JP3268822B2 - Distance measuring 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 panoramic camera equipped with, for example, an active auto-focus unit and capable of switching the screen size on a film, or a dark room (lab) based on information recorded on a film. The present invention relates to a distance measuring device in a trimming camera or the like for setting an enlargement magnification arbitrarily.

[0002]

2. Description of the Related Art Conventionally, for example, in a camera having a panoramic mode, the enlargement magnification at the time of printing when photographing in a panoramic mode indicating a wider range than a normal photographing range is larger than that in a normal mode. Is doubled.

Therefore, in this type of camera, the lens performance and auto focus (AF; Auto Focu
s) Performance requires twice the accuracy of normal. further,
Blur and flare, which was not a problem in the standard mode, will be noticeable.

In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. Sho 62-50741 discloses a technique in which the depth of field is increased by restricting a program diagram so as not to open the aperture during trimming photographing. There is disclosed a technique for improving print quality.

Further, Japanese Patent Application Laid-Open No. 64-38735 discloses a technique in which multi-point AF is adopted in a normal mode and one-point AF is adopted in a panoramic mode to measure the distance to a main subject. .

[0006]

However, in the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 62-50741, when taking a picture without opening the aperture, the shutter time is delayed and camera shake may occur. At the time of flash shooting, a problem that the flash light does not reach occurs. Also,
According to the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 64-38735, even when the multipoint AF is set to one-point AF and the projected spot surely hits the subject, the enlargement magnification is 2 times in the panorama mode as compared with the normal mode. Therefore, the developed photograph may become out of focus with the AF accuracy in the normal mode.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to improve focusability even in photographing in a panoramic mode or a trimming mode having a different magnification from normal photographing in a normal mode. The goal is to get high photos.

[0008]

In order to achieve the above object, a first aspect of the present invention is to provide a light projecting means for projecting a pulse light to a subject, and a photoelectric conversion means for receiving reflected light from the subject. A photoelectric conversion unit for performing conversion, a distance calculation unit for calculating a subject distance based on an output from the photoelectric conversion unit, and a first shooting mode for instructing a normal shooting range, which is different from the normal shooting range A photographing mode setting means for selectively setting a second photographing mode in which a photographing range is instructed and the enlargement magnification at the time of printing is larger than that at the time of setting the first photographing mode; Control means for determining the number of times light is projected by the light projecting means based on the magnification, wherein the control means causes the light projecting means to emit light when the second shooting mode is set. Characterized by increasing the number of times A second aspect is characterized in that the control means further determines the number of times of light emission of the light emitting means based on F number information. A third aspect is characterized in that the control means further determines the number of light projections of the light projection means based on a subject luminance value and focal length information of a photographing lens of the camera. A fourth aspect is characterized in that the control means further determines the number of light projections of the light projection means based on subject distance information. In a fifth aspect,
The image forming apparatus further includes an integrating means for performing integration based on an output of the photoelectric conversion means, wherein the control means variably controls an integration time of the integrating means according to the determined number of times of light projection. A sixth aspect is characterized in that the control means sets the integration time shorter than a normal integration time when the determined number of light projections exceeds a predetermined number of light projections. A seventh aspect is characterized in that the control means sets the integration time to a normal integration time when the determined number of light projections does not exceed a predetermined number of light emission.

[0009]

According to a first aspect of the present invention, a pulse light is projected onto a subject by a light projecting means.
The reflected light from the subject is received by the photoelectric conversion means, photoelectric conversion is performed, the subject distance is calculated by the distance calculation means based on the output from the photoelectric conversion means, and the normal shooting range is set by the shooting mode setting means. A first shooting mode for instructing, and a second shooting mode for instructing a shooting range different from the normal shooting range, wherein the enlargement magnification at the time of printing is larger than when the first shooting mode is set. And the mode is selectively set, the control means determines the number of light projections of the light emitting means based on the enlargement magnification, and the control means sets the second shooting mode. The number of times of light emission by the light emitting means is increased. In the second aspect, the control means determines the number of times of light projection by the light emitting means based on F number information. In a third aspect, the control means determines the number of times of light projection by the light emitting means based on a subject luminance value and focal length information of a photographing lens of the camera. In a fourth aspect,
The control means determines the number of times light is projected by the light emitting means based on subject distance information. In the fifth aspect, integration is performed by the integration means based on the output of the photoelectric conversion means, and the integration time of the integration means is variably controlled by the control means in accordance with the determined number of times of light emission. Sixth
In the aspect, when the determined number of light projections exceeds a predetermined number of light projections, the integration time is shorter than a normal integration time. In a seventh aspect, when the number of light projections determined by the control means does not exceed a predetermined number, the integration time is set to a normal integration time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a description will be given of a technique which is a premise of the distance measuring apparatus of the present invention.

