JP3442445B2 - Camera with ranging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a distance measuring device which projects a distance measuring light beam onto a subject and measures the distance to the subject by a signal generated by the reflected light.

[0002]

2. Description of the Related Art In general, a so-called active AF technique for projecting a distance measuring light beam to a subject to measure a distance is widely known, and since a distance can be measured even in a dark place and a structure is simple, It is adopted and installed in many cameras.

However, there has been a problem that it becomes difficult to detect the reflected signal light from the subject of the distance measuring light when the subject position becomes far. Therefore, when the signal light cannot be detected, the focus is adjusted to a finite distance of about 10 m,
Depending on the depth of field of the taking lens, it was designed to cover the range of infinity from 7 to 8 meters.

That is, in the design for completely focusing on the landscape when the landscape is photographed, the subject cannot be focused on the unmeasurable area around 10 m, so the landscape is sacrificed. Therefore, for example, Japanese Patent Laid-Open No. 63-
As disclosed in Japanese Patent No. 214726, there is proposed a technique for completely focusing on a landscape only when a manual button is set. Further, Japanese Patent Application Laid-Open No. 4-299307 discloses a technique of discriminating between outdoor and indoor, and focusing on a landscape at infinity (∞) when it is determined to be a long distance and outdoor.

[0005]

However, the conventional technique described in the above-mentioned Japanese Patent Laid-Open No. 63-214726 is set by a manual button, so that the operation is troublesome in addition to being separated from the flow of automation. , It's not suitable for filming haiku.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 4-299307, the outdoor and the indoor are determined by the brightness of the subject, so that the infinity position is set at the time of photographing a person or the like on a brightly illuminated stage. Since the subject is focused, the actual subject position may not match.

Therefore, the present invention eliminates the need for complicated manual operation, controls the focusing of a long-distance non-measurable range by the photographic lens aperture value, and has a range finder that deteriorates AF due to the brightness of the subject. The purpose is to provide.

[0008]

In order to achieve the above object, the present invention provides a light projecting means for projecting a light beam for distance measurement to a plurality of points in a photographic screen, and the above-mentioned plurality of points. In a camera having a distance measuring device that includes a light receiving unit that receives reflected light of a light beam for distance measurement, and that adjusts the focus of the photographing lens based on the output of the light receiving unit, the amount of light received by the light receiving unit for the plurality of points is a predetermined amount or less, and if the difference is smaller than a predetermined value, a determination unit and distance of the <br/> Utsushitai is distant, the distance of the object by the judgment means in the distance There is provided a camera having a distance measuring device including a switching unit for setting the focusing position of the photographing lens to an infinite position when it is determined that there is. It also projects a distance measuring light beam to the subject.
And a luminous flux for distance measurement from the subject.
And a light receiving means for receiving the reflected light of
In a camera having a distance measuring device for determining a focusing position of a photographing lens based on an output, a photometric unit that measures a plurality of areas in a screen and outputs a plurality of photometric values, and a plurality of the photometric values A light receiving means for determining whether or not the difference is smaller than a predetermined value.
If the amount of light is less than or equal to a predetermined amount of light and the difference between the plurality of photometric values is smaller than a predetermined value by the determination means, a distance measuring device that moves the taking lens to a focus position suitable for landscape photography is provided. A camera having is provided.

[0009]

[Action] camera having the above-described distance measuring device, photo
Distance measurements are performed for multiple points on the screen, and the
The amount of light received by the light means is less than the specified amount of light, and the difference is specified
If the value is smaller than the value, the subject distance is set to the far
Is focused at an infinite position. Also this turtle
The photometers multiple areas on the screen
The difference in the photometric values of is less than the specified value, and the subject is
If there is, the shooting lens is in a focus position suitable for landscape photography.
Be adjusted to.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a schematic structure of a camera having a distance measuring device according to the present invention, which will be described.

This range finder has a sequence of the entire device,
An arithmetic control circuit (CPU) 10 for controlling the arithmetic operation, an infrared light emitting diode (IRED) 1 for projecting distance measuring light toward a subject, and an IRED connected to the CPU 10.
A driver 5 for driving the light source 1, a light position detection element (PFD) 4 for receiving and photoelectrically converting the reflected light from the subject,
An AF circuit 6 that amplifies a detection signal photoelectrically converted by the PFD 4, performs analog calculation, integration, etc., a light projecting lens 2 and a light receiving lens 3 that collect the distance measuring light and reflected light, and to receive visible light. Of the photodiode (PD) 9 of
The signal detected by D9 is amplified and A / D converted, and the CP
BV circuit 8 for outputting to U10, further SV circuit 7 for inputting film sensitivity at the time of photographing, and photographing lens 12
And a lens feeding unit 11 for feeding and controlling the photographing lens 12.

The distance measuring device having the above-described structure is composed of a CPU
10 drives the driver 5, and the infrared light emitting diode (I
The distance measuring light is emitted from the RED) 1 through a light projecting lens 2 toward a subject (not shown).

Then, the reflected light reflected by the subject enters the PFD 4 through the light receiving lens 3. This PFD
The detection signal photoelectrically converted by 4 is input to the AF circuit 6, and the detection signal is amplified, analog-calculated, integrated, etc., and the CPU 10 performs the principle of triangulation or the relationship between the object distance and the signal light amount. Calculate the subject distance from.

The visible light signal received by the photodiode (PD) 9 and photoelectrically converted is input to the BV circuit 8. The BV circuit 8 amplifies and A / D converts the visible light signal and outputs it to the CPU 10.

Further, the CPU 10 includes the BV circuit 8 and the S
Based on the aperture and the shutter speed at the time of shooting output from the V circuit 7, arithmetic processing is performed, and the lens feeding unit 11 is driven so that the subject is controlled to be in focus.

Next, in FIG. 2, the reciprocal of the subject distance L (1
6 is a graph showing the relationship between / L) and the lens feed-out position k that provides the optimum focus. However, since the lens has a depth of field, the portion that is within the permissible width shown by the dotted line in the figure appears to be in focus even with an open aperture.

Therefore, the AF can determine up to L ₀ ,
Even if the distance cannot be measured further than that, if the photographing lens 12 (lens for feeding) is designed to be moved to the k ₀ feeding position, the distance from L ₀ to the infinite distance will be constant. You can take a focused photo.

However, since the position at which the scenery photograph is most beautifully focused is the position of k ∞, some users are not satisfied with the scenery as a result of focusing to some extent as described above. .

However, when the taking lens 12 is extended to the position of k∞, the allowable width is limited to L∞. In particular, AF is required to have high performance so that it can cope with L ∞ which is a long distance from L ₀ . This affects the cost and complexity and size of the device, and is not a requirement that can be solved immediately. Further, the AF can not be determined only up to L _0, the resulting out Repetitive the position of k∞, becomes camera focus may not be achieved between L∞ of L _0.

This is based on the above-mentioned Japanese Patent Laid-Open No. 4-299307.
This is also a problem that can occur in the gazette. However, in a scene where the aperture of the taking lens is narrowed, the allowable value can be extended to the portion a.

In this embodiment of the present invention, attention is paid to this allowable value. FIG. 3 shows a configuration of a distance measuring device mounted on a camera as a first embodiment and will be described. This range finder includes, for example, three IREDs 1a, 1b, 1c and three PSDs 4
A, 4b, and 4c are sequentially driven so that three points on the photographic screen can be distance-divided in a time-division manner.

These IREDs 1a, 1b and 1c are C
The light is sequentially emitted by the driver 5 controlled by the PU 10, and the light is projected through the lens 2 in three directions as shown in the figure. These distance measuring lights are reflected by the subject within the photographing range, pass through the light receiving lens 3, and enter the PSDs 4a, 4b, 4c arranged at the corresponding positions. Since the lens 2 and the lens 3 are arranged apart from each other by a predetermined distance (baseline length), the incident position of the reflected signal light on each PSD depends on the subject distance L according to the principle of triangulation. Change.

The preamplifiers 21 and 22 are provided in the PSDs 4a and 4 respectively.
It is a circuit that amplifies the two output signal currents from b and 4c and guides them to the ratio calculation circuit 23 and the addition circuit 24. The ratio calculation circuit 23 compresses and differentially calculates the _two output currents I ₁ and I ₂ from the PSDs 4a, 4b and 4c to calculate I ₁ / I ₂ .
It is a circuit that operates in the form of (I ₁ + I ₂ ). Above PSD
Due to their characteristics, 4a, 4b and 4c output _two signal currents I ₁ and I ₂ corresponding to the incident position X of light.
If the length of D is t,

[0024]

[Equation 1] The relationship is established.

