JPH01222235A - Camera - Google Patents

Abstract

PURPOSE:To perform accurate range-finding even to an object in which luminance difference is large by symmetrically providing light receiving means one by one on both sides of a light projecting means provided on a line which passes the center of the photographic lens of a camera. CONSTITUTION:The light projecting means is provided on the line which passes the center of the photographic lens 2 of the camera and the light receiving means are symmetrically provided one by one on both sides of the light projecting means. Namely, PSDs (Position Sensing Device) 17 and 19 for receiving infrared reflected light are disposed on the rear side of condensing lenses 14 and 16 as the light receiving means and a diode 18 for emitting infrared light is disposed on the rear side of the condensing lens 15 as the light projecting means. When the positions of the PSDs 17 and 19 to the light emission diode 18 are accurately adjusted, output currents from the PSDs 17 and 19 are canceled each other and the erroneous detection of an object distance caused by the luminance difference is evaded even if the luminance of the object is partially extremely different. Thus, erroneous range-finding is not caused and accurate range-finding can be performed.

Description

[Detailed description of the invention] (Application field of Masatojo) The present invention relates to a trinocular distance measuring camera.

(Prior Art) Autofocus cameras have become popular in recent years. An autofocus camera is a camera that measures the distance to the subject and automatically moves the photographic lens according to the measured distance, eliminating the need for the photographer to manually focus. However, there are various distance measurement methods known for this type of camera, including the aqua-passive method. ≠φ The Titz method emits infrared light from the camera toward the subject, and the infrared light reflected from the subject is converted into PSD (Po5ition Sensing D).
This is a distance measurement method that measures the distance to the subject using the principle of triangulation from the output current of light received by a light-receiving element called ``device''.Passive type measures the distance to the subject without emitting light from the camera toward the subject. This is a distance measurement method in which two different subject images are formed using light from the camera, and the distance to the subject is measured using the principle of triangulation based on the deviation of the images.

There are two types of passive methods: the TTL method, which measures distance through the photographic lens, and the external light method, which measures distance without using the photographic lens.
Considering the fact that the device is relatively simple and it is easy to add an auxiliary flashing means to improve distance measurement performance in low brightness, lens-shutter cameras are equipped with the external light passive method and the above-mentioned active method. Eve method is commonly used.

All of these methods are so-called twin-lens systems that emit light toward the subject or receive light from the subject through two windows placed a certain distance apart in front of the camera, and are based on a concept that emphasizes the brightness of the subject. The distance is measured based on the following.

However, some parts of the subject may be exposed to strong light and the brightness of that part is extremely high.5 On the other hand, some parts of the subject may have extremely low brightness, or two dark objects may be in front of a white wall. There are cases where there are two areas with markedly different brightness adjacent to each other, such as when two parts are located slightly apart from each other, but when such objects are measured using the twin-lens distance measuring method that emphasizes brightness as described above, Since the light-receiving element outputs an output in response to brightness, the center of the subject image detected by the light-receiving element based on the brightness may deviate from the center of the actual subject, making accurate distance measurement impossible.

(Objects and Structure of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to enable accurate distance measurement even for objects with large differences in brightness. A light projecting means was provided on a straight line passing through the center of the photographing lens of the camera, and one light receiving means was provided symmetrically on each side of the light projecting means to constitute a trinocular distance measuring device.

(Example) The present invention will be explained below based on the drawings.

FIG. 1 shows a front view of an embodiment of a camera according to the invention.

A photographic lens 2 is installed in the front center of the camera body l,
Above this, a finder light window 3, a finder light receiving window 4, and a strobe light emitting window 5 are provided side by side, and a release button 6 is provided on the top surface of the main body. 7 is the part of the camera body l that bulges out at the front, and this is where the battery is housed. Other components provided on the camera body l, such as a film counter and a self-timer operation button, are omitted.

Next to the photographing lens 2 (on the right side in the figure), three windows 8, 9, 10 of a three-limit rangefinder are arranged vertically in a row, and each window has a resin cover 11°, 12, 13 is fitted, and a condensing lens is placed behind it. Among these three windows, window 9 is a window for emitting infrared light, the other two windows 8 and 1O are windows for receiving infrared reflected light, and window 8 is for receiving infrared reflected light. and lO are arranged symmetrically around the window 9 for infrared light emission.

Figure 2 shows the internal configuration of the three-limit rangefinder.

In the trinocular distance measuring device, condensing lenses 14, 15, and 16, which are also made of resin, are fitted behind the m-fat covers 11, 12, and 13; PSDs 17 and 19 for receiving infrared reflected light, and a diode 1 for emitting infrared light behind the condensing lens 15.
8 are arranged. PSDl7, 19 and diode 1
8 is screwed to one mounting plate 20, as shown in exploded view in FIG.
It is fixed to the mounting plate 20 with screws 23 and 24 via protrusions 21a and 22a provided on parts of and 22. At this time,
Connection terminals of the PSDs 17 and 19 and the diode 18 extend through long holes 20a and 20b formed in the mounting plate 2o.

