JP3164636B2 - Viewfinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder provided in, for example, a single-lens reflex camera or the like for visually recognizing a subject image. About the finder.

[0002]

2. Description of the Related Art A viewfinder provided with a visual line detection device is:
For example, it is disclosed in JP-A-2-5.

The gaze detection device disclosed in this publication is provided around a pentaprism of a single-lens reflex camera, and converts a light beam emitted from a light source such as a light emitting diode to a photographer's eye as a parallel light beam through an eyepiece of a viewfinder. The light is made incident, the light reflected from the eyes is collected, received by a light receiving element such as a CCD sensor, and the output from the light receiving element is processed electrically to detect the direction of the line of sight.

[0004] By the way, general single-lens reflex cameras include:
It has a diopter adjustment mechanism that moves a part of the lens system that constitutes the finder in the optical axis direction so that the diopter of the finder can be changed according to the visual acuity.

[0005]

However, since the above-mentioned conventional finder is not designed in consideration of diopter adjustment, for example, an eyepiece lens closest to the eye is adjusted in the optical axis direction for diopter adjustment. When moved, the parallelism of the luminous flux incident on the eye changes, and the optical positional relationship between the eye and the light receiving element of the eye gaze detection device changes, making it impossible to detect the gaze under certain conditions. Occurs.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has been made even when a part of an optical element constituting the finder is moved to adjust the diopter of the finder. It is an object of the present invention to provide a finder that can suppress a change that this adjustment gives to gaze detection and can detect a gaze direction under certain conditions regardless of the adjusted diopter.

[0007]

In order to achieve the above object, a finder according to the present invention comprises: a light projecting optical system for making measurement light incident on an eye through a part of the finder; A light receiving optical system that receives light and detects the direction of the line of sight, and moves at least a part of a lens constituting a viewfinder in the optical axis direction while maintaining a state in which light for measurement is incident on the eye as a parallel light beam. And a diopter adjustment mechanism.

[0008]

Embodiments of the present invention will be described below.

[0009]

FIG. 1 shows an optical system of a finder according to a first embodiment. Here, a single-lens reflex camera incorporating a visual line detection device will be described as an example.

The finder according to the first embodiment includes a pentaprism 1, an eyepiece lens 2 composed of a negative lens 2a and a positive lens 2b, a dichroic prism 40, and an optical path separated from an optical path of subject light by the dichroic prism 40. An eye-gaze detecting device including a light projecting optical system 10 and a light receiving optical system 20 is provided.

The light projecting optical system 10 has a semiconductor laser 11 that emits infrared light as a light source. Semiconductor laser 11
Are arranged such that the laser beam is incident on the polarization beam splitter 30 as P-polarized light. The measurement light beam emitted from the semiconductor laser 11 passes through the polarization beam splitter 30, is converted into circularly polarized light by the 波長 wavelength plate 31, and enters the dichroic prism 40.

Separation surface 41 of dichroic prism 40
Has the property of reflecting infrared light and transmitting visible light. Therefore, the measuring light beam from the light projecting optical system is reflected by the separation surface 41 and enters the photographer's eye 3 as a parallel light beam.

The laser light reflected by the photographer's eye 3 is
At the time of incidence, the direction of rotation of the electric field vector becomes circularly polarized light in the opposite direction, is reflected again by the separation surface 41 of the dichroic prism 40, and is converted by the quarter-wave plate 31 into linearly polarized light that becomes S-polarized light with respect to the polarization beam splitter 30. You. Therefore, the reflected laser light is reflected by the polarization beam splitter 30.
And forms an image on the CCD line sensor 22 via the re-imaging lens 21.

Since the principle of gaze detection is described in the publications and the like cited in the prior art, the details are omitted here.
For example, the direction of the line of sight is detected based on the positional relationship between the first Purkinje image formed by the reflected light from the eye and the center of the pupil image.

On the other hand, a visible light beam which is reflected by a quick return mirror 4 via a photographic lens (not shown) and forms an object image on a focusing screen 5 is condensed by a condenser lens 6 and erected by a pentaprism 1. After being formed into an image, the light passes through the dichroic prism 40 via the eyepiece lens 2 and reaches the eye 3 of the photographer.

The positive lens 2b of the eyepiece lens 2 can be adjusted in the direction of the optical axis indicated by the arrow A in the figure, and the diopter of the finder can be changed according to the eyesight of the photographer by this adjustment. In addition, since the positional relationship between the eye gaze detecting device and the eye 3 is not changed by this adjustment, the direction of the eye gaze can be detected under a constant condition regardless of the adjusted diopter.

[0017]

Second Embodiment FIGS. 2 and 3 show a second embodiment of the present invention. In the second embodiment, the eyepiece lens 2 includes a negative lens 2a similar to that of FIG. 1 and a positive lens 2d having a separation surface 2c acting as a dichroic mirror inside. The positive lens 2c combines the functions of the positive lens 2b and the dichroic mirror 40 of FIG.
The number of optical elements can be reduced compared to the example of FIG. 1 to reduce the space occupied.