Therefore, when the CPU 10 inputs I ₁ / (I ₁ + I ₂ ) from the ratio calculation circuit 23, 1 / L can be calculated from a predetermined relational expression. In addition, the adder circuit 24
Is a circuit for calculating I ₁ + I ₂ of the outputs of the PSDs 4a, 4b, 4c. This output is input to the integrating circuit 25. Even if I ₁ + I ₂ is weak, it is necessary to integrate it over time. The signal component can be detected from the noise component.

For example, since noise of a circuit is randomly generated with respect to a directional signal, the noise is canceled by integrating over time, which facilitates signal extraction. Further, the output of the integration circuit 24 has a relationship inversely proportional to the square of the subject distance L if the light projection amount, the reflectance of the subject, and the integration time are constant. Therefore, from the output of the integration circuit 24, the CPU 10 can determine whether or not the subject is a long distance, and compared with the ratio calculation circuit 23, the distance that can be determined is long due to the integration effect.

The light condensed by the lens 20 is incident on a light receiving element for measuring visible light. This light receiving element covers a small light receiving area 9b for measuring a minute portion in the center of the screen and the entire screen. Large light receiving area 9a
It is divided into two parts. These two photometrys are referred to as spot photometry and average photometry, but the AE circuit 8 amplifies the outputs of these light receiving elements and performs A / D conversion, and the CPU 10
On the other hand, it is provided to output a photometric signal.

Further, the switches 26 and 27 are each 1st
Release SW and 2nd release SW, which are closed when the release button of the camera is half-pressed and pressed,
The timing immediately before the photographer starts photographing and the timing at which photographing starts are input to the CPU 10. An SV circuit 7 for inputting film sensitivity is provided, and as in FIG.
It is detected when the film cartridge is attached and is sent to the CPU 10.

The CPU 10 controls the driver 28 to drive the motor 29 and rotate the feed screw 30 to move the taking lens (focusing lens) 12 along the rail 31.

The operation of the distance measuring device configured as described above will be described with reference to the flowchart of FIG.
First, prior to the input of the 1st release SW, the value of the sensitivity of the film used in advance is detected by the SV circuit 7, and the CPU 1
To 0 (step S1). When the photographer presses the release switch (step S2), the photometric sensors 9a and 9b are sequentially switched to perform photometry on the entire screen at the time of shooting and the central portion of the screen where the main subject is highly likely to exist (step S3). S4).

Further, the subject distance Lb and the reflected signal light amount Pb are measured using the IRED 1b and the PSD 4b which project the distance measuring light on the central portion of the screen (steps S5 and S6).

In 10% to 20% of general photographs, since the main subject does not exist in the center of the screen, IRED1a,
The PSD 4a or the IRED 1c or PSD 4c is used to measure the distance between the left and right sides of the screen and measure the amount of reflected light (steps S6 to S10).

Next, it is determined whether or not the photographer has pushed the 2nd release SW (step S11), and if the 2nd release SW has not been pushed (NO), 1st.
It is determined whether or not the release SW is turned on (step S12). In this determination, if the photographer releases the release SW and the 1st release SW is off (N
O), the process returns to step S2, and when the second release is pressed (YES), the reflected signal light amounts Pa, Pb,
Pc is compared with the predetermined light amount value P ₀ (step S13).
When it is determined that both are equal to or more than the predetermined light amount value (N
O), the closest distance among the subject distances La, Lb, and Lc is set to Lp (step S18), and the focusing lens 12 is driven and controlled so as to be in focus with this Lp (step S19). In such a case, the subject is too far away to measure the distance correctly, and it is necessary to focus on the long distance in some way.

Therefore, in the conventional camera, as described with reference to FIG. 2, the lens extension position k ₀ , which seems to be in focus to some extent, is focused on the distance from ∞ to L ₀ . However, in the present embodiment, for example, even in a landscape photograph, the purpose is to accurately focus, so depending on the case, according to the following flowchart,
Focus exactly where the subject position is ∞ (Fig. 2
The lens is controlled to k∞.

