JP2000137159A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera capable of obtaining more excellent focusing by eliminating an error in AF due to temperature and humidity, environmental change and deformation caused when force is exerted while miniaturizing the camera as a whole by using a small-sized AF module. SOLUTION: This camera is provided with a window part for range-finding on its front part, and a barrier 25 is moved between a closing position where it covers over the window part of a passive AF module 15 and light projecting and receiving lenses 12, 13a and 13b exposed on the front part of the camera and an opening position where the window part and the lenses 12, 13a and 13b are exposed. The barrier 25 is provided with a light guide 26 to be opposed to the window part in the state of the above closing position, and signal light for calibration is made incident on sensor arrays 14a and 14b through the light receiving lenses 13a and 13b. The deformation of the module 15 is detected by a CPU 17 based on the control of the signal light for calibration and output signals from the sensor arrays 14a and 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a distance measuring device used for a camera or the like, and more particularly to a camera for calibrating a distance of a passive type autofocus (AF) unit.

[0002]

2. Description of the Related Art There are two types of distance measuring devices, an active type that projects light for distance measurement on an object (subject) and a passive type that uses an image signal of the object. Can be classified as

Conventionally, an active type distance measuring apparatus uses reflected signal light, so that it has low accuracy for objects having a low reflectance or a distant subject, and a passive type distance measuring apparatus uses an image signal. It has been said that accurate distance measurement cannot be expected for a dark scene where it is difficult to obtain an image, or a subject such as a flat plate with little shading.

[0004]

However, in addition to these fundamental differences, further research has revealed that there is a problem that, when actually created and used, cannot be easily overcome in terms of configuration.

One of them is a passive triangulation AF.
In the case of, there was a problem that the temperature and humidity were easily affected. Here, as is apparent from Japanese Patent Application Laid-Open No. 57-64204, it has long been known that AF requires temperature correction.

However, with the recent increase in the focal length of a camera with a zoom lens, a minute error due to such an environmental change is not allowed. On the other hand, as the size of the camera is reduced, the size of the AF module is steadily reduced, and plastic materials are frequently used in order to reduce the cost, so that the AF module is easily affected by changes in the temperature and humidity of the optical system.

When correction is performed by the temperature sensor as in the prior art, the error of the sensor and the temperature difference due to the difference between the layout and the position of the AF module and the temperature sensor in the camera cannot be ignored. Correction was not possible. In addition, due to the decrease in strength due to the miniaturization of the camera, it is necessary to take measures against erroneous distance measurement when a force is applied.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made to reduce the size of an entire camera using a small AF module, and to reduce the temperature, humidity, environmental change, and deformation caused by the application of force. It is an object of the present invention to provide a camera capable of obtaining a better focus by eliminating an error of the camera.

[0009]

That is, the present invention provides a first mode in which a subject can be measured by distance and a second mode in which a distance measurement calibration operation prior to ranging can be performed. Features. Further, the present invention provides a distance measuring means having a window for distance measurement at the front of the camera, and a closed position for covering the window of the distance measuring means and the taking lens exposed at the front of the camera when the camera is not used. And a barrier which is movable between an open position for exposing the window of the distance measuring means and the photographing lens when the camera is in use, and in the closed position, A light guiding means provided on the barrier so as to face the window of the distance measuring means and guiding the signal light for calibration to be incident on the light receiving section of the distance measuring means, and controlling and controlling the signal light for calibration Detecting means for detecting deformation of the distance measuring means based on an output signal of a light receiving section of the distance measuring means.

A camera according to the present invention can be modified into a first mode and a second mode, and a subject can be measured in an eleventh mode, and a distance measurement calibration prior to the distance measurement in a second mode. Enable operation.

In the camera according to the present invention, a window for distance measurement as a distance measuring means is provided at a front portion of the camera, and a barrier is provided when the camera is not used. The camera is movable between a closed position covering the window and the taking lens exposed at the front of the camera, and an open position exposing the window of the distance measuring means and the taking lens when the camera is in use. The barrier is provided with light guiding means so as to face the window of the distance measuring means when in the closed position, and the calibration signal light is transmitted to the light receiving part of the distance measuring means. Incident. Based on the control of the calibration signal light and the output signal of the light receiving section of the distance measuring means, the detecting means detects the deformation of the distance measuring means.