After these light-emitting elements and light-receiving elements are attached to the mounting plate 20, the whole is fixed to a predetermined portion of the camera body l.

After installation, turn screw 23.24 to set PSD17.1.
Since the holding frames 21 and 22 of 9 can be moved vertically (in the longitudinal direction of the screws), the positions of the PSDs 17 and 19 relative to the diode 18 can be finely adjusted. For this adjustment, a reference reflector is provided at a certain distance in front of the camera, and the infrared light generated by the diode 18 is reflected by the reference reflector, and the reflected light passes through the condenser lens 14.16 and passes through the PSD17.
．． When the light is received by PSDl 7.19, which will be described later.
19 output currents and Il, I2 and Il', I2'
PSD 17 so that each voltage output corresponding to
．． Adjust the position of 19 using screws 23 and 24. In this embodiment, since the PSD17.19 and the diode 18 are arranged vertically in a line, the position adjustment of the elements is simple and requires adjustment only in the vertical direction.

FIG. 4 is a Turok diagram of the electric circuit of the trinocular distance measuring device, in which the same reference numerals as in FIG. 2 indicate the same components.

The infrared light emitting diode 18 is driven by the light emitting circuit 25 and emits infrared light toward the subject 26 . Infrared light reflected from the subject 26 is received by the PSDs 17 and 19,
There are two currents from PSD17 and 19 depending on the position where the reflected infrared light hits! , and 12 and ■1° and 1,
1 outputs.

Outputs I and I2 from PSD17 and output currents 11° and qI2° from PSD19 are added together (
) 1 + x so) and (■ deficiency + I2°) are applied to the current-voltage conversion circuits 28a and 28b and converted into a voltage value. Current-voltage conversion circuit 28a.

The voltage output from 28b is amplified by amplifier circuits 29a and 29b, then logarithmically compressed by logarithmic compression circuits 30a and 30b, and then a differential voltage is obtained by differential amplifier circuit 31. The output S of the sample hold circuit 32 is as follows.

Here, G is the gain (constant) of the entire arithmetic circuit, and E2 is the reference voltage.

As explained above, when the output currents of PSDs 17 and 19 are connected to add, the brightness of the object will be partially extreme if the position of PSDs 17 and 19 relative to the light emitting diode 18 is adjusted accurately. Even if they are different,
The output currents of PSDI 7' and PSDI 19 cancel each other out, and erroneous detection of object distance due to a difference in brightness is eliminated.

5" and 6 show an embodiment in which the three windows of the trinocular distance measuring device are arranged in a positional relationship different from that in FIG. 1, and the same reference numerals in each figure indicate the same components.

In the embodiment shown in FIG. 5, three windows 8, 9 and 10 are arranged in a straight line at a slight angle from the vertical.

In this example as well, since the array is in a straight line, the PSD
is easy to adjust.

The embodiment of FIG. 6 has two windows 8 and 1 for a central window 9.
Three windows are arranged with O slightly shifted from the center of the camera. In this embodiment, since it is necessary to adjust the PSD in the horizontal and vertical directions, it takes a little more effort than the above two embodiments.

The internal structure of the distance measuring device in both the embodiments shown in FIGS. 5 and 6 is the same as that shown in FIGS. 2 and 3.

(Effects of the Invention) As explained above, in the present invention, the light projecting means is provided on a straight line passing through the center of the photographing lens of the camera, and one light receiving means is provided on each side of the light projecting means. Because it constituted a seven-trinocular distance measuring device.

Accurate distance measurement is possible without any erroneous distance measurement by the twin-lens distance measurement device even for subjects whose brightness differs significantly in parts.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of a trinocular distance measuring camera according to the present invention, Fig. 2 is a sectional view of the trinocular distance measuring device, and Fig. 3 is an exploded perspective view of the trinocular distance measuring device. 4 is an electric circuit of a trinocular distance measuring device, and FIGS. 5 and 6 are front views of two other different embodiments of a trinocular distance measuring camera according to the present invention. l...Camera body, 2...Photographing lens, 3...Light receiving window for finder, 4...Light receiving window for finder, 5...
... Strobe light emitting window, 6... Release button, 8, 9
゜lO...Window, 11N13...Resin cover, 14 to 16...Condensing lens, 17.19-PSD, 1 B-
・・Light emitting diode, 20−・・Mounting frame

Claims (2)

[Claims] (1) A trinocular distance measuring camera characterized in that a light projecting means is provided on a straight line passing through the center of the photographic lens, and light receiving means are arranged symmetrically on each side of the light projecting means. (2) The camera according to claim 1, wherein the light projecting means and the two light receiving means are arranged in a straight line.