Next, in the determination at step S13,
When it is determined that the reflected signal light amounts Pa, Pb, and Pc are all less than or equal to the predetermined light amount value P ₀ (Y).
ES), the aperture at the time of shooting is calculated from the obtained photometric result and the film sensitivity (step S14).

Generally, the camera determines the combination of the aperture of the taking lens and the shutter speed from the result of photometry and the film sensitivity. In step S14, the shutter is opened in order to make the depth of field as deep as possible to secure the focus. The speed is set to the limit of the camera shake limit, and the value when the aperture is stopped is calculated.

On the other hand, in the flowcharts after step S18 other than the photographing of such a long distance photograph, the aperture value calculation is performed in which the shutter speed is more important than the aperture value (step S20).

Aperture value F obtained in step S14
Then, a predetermined aperture F ₀ is compared (step S15), and if the aperture is narrower than the predetermined aperture F ₀ (YES), the landscape photograph is focused on ∞ so that the photograph can be taken with the best focus. (Step S16). This is shown in Figure 2 (a).
This is because, as shown by, when the diaphragm is stopped down, the depth of field becomes deeper and it becomes possible to cover up to the distance measurement limit L ₀ .

[0039] However, in the determination in step S15, if it is determined not to put aperture until cover L ₀ shown in FIG. 2 (NO), the reflected signal light amount Pa of each distance measurement point, Pb, the Pc The difference ΔP between the maximum value and the minimum value is calculated (step S21). Next, the predetermined value ΔP ₀ is compared with the difference ΔP (step S22).

If the difference ΔP is small in this comparison, (YE
S), that is, when the reflected light amounts Pa, Pb, and Pc have no difference and are uniform, it is determined that the probability of being a landscape photograph is high, and the process returns to step S16.

However, in the determination of step S22, the difference ΔP
If is large (NO), the difference ΔBV between the average photometry and the spot photometry is calculated (step S23). With this judgment,
If the difference ΔBV is smaller than the predetermined value ΔBV ₀ (YE
S), the process returns to step S16 to focus on ∞. This is a result of assuming that the photometric value is uniform in landscape photography.

However, in the determination of step S24, the difference ΔB
When V is larger than the predetermined value ΔBV ₀ (NO), the process shown in FIG.
Focusing on k ₀ shown in step S16, S16
When the focusing is completed in 20 and S25, exposure is performed (step S17).

As described above, the camera having the distance measuring device of the first embodiment is superior to the conventional camera in rendering a landscape photograph. Next, with reference to FIG. 7, a camera having a distance measuring device according to a second embodiment of the present invention will be described.

In the flow charts of FIGS. 5 and 6 of the first embodiment described above, the process branches to step S21 and the object position is ∞.
As described above, since it is not possible to expect a change in the depth of field due to the aperture when the taking lens is extended, it becomes impossible to focus on a range of ΔLx closer than L∞ as shown in FIG. Regardless of the photometric value, that is, the brightness of the subject, it is necessary to measure the distance to a long distance L ₀ .

In the light projection type AF, however, the brighter the subject, the lower the S / N of the signal light, and the shorter the distance that can be measured. This embodiment is shown in FIG.
As shown in (2), when the diaphragm is open, the feeding position is controlled like A (step pattern A), the diaphragm is narrowed,
When the depth of field is deep, the extension position of the focusing lens is controlled like B (step pattern B).

That is, in the stepped pattern A, since the subject brightness is dark and the S / N for distance measurement is improved, it is premised that the distance can be measured up to L _0A . On the other hand, the step pattern B is
Since the S / N of the distance measurement is deteriorated due to the brightness of the subject, the distance measurement is set to L _0B , which is a short distance from L _0A , and beyond that, the focus is on ∞. Regarding the determination distances L _1A and L _1B of the next focusing stage, L _1B is closer than L _1A, and it works in the direction of covering the deterioration of the S / N of the distance measurement.

This is aimed at the effect that the reflected signal light increases and the S / N is improved as the subject is closer. The second embodiment will be described with reference to the flowchart shown in FIG.

First, the CPU inputs information on film sensitivity, subject brightness, and subject distance (steps S31 to S3).
3) The aperture is calculated based on the subject brightness and the film sensitivity (step S34).

When the calculated aperture value is small (bright) (NO), the depth of field is taken into consideration and focusing is performed with the step pattern B shown in FIG. 7 (step S3).
7), exposure is performed (step S38).

On the other hand, when the aperture is not narrowed and the aperture value is large (dark) (YES), the step pattern A is focused (step S36) and exposed (step S3).
8).

Therefore, according to the present embodiment, the lens control is switched up to the farthest distance depending on the aperture value of the taking lens, so that the deterioration of AF due to the brightness of the subject can be covered.

As described above, the camera having the distance measuring device of this embodiment can switch the focusing control of the non-measurable range at a long distance depending on the photographing lens aperture value at the time of photographing, and can take a beautiful landscape photograph. it can. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and applications can be made without departing from the scope of the invention.

[0053]

As described above in detail, according to the present invention, complicated manual operation is not required, focusing control is performed in a long distance non-measurable area by the photographing lens aperture value, and AF is performed according to the brightness of the subject. It is possible to provide a camera having a distance measuring device that deteriorates.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a camera having a distance measuring device according to the present invention.

FIG. 2 is a graph showing the relationship between the reciprocal of the subject distance L (1 / L) and the lens extension position k that provides the optimum focus.

FIG. 3 is a diagram showing a configuration of a distance measuring device (camera) as a first embodiment according to the present invention.

FIG. 4 is a diagram showing a focusing control pattern according to a relationship between a moving-out position of a photographing lens and a subject distance in a camera having the distance measuring apparatus according to the first embodiment.

FIG. 5 is a first half flowchart for explaining the operation of the distance measuring apparatus according to the first embodiment.

FIG. 6 is a second half flowchart for explaining the operation of the distance measuring apparatus according to the first embodiment.

FIG. 7 is a diagram showing a focus control pattern according to the relationship between the moving-out position of the photographing lens and the subject distance in the camera having the distance measuring apparatus of the second embodiment.

FIG. 8 is a flowchart for explaining the operation of the distance measuring apparatus according to the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Infrared light emitting diode (IRED), 2 ... Emitter lens, 3 ... Light receiving lens, 4 ... Optical position detection element (PFD),
5 ... Driver, 6 ... AF circuit, 7 ... SV circuit, 8 ... BV
Circuits, 9 ... Photodiode (PD), 10 ... Arithmetic control circuit (CPU), 11 ... Lens feeding section.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-31107 (JP, A) JP-A-1-187510 (JP, A) JP-A-60-3607 (JP, A) JP-A-59- 204012 (JP, A) JP-A-5-103250 (JP, A) JP-A-4-299307 (JP, A) Actual development Sho 60-191014 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B ^7/ 28-7/40

Claims (2)

(57) [Claims] 1. A light projecting means for projecting a distance measuring light beam to a plurality of points in a photographic screen, and a light receiving means for receiving a reflected light of the distance measuring light beam from the plurality of points. In a camera having a distance measuring device for focusing a photographing lens on the basis of the output of the light receiving means, the light receiving amount of the light receiving means with respect to the plurality of points is not more than a predetermined light amount, and the difference is smaller than a predetermined value. in this case, a determination unit and distance of the Utsushitai is distant, when the distance of the object is determined to be distant by the determination means, an infinite positions focusing position of the photographing lens A camera having a distance measuring device, comprising: 2. A light flux for distance measurement is projected onto a subject.
Means for projecting light and the reflection of the light flux for distance measurement from the subject.
And a light receiving means for receiving the emitted light, and the output of this light receiving means
In a camera having a distance measuring device for determining the focusing position of a photographing lens based on the above, a photometric means for measuring a plurality of areas in a screen and outputting a plurality of photometric values, and a difference between the plurality of photometric values. And a plurality of photometric values determined by the determining means, the light receiving amount of the light receiving means is less than or equal to a predetermined light amount , and the determining means determines whether or not is smaller than a predetermined value. A camera having a distance measuring device characterized in that, when it is determined that the difference is smaller than a predetermined value, the photographing lens is moved to a focus position suitable for landscape photography.