According to the present invention, the position of the light projected through a light emitting unit or a light guiding unit provided on a movable barrier unit provided in front of the camera can be changed by changing the shape of the distance measuring device due to an environmental change. The distance is monitored by a distance measuring device, and calibration of distance measurement is performed prior to photographing. Then, when taking a picture with the barrier open, from the above calibration (calibration) result,
The distance measurement error caused by the change in the shape of the distance measuring device is corrected, and the focusing is accurately performed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. First, as an example, a method of detecting a shift of a light receiving lens constituting a distance measuring device of a camera will be described with reference to FIG.

As shown in FIG. 2A, the light receiving lens 2 has a function of receiving light from the subject 1 and projecting the image 1b on the sensor array 3. Sensor array 3
Outputs an electric signal in accordance with the distribution of light intensity of an image. Since the sensor array 3 has sensors arranged in an array, as shown in FIG. 2B, instead of light from the subject 1, an LED (light emitting diode) is used from a predetermined position.
When an optical signal is projected by 5 or the like, the incident position x of the light can be obtained depending on which sensor the light is incident on.

Therefore, as shown in FIG. 2C, when the light receiving lens is displaced by ΔB from the position 2 to 2 ′, the shift of the light position x by Δx can be detected. Using this Δx, the light receiving lens 2
To the light receiving lenses 2, 2 'and the sensor array 3
From the distance f therebetween, the shift ΔB of the light receiving lens is obtained.
That is, ΔB = (g / g + f) Δx (1)

Next, a first embodiment of the present invention will be described. FIG. 1 is a configuration diagram showing an example of the first embodiment of the camera of the present invention. In FIG. 1, an infrared light emitting diode (IRED) 11 for active AF projects distance measuring light onto an object (subject) 10, and a current flows through a light emitting circuit 18 described later. Is emitted by The light projected from the IRED 11 is focused on the object 10 by the light projecting lens 12.

Light from the object 10 is received by the light receiving lens 1.
Sensor arrays 14a and 14b via 3a and 13b
It is led to. These light receiving lenses 13a and 13b and the sensor arrays 14a and 14b are housed in a package to form a so-called passive AF module 15.

In the passive type, each light receiving lens 13
The image signal of the object 10 is obtained by each line sensor via a and 13b, and the deviation of the image position due to the parallax is obtained by a triangulation method. In the first embodiment, in the case of active AF, the passive AF is used as a light receiving unit.
The position of the reflected signal light is obtained by using the light receiving lens 13b and the sensor array 14b.

As described above, in a distance measuring apparatus of a system capable of switching between the active AF mode and the passive AF mode, for example, the active AF is used for a subject having a low contrast, and the passive AF is used for a scene where no signal light is returned. By doing so, it is possible to measure the distance without making various scenes weak.

The CPU 17 is composed of arithmetic control means such as a one-chip microcomputer (hereinafter abbreviated as "microcomputer"). In addition, the CPU 17 controls the distance measurement methods described above, determines the distance measurement results by these methods, selects a correct result, and compares a result that is unlikely to be correct by comparing the two results. It has a determination selection unit 17a that corrects and corrects.

The CPU 17 is connected to a light emitting circuit 18 for causing the IRED 11 to emit light by passing a current through the IRED 11, and a temperature measuring unit 19 for monitoring a change in environment. In the temperature measuring section 19, calibration is performed in any scene, for example, from a low-temperature shooting at a ski resort to a high-temperature, high-humidity shooting on the coast, and a distance measurement result based on temperature and the like is performed. Is corrected so that correct focusing is achieved.

The CPU 17 has a focusing unit 20, E which is used when applied to AF or the like of a camera.
An EPROM 21, a warning unit 22, and a power switch 23 for turning on the power are provided, and these determinations and control are performed.

Further, a light projecting lens 12 and a light receiving lens 13
A barrier 25 movable in the illustrated arrow A direction is provided on the front surface of the camera body (not shown) so as to cover the front surfaces of the camera bodies 13a and 13b. The barrier 2 includes the barrier 2
A light guide path 26 is provided to face the light projecting lens 12 when the lens 5 is in the closed position, and to make the calibration signal light incident on the light receiving lenses 13a and 13b.

