JPH04138436A - Camera having focus detection means and detection means for line of sight - Google Patents

Abstract

PURPOSE:To always achieve a photographing function under an excellent state by providing an adjustment means which adjusts the focusing state of a photographing system based on a signal from a selection means and an inhibition means which inhibits the operation of the adjustment means by depending on one output signal of a signal obtained by a detection means for a line of sight and a signal obtained by a focus detection means. CONSTITUTION:Based on the signal concerned with a gazing direction obtained by an arithmetic means being one element of the detection means for a line of sight, one focus detection signal among the plural focus detection signals which are sent from the focus detection means 6a and which are based on plural range-finding areas is selected by the selection means 102. Based on the focus detection signal from the selection means 102, the focusing state is adjusted by driving the focus part of the photographing system 1 by a spreading means 103. By the inhibition means 104, the operation of the adjustment means 103 is inhibited by depending on one output signal of the output signal from the arithmetic means 101 being one element of the detection means for a line of sight and the output signal from the focus detection means 6a. Thus, the malfunction of photographing is prevented and the various kinds of photographing functions are achieved under the excellent state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a camera having a focus detection means and a line of sight detection means, and in particular detects the line of sight direction of a photographer looking into the field of view of a finder with the line of sight detection means; A plurality of focuses obtained by a focus detection means having a function of determining a gaze direction and a gaze point within the viewfinder field of view and detecting a focus state in a plurality of areas of the subject based on a signal obtained by the line of sight detection means. A photographic camera, a video camera, which selects one focusing signal from the signals and adjusts the focusing state of the shooting system.
This is suitable for Sv cameras and the like.

(Prior art) Line-of-sight detection has conventionally been used to detect the direction of the photographer's line of sight and to determine which area (position) within the viewfinder field of view the photographer is observing. Various cameras have been proposed in which various photographic functions such as automatic focus adjustment and automatic exposure are controlled based on signals from the line of sight detection means.

For example, Japanese Patent Application Laid-Open No. 61-61135 proposes a camera that mechanically controls the distance measuring direction of a focus detection device based on an output signal from a line of sight detection means to adjust the focus state of the photographing system. There is.

Furthermore, in Japanese Patent Application Laid-Open No. 1-241511, the present applicant discloses an automatic exposure control system having a line of sight detection means for detecting the gaze direction of a photographer, a focus detection means having a plurality of distance measuring fields, and a plurality of photometric sensitivity distributions. The present invention proposes a camera having a means for detecting the line of sight, and controlling the driving of the focus detecting means and the automatic exposure control means based on the output signal from the line of sight detecting means.

Conventional cameras automatically set shooting conditions such as focus adjustment and exposure control based on the central area within the viewfinder field of view, whereas the camera proposed in the same publication automatically sets shooting conditions such as focus adjustment and exposure control based on the central area within the viewfinder field of view. (There may be multiple areas) is selected based on the photographer's will, and focus adjustment, exposure control, etc. are performed in the selected area. This makes it possible to separate the automatic control of the composition, which is the most important factor in image creation, and allow the photographer to shoot under the conditions he or she desires.

(Problem to be solved by the invention) Autofocus detection methods conventionally used in cameras can be roughly divided into passive methods that use natural light coming from the subject, and passive methods that use the natural light coming from the camera side and There are two types: an active method that uses reflected light from the

Among the passive methods, there are a contrast detection method which is performed by grasping the sharpness of the object image, and a correlation method which is performed by photoelectrically detecting the coincidence of double images of the object based on the principle of triangular distance measurement. In either method, this passive method grasps the light intensity distribution on the subject surface and performs image analysis to detect focus, so if the subject has extremely low brightness or extremely low contrast, the image A sufficient light intensity distribution pattern, which is the basis for analysis, cannot be obtained, and focus detection tends to become impossible or detection accuracy tends to decrease.

First, with the active method, (a) if the reflectance of the subject surface is low, the amount of reflected light will be insufficient.

(b) If there are high-luminance objects around, it becomes difficult to distinguish them from the projected light component.

(c) As the distance to the subject increases, the reflected component of the projected light decreases.