In the example of FIG. 2, the diopter can be adjusted by moving the negative lens 2a in the optical axis direction A, similarly to the example of FIG. 1, and this adjustment does not affect the visual line detection device.

In the example shown in FIG. 3, the positive lens 2d surrounded by a broken line and the visual axis detection device are integrated to adjust the diopter.
The light projecting optical system 10 and the light receiving optical system 20 are configured to be integrally movable in the optical axis direction A of the eyepiece lens 2. Also in this example, the optical positional relationship between the eye 3 and the light receiving element 25 does not change due to the diopter adjustment, and the direction of the line of sight can be detected under certain conditions.

[0020]

Third Embodiment FIGS. 4 and 5 show a third embodiment of the present invention. In the third embodiment, the dichroic prism 40 is provided between the eyepiece lens 2 composed of one positive lens 2b and the pentaprism 1.

In the example of FIG. 4, the optical axis direction A of the positive lens 2b
When the diopter is adjusted by moving to the position, the light projecting optical system 10 and the light receiving optical system 20 of the visual line detection device surrounded by a broken line move integrally in the direction B in conjunction therewith. Thus, the influence of the movement of the positive lens 2b on the visual line detection device can be offset by moving the visual line detection device.

Also, in the example of FIG.
A concave lens 32 is provided between the four-wavelength plate 31 and the dichroic prism 40. When adjusting the diopter by moving the positive lens 2b in the optical axis direction A, by moving the concave lens 32 in the direction B, This cancels out the effect on the gaze detection device due to diopter adjustment. In the example of FIG. 5, the laser light from the light projecting optical system 10 can be incident as a parallel light beam, but the performance of the image changes.

[0023]

Fourth Embodiment FIGS. 6 and 7 show a fourth embodiment of the present invention. In the fourth embodiment, the light projecting optical system 10 and the light receiving optical system 20 are located on the opposite side of the eyepiece lens 2 with the pentaprism 1 interposed therebetween.
Is provided.

A prism 27 is joined to the pentaprism 1 at a position facing the eyepiece lens 2, and a joint surface 51 is formed as a dichroic surface having characteristics of reflecting visible light and transmitting infrared light.

In the example of FIG. 6, when adjusting the diopter by moving the eyepiece lens 2, the line-of-sight detection device surrounded by a broken line is integrally moved. In the example of FIG. 7, only the concave lens 32 is moved in the optical axis direction at the time of diopter adjustment. Other configurations and operations are the same as those in the third embodiment.

[0026]

As described above, according to the present invention, even when a part of the lens constituting the viewfinder is moved to adjust the diopter, at least the light from the projection optical system of the line-of-sight detection device is adjusted. Since the luminous flux emitted and incident on the eye can be kept parallel, the influence on the visual line detection device is small, and the direction of the visual line can be detected accurately.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of a finder according to the present invention.

FIG. 2 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a modification of the second embodiment.

FIG. 4 is an explanatory view showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a modification of the third embodiment.

FIG. 6 is an explanatory diagram showing a fourth embodiment of the present invention.

FIG. 7 is an explanatory view showing a modification of the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pentaprism 2 ... Eyepiece lens 3 ... Eye 10 ... Projection optical system 11 ... Semiconductor laser 20 ... Light receiving optical system 30 ... Polarization beam splitter 32 ... 1/4 wavelength plate

Claims (4)

(57) [Claims] 1. A finder for guiding a light beam from a subject passing through a photographic lens to an eye of a photographer via an eyepiece lens, wherein a light projecting optical system for causing measurement light to enter the eye via a part of the finder. And, a light receiving optical system that receives the reflected light from the eye and detects the direction of the line of sight, and at least a part of the eyepiece lens while maintaining a state where the light for measurement is incident on the eye as a parallel light flux. A finder, comprising: a diopter adjustment mechanism for moving in a direction of an optical axis. 2. The apparatus according to claim 1, further comprising a light beam separating means for separating an optical path of the light projecting optical system and the light receiving optical system from an optical path of a light beam from the subject, wherein the eyepiece lens is located closer to the photographing lens side than the light beam separating means. The finder according to claim 1, wherein the finder is provided. 3. A light beam separating means for separating an optical path of the light projecting optical system and the light receiving optical system from an optical path of a light beam from the subject, wherein the light beam separating means captures the image from at least a part of the eyepiece lens. 2. The diopter adjustment mechanism provided on the lens side, wherein the diopter adjusting mechanism integrally moves or interlocks the light projecting optical system and the light receiving optical system integrated with at least a part of the eyepiece lens. 3. The finder described in. 4. A light beam separating means for separating an optical path of the light projecting optical system and the light receiving optical system from an optical path of a light beam from the subject, wherein the light beam separating means captures the image from at least a part of the eyepiece lens. Provided on the lens side, an adjusting lens is provided in an optical path of the light projecting optical system and the light receiving optical system, and the diopter adjusting mechanism causes at least a part of the eyepiece lens and the adjusting lens to interlock. The finder according to claim 1, wherein: