JPH0781857B2 - Camera rangefinder - Google Patents

Description

The present invention relates to a distance measuring device for a camera.

[Conventional technology]

For example, Japanese Patent Laid-Open No. 59-1298 discloses a distance measuring device in which the focusing range is made horizontally long at the center of the screen to eliminate the need for prefocus and to freely determine the composition.
It is described in No. 09. This range finder has a line-shaped light projecting unit that projects the central part of the photographic screen in a horizontally long strip shape, and a plurality of light receiving elements that are laterally elongated according to the width of the light beam projected from the light projecting unit. And a line sensor arranged in a line. The light projecting unit projects a horizontally long near-infrared light toward a subject, and the near-infrared light reflected and returned by the subject is received by a line sensor. The output of this line sensor is sent to a binarization circuit consisting of a comparator and compared with a constant threshold level, and becomes "1" when near infrared light is incident to some extent, and "0" otherwise. Then, the binarized signal is output. This binarized signal is sent to a logic circuit, and when there are two or more subjects with different shooting distances, the binarized signal of the closest subject is taken out, and this binarized signal is extracted. The taking lens is positioned according to the terminal position where the signal is output.

[Problems to be solved by the invention]

However, in this distance measuring device, the light projecting unit projects a horizontally elongated light beam extending in the lateral direction of the camera body onto the subject, and the elongated line sensors are arranged in the vertical direction of the camera body. In a scene in which a plurality of people are lined up, there is no problem if the camera posture is in the horizontal position, but there is a problem that distance measurement cannot be performed when the camera posture is in the vertical position.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a distance measuring device for a camera, which can accurately measure the distance whether the camera is in a horizontal position or a vertical position.

[Means for solving problems]

The present invention provides at least one light projecting unit that projects a slit-shaped light beam extending in two different directions, for example, a horizontal direction and a vertical direction of a camera body, and a plurality of pixels divided along the two directions. It is provided with a sensor.

As the sensor, one area sensor in which a plurality of pixels are two-dimensionally arranged or two horizontally long line sensors arranged in different directions is used. When the area sensor is used, it is treated in the row and column directions so that it can be treated in the same manner as two line sensors in which elongate pixels are arranged in the vertical direction and the horizontal direction, respectively. For these sensors, CCD, MOS
A mold or the like can be used.

When the width of the slit-shaped light flux is wider than one side of the pixel, it is necessary to separately emit two types of slit-shaped light flux. When projecting these two types of slit-shaped light beams separately, it is necessary to rotate the oblong slit by 90 degrees or rotate the rod-shaped light source placed behind the cross-shaped or X-shaped slit by 90 degrees. is there. Alternatively, two rod-shaped light sources may be arranged in the shape of a cross or an X behind the cross-shaped or X-shaped slit, and these rod-shaped light sources may sequentially emit light.

When the widths of the two kinds of slit-shaped light fluxes are narrower than one side of the pixel, the output in each column direction is small when grouped in the direction orthogonal to the slit-shaped light fluxes, for example, in the lateral direction, so that influence Receive almost no Therefore, when a narrow slit-shaped light beam is used, two types of slit-shaped light beams can be simultaneously projected.

The object distance is determined by using two kinds of signals output from each sensor in the case of a line sensor, and by using two kinds of outputs grouped in the row and column directions in the case of an area sensor. Of the two obtained subject distances, the one with the shortest distance is prioritized, the group with the highest output is prioritized, or
The output of one group can be calculated by a weighted average value.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

In FIG. 1, a camera body 1 has a taking lens 2 fixed to the front surface thereof in a substantially central portion thereof, a viewfinder 3 and a stroboscopic light emitting section 4 disposed on an upper portion thereof, and a release button on the camera body 1. 5 are provided.
When the release button 5 is pressed halfway, distance measurement is performed, and when the release button 5 is further pressed, the influencing lens 2 is set according to the distance measurement result, and the shutter is operated immediately after that. The camera body 1 is diagonally above the photographing lens 2.
The light projecting section 6 for projecting the elongated slit-shaped light fluxes extending in the vertical and horizontal directions is arranged, and the slit-shaped light fluxes in the vertical and horizontal directions are separately or simultaneously projected to the subject. . An area sensor 7 having a plurality of pixels divided in the horizontal and vertical directions is disposed diagonally below the photographing lens 2 at a position separated from the light projecting unit 6 by a base line length L. The base line length L intersects the optical axis of the taking lens 2 and is inclined at 45 degrees, thereby preventing the parallax between the distance measuring device and the taking lens 2.

