15 to detect the current position of the center of gravity of the PSD light receiving element 14, and obtains the detected value χ1. Next, this centroid detection operation is performed at equal time intervals, and the detected value χk is obtained.

Then, the previous and current detected center of gravity values 1χ and −χ are compared with 1 and a certain constant value ε, and when the detected center of gravity value is larger than the certain constant value ε, it is determined that the subject 10 has entered the focus area 19. Then, a light emission signal is applied from the processing circuit 15 to the light emitting element 12 in a normal focusing sequence, the element 12 emits light, and the light is projected onto the subject 10 through the light projection lens 11. Then, the reflected light from the subject 10 enters the PSD light receiving element 14 via the light receiving lens 13, which detects the in-focus point, activates the release sequence, drives the AF of the photographic lens, drives the shutter, and releases the photographic film. A series of shooting operations including winding are performed, and the waiting shooting ends.

In this way, according to this embodiment, the active type element itself is used to detect that a subject has entered the focus area, and after detection, the light emitting element emits light to detect the in-focus point. Compared to methods that repeatedly drive a CCD, etc. to perform distance measurement calculations, or generate LEDs, etc. to repeatedly measure distances, power consumption is much lower, sensors and processing circuits can be simplified, and space is saved. This has the effect of reducing costs.

FIG. 5 is a configuration diagram of main parts of a distance detection device showing a second embodiment of the present invention. The distance detection device of this second embodiment uses three pairs of LEDs and PSDs, and the light emitting elements 2
2a to 22c and light receiving elements 24a to 24c are used to detect multiple focal points. That is, 3
Light emitting elements 22a to 22c consisting of LEDs are arranged in parallel,
A projection lens array 21a to 21c formed of a plastic lens or the like is arranged in front of the light emitting element 22a to 21c.
22c projects light beams to focus areas 23a to 23c (see FIGS. 6(a) and 6(b)) each determined by a projection lens, and three light receiving elements 24a to 24C of PSDI-PSD3. A light-receiving lens array 25a to 25C is disposed in front of the light-receiving lens array, and each light-receiving lens is configured so that the reflected light flux from the focus areas 23a to 23c is incident on each of the light-receiving elements 24a to 24c.

Further, a processing circuit, a sequence control circuit, and a mode select for operating the light emitting elements 22a to 22c and the light receiving elements 24a to 24c arranged in this way at appropriate times are configured in the same manner as in the first embodiment.

FIGS. 6(a) to 6(d) show the movement of the center of gravity of the light receiving elements 24a to 24c made up of the PSD1 to PSD3. The focus areas 23a to 23c are provided within the viewfinder field of view 26, and when the subject 20 is a moving object, the subject 20 moves as shown in FIGS. 6(a) to 6(b). Accordingly, PSD, ~PS
As shown in FIGS. 6(C) to 6(d), the center of gravity of each of the light receiving elements 24a to 24c of D3 is determined by its PSD P.
A change in the center of gravity appears in SD3.

2' The operation of the distance detection device of this second embodiment is similar to the sequence flow of the first embodiment shown in FIG. 4, but three pairs of LED and PSD are used. Therefore, the center of gravity is detected for each pair of LED and PSD, the amount of change is detected, and if a certain - constant value ε or more occurs, a focused point detection sequence is performed at the two locations where it occurred, and the focused point positions at the two locations are evaluated. The in-focus position is determined, and a series of photographing operations such as a shutter sequence are started.

According to the second embodiment, similarly to the first embodiment, by detecting a change in the center of gravity using a plurality of active PSD light receiving elements originally included in the distance detection device, a moving object can be photographed. can be detected, and the cost is reduced by projecting light to the PSD whose center of gravity has changed.

The advantageous effect is that it is possible to detect a moving object and detect a focus on the moving object with low current consumption.

Next, FIG. 7 shows a flowchart of a distance detection device according to a third embodiment of the present invention.

In this third embodiment, the waiting mode and distance information are set by mode selection. Next, the detected value χ1 is obtained by the PSD center of gravity detection process, and then the center of gravity of the PSD is continuously detected at equal time intervals to obtain the detected value χ.
It is determined whether 1 in 1χ1-χ is larger or smaller than a constant value ε. By this check, 1χ is lower than a certain constant value ε.

If χk l is small, the detection is further continued, and if it is large, the LED light emitting element is made to emit light to detect a focused point, and the measured distance information and the set distance information are compared. When the measured distance information matches the set distance information as a result of this check, a release sequence is entered and a series of photographing operations including AF driving of the photographing lens, shutter release, and film winding are performed. If they do not match, the flow returns to the center of gravity detection process step and repeats the above steps.

Note that the distance information may be set using a focus lock.

[Effects of the Invention] As described above, the present invention focuses on the fact that in a light receiving element used in an active type distance detection means, a change appears in the output when a subject enters the focus area from a steady state. By using this, the normal active method is used to start in-focus point detection to perform wait shot, so automatic focus adjustment cameras that use the active method can also use low current consumption and low cost for wait shot. It is possible to realize a focus system that can perform the following.

Further, by using multi-point light receiving elements, it is possible to easily detect a moving object and detect a focus on the moving object.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the present invention. FIG. 2 is a schematic configuration diagram of a distance detection device showing a first embodiment of the present invention. FIGS. 3(a) to (d) are light receiving elements made of PSD FIG. 4 is a flowchart showing the operation of the distance detecting device of the first embodiment in the waiting mode, and FIG. A schematic configuration diagram of the main parts of the distance detection device showing the second embodiment, FIGS. 6(a) to 6(d) are the PS in the second embodiment.
7 is a flowchart showing the operation of the distance detecting device according to the third embodiment of the present invention. FIG. 1......Light projecting means 2...
.........Light receiving means 3...
・・・・・・Control means Horse 2 Figure Horse 3 Figure (C) (d) - [- PSDtljiifLt 21- PSDt+v Position 35 Figure Horse 6 ((1) (b) (C) (d)

Claims (1)

[Claims] (1) A light projector that projects light toward a predetermined range of the photographic field of view; and a light projector that receives reflected light of the projected light and other natural light within the predetermined range, and outputs a light reception signal. A distance detection device comprising: a light receiving means; and a control means for controlling the light emitting means and the light receiving means, processing the light reception signal, and outputting a signal corresponding to a distance to an object within the predetermined range. In the light reception signal of the light receiving means, if the situation within the predetermined range does not change, the center of gravity output is constant, and if the situation changes, the center of gravity output changes, and this change exceeds a certain amount. In the distance detecting device, the control means causes the light projecting means to project light.