Next, with reference to FIG. 3, the principle of the above-described distance measurement will be described. In FIG. 3, in the case of the active AF, when the IRED 11 is projected, triangulation is performed at a distance (base line length) S between the light emitting and receiving lenses. For example, when the distance measuring the distance L _2, since the reflected signal light is incident on the position of x from the optical axis of the light receiving lens, by the incident position x is obtained from the sensor array 14b,
The distance to the object is determined. Assuming that the distance is L, the relational expression of x = S × f / L is satisfied, where f is the focal length of the light receiving lens.

On the other hand, in the case of the passive AF, based on the distance (base length) B between the light receiving lenses 13a and 13b disposed on the front surface of the two sensor arrays 14a and 14b, the distance between the distance L and x in the figure is determined. Satisfies the following relationship (2). Here, f is the focal length of the light receiving lens. x = B · f / L (2) Here, x is a relative shift amount of the image signal, and an image of the subject 11 formed on the sensor arrays 14a and 14b is a relative shift between the images 10a and 10b. It shows the amount.

When the image 10a on the light receiving lens 13a and the sensor array 14a side is on the lens optical axis, the light receiving lens 13a
b, the image 10b on the sensor array 14b side is shifted from the optical axis by x.

Here, the structural features of the passive AF will be described. The sensor arrays 14a and 14b are generally configured on the same semiconductor chip. Therefore, if the base line length B is increased, the size of the semiconductor chip is increased and the cost is increased. In the case of active AF, IR
If the light from the ED 11 directly enters the light receiving element, the reflected signal light cannot be correctly determined.

Therefore, in the active AF, it is difficult to form the lenses by using the same light transmitting / receiving lens as the same member. In the case of the passive AF, both lenses can be integrally formed of the same plastic material. As a result, it is possible to reduce the size, reduce the cost of members, and improve the accuracy of the distance between the lenses.

That is, reducing the distance between the sensor arrays 14a and 14b and reducing the distance between the light receiving lenses 13a and 13b is advantageous in terms of component mounting accuracy and cost in the case of passive AF.

However, when used in a camera or the like, the accuracy of the autofocus is not necessarily in a direction to be improved. For example, as shown in FIG. 1, if a plastic lens in which the light receiving lenses 13a and 13b are integrally formed deforms due to temperature or humidity, it immediately causes a distance measurement error. .

[0031] If, if it has become the B ₁ affected the baseline length B, even if the subject distance LH shown in the following formula (3) is ranging, the deviation amount x of the image is x ₁ and turn into. x ₁ = (B ₁ · f) / L _H (3) L _P = (B · f) / x (4) Thus, the focusing distance L _P obtained by transforming the equation (2) is obtained. When substituted into the above expression (4), the relationship of L _P = (B / B ₁ ) · L is obtained as in the following expression (5).

L _P = (B · f / B ₁ f) · L _H = (B / B ₁ ) · L _H (5) For example, if B is doubled and B ₁ = 2B, the position of x Is also doubled, x ₁ = 2x, so if focusing is performed without knowing this change, the camera uses the above equation (3) to replace the camera with a half of the actual distance by the above equation (5). The focus will be adjusted as follows.

That is, although the passive AF is suitable for miniaturization, it can be said that the AF is extremely sensitive to minute shape changes due to such environmental changes. On the other hand, such a change is relatively unlikely to occur on the active AF side according to the first embodiment having a base line length larger than B. Depending on the configuration, B may be several tens of mm for several mm. This is more advantageous because the problem of light incidence between the light emission and reception is eliminated.

In the active AF, the size does not directly affect the cost as the passive type. Therefore, even provisionally changed S within S _1, the distance measuring characteristic, as the graph shown in FIG. 4, does not become a great distance calculation as passive.

Here, L ₀ is the actual distance, and the error distance is shown as L _E1 on the active side and L _E2 on the passive side. For example, in the example described above, L that is twice as large as L obtained by the above equation (4) may be set as the focusing distance. That is, for the above equation (5),
By multiplying by B ₁ / B, the correct distance is L _P = L _H.

Therefore, when the temperature measuring section 19 shown in FIG. 1 outputs a result greatly deviating from the normal temperature, priority is given to the active AF, or by utilizing such characteristics,
The distance of the same subject using the results when the distance measurement in each mode, to previously obtain the correction coefficient B / B ₁ for correcting the passive results with the results of the active, from the next time of ranging, the correction The result of the passive AF may be corrected using the coefficient.

Although this method assumes that there is almost no error in the active AF, there is actually an error on the active side as shown in FIG. Not suitable for matching.

Therefore, as shown in FIG. 5, a barrier 25 is provided so as to hide the front lens of the camera body 27 in a state other than the photographing state. And, as mentioned above,
A light guide path 26 is provided inside the barrier 25. FIG. 5A shows a state where the barrier 25 is opened, and FIG. 5B shows a state where the barrier 25 is closed.

FIG. 6 shows the barrier 25 and the light emitting / receiving lens 1.
FIG. 2 is a diagram showing a relationship between the first and second and 13a and 13b. The photographing state, as shown in FIG. 6 (a), the barrier 25 is retracted is moved in an arrow A ₁ direction. In this state, the barrier 25 has no function. And FIG.
As shown in (b), a barrier to the arrow A ₂ direction 2
5 is moved and closed, the active light source (I
The light of the RED 11) is transmitted through the light guide path 26 to the light receiving lens 1
3a and 13b.

Assuming that the interval between the light emitting portions of the light guide path 26 is B, which is the same as the base length of the passive AF, if there is no deformation of the lens, as shown in FIG.
Light rays are incident in parallel, for example, 4
The fourth and tenth sensors 14 ₄ and 14 ₁₀ are incident.
This sensor interval x has a relationship of x = B.

That is, assuming that the distance between the fourth and tenth sensors 14 ₄ and 14 ₁₀ is x in the example in FIG. 7A, the fourth and tenth sensors 14 ₄ and 14 ₁₀ If the monitor light is incident on each of the light receiving lenses 13, it is considered that the light receiving lens 13 is not deformed as designed. At this time, the distance measurement result can be considered as designed.

However, as shown in FIG. 7B, when each of the light receiving lenses 13 is deformed by ΔB, as shown in the following equation (6), the value B ₁ after the deformation of B becomes the monitor light incident position change. It is determined from the quantity Δx.

ΔB = (g / (g + f)) · Δx B ₁ = B + 2ΔB = B + (2g / (g + f)) · Δx (6) This Δx can be detected by the sensor array 14 and there is no lens deformation. Sometimes the fourth and tenth sensors 14 ₄ , 1
4 The monitor light incident on ₁₀ is, for example, 3rd and 11th.
If the light is incident on the second sensor 14 ₃ , 14 ₁₁ , it can be determined that it is different from the design.

For example, if the pitch of the sensor array 14 is 20
In this case, assuming that Δx is 20 μm, FIG.
Distance g in, based on f, the base length B ₁ when the lens deformation is obtained by calculation. When the distance measurement from the B ignores the change of B _1, but the error, if detected beforehand B ₁ in this manner, by performing a distance measurement calculation Given this B _1, correct measurement result Can be obtained.

As described above, according to the present invention, prior to the distance measurement, the calibration function of the distance measuring device is achieved by light from inside the barrier. Next, with reference to the flowchart of FIG. 8, an operation of the camera control CPU (microcomputer) 17 in which sequence is determined and a correct distance measurement result is obtained by correction calculation will be described.

First, in step S1, the barrier 25
Is determined. Here, when the barrier 25 is in the open state, the calibration which is a feature of the present invention cannot be performed.

In this step S2, the temperature measuring unit 1
9 is performed. Next, in step S3, it is determined whether or not the temperature measurement result is normal temperature. Here, if it is determined that the temperature is normal, the process proceeds to step S8. On the other hand, if the temperature deviates from the normal temperature, the process proceeds to step S4, a warning is issued by the warning unit 22, and then the process proceeds to step S8.

By the way, room temperature is a very vague expression, and it is considered that there is a difference between room temperature in Russia with snow scenery and room temperature in Italy where lemon flowers bloom. Is based on the temperature at which the AF adjustment was performed during the production of. Therefore, even if it is manufactured in the subtropical region in southern China, normal temperature is set at 30% of the annual average temperature.
If the adjustment is performed in a factory where air conditioning is effective, the room temperature at that time is considered as a reference. This reference temperature is input to the EEPROM 21 as a memory means, and a warning is given as a result of comparing the stored contents with the temperature when the camera is used.