For these reasons, focus detection tends to become impossible or detection accuracy tends to decrease.

As described above, in any of the focus detection methods, there are cases where focus detection becomes impossible or the detection accuracy decreases.

For this reason, even if a focus detection area (range-finding point) is set based on the signal of the direction of the photographer's gaze obtained by the line-of-sight detection means installed in the camera, a focus signal cannot be obtained in that area. Even if it is obtained, it may be unreliable.

In addition, when using automatic focus detection, there are some subject patterns that cannot be detected or have a large detection error, so when the photographer's gaze is directed toward such a subject, a highly accurate focus signal is required. There was a problem that it was not possible to obtain

Furthermore, as a line of sight detection means, a photographer generally has a tendency to focus on the background and peripheral objects in addition to the main subject to be photographed. For this reason, it is necessary to identify the true direction of gaze (point of gaze) from the time course of movement in the direction of the photographer's line of sight. However, line of sight detection becomes difficult depending on the movement force of the line of sight, and if there is strong ghost or external light noise in the detection optical system, the accuracy of line of sight detection decreases. For this reason, it becomes very difficult to detect the gaze direction within the finer field of view from the gaze direction.

On the other hand, in the automatic focus detection means of recent cameras, the range of the screen to be measured does not necessarily cover the entire photographic screen, and a plurality of range-finding fields of view are often set in a part of the screen. In other words, since the main subject is rarely at the edge of the screen, the area of the center excluding the four edges of the screen is 1/1 of the entire screen.
An automatic focus detection area is set in an area of about 0 to 1/2.

With a camera configured in this manner, if the direction of gaze of the photographer is outside the focus detection area, focus detection becomes impossible.

Conventional cameras are configured so that the target area for automatic focus detection simply moves in response to movement in the direction of the photographer's line of sight. That is, even if a part of the focus detection means or the line of sight detection means becomes undetectable or a mismatch occurs in control 1-, no countermeasures have been taken into consideration.

For this reason, even when a camera is provided with such a focus detection means and a line of sight detection means, there is a problem in that these functions of the camera may not be fully demonstrated.

In the present invention, when it is determined that the detection operation of the focus detection means, the line of sight detection means, etc. is impossible or that a reliable signal cannot be obtained, the focusing operation of the photographing system is set to L + h, or the focusing operation is set in advance. To provide a camera having a focus detecting means and a line of sight detecting means, which can always exhibit a photographing function in a good state by performing certain operations.

(Means for Solving the Problems) A camera having a focus detection means and a line of sight detection means of the present invention includes a line of sight detection means for detecting the gaze direction of a photographer looking into the viewfinder field of the camera, A focus detection means for detecting a focus state in a plurality of areas within the viewfinder field of view, and one goldfish signal selected from among a plurality of goldfish signals obtained by the focus detection means based on a signal obtained by the line of sight detection means. a selection means, an adjustment means for adjusting the focus state of the imaging system based on a signal from the selection means, and an output of at least one of a signal obtained by the line of sight detection means and a signal obtained by the focus detection means. It is characterized in that it has a prohibition means for prohibiting the operation of the adjustment means depending on the signal.

In addition, as another aspect of the present invention, for example, (I) the inhibiting means operates when one goldfish signal selected by the selecting means is determined to be unusable.

(n) The inhibiting means is activated when the gaze direction cannot be detected by the visual line detecting means or when it is determined that the reliability of the signal obtained by the visual line detecting means is low.

(III) When it is determined that the gaze direction obtained by the line of sight detection means does not exist within any of the plurality of detection regions within the viewfinder field of view detected by the navigation focus detection means, the prohibition means is activated. do.

(■) The light-emitting means and/or sound-emitting means provided in a part of the +'+f camera were operated in conjunction with the operation of the prohibition means.

It is characterized by the following.

(Embodiment) FIG. 1 is a schematic diagram of a main part of a first embodiment of the present invention when applied to an eye reflex camera, and FIG. 2 is an explanatory diagram of a portion of FIG. 1.

