JP3310079B2 - Camera 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 distance measuring apparatus which has two distance measuring units for measuring the distance to a subject and can accurately measure the distance to the subject.

[0002]

2. Description of the Related Art In general, there are an active distance measuring method and a passive distance measuring method as methods for measuring the distance to a subject in a camera.

In the active distance measuring method, light is emitted from a light projecting unit having a light emitting element such as an LED through a light projecting lens toward a subject, and the light reflected by the subject is transmitted through a light receiving lens to a PSD provided in the light receiving unit. The light is received by a light receiving element such as. In PSD, the reflected light from the subject is PS
An electric signal is output according to the position on the D light receiving surface. Therefore, based on this output, the position of the reflected light on the PSD light receiving surface can be known, and further, the angle at which the reflected light enters the light receiving unit can be known. Then, based on the incident angle and the distance between the light projecting lens and the light receiving lens,
The distance to the subject is measured based on the so-called triangulation principle.

On the other hand, in the passive distance measuring method, natural light reflected by a subject is received by two light receiving units provided. The light receiving section includes a light receiving element such as a CCD and a light receiving lens disposed in front of the light receiving element. The CCD is a pixel-type light receiving element having a plurality of pixels that output a single analog signal, and the output of the CCD is an array of a plurality of analog signals. Based on the phase difference between the two analog signal arrays output from the two CCDs,
The difference between the angles at which the reflected light enters the two light receiving units can be known. Then, based on the angle difference and the distance between the two light receiving lenses, the distance to the subject is measured by the so-called triangulation principle.

A method of obtaining a distance to a subject based on a phase difference is well known.
No. 311.

[0006]

In both the active distance measurement method and the passive distance measurement method, the distance to the subject is measured based on the distance between the two lenses. Will cause a ranging error. Fluctuations in the lens spacing are caused by temperature fluctuations and the like, and when the temperature becomes much higher or lower than room temperature, the fluctuation in the lens spacing becomes larger. Further, since the distance measurement error depends on the magnitude of the variation with respect to the original lens distance, it can be said that a distance measuring unit having a large lens distance is more resistant to temperature fluctuation.

On the other hand, when comparing the active distance measuring section with the passive distance measuring section, the lens distance of the active distance measuring section is often larger. In such a case, the active distance measurement unit is more resistant to temperature fluctuations, and the distance measurement error when the temperature becomes high or low is reduced.

[0008] In addition to the lens interval, a distance measurement error also occurs when the interval between the light receiving lens and the light receiving element or the focal length of the light receiving lens fluctuates with temperature. For the same reason as described above, a distance measuring section having a larger distance between the light receiving lens and the light receiving element and a larger focal length of the light receiving lens is more resistant to temperature fluctuation.

An object of the present invention is to reduce the distance to a subject by using the distance measurement value of the distance measurement unit that is more resistant to temperature fluctuation when the temperature becomes extremely high or low than normal temperature. It is an object of the present invention to provide a camera distance measuring device capable of measuring accurately.

[0010]

In order to achieve the above object, the invention according to claim 1 provides a light projecting lens or a light from a subject acting on the light to project the light to the subject. A first lens which is one of a light receiving lens acting on the light to receive the light, and a first distance measuring unit having a second lens acting on the light to receive the light from the subject; A third lens, which is one of a light projecting lens acting on the light to project light to the subject or a light receiving lens acting on the light to receive light from the subject, and the subject A fourth lens that acts on the light to receive light from the second lens and the distance between the third lens and the fourth lens is smaller than the distance between the first lens and the second lens. Distance measuring unit and temperature measurement device for measuring camera temperature It is determined that the temperature of the camera is lower than the first predetermined temperature or higher than the second predetermined temperature which is higher than the first predetermined temperature based on the output of the temperature measurement device. A selection device for selecting an output of the first distance measuring unit as a distance measurement value used in photographing.