If the lens material is characteristic and the deformation occurs above a predetermined humidity, a humidity sensor is mounted instead of the temperature measuring section 19 having a temperature sensor to determine whether the humidity is higher or lower than the humidity. May be output as a warning.
The user may close the barrier 25 by this warning.

On the other hand, if the barrier 25 is in the closed state in step S1, the calibration can be performed, so that the process proceeds to step S5 to start the timer count.

Next, in step S6, it is determined whether a predetermined time has been counted. Here, when the counting is performed, the process proceeds to step S7, and the light emission and the light reception are performed according to the above-described principle every time a predetermined time elapses.
Δx based on the amount of lens displacement is detected by the sensor array 14. On the other hand, if the predetermined time is not counted in step S6, the process proceeds to step S8.

In step S8, the open / closed state of the barrier 25 is determined. If the barrier 25 is closed, the process proceeds to step S5. If the barrier 25 is open, the release operation of the user is determined in the following step S9. If the release operation has not been performed in step S9, the process proceeds to step S1, and the operations in steps S1 to S8 described above are repeated.

On the other hand, when the release operation is performed in step S9 and the shooting operation starts, the distance measurement is performed in step S10. Next, in steps S11 and S12,
The distance calculation is performed in consideration of the base line length deviation described above.
The focusing distance obtained at this time is set to L _P , lens control by the focusing unit 20 is performed in the following step S13, and photographing is performed in step S14.

As described above, according to the first embodiment, by merely providing the light guide path inside the barrier 25, the error of the passive AF which is sensitive to the temperature and humidity and easily shifts can be canceled, and the correct focusing can be achieved. It is possible to provide a camera that can perform the operation.

In the first embodiment described above, an example is described in which the light guide is provided in the barrier. However, it is not necessary to stick to the light guide, and the active AF light source and the auxiliary light of the camera may be used. The idea of the present invention is not limited.

That is, as shown in FIG. 9 or FIG. 10, even if a light source for calibration is provided in the barrier, the same effect can be expected as long as the reference light spot width can be secured. FIG. 9 is a configuration diagram illustrating an example in which a light source for calibration is provided in a barrier.

In FIG. 9, the light projecting element 3
1 and, in this case, a reflecting portion 29
a, 29b are formed. Then, the light from the light projecting element 31 is reflected by the reflecting portions 29a and 29b via the optical path 29, and is guided to the passive AF module 15 via the light receiving lenses 13a and 13b. This enables calibration.

FIG. 10 is a configuration diagram showing another example in which a light source for calibration is provided in the barrier. In FIG. 10, two light projecting elements 31 are provided in a barrier 25.
a and 31b are provided.
It is fixed with a metal member or the like (not shown) so that the interval between 1a and 31b does not shift. Then, monitor light was sent at the reference interval to enable calibration.

As described above, in the examples shown in FIGS. 9 and 10, the light emitting element is required in the barrier, but the light guide is not required. In the embodiment shown in FIGS. 9 and 10, the gap between the reference monitor lights is inspected by the sensor array in a state where the barrier is closed, thereby detecting the deviation of the deformation base line length of the light receiving lens. Furthermore, not only which sensor the light has entered, but also a correlation calculation used in general passive AF,
It is needless to say that the use of a technique such as interpolation calculation makes it possible to monitor a light position deviation finer than the sensor pitch.

The present invention can be applied to calibration of active AF depending on the application. FIG.
1 shows the configuration of the second embodiment of the present invention, in which (a) shows a state in which the barrier is closed, and (b) shows a state in which the barrier is opened when photographing.

As shown in FIG. 11, the distance measuring light projected from the IRED 11 through the light projecting lens 12 is reflected by a subject (not shown),
The light is detected by a light position detecting element (PSD) 14. Since the distance measurement is performed from the position x of the reflected signal light based on the principle of triangulation, calibration can be performed if it is possible to determine whether the light projecting and light receiving lenses and elements are at the correct positions.

Therefore, in the second embodiment, a sensor array 32 capable of judging the position of light projection inside the barrier 25 and a light receiving lens 13 projecting light onto the PSD 14
Light emitting element 31 for determining the relative position of the
Is provided. These are the ones whose correct positional relationship is guaranteed.