In the figure, 10 is an eyepiece lens, 94 is an optical block, and a dichroic mirror 95 that is transparent to visible light and semi-transparent to infrared light is provided obliquely therein, and also serves as an optical path splitter. 11 is a light receiving lens, 93 is a mirror, and 14 is a light receiving element array. The light-receiving lens 11 and one row of photoelectric elements 14 constitute one element of the light-receiving means. The charging element array 14 normally uses a device in which a plurality of photoelectric elements are arranged one-dimensionally in the vertical direction of the drawing, but if necessary, a device in which charging elements are arranged two-dimensionally is used.

A light source 13 is composed of, for example, an infrared light emitting diode. 91 is a light projecting lens, 7 is a focusing plate, and a light splitting surface 92 is obliquely provided inside thereof. The light splitting surface 92 consists of a half mirror or a dichroic mirror.

In the same figure, the infrared light from the light $113 is transmitted through the projection lens 9.
1, the light is introduced into the focusing plate 7, and the light is split by the light splitting surface 92.
and enters the eyepiece lens 10 via the pentaprism 8. The infrared light that enters and exits the eyepiece lens 10 passes through the dichroic mirror 95 and illuminates the eyeball 15 of the observer located near the eyepoint E. The infrared light reflected by the eyeball 15 is reflected by the dichroic mirror 95, converged by the light-receiving lens 11, and reflected by the mirror 93 to form, for example, a Purkinje image on the charging element array 14 based on the reflection from the eyeball.

The calculation means 101 uses the signal from the photoelectric element array 14 to determine the gaze direction of the photographer's eyeball 15, as well as the gaze direction and gaze point within the viewfinder field of view.

The line of sight detection method in this embodiment is, for example, disclosed in Japanese Unexamined Patent Application Publication No. 1-241511 proposed by Mizuhiro et al.
Since this is described in detail in Japanese Patent No. 274736 and the like, and is not the gist of the present invention, the details will be omitted.

In this example, each of the above-mentioned elements 10.11゜13.14
, 91, 94, and 101 constitute one element of the line of sight detection means. Reference numeral 1 denotes a photographing system (also referred to as a photographic lens), and 2 a quick return mirror 3, which is a sub-mirror and is fixed to the quick return mirror 2. 4 is the photosensitive surface (image surface), 5
is the shutter. Reference numeral 6a denotes focus detection means, which has a so-called multi-point focus detection function for detecting focus states at a plurality of positions (areas) within the viewfinder field of view.

Reference numeral 102 denotes a selection means, which outputs a plurality of focus detection signals based on a plurality of distance measurement areas sent from the focus detection means 6a based on No. 48 regarding the gaze direction determined by the calculation means 101, which is an element of the line of sight detection means. One focus detection signal (goldfish signal) is selected from (goldfish signals).

Reference numeral 103 denotes an adjusting means, which drives a focus section (not shown) of the photographing system 1 based on a focus detection signal from the selection means 102 to adjust the in-focus state. Reference numeral 104 denotes a prohibition means, which prohibits the operation of the adjustment means 103 depending on one of the output signal from the calculation means 101, which is an element of the line of sight detection means, and the output signal from the focus detection means 6a. are doing. Reference numeral 105 denotes a light emitting means, which has a light source section and a drive circuit, and lights an indicator lamp or a warning lamp based on the operation of the inhibiting means 104. Reference numeral 106 denotes a sounding means, which operates a sounding buzzer based on the operation of the inhibiting means 104.

The focus detection method of the focus detection means 6a in this embodiment is not the gist of the present invention, and a known technique is applied, so only an outline thereof will be explained below using FIG. 2. do.

Screen frame 1 near the planned focal plane in Fig. 2
41, five ranging fields 142a, 142b,...
142e, and a series of known focus detection systems is configured for each field of view. For example, the distance measurement field of view 142 at the left end in the same figure
The imaging light beam that has passed through the rectangular field mask aperture a is deflected by the left end lens of the integrally molded compound field lens 143, and is then directed to a pair of secondary imaging lenses 144a.

144a.