According to a second aspect of the present invention, a first light receiving lens for collecting light from a subject and a first light receiving element for detecting light collected by the first light receiving lens are provided. A second light receiving lens, comprising: a first distance measuring unit; a second light receiving lens for collecting light from the subject; and a second light receiving element for detecting light collected by the second light receiving lens. And the distance between the second light receiving element and the first light receiving lens
A second distance measuring unit smaller than the distance between the light receiving elements, a temperature measuring device for measuring the temperature of the camera, and whether the temperature of the camera is lower than the first predetermined temperature based on the output of the temperature measuring device. Or a second temperature which is higher than the first predetermined temperature.
And a selecting device for selecting an output of the first distance measuring unit as a distance measurement value used in photographing when it is determined that the temperature is higher than the predetermined temperature.

Further, according to a third aspect of the present invention, there is provided a first distance measuring section having a first light receiving lens for condensing light from a subject, and a second light receiving lens for condensing light from the subject. A second distance measuring unit having a focal length of the second light receiving lens smaller than a focal length of the first light receiving lens, a temperature measuring device for measuring a temperature of the camera, and an output of the temperature measuring device. When it is determined that the temperature of the camera is lower than the first predetermined temperature or higher than a second predetermined temperature that is higher than the first predetermined temperature, A selection device for selecting an output as a distance measurement value used in photographing.

[0013]

In the present invention, the temperature of the camera is measured by the temperature measuring device, and it is determined by the selecting device whether the temperature is lower than the first predetermined temperature or higher than the second predetermined temperature. If so, the distance measured by the distance measuring unit with the larger lens interval or the like is selected as the shooting distance. Otherwise, the distance measured by the distance measuring unit with the smaller lens distance or the like is selected as the shooting distance.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same or corresponding parts have the same reference characters allotted.

FIG. 1 is a block diagram showing a distance measuring device for a camera constructed according to the present invention. Each component is built in the camera, and the arrows indicate the signal transmission direction. FIG. 2 is a diagram showing the entire camera.

First, an active distance measuring section as a first distance measuring section includes a light projecting section 1, a light receiving section 2, and a distance measuring operation circuit 3. FIG. 3A is a plan view of the light projecting unit 1 and the light receiving unit 2, and FIG. 3B is a front view showing a part of the sectional view. An LED 4 as a light emitting element is arranged in the light projecting unit 1, and light emitted from the LED 4 is projected on a subject (not shown) through a light projecting lens 5 arranged on the front surface of the light projecting unit 1. You. The light reflected by the subject reaches the light receiving lens 6 arranged on the front surface of the light receiving unit 2 and condenses on a light receiving surface of a PSD 7 which is a light receiving element arranged in the light receiving unit 2. The light condensing position on the PSD 7 varies depending on the angle at which the reflected light from the subject enters the light receiving unit 2, and the PSD 7 outputs a signal corresponding to this light condensing position. Therefore, PSD
7 and the distance d1 between the light projecting lens 5 and the light receiving lens 6
(See FIG. 3A), the distance to the subject can be measured based on the so-called triangulation principle. It is the distance measurement arithmetic circuit 3 that converts the output signal of the PSD 7 into the distance to the subject.

The passive distance measuring section as a second distance measuring section is composed of a right light receiving section 8, a left light receiving section 9, and a distance measuring operation circuit 10. FIG. 4A is a plan view of the right light receiving unit 8 and the left light receiving unit 9, and FIG. 4B is a front view showing a part of the cross section. Natural light reflected by the subject and the background reaches the light receiving lenses 10 and 11 disposed in front of the right light receiving unit 8 and the left light receiving unit 9, respectively. Focus on top. CCD12,
13 is a pixel type light receiving element for outputting a plurality of signals,
The outputs of the CCDs 12, 13 are an ordered collection or array of a plurality of analog signals. In FIG. 4B, the stripe patterns shown on the CCDs 12 and 13 indicate each pixel. The CCD 12 receives and detects reflected light coming from the subject at a certain incident angle.
Receives reflected light coming from the same subject at an incident angle slightly different from the incident angle. This difference in the incident angles is due to the fact that the mounting positions of the CCD 12 and the CCD 13 differ by the distance d2 (the distance between the center lines) shown in FIG. Therefore, CCD
The arrangement of the output signals of the CCD 12 and the CCD 13 has a phase difference corresponding to the difference between the incident angles. This phase difference and the interval d2
By calculating the difference between the incident angles by the distance measurement arithmetic circuit 10 based on the above, the distance to the subject can be measured based on the principle of triangulation.

Here, the lens distance d of the active distance measuring unit
1 is larger than the lens distance d2 of the passive distance measuring unit.

The camera is provided with a temperature measuring device 14 for measuring the temperature of the camera itself or the temperature around the camera.

The distance measurement value selection circuit 15 includes a temperature measurement device 14.
If the temperature is extremely higher or lower than the normal temperature based on the output signal of, for example, the temperature is equal to or lower than the first predetermined temperature (0 ° C.) or equal to or higher than the second predetermined temperature (35 ° C.) If it is determined that the distance is determined, the output of the active distance measuring unit is selected as a distance measurement value used in photographing. If the temperature is between the first predetermined temperature and the second predetermined temperature, The output of the passive ranging unit is selected as the ranging value.

The reason why the output of the active distance measuring section is used when the temperature is much higher or lower than room temperature is as follows. In other words, in both the active distance measuring unit and the passive distance measuring unit, the distance to the subject is measured based on the distance between the two lenses. become. The fluctuation of the lens interval is caused by the temperature fluctuation, and when the temperature becomes much higher or lower than the normal temperature, the fluctuation of the lens interval becomes large. Also, since the distance measurement error depends on the magnitude of the relative variation with respect to the lens interval, even if the variation is the same, when the lens interval is large, the relative magnitude of the variation with respect to this becomes small and measurement is performed. On the contrary, when the distance between the lenses is small, the relative amount of the fluctuation amount becomes large, and the distance measurement error becomes large. Therefore, the active distance measurement unit having a large lens distance has a smaller distance measurement error at high or low temperatures.

Next, the operation of the camera distance measuring apparatus according to the present invention will be described with reference to FIG. First, when a release switch (not shown) is turned on (step S1), the temperature of the camera is measured by the temperature measuring device 14 (step S2). Next, the distance value selection circuit 15
Determines whether the temperature is equal to or lower than 0 ° C. based on the output of the temperature measuring device 14 (step S3). If so, active distance measurement is performed in accordance with a command from the distance measurement value selection circuit 15 (step S4). Otherwise, it is determined whether the temperature is 35 ° C. or higher (step S4).
5). If so, the process proceeds to step S4 described above. Otherwise, passive ranging is performed in accordance with a command from the ranging value selection circuit 15 (step S6). Therefore, if the temperature is 0 °
If the temperature is between C and 35 ° C., passive distance measurement is performed. If the distance is outside this range, active distance measurement is performed.

Subsequently, step S4 or step S6
The photographing distance of the photographing lens is set based on the distance measurement value obtained in step (step S7), and then the photographing process is performed (step S8).

Here, it is assumed that the first distance measuring unit is an active distance measuring unit and the second distance measuring unit is a passive distance measuring unit. However, the lens distance of the first distance measuring unit is larger. If the distance between the lenses is larger than the lens distance of the second distance measuring unit, both the first distance measuring unit and the second distance measuring unit may be active distance measuring units, or the first distance measuring unit and the second distance measuring unit may be the same. Both the two distance measuring units may be passive distance measuring units, or the first distance measuring unit may be a passive distance measuring unit and the second distance measuring unit may be an active distance measuring unit.

In the above description, the lens interval d1,
Although d2 has been discussed, a similar problem occurs with respect to the distance d3 shown in FIG. 6, that is, the distance d3 between the light receiving lens 6 and the light receiving surface 16 of the light receiving element 7. That is, if the distance d3 between the light receiving lens 6 and the light receiving surface 16 fluctuates in accordance with the temperature fluctuation, a distance measurement error occurs. However, the distance measurement error decreases as the distance d3 increases. Therefore, when the temperature of the camera is much higher or lower than room temperature, if a distance measuring unit having a large distance between the light receiving lens and the light receiving surface is used, a distance measuring error due to a temperature fluctuation can be reduced.

The distance d3 shown in FIG. 6 coincides with the focal length of the light receiving lens 6. However, if the light receiving lens 6 is deformed due to a temperature change, the image on the light receiving surface 16 is blurred, so that a distance measurement error occurs. Will occur. Therefore, as in the case of the distance between the lenses and the distance between the light receiving lens and the light receiving surface, when the temperature of the camera is much higher or lower than room temperature, a distance measuring unit using a light receiving lens having a long focal length may be used. If this is the case, it is possible to reduce the distance measurement error due to temperature fluctuation.