Therefore, in the second embodiment,
When the light projecting element 31 is projected when the barrier is closed and the position of the light on the PSD 14 is different from the design, it means that the positions of the light receiving lens 13 and the PSD 14 are shifted.
The same applies to the light emitting lens side, and the sensor array 3 on the barrier 25 side is used.
In 2, if no light is incident on the designed position,
It is considered that the light projecting lens 21 and the light projecting element are shifted.

If the light position monitoring function by the element inside the barrier is used, even if the plastic lens or frame is deformed due to the change in temperature and humidity in the active AF, it is detected and corrected. Since accurate AF can be achieved, correct focusing can be achieved.

Since the barrier has the function of protecting the lens, hardness is required, and the position between the elements on the inner surface of the barrier becomes accurate. That is, the function originally possessed by the barrier is the same as the function intended by the present invention, and a reasonable design is possible.

Even if the barrier is deformed and g or the like shown in FIG. 7 is changed, as shown in FIG. 12, three light projecting portions (31a, 31b, 31c) are used, and B
If it even so as not to change _LED, the difference B _SPOT the incident position of the B _LED apart light, since the _{B SPOT = (f / g)} · B LED relationships, g from B _LED is g = ( B _LED / B _SPOT ) · f. If this g is used in the above equation (6), even if the barrier is deformed, it is possible to cancel the deviation of the base line length and perform correct focusing.

In order to monitor the deformation of f, FIG.
The method as shown in FIG. That is, the _LED 311 of the light emitting diameter φ _LED is disposed at a position away from the light receiving lens 13 by g and g + d, respectively, on the barrier side. This d
Is attached by adopting a fixing method such as applying a screw to a metal so as not to be changed by deformation. Two L
If ED of phi _LED are the same, the difference between the d changes the light spot diameter phi _SPOT for imaging on the sensor array. Here, one LED 31 ₁ is φ _SPOT1 and the other LE 31
_{D3 12} is φ _SPOT2 .

At this time, the relationship between φ _LED and φ _SPOT1 and φ _SPOT is as shown in the following equations (7) and (8). If g is canceled out by simultaneous equations, f becomes φ _SPOT1 and φ _SPOT1 .
It can be obtained from the change in _SPOT2 . φ _SPOT1 = (f / g) · φ _LED φ _SPOT2 = (f / (d + g)) · φ _LED (7) g = (φ _LED / φ _SPOT1 ) · f = (f / (d + (φ _LED / φ _SPOT1))) · _{φ LED Thus, f = (φ sPOT2 / φ} LED) · (d + (φ LED / φ SPOT1)) ... (8) in FIG. 12, as in the case where g is determined, the f Changes can also be detected by the method shown in FIG. 13, and if the distance measurement is performed using the obtained f, even if the AF optical system is different from the design value due to deformation or the like, the barrier may be changed each time. Calibration is possible simply by closing the button, and accurate ranging can be performed.

As described above, according to the second embodiment, it is possible to cope with a case where not only the base line length but also the focal length and the distance between the barrier and the AF are changed. In the above-described embodiment, the member covering the lens of the camera is collectively referred to as a barrier. However, instead of the sliding type as shown in FIG. 5, a system with an opening / closing lid 34 as shown in FIG. Needless to say, this is possible.

According to the above embodiment of the present invention,
The following configuration can be obtained. (1) A distance measuring device having a distance measuring window at the front of the camera, an open position exposing a front surface of the photographing lens and the distance measuring window, a front surface of the photographing lens, and the distance measuring device. In a camera having a barrier that moves between a closed position that covers a window portion, when in the open position, the distance can be measured by the distance measuring device, and when in the closed position, A camera capable of calibrating a distance measuring device.

(2) In the camera described in (1) above, the camera is provided on the barrier so as to face a window of the distance measuring means when the camera is at the closed position, and A camera having light guide means for guiding calibration signal light to enter a light receiving unit.

(3) A distance-measuring device having a window for distance measurement at the front of the camera, and a cover for covering the window of the distance-measuring means and the photographing lens exposed to the front of the camera when the camera is not used. In the camera having a position and a barrier movable between an open position for exposing the window portion of the distance measuring means and the photographing lens when the camera is in use, when the camera is in the closed position, Light guide means provided on the barrier so as to face the window of the distance measuring means, and guiding the signal light for calibration to enter the light receiving portion of the distance measuring means; and controlling the signal light for calibration. And a detecting means for detecting deformation of the distance measuring means based on an output signal of a light receiving section of the distance measuring means.