Auto focus (AF; Auto) by an active triangulation method applied to compact cameras and the like.
Focus) device is configured based on the principle of ranging as shown in FIG. That is, the light projecting lens 111 and the light receiving lens 113 having optical axes parallel to each other are located apart from each other by the base line length S, and a near-infrared light emitting LED (hereinafter, referred to as IRED) 102 is provided on the light projecting lens optical axis. On the optical axis of the light receiving lens, a position detecting element (hereinafter, referred to as PSD) 101 having a length b and having an end surface at a position shifted by a is disposed. Then, the light energy projected from the IRED 102 is reflected by the subject 112 at a distance L, and forms an image on the PSD 101 through the light receiving lens 113.

The PSD 101 has two output terminals 1ch
And the two channels, and when the stationary photocurrent component such as sunlight is removed, the relationship expressed by the following equation is established between the output currents i ₁ and i ₂ and the incident position x of the reflected spot light. .

[0013]

(Equation 1) Then, assuming that the focal length of the light receiving lens 13 is f _j , the incident position x is obtained by the following equation. x = S · f _j / L (2) Further, the following equation is obtained from the above equations (1) and (2).

[0014]

(Equation 2) Therefore, the reciprocal of the subject distance L can be obtained by obtaining i ₂ / i ₁ + i ₂ .

FIG. 10 is a main part circuit diagram of a conventional distance measuring apparatus based on the active triangulation. IR not shown
Before the ED emits light, the operational amplifier A
Analog switch A arranged on the output side of A11 and A12
S11 and AS12 are on. Accordingly, all the steady photocurrent flowing through the PSD flows through the transistors Q11 and Q12 due to the negative feedback of the amplifiers A11 and A12, and the capacitors C11 and C12 are charged with the base potential required for that.

Immediately before the IRED emits light, the analog switch AS on the output side of the operational amplifiers A11 and A12.
When the AS 11 and the AS 12 are turned off, the potentials required for flowing the steady photocurrent are stored in the capacitors C 11 and C 12.

Next, the increments i ₁ and i ₂ of the photocurrent caused by the reflected light from the subject due to the IRED projection flow into the bases of the amplification transistors Q13 and Q14. Assuming that the DC current gain of the transistors Q13 and Q14 is β, β
_i1 and β _i2 flows through the logarithmic compression diode Q15, Q16. The cathode of the logarithmic compression diodes Q15, Q16 is input to the base of the differential increase amplifier Q19, Q20 of the constant current I _0.

The transistors Q19 and Q20
I ₁ the collector current of the _', i _2', transistor Q15, Q
Assuming that the reverse saturation current of 16, Q19 and Q20 is I _S and the thermal voltage is V _T , the following relational expressions are established for these transistor diodes.

[0019]

(Equation 3) By substituting this equation (5) into i ₁ + i _{2 ′} = I ₀ (6), the following equation is established.

[0020]

(Equation 4) On the other hand, the current I _INT for integrating the integration capacitor C13 is i
Equal to _{1 '} .

Therefore, as shown in FIG. 11, the capacitor C13 is applied for a fixed time t ₁ by I _{INT in a} double integration method.
Charged, followed by discharge in the opposite direction to the constant current I _G, the following equation is obtained when measuring the time t ₂ to return to the original voltage. t ₁ × I _INT = t ₂ × I _G (8) Further, from the above equations (7) and (8), a relation expressed by the following equation is obtained.

[0022]

(Equation 5) Therefore, since the following relationship is established from the expressions (3) and (9), the subject distance L can be obtained by measuring t ₂ .

[0023]

(Equation 6) Here, the error Δ1 / l of the distance measurement data 1 / l output from the AF circuit generally has a relationship represented by the following equation.

[0024]

(Equation 7) In the above equation (11), 1 represents the subject distance, BV represents the subject brightness, n represents the number of times of light emission of the IRED, and t _INT represents the signal current integration time of the circuit per one time. On the other hand, if the allowable circle of confusion in the normal mode is δ ₀ , the allowable defocus Δf _{c1 on the} image plane is as follows.