FIG. 2 shows an example of the light projecting section. As the light source, a light emitting diode 10 that emits near infrared light is used,
A liquid crystal panel 11 and a projection lens 12 are arranged in front of it. Electrode patterns of slits X and Y are formed on the liquid crystal panel 11, and by sequentially making them transparent, a slit-like light beam Sx extending in the horizontal direction and a slit-like light beam Sy extending in the vertical direction (first Project the light toward the subject (see Fig. 4). Instead of the liquid crystal panel 11, a slit plate having one slit may be used and rotated by 90 degrees. Further, the slit-shaped light beams Sx and Sy may be crossed in an X shape at an angle smaller than 90 degrees.

FIG. 3 shows an example of the distance measuring device of the present invention. The same parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals. When the release button 5 is pressed, the release switch 20 is turned on and a distance measurement start signal is sent to the microcomputer 21. This microcomputer 21
Predetermined sequence control is executed according to the program stored in ROM. The clock pulse generator 22 sends the generated clock pulse to the driver 23 to drive the area sensor 24. Lens 25 in front of this area sensor 24
Are arranged, and the reflected light from the subject is imaged on the area sensor 24. As the area sensor 24, a CCD or MOS storage type image area sensor having sensitivity in the infrared region is used. As shown in FIG. 4, pixels P11 to Pnn are arranged in n rows and n columns. Each of these columns or each of the n columns of the rows 1 to n receives the reflected light from the subject at the shortest distance. Thus, by aligning the rows and columns of the pixels P11 to Pnn with the direction in which the slit-shaped light flux x, y extends, the slit-shaped light flux x, y
When the position of the reflected light that has entered the area sensor 24 when the subject is illuminated with, the output from the area sensor 24 can be simply added in row and column units of the pixel array. It is also advantageous in maintaining the distance measurement accuracy. A visible light cut filter is preferably attached to the light receiving surface of the area sensor 24 in order to eliminate the influence of visible light.

The time series signal read from each pixel of the area sensor 24 is amplified by the amplifier 26, and then the A / D converter 27.
Converted to digital signal Dij by microcomputer 2
Captured in RAM 1 This microcomputer 21
Drives the light emitting diode 10 which emits near-infrared light through the driver 30, and the liquid crystal panel through the driver 31.
Drive 11 Further, the photographing lens 2 is moved to the in-focus position by controlling the rotation direction and the rotation amount of the motor 33 via the driver 32.

FIG. 5 shows data acquisition when two types of slit-shaped light beams are separately projected. When the release button 5 is pressed, the microcomputer 21 drives the liquid crystal panel 11 to make the slit Y extending in the vertical direction of the camera body 1 transparent, and causes the light emitting diode 10 to emit light in this state. The light reflected by the subject is imaged on the area sensor 24 via the lens 25. This reflected light is incident on the pixel corresponding to the distance to the subject and the position in the slit-shaped light flux Sy. The area sensor 24 photoelectrically converts incident light and accumulates the obtained signal charge. After this charge accumulation, the signal charge of each pixel is transferred and read by the clock pulse from the driver 23. The time-series signal read from each pixel is amplified by the amplifier 26 and then A /
After being converted into a digital signal Dij by the D converter 27, the synchronizing signal from the driver 23 is taken into the microcomputer 21 as an address. This signal Dij is added for each pixel column to calculate n pixel column signals Dij.
For example, the pixel column signal D1 with j = 1 is the pixel P1
The output of 1, P21, ..., Pn1 is added.