On the front surface of the secondary imaging lenses 144at and 144a2,
A diaphragm (not shown) is placed. Secondary imaging lens 144
The field of view 142 is located above the luminous flux controller charging element (hereinafter referred to as a charging conversion element) column 145a+ that has passed through the r.
Re-form the optical image of a. On the other hand, the secondary imaging lens 144a
The light flux that has passed through 2 is placed on the photoelectric element array 145a2 in the field of view 1.
The optical image of 42a is re-imaged. The aperture (not shown) near the aforementioned secondary imaging lens is imaged approximately on the exit pupil of the photographing lens by the field lens, so that the optical system constitutes a so-called pupil splitting focus detection device. Five of these are installed, and the members that can be manufactured as one piece are structurally integrated.

The concept of such a focus detection device is a known technique, and the figure shows a plurality of such techniques arranged side by side.

A known technique is also used for calculating and determining the defocus of the photographing lens 1 from the output signal of the charging element array.

Normally, the signals from the photoelectric element array are output serially and input manually to an A/D conversion port of a microcomputer.

A microcomputer in the camera sequentially AD converts the serial signals at appropriate timing and stores them in memory. When the reading of the serial signal is completed, the similarity between the light intensity distribution patterns of the two images formed by the bare secondary imaging lens is calculated by a correlation calculation, and the defocus of the photographing lens 1 is detected.

In this embodiment, the microcomputer used for the focus detection means and the microcomputer used for the line of sight detection means may be the same, or may be different hardware that operates in conjunction with each other. good. Since the present invention describes a methodology for mutually relating focus detection calculations and line-of-sight detection calculations, it is premised on hardware that can control the entire system based on a unified flow.

Next, each operation of the first embodiment shown in FIG. 1 will be explained using the flowchart in FIG. 3.

First, in a switch (SW) state detection routine (001), when a half-pressed state or a fully-pressed state of the release button is detected, the process proceeds to step (002) and subsequent steps, and the direction of the photographer's line of sight is detected. Generally, the photographer's line of sight focuses not only on the main subject, but also on the background and surrounding areas of the main subject, so it is necessary to statistically extract the photographer's intention by following the movement of the line of sight from side to side for a predetermined period of time. do.

That is, steps (002) to (004) show a process for detecting the gaze direction once, and in step (007), based on these gaze detections, the photographer's intended gaze point (gazing direction) is determined. The extraction is performed by a predetermined calculation, and in step (008), the determination means determines whether or not the extracted calculation result has reliability for use in controlling the camera.

If the results of gaze calculation (step (003)) and gaze point extraction (step (007)) are defective, the process returns to step (002) to accumulate gaze data again, and at that time, the number of detection failures is calculated in step (005). ), and if NG is repeated a predetermined N0 times or more, step (006)
If it is judged as , it is considered undetectable. Note that the following method is the simplest method for extracting and determining the gaze point.

The screen area corresponding to the viewfinder field of view is divided into a finite number of small areas, and the distance measurement field of view is arranged at the center of each small area. For example, in FIG. 4(A), the small areas 146a to 14 are centered around the five distance measurement fields of view 142a to 142e.
6e and a small area 146f that does not include the distance measurement field of view. A total of 6 small areas (146a~
146e), if a predetermined ratio or more of data is concentrated in a specific area, and the number N is an amount greater than a predetermined value, the specific area is regarded as an area where the main subject exists (point of interest);
The distance measurement field located at the center is extracted. or small area 1
If the area is around 46f, it is determined that it is outside the distance measurement range.

In general, the line of sight of the photographer's eyes rarely moves continuously and smoothly, but often moves discontinuously at distant points.

Therefore, if you take into account the direction of the line of sight, the time at which you stopped, etc., you can extract even better intentions.

When the distance measurement fields of view are separated from each other as shown in FIG. 4(B), it may be better to also separate the small areas. In the distance measurement sequence of step (010), distance measurement is performed at the extracted gaze point. Step (0
The method in 11) is publicly known. For example, the contrast of an optical image, the sum of the squares of differences between adjacent pixel outputs, the shape of two comparative optical images, similarity, etc., or a combination thereof, is often used as a criterion for passive focus detection.