[0027]

As described above, according to the present invention, the first distance measuring section, the second distance measuring section having a lens distance smaller than the lens distance of the first distance measuring section, A temperature measuring device for measuring the temperature, and a temperature of the camera is lower than a first predetermined temperature or higher than a second predetermined temperature that is higher than the first predetermined temperature, based on an output of the temperature measuring device. A selection device for selecting the output of the first distance measurement unit as a distance measurement value used in photographing when it is determined that the temperature is high, so that even if the temperature is much higher or lower than room temperature, Thus, it is possible to obtain a camera distance measuring device capable of accurately measuring the distance to the subject.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a camera distance measuring device configured according to the present invention.

FIG. 2 is a diagram showing the entire camera.

FIG. 3A is a plan view showing a configuration of a light projecting unit and a light receiving unit of an active distance measuring unit, and FIG. 3B is a front view showing a part of the same in cross section.

FIG. 4A is a plan view showing a configuration of a right light receiving unit and a left light receiving unit of a passive distance measuring unit, and FIG. 4B is a front view showing a part of the same in cross section.

FIG. 5 is a flowchart showing the operation of the present invention.

FIG. 6 is a diagram illustrating a distance between a light receiving lens and a light receiving element, and a focal length of the light receiving lens.

[Explanation of symbols]

5: light projecting lens, 6: light receiving lens, 7: PSD, 10,
11: light receiving lens, 12, 13: CCD, 15: distance measurement value selection circuit, d1, d2: lens interval, d3: light receiving lens / light receiving element interval (focal length).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B ^7/ 28-7/40 G03B 13/36

Claims (4)

(57) [Claims] 1. A first lens, which is one of a light projecting lens that acts on light to project light to a subject and a light receiving lens that acts on the light to receive light from the subject. A first distance measuring section having a lens and a second lens acting on the light to receive light from the subject; and acting on the light to project light onto the subject. A third lens which is one of a light projecting lens or a light receiving lens acting on the light to receive light from the subject;
And a fourth lens acting on the light to receive light from the subject, wherein the distance between the third lens and the fourth lens is equal to the distance between the first lens and the second lens. A second distance measuring unit that is smaller than the distance between the lenses, a temperature measuring device that measures the temperature of the camera, and a temperature of the camera that is lower than a first predetermined temperature based on an output of the temperature measuring device. Alternatively, when it is determined that the temperature is higher than the second predetermined temperature, which is higher than the first predetermined temperature, the output of the first distance measuring unit is selected as a distance measurement value to be used in photographing. And a selection device for the camera. 2. A first distance measuring section having a first light receiving lens for condensing light from a subject, and a first light receiving element for detecting light condensed by the first light receiving lens; A second light receiving lens that collects light from the subject, and a second light receiving element that detects light collected by the second light receiving lens, wherein the second light receiving lens and the second light receiving element A second distance measuring unit in which the distance between the light receiving elements is smaller than the distance between the first light receiving lens and the first light receiving element; a temperature measuring device that measures the temperature of the camera; When it is determined that the temperature of the camera is lower than a first predetermined temperature or higher than a second predetermined temperature that is higher than the first predetermined temperature, To select the output of the ranging unit as the ranging value to be used for shooting. And a distance measuring device for a camera comprising the selecting device. 3. A first distance measuring unit having a first light receiving lens for condensing light from a subject, and a second light receiving lens for condensing light from the subject, wherein the second light receiving lens has a second light receiving lens. A second distance measuring unit in which the focal length of the light receiving lens is shorter than the focal length of the first light receiving lens; a temperature measuring device for measuring the temperature of the camera; When it is determined that the temperature is lower than the first predetermined temperature or higher than a second predetermined temperature that is higher than the first predetermined temperature, the output of the first distance measuring unit is determined. And a selecting device for selecting a distance value to be used in photographing. 4. A camera distance measuring apparatus according to claim 1, wherein said first distance measuring section is of an active type, and said second distance measuring section is of a passive type.