Next, the microcomputer 21 makes the slit X transparent, makes the light emitting diode 10 emit light in this state, and sequentially reads the output of each pixel of the area sensor 24 that receives the reflected light from the subject. The read time-series signal is amplified and then converted into a digital signal Dij before being taken into the microcomputer 21. This signal Dij is added row by row to calculate the pixel row signal Di. For example, i
Pixel row signal D1 with = 1 is pixel P11, P12, ...
It is the sum of the outputs of P1n.

When the width of the slit-shaped light flux Sx, Sy is extremely narrow,
For example, the reflected light from the slit-shaped light beam Sx is the pixel column signal.
Even if it affects Dj, its value is small. Therefore, since the influence thereof is small, it is possible to project the slit-shaped light beams Sx and Sy at the same time. In this case, as shown in FIG. 6, a cross-shaped slit is provided in front of the light emitting diode 10.
A slit plate 40 forming 40a is arranged. FIG. 7 shows data acquisition in the case of simultaneous light emission. When the light emitting diode 10 emits light, a cross-shaped slit light beam is projected toward the subject, and the reflected light is an area sensor.
It is incident on 24 and photoelectrically converted. The signal accumulated in each pixel of the area sensor 24 is sequentially read, amplified and digitally converted, and the obtained signal Dij is taken into the microcomputer 21. This microcomputer
21 calculates the pixel column signal Dj by adding the signal Dij for each column, and adds the signal Dij for each row to obtain the pixel row signal Di.
To calculate.

The object distance is detected from the signals Dj and Di calculated by the procedure described above.
There are various methods as described later. The taking lens 2
Starts at infinity and reaches the shortest distance in n steps. If the reflected light does not enter the area sensor 24, the taking lens 2 is not extended. In this case, the photographing lens 2 is in focus at infinity.

FIG. 8 shows a distance measuring mode 1 in which an object at a short distance side is focused, and is suitable for projecting two kinds of slit-shaped light fluxes through a slit having a relatively wide width. Of course, it can also be used when projecting a cross-shaped slit-shaped light beam through a cross-shaped slit having an extremely narrow width. First, the microcomputer 21 sequentially reads the pixel column signal Dj from the ROM. This reading is sequentially read from the signals D1 to Dn of the pixel column on the far side, and is compared with the threshold level S shown in FIG. The comparison with the threshold level S is to remove the influence of near infrared light existing in the shooting scene.

During the comparison, when it is determined that the pixel column signal Dj is larger than the threshold level S, when the reflected light from the subject is incident on any one of the pixels belonging to the pixel column that output the signal. Is. In this case, the pixel column number is extracted as j1.
The comparison is further continued, and this time, a column in which the pixel column signal Dj becomes smaller than the threshold level S is detected, and this is designated as j2. As shown in FIG. 9, these two types of comparisons detect the range of pixel rows in which the reflected light from the same subject is incident, and since this comparison is performed from the near side, The subject A in the distance is prioritized. Next, the intermediate position Lj where the reflected light from the subject A located at this short distance is incident is calculated. For example, when the reflected light from the subject A enters from the 10th row to the 6th row, the 8th row shows the intermediate position.
It becomes Lj.

Next, the pixel row signal Di is sequentially extracted and compared with the threshold level S to detect the range of the pixel row on which the reflected light from the object located at the closest distance is incident, and the intermediate position Li To calculate. It is determined which of the intermediate positions Lj, Li in the column direction and the row direction thus obtained is the short distance position. For example, when Lj is "8" and Li is "6", Lj is prioritized and the photographing lens 2 is set at a position shifted by 8 steps from infinity. When both Lj and Li are “0”, the Stetz number is “0”.