Furthermore, in active type focus detection, the magnitude of the reflected light signal is often used. In any case, distance measurement in the photographer's gaze direction and its determination are performed based on the reliability determination of some distance measurement results. If it is determined that the distance measurement result can be used, the process proceeds to step (012), and the selected distance measurement point position and distance measurement information are determined based on the above result.

Then, the state of the lens drive prohibition flag, which will be described later, is checked, and if it is in the reset state, the process proceeds to step (015), and the focus section of the photographic lens is driven by the adjusting means.

On the other hand, in step (011), a distance measurement point is selected based on the gaze point information, and it is determined that the distance measurement result does not have enough precision (reliability) to be used for controlling the camera, or in step (006). ), or if it is determined in step (009) that the gaze point is outside the range to be measured, a lens drive prohibition flag is set in step (013). If it is detected in step (014) that the prohibition flag is set, step (01
In step 6), a warning is displayed and the lens is not driven for focusing.

As a warning method, for example, a sounding buzzer by a sounding means, blinking of a focus indicator lamp at a specific period by a light emitting means, color change, lighting of a warning lamp, etc. can be applied. When step (016) is reached, lock in this state,
One way to set up a sequence is to monitor the release switch status and prevent escape unless there is a change.

Also, at step (016)! After activating the notification device, press N.
Reset the G counter and return to step (002).
The sequence may be turned around. In this configuration, even if the prohibition flag is set for some reason, if the sequence reaches step (012) again and the distance measurement point and distance measurement information at that position can be determined, the prohibition flag will be reset in this step. It can also be configured to include lens driving.

Note that in the present invention, line of sight detection, gaze point extraction, and distance measurement operations may be continuous, or may be performed arbitrarily without having to determine the temporal relationship. In addition, there are cases where it is desirable to operate in parallel because the time required to control the camera is shorter.

FIG. 5 is a flowchart diagram of a second embodiment of the present invention based on such parallel operation. Next, the operation of the second embodiment shown in FIG. 5 will be explained. When the switch (SW) state detection routine (021) detects that the release button is half-pressed or fully pressed, steps (022) to (
The process proceeds to step 023), where the line of sight direction of the photographer is detected.

Next, in step (025), a gaze point (gazing direction) according to the photographer's intention is extracted by a predetermined calculation, and in step (026), it is determined whether the result of the extraction calculation has a reliability enough to be used for controlling the camera. Determine. Judgment result is N
In the case of G, the process returns to step (022) via a counter operation (steps (029) and (030)) to accumulate visual line data again.

While the line of sight detection system repeats the above operation, the distance measurement system performs full field distance measurement in parallel in steps (027) to (028). Since the sensor that receives the optical image of each field of view is provided for each field of view, the photoelectric conversion operations of the sensors of all the fields of view can be started simultaneously. Regarding the subsequent signal processing calculations of the multi-point distance measurement system, the defocus amount or distance of each distance measurement point is measured using a known technique.

The determination of gaze point extraction in step (026) is OK,
If this gaze point is within the distance measurement target range and the step (0
When the distance measurement up to 28) is completed Y, the accuracy and reliability of the distance measurement data in the direction of the gaze point is determined in step (032). If the determination result is 0, the distance measuring point position is determined in step (034). If the judgment result is NG, step (03
Proceed to 3). Step (033) is performed when a malfunction or mismatch occurs in the gaze detection system or focus detection system, including when the gaze direction (line of sight direction) cannot be detected, when the gaze point is outside the distance measurement target range, etc. Set the lens drive prohibition flag.

After going through steps (033) and (034), the process reaches step (035), where the content of the lens drive prohibition flag is checked, and if it has been reset, the process proceeds to step (036).
According to the details determined in step (034), the adjustment means drives the focus lens of the photographic lens for focusing. The following sequence is not essential, but after the lens drive is completed, perform distance measurement (037) and check the focus (038).
If in focus, proceed to the next sequence (not shown) such as display and AF lock operation, or if not in focus, proceed to step (03).
Return to step 6) and drive the lens for correction. This distance remeasuring sequence can also be implemented in the previous embodiment.