(4) In the camera described in the above (3), the light guide means of the barrier is a light source for a distance measuring auxiliary light or a light source for displaying a self-timer operation disposed on a front surface of the camera. A camera configured to guide emitted light to the light receiving unit.

[0074]

As described above, according to the present invention,
It is possible to provide a small-sized AF camera that can accurately correct an error due to a change in environment or pressure of a small-sized AF module and can perform focusing with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a first embodiment of a camera of the present invention.

FIG. 2 is a diagram for explaining a method of detecting a shift of a light receiving lens included in a distance measuring device of a camera.

FIG. 3 is a diagram for explaining the principle of distance measurement by the active AF and the passive AF method.

FIG. 4 is a graph of a distance measurement characteristic showing a relationship between an actual 1 / L and a calculated 1 / L.

5A is an external view of the camera with the barrier 25 opened, and FIG. 5B is an external view of the camera with the barrier 25 closed.

6A is a diagram illustrating an optical path of distance measuring light with a barrier 25 opened, and FIG. 6B is a diagram illustrating an optical path of distance measuring light with a barrier 25 closed. is there.

7A is a diagram illustrating a state of light incident on the sensor array 14 when the lens is not deformed, and FIG. 7B is a diagram illustrating a state of light incident on the sensor array 14 when the lens is deformed. FIG.

FIG. 8 is a diagram for explaining the operation of the first embodiment of the present invention, in which sequence is determined by a camera control CPU (microcomputer) 17 and a correct distance measurement result is obtained by a correction operation. 5 is a flowchart for explaining the operation of FIG.

FIG. 9 is a configuration diagram illustrating an example in which a light source for calibration is provided in a barrier.

FIG. 10 is a configuration diagram showing another example in which a light source for calibration is provided in a barrier.

11A and 11B show a configuration of a second embodiment of the present invention, in which FIG. 11A shows a state in which a barrier is closed, and FIG.
FIG. 5 is a diagram showing a state at the time of shooting with a barrier opened.

FIG. 12 is a diagram showing an example of a modification of the second embodiment in which three light projecting units are configured.

FIG. 13 shows a further modification of the second embodiment,
FIG. 9 is a diagram showing an example of a case where a configuration for monitoring the deformation of f in FIG.

FIG. 14 is an external view of a camera showing an example in which an opening / closing lid is used instead of a barrier.

[Explanation of symbols]

 1 subject, 2, 13a, 13b light receiving lens, 3 sensor array, 5 LED (light emitting diode), 10 object (subject), 11 infrared light emitting diode (IRED), 12 light projecting lens, 14, 14a, 14b sensor array , 15 passive AF module, 17 CPU, 17a judgment selection section, 18 light emitting circuit, 19 temperature measuring section, 20 focusing section, 21 EEPROM, 22 warning section, 23 power switch, 25 barrier, 26 light guide path.

Continued on the front page F term (reference) 2H011 AA01 BA05 BA06 BA14 BB00 DA00 DA08 2H051 AA02 BB07 BB10 CA04 CA12 CB20 CC03 CD21 CD22 CD30 EB19 EB20 GB16 GB19 2H083 CC03 CC21 CC61 5J084 AA03 AA05 AB07 AD07 BA02 BA38 DA01

Claims (3)

[Claims] 1. A first mode in which a subject can be measured for distance,
A camera capable of being displaced into a second mode enabling a distance measurement calibration operation prior to a distance measurement. 2. A distance-measuring means having a distance-measuring window at a front portion of a camera, and a closed position for covering a window portion of the distance-measuring means and a photographing lens exposed at a front portion of the camera when the camera is not used. And a barrier which is movable between an open position for exposing the window of the distance measuring means and the photographing lens in a camera use state, wherein the camera is in the closed position. A light guide means provided on the barrier so as to face the window of the distance measuring means, and guiding the calibration signal light to enter the light receiving portion of the distance measuring means; and A camera for detecting deformation of the distance measuring means based on an output signal of a light receiving section of the distance measuring means. 3. The method according to claim 1, further comprising controlling the calibration signal light at the barrier closed position and outputting a signal from the light receiving unit to measure the distance at the time of shooting at the barrier open position. The camera according to claim 2, further comprising a correction unit configured to correct a distance measurement error.