FIG. 10 shows a distance measuring mode 2 in which an object at the closest distance side is detected and the pixel row or pixel row in which the reflected light from the object is the strongest is focused.
Focusing at a distance corresponding to the row or column of pixels with the strongest reflected light is considered to be because the object at the distance corresponding to the row or column with the strongest reflected light occupies the largest area in the screen. Because. In this distance measurement mode, the average value Av of the pixel column signal Dj is calculated, and the average value Av is sequentially compared from the output of the pixel column on the short distance side, and the pixel column signal Dj becomes larger than this average value Av. Find column j1. Next, the pixel column j2 whose output is smaller than the average value Av is calculated. Among these pixel columns j1 to j2, the pixel column jp having the peak value Djp is detected. This peak value Djp
The calculation procedure of is shown in FIG. In the case of FIG. 9, the pixel row located one distance away from the distance measurement mode 1 has the peak value Djp.

Similarly, find the average value Av of the pixel row signal Di, read out the output Di sequentially from the pixel row of the short distance, and average the average value.
Compared with Av, the object at the shortest distance is detected, and the pixel row ip having the peak value Dip is detected.
Next, the peak value Djp of the signal in the column direction is compared with the peak value Dip in the row direction to detect the pixel column or row having the larger peak value. For example, if the maximum peak value is jp and the value is "4", the taking lens 2 is set at a position shifted by 4 steps from the far distance side.

FIG. 12 shows a distance measurement mode in which the output of each pixel column or row is weighted more as the distance is closer to obtain a weighted average, and focusing is performed according to the weighted average. The weighted average Lj is calculated by multiplying the pixel column signal Dj by the weighting coefficient Kj. As shown in FIG. 13, the coefficient Kj has a larger value on the closer side. The closer the distance is, the greater the weight is because the subject at the closer distance has a higher probability of being the main subject. Similarly, the pixel row signal Di is multiplied by the weighting coefficient Ki to calculate its weighted average Li.
The weighted average Lj and Li thus obtained are added to calculate a numerical value L. As shown in FIG. 14, the taking lens 2 is moved to a position shifted by 1 step from infinity according to the calculated value L.
Set.

FIG. 15 shows an embodiment in which the focus is adjusted according to the position of the pixel column or row which becomes the peak value in the output of the area sensor. The pixel row jp having the maximum value (peak value) in the pixel row signal Dj and its value Djp are detected. Similarly, for the pixel row signal Di, the peak value
Detect Dip and the pixel row ip that outputs it. These two peak values Djp and Dip are compared and the larger one is selected. For example, the peak value Dip of the pixel row is larger, and the pixel row that outputs this peak value Djp is
For example, in the case of the fourth row, the taking lens 2 is positioned at the lens position shifted from infinity to the short distance side by 4 steps.

FIGS. 16 to 20 show five kinds of photographing scenes as samples, and show the incident state of the reflected light from the subject to the area sensor 24 and the waveforms of the signals Dj and Di.
The distance measurement modes 1 to 4 described above are applied to these samples.
The subject to be focused when is applied is as shown in the following table. It should be noted that the camera posture is horizontal in FIGS. 16 to 20. However, if the camera pose is vertical,
Since only the signals Dj and Di are exchanged, the focus position does not change.

FIG. 21 shows an embodiment using two line sensors. In this embodiment, the base line lengths L1 and L2 extend in the horizontal direction and the vertical direction of the camera body 1, and the respective base line lengths L1 and L2.
Two line sensors that are vertically long in the direction orthogonal to
2, 43 are arranged on the front surface of the camera body 1, respectively. In this embodiment, the signal D from the two line sensors
Since j and Di can be directly obtained, there is an advantage that the signal processing becomes simple. Since the distance measuring means is the same as the area sensor, its explanation is omitted.

〔The invention's effect〕

According to the present invention having the above-mentioned configuration, the slit-shaped light flux is projected in order to project a cross-shaped or X-shaped slit-shaped light flux toward a subject by emitting light once or twice and to receive light reflected by the subject. Since the area sensor or the two line sensors divided along the direction of is used, the distance can be correctly measured whether the camera is in the horizontal position or the vertical position.