On the other hand, if the prohibition flag is set in step (035), the process proceeds to step (039) and displays a warning etc.
No lens drive is performed. As a warning method, as in the first embodiment, a sounding buzzer, blinking of a focus display lamp at a specific period, color change, lighting of a warning lamp, etc. are effective. When step (039) is reached, one way of assembling a sequence is to lock in this state and prevent escape unless there is a change while monitoring the release switch state.

Also, after activating the warning device in step (039), N
The G counter may be reset and the process returns to step (002) to repeat the sequence. In this configuration, even if the prohibition flag is set for some reason, the sequence will go to step (034) again, and if the distance measurement point and the distance measurement information at that position can be determined, the prohibition flag will be flagged in this step. It can be configured to include a reset operation, and can be configured to lead to lens driving.

Although each of the above embodiments has been described using a passive force type focus detection system, the present invention has similar effects even in an active type multi-point distance measuring system.

In addition, even in cases where the two-dimensional imaging device for the TV screen and the light receiving means for focus detection are shared, such as in the focus detection method used in video cameras, the screen can be divided appropriately (overlapping is allowed). By doing so, a multi-point focus detection system can be substantially configured, and the present invention can be effectively used in combination with a line-of-sight detection system.

(Effects of the Invention) According to the present invention, when performing the focusing operation of the photographing system using the signal from the line of sight detection means 111 and the signal from the focus detection means as described above, By configuring each element to prohibit the focusing operation or issue a warning when distance measurement (focus detection) of the distance measurement field of view or detection of the gaze point is impossible, it is possible to improve shooting efficiency. It is possible to achieve a camera having a focus detection means and a line of sight detection means that can prevent malfunctions of the camera and perform various photographing functions in good conditions.

[Brief explanation of the drawing]

Figure 1 shows the first example when the present invention is applied to a single-lens reflex camera.
FIG. 2 is an explanatory diagram of the - part of FIG. 1, FIG. 3 is a flowchart of the first embodiment, and FIG.
A) and (B) are explanatory views of the photographing screen of the camera according to the present invention, and FIG. 5 is a flowchart of the second embodiment of the present invention. In the figure, 1 is a photographing system, 10 is an eyepiece, 11 is a light receiving lens, 13 is a light source, 14 is a light receiving element array, 15 is an eyeball, 92
95 is a light splitting surface, 95 is a dichroic mirror, 4a is a photosensitive surface, 5 is a shutter 6a, a focus detection means, 101 is an arithmetic means, 102 is a selection means, 103 is an adjustment means, and 104 is an inhibiting stage.

Claims (5)

[Claims] (1) A line-of-sight detection means for detecting the direction of gaze of the photographer looking into the viewfinder field of the camera, a focus detection means for detecting the in-focus state in multiple areas within the viewfinder field of the photographing system, and selection means for selecting one focus signal from among the plurality of focus signals obtained by the focus detection means based on the signal received by the focus detection means; and adjusting the focus state of the photographing system based on the signal from the selection means. adjustment means to
A focus characterized by comprising a prohibition means for prohibiting the operation of the adjustment means depending on an output signal of at least one of the signal obtained by the line of sight detection means and the signal obtained by the focus detection means. A camera having a detection means and a line of sight detection means. (2) The focus detecting means and line of sight detecting means according to claim 1, wherein the inhibiting means is activated when one focusing signal selected by the selecting means is determined to be unusable. camera. (3) Claim 1 characterized in that the prohibition means is activated when the gaze direction cannot be detected by the gaze detection means or when it is determined that the reliability of the signal obtained by the gaze detection means is low. A camera having the focus detection means and line of sight detection means described above. (4) When it is determined that the gaze direction obtained by the line of sight detection means does not exist within any of the plurality of detection regions within the viewfinder field of view detected by the focus detection means, the prohibition means is activated. A camera comprising a focus detection means and a line of sight detection means according to claim 1. (5) The focus detection means according to claim 1, 2, 3 or 4, characterized in that a light emitting means and/or a sounding means provided in a part of the camera is operated in conjunction with the operation of the inhibiting means. and a line of sight detection means.