[0025]

(Equation 8)

In the above equation (12), F is the F number of the lens at the time of photographing, m is the trimming rate corresponding to the enlargement magnification at the time of printing, this trimming rate is m = 1 in the normal mode, and the panorama mode. Then, m = 2.
Further, the following relationship is established between the distance measurement data error .DELTA.1 / l and the image plane error Delta] f _c2.

[0027]

(Equation 9) In the above equation (13), f _TL indicates the focal length of the taking lens. Therefore, the (7), (8) and (9), in order to be Δf _c1> Δf _c2 will be may be satisfied a relation of the following equation.

[0028]

(Equation 10) Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of the first exemplary embodiment of the present invention.

As shown in FIG. 1, the distance measuring section 1, the light measuring section 2, the focal length detecting section 3, and the trimming signal generating section 4 are connected to a control section 6, respectively. The photometer 2 is further connected to an F-number calculator 5, which is connected to a controller 6. The output terminal of the control unit 6 is connected to the distance measuring unit 1.

In such a configuration, in the distance measuring section 1,
The IRED (not shown) emits light, and the subject distance 1 is calculated based on where the reflected light from the subject returns on the PSD (not shown). The distance measurement accuracy at this time is as shown in FIG.
Since the number of times of light emission n and the integral time t _INT are proportional to the half power, the AF accuracy can be improved by increasing the values of the number of times of light emission n and the integration time t _INT . However, the release time lag becomes longer with this, which may cause a missed shutter chance.

The trimming signal generator 4 calculates a trimming ratio m, and outputs a selection signal to the controller 6 for selecting a panorama mode or a normal mode in a panoramic camera, for example. Then, in the photometry unit 2, the subject brightness BV
The value is calculated and output to the F-number calculation unit 5 and the control unit 6. The F-number calculator 5 calculates the subject brightness BV
An F number is set based on the value, and the F number is output to the control unit 6. Further, the focal length detecting unit 3 calculates the focal length f _{TL of the} lens, and the distance measuring unit 2 obtains distance information 1 / l by the pre-ranging operation. These values are output to the control unit 6. Then, the control unit 6 determines the number of times of light emission n and the value of the integration time _tINT based on these input values and outputs the values to the distance measuring unit 1. Next, FIG.
FIG. 6 is a diagram illustrating a configuration of a second exemplary embodiment of the present invention.

As shown in FIG.
ED13 and PSD14 are connected,
13 and the PSD 14 at a position facing the PSD 14.
1. The light receiving lens 12 is disposed on a parallel optical axis separated by a predetermined base line length.

A photo diode (PD) 17 is connected to an auto exposure (AE) circuit 18, and an AE light receiving lens 16 is disposed at a position facing the PD 17. I have.

Further, a gray code 20 is attached to the lens barrel of the zoom lens 19, and the gray code 2
The zoom encoder 21 is connected to 0. The AF circuit 15, the AE circuit 18, and the zoom encoder 21 are connected to a control unit 23.
Is a panorama mode / normal mode selection switch (hereinafter referred to as P / NSW) corresponding to the trimming signal generator 4 in FIG.
22). In such a configuration, the AF circuit 15 having the configuration shown in FIG. 10 described above calculates distance measurement information 1 / l and outputs it to the control unit 23.

The AE circuit 18 logarithmically compresses the photocurrent of the subject image input to the AE light receiving element PD17 through the AE light receiving lens 16, and subjects the photocurrent to the subject brightness BV.
It is calculated as a value and output to the control unit 23. Further, an operation is performed along the program diagram, and the aperture value F at the time of shooting at the current brightness is output to the control unit 23.

Further, the zoom lens 1 whose focal length f _TL is changed by being rotated by a motor (not shown)
In 9, the current focal length f _TL is calculated by the gray code 20 affixed to the lens barrel and the zoom encoder 21, and output to the control unit 23.

When the P / NSW 22 is turned off in the normal mode and turned on in the panorama mode, the trimming rate m is changed, and the signal is output to the control unit 23. The control unit 23 determines the optimal number n of light emission of the IRED 13 or the number of light emission per one based on the distance measurement information 1 / l, the subject brightness BV value, the aperture value F, the focal length f _TL , and the trimming rate m. An integration time t _INT is set for the AF circuit 15. Hereinafter, the specific operation of the above embodiment will be described with reference to the flowcharts of FIGS. First, with reference to the flowchart of FIG.
An operation example will be described.

The operation is started (step S100), and first, it is detected whether or not the P / NSW 22 is turned on (step S101). When the P / NSW 22 is turned on, the trimming rate m is set to "2" (step S102), and when the P / NSW 22 is turned off, the trimming rate m is set to "1" (step S103). Then, the number of times of light emission n is set by the following equation (step S10).
4) Subsequently, the AF operation is performed (step S105). n = m ² ・ N ₀ … (15)

Then, the distance measurement information 1 / l is calculated (step S106), and after the lens is extended (step S106).
107), a shutter operation is performed (step S108),
All the operations are completed (step S109).

As described above, the present operation example is characterized in that the number of times of light emission of the IRED 13 is controlled based only on the trimming rate information. Then, it is determined whether the reference light emission frequency N ₀ is quadrupled or used as it is by turning on / off the P / NSW 22. Next, a second operation example of the embodiment will be described with reference to the flowchart of FIG.

The operation is started (step S200). First, a photometric operation is performed (step S201), and an F number is obtained based on a program diagram (step S202). Then, it is detected whether or not the P / NSW 22 is turned on (step S203). If the P / NSW 22 is turned on, the trimming ratio m is set to “2” (step S204), and the P / NSW 22 is turned off. In this case, the trimming rate m is set to "1" (step S205). Then, the number of times of light emission n is obtained by the following equation (step S206), and the AF operation is performed (step S207).

[0042]

[Equation 11] Note that, in the above equation (16), F ₀ indicates the reference F number.

Subsequently, distance measurement information 1 / l is calculated (step S208), and after the lens is extended (step S208).
209), a shutter operation is performed (step S210),
All the operations are completed (step S211). As described above, the present operation example is characterized in that the number of times of light emission of the IRED 13 is controlled based on information on the trimming rate and the F-number. Next, a third operation example of the embodiment will be described with reference to the flowchart of FIG.

The operation is started (step S300). First, a photometric operation is performed (step S301), and the object brightness BV is measured.
A value is calculated (step S302). Then, after calculating the F number (step S303), the focal length f _TL is detected (step S304). Then, the trimming rate m is detected (step S305), and the number of times of light emission n is obtained by the following equation (step S306).

[0045]

(Equation 12) In the above equation (17), BV ₀ is a reference luminance value, f
₀ indicates a reference focal length.

After calculating the number of times of light emission n in this way, an AF operation is performed (step S307), and distance measurement information 1 / l is calculated (step S308). After the lens is extended (step S309), the shutter operation is performed (step S310), and all the operations are completed (step S311).

As described above, in the present operation example, the trimming ratio,
F number, subject brightness, focal length
The feature is that the number of times of light emission of the RED 13 is controlled. Next, a fourth operation example of the embodiment will be described with reference to the flowchart of FIG.

The operation is started (step S400). First, a pre-AF operation is performed (step S401), and the distance measurement information 1 is set.
/ L is calculated (step S402). Then, a photometric operation is performed (step S403), and a subject brightness BV value is calculated (step S404).

After calculating the F number (step S405), the focal length _fTL is detected (step S4).
06). Subsequently, the trimming ratio m is detected (step S).
407), the formal light emission frequency n is obtained by the following equation (step S408).

[0050]

(Equation 13)

After calculating the formal light emission number n in this way,
The AF operation is performed (step S409), and the distance measurement information 1 / l
Is calculated (step S410). After the lens is extended (step S411), the shutter operation is performed (step S412), and all the operations are completed (step S413).

As described above, in this operation example, the trimming ratio,
It is characterized in that the number of times of light emission of the IRED 13 is controlled based on the information of the F number, the subject brightness, the focal length, and the subject distance. Next, a fifth operation example of the embodiment will be described with reference to the flowchart of FIG.

The operation is started (step S500). First, the pre-AF operation is performed (step S501), and the distance measurement information 1 is set.
/ L is calculated (step S502). Then, a photometric operation is performed (step S503), and a subject brightness BV value is calculated (step S504).

After calculating the F number (step S505), the focal length information _fTL is detected (step S506). Then, the trimming ratio m is detected (step S507), and the number of times of light emission n is obtained by the above equation (18) (step S508).

[0055] Subsequently, it is determined whether or not the number of emissions n exceeds the N _MAX affecting limit time lag.
If the number n of light emission exceeds N _MAX , the normal integration time t _INT is multiplied by N _MAX / n (step S
510), and set n to N _MAX (step S511),
If N _MAX has not been _exceeded , t _INT is set to t _INT0 (step 512).

Then, an AF operation is performed (step S51).
3) The distance measurement information 1 / l is calculated (step S51).
4). Then, after the lens is extended (step S
515), perform a shutter operation (step S516),
All the operations are completed (step S517). As described above, in this operation example, when the integration time t _INT is variable,
The AF accuracy can be improved without significantly increasing the release time lag.

As described in detail above, according to the present invention, even if the trimming information, the subject luminance information, the F-number information, the focal length information, and the subject distance information change, the diameter of the confusion circle always becomes optimal. The number of times of light emission and the integration time of the IRED can be determined.

[0058]

According to the present invention, there is provided a distance measuring apparatus capable of obtaining a photograph having high focus even in the panorama mode and the trimming mode having different enlargement magnifications from the normal photography in the normal mode. be able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing the number of times of light emission of a near-infrared light emitting diode and an integration time in the first embodiment.

FIG. 3 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a flowchart illustrating a first operation example of the embodiment.

FIG. 5 is a flowchart illustrating a second operation example of the embodiment.

FIG. 6 is a flowchart illustrating a third operation example of the embodiment.

FIG. 7 is a flowchart illustrating a fourth operation example of the embodiment.

FIG. 8 is a flowchart illustrating a fifth operation example of the embodiment.

FIG. 9 is a diagram illustrating a principle of distance measurement of an autofocus device based on an active triangulation method.

FIG. 10 is a main part circuit diagram of a distance measuring device based on an active triangulation method.

FIG. 11 measures the time t ₂ until the capacitor C13 is charged by I _{INT for a} certain time t ₁ by the double integration method, then discharged in the opposite direction by the constant current _IG , and returns to the original voltage. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Distance measuring part, 2 ... Light measuring part, 3 ... Focal length detecting part, 4 ... Trimming signal generating part, 5 ... F number calculating part, 6 ... Control part, 11 ... Light emitting lens, 12 ... Light receiving lens, 13 ... Near infrared light emitting diode, 14 ... Position detecting element, 15 ... Autofocus circuit, 16 ... Autofocus light receiving lens, 17 ... Photodiode, 18 ... AE circuit, 19 ...
Zoom lens, 20: Gray code, 21: Zoom encoder, 22: Panorama mode / normal mode selection switch, 23: Control unit.

Claims (7)

(57) [Claims] 1. A light projecting means for projecting pulse light to a subject, a photoelectric conversion means for receiving reflected light from the subject and performing photoelectric conversion, and a subject distance based on an output from the photoelectric conversion means. A distance calculating means for calculating, and a first for indicating a normal photographing range
Shooting mode and a shooting range different from the
This is the mode for specifying the frame
A photographing mode setting means for selectively setting a second photographing mode having a rate larger than that at the time of setting the first photographing mode; and determining the number of light projections of the light projecting means based on the enlargement magnification. comprising a control means, said control means, the second imaging mode is set
A distance measuring device for a camera, wherein the number of times light is projected by the light projecting means is increased . 2. The camera distance measuring apparatus according to claim 1, wherein said control means further determines the number of times of light emission of said light emitting means based on F number information. 3. The camera according to claim 1, wherein said control means further determines the number of light projections of said light projection means based on a subject luminance value and focal length information of a photographing lens of the camera. Distance measuring device. 4. The distance measuring apparatus for a camera according to claim 1, wherein said control means further determines the number of light projections of said light projecting means based on subject distance information. 5. An integrator for performing integration based on an output of the photoelectric converter, wherein the controller variably controls an integration time of the integrator in accordance with the determined number of times of light emission. The distance measuring device for a camera according to any one of claims 1 to 4, wherein: 6. The method according to claim 5, wherein the control unit sets the integration time to be shorter than a normal integration time when the determined number of light projections exceeds a predetermined number of light projections. A distance measuring device for the camera according to the above. 7. The control unit according to claim 5, wherein the control unit sets the integration time to a normal integration time when the determined number of light projections does not exceed a predetermined number of light projections. Camera ranging device.