[Brief description of drawings]

FIG. 1 is a front view of a camera embodying the present invention. FIG. 2 is a perspective view showing an example of the light projecting section. FIG. 3 is a block diagram showing an embodiment of the distance measuring device of the present invention. FIG. 4 is an explanatory diagram showing the relationship between the photographing screen and the area sensor. FIG. 5 is a flow chart showing a procedure of data acquisition when FIG. 5 and two types of slit-shaped light beams are separately projected. FIG. 6 is a perspective view showing an example of a light projecting unit that projects a cross-shaped slit-shaped light beam. FIG. 7 is a flowchart showing a data acquisition procedure when a cross-shaped slit-shaped light beam is used. FIG. 8 is a flow chart showing a distance measuring mode in which a pixel column or row in the middle of a plurality of pixel columns or rows that receive reflected light from a subject at the closest distance is detected and focused. FIG. 9 is a graph showing the in-focus position in the distance measuring mode shown in FIG. FIG. 10 is a flowchart showing a distance measuring mode in which a pixel having a peak value is detected and focused from a plurality of pixel columns or rows that receive reflected light from a subject at the closest distance. FIG. 11 is a flowchart showing the peak value detection subroutine of FIG. FIG. 12 is a flow chart showing a distance measuring mode for focusing using a weighted average. FIG. 13 is a graph showing weighting factors. FIG. 14 is a graph showing the relationship between the weighted average and the lens set position. FIG. 15 is a flow chart showing a distance measuring mode in which a pixel column or row having a peak value is detected and focused. 16 to 20 are explanatory views showing a sample of a shooting scene and a light receiving state of the area sensor, respectively. FIG. 21 is a front view of a camera showing an embodiment using two line sensors. 1 …… Camera body 2 …… Shooting lens 6 …… Emitting section 7 …… Receiving section L …… Base line length 10 …… Light emitting diode 11 …… Liquid crystal panel Sx, Sy …… Slit-shaped luminous flux 24 …… Area sensor Dij …… Area sensor output signal Dj …… Pixel column signal Di …… Pixel row signal S …… Threshold level 40 …… Slit plate 42, 43 …… Line sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirokazu Yokoo, 26-26-30 Nishiazabu, Minato-ku, Tokyo Fuji Photo Film Co., Ltd. (56) References JP-A-59-129809 (JP, A) JP-A-SHO 58-156910 (JP, A) JP-A-58-178329 (JP, A) JP-A-59-65203 (JP, A)

Claims (4)

[Claims] 1. A light projecting portion and a light receiving portion are arranged on the front surface of a camera body with a certain base line distance from each other, and a light flux for distance measurement is projected from the light projecting portion toward the subject to emit light from the subject. In a distance measuring device for a camera, which receives reflected light by the light receiving unit and measures a subject distance based on the light receiving position, the light projecting unit extends in mutually different first and second directions. The slit-shaped light beams are projected simultaneously or separately, and the light receiving unit is orthogonal to the second direction and a first sensor in which a plurality of elongated pixels are arranged in the first direction in a direction orthogonal to the first direction. A second sensor in which a plurality of pixels elongated in the second direction are arranged in the second direction, and the first sensor receives the light reflected by the object and returned from the slit-shaped light flux extending in the first direction. , Second
A distance measuring device for a camera, characterized in that, of the slit-shaped luminous flux extending in the direction, the light reflected by the subject and returned is received by the second sensor, and the subject distance is measured based on the light receiving positions of these sensors. . 2. The first and second directions are a horizontal direction and a vertical direction of a camera body, and the light projecting portion projects a cross-shaped slit-shaped light beam. A distance measuring device for a camera according to the item. 3. The distance measuring device for a camera according to claim 1, wherein the light receiving section is an area sensor including a plurality of pixels finely divided in a first direction and a second direction. . 4. The distance measuring device for a camera according to claim 1, wherein the first sensor and the second sensor are separate line sensors.