JP3774528B2 - SLR camera viewfinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single-lens reflex camera finder having a display function for displaying various photographing information in the finder, and a visual axis detecting function for detecting the visual line of the photographer.
[0002]
[Prior art]
In a conventional single-lens reflex camera of this type, an object image formed on a focusing screen by a photographic lens, a photometric range arranged at the focusing screen or an optically equivalent position, an autofocusing ranging area, Various types of in-finder display devices for cameras have been proposed in which photographing information is simultaneously observed through a finder optical system.
[0003]
(a) For example, as disclosed in Japanese Patent Laid-Open No. 55-18664, a relief hologram recorded by converting recording information due to interference between an object wave and a reference wave into surface irregularities is recorded on a focusing screen. It is known that the display is arranged in the vicinity, and the hologram image is reproduced on a focusing screen to display in the viewfinder. (b) Further, as disclosed in Japanese Patent Application Laid-Open No. 58-181034, a liquid crystal display plate is disposed on a focusing screen, and an in-finder display is performed using the liquid crystal display plate.
[0004]
[Problems to be solved by the invention]
However, the relief hologram structure of the conventional example (a) requires advanced technology for production, and is expensive and it is extremely difficult to form a high-quality hologram image on the focusing screen. Have a problem.
[0005]
In the configuration of the conventional example (b), the position in the optical axis direction of the liquid crystal display does not exactly coincide with the image forming position on the focusing screen of the photographing lens, and the diopter at the time of finder observation is slightly shifted, A liquid crystal member is always present in the finder optical path of a single-lens reflex camera that requires a clear and delicate visual sensation, and the finder image quality and light quantity are unavoidably reduced.
[0006]
On the other hand, in recent years, automating of camera focusing and exposure determination has progressed, and the burden on the photographer has been reduced. However, as one method of reflecting the photographer's intention, the photographer's observation direction is detected, and the focus or Proposals such as adjusting the exposure have been made and put into practical use.
[0007]
In view of the above problems, the object of the present invention can be displayed on the entire surface of a finder image so as to overlap an object image formed on a focusing screen of a single-lens reflex camera without degrading a photometric range or an autofocus area. It is an object of the present invention to provide a compact single-lens reflex camera finder having a display function and a gaze detection function for detecting a gaze direction of a photographer in order to control a photometric range and a focus point.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a finder for a single-lens reflex camera according to the present invention is provided with a first optical member disposed immediately before an eyepiece in the finder optical path, and an optical path separated by the first optical member. A second optical member, information projection means arranged to guide information made up of letters, figures, etc. to the photographer's pupil so as to be superimposed on the finder optical path by the first optical member; Illuminating means for illuminating the pupil, and light reflected from the photographer's cornea and pupil illuminated by the illuminating means are guided and separated from the finder optical path by the first optical member to detect the observation direction of the photographer and a visual axis detecting means, single-lens separates the optical path in the sight line detecting means from the optical path and the photographer's pupil to reach the pupil of the photographer from the information projection unit by the second optical member Refukame The first optical member is a dichroic mirror whose reflection and transmission characteristics change depending on an incident wavelength, and the normal vector of the dichroic mirror is provided in the finder optical path and the single-lens reflex camera. It is installed so that it is in the plane defined by the normal vector of the quick return mirror, and the hue change of the finder caused by the difference in the angle of incidence of the finder light to the dichroic mirror is changed from the photographing lens to the quick return mirror. It is characterized in that it cancels out the hue change caused by the difference in the incident angle of the light beam .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail based on the illustrated embodiments.
FIG. 1 is a configuration diagram of the embodiment. XO represents the finder optical axis from the taking lens 1 to the photographer's pupil e, X1 represents the display optical axis from the light source 2 to the photographer's pupil e, and X2 represents the pupil image from the photographer's pupil e. The optical axis reaching the sensor 3 to be detected is shown.
[0010]
A photographing lens 1, a quick return mirror 4, a focusing screen 5, a penta roof prism 6, an optical member 7 including a half mirror placed obliquely in the optical path, and an eyepiece 8 are arranged along the optical axis XO. Along the optical axis X2, a light source 2, a condenser lens 9 comprising a Fresnel lens, a liquid crystal panel 10 for recording information, an optical member 11 comprising a dichroic mirror and placed obliquely in the optical path, a projection lens 12, An optical member 7 and an eyepiece 8 are arranged. Further, the eyepiece 8, the optical member 7, the projection lens 12, the optical member 11, the imaging lens 13, and the sensor 3 are arranged along the optical axis X2. An illumination light source 14 that illuminates the photographer's pupil e is provided in the vicinity of the eyepiece 8.
[0011]
Here, the focal length of the eyepiece lens 8 is set slightly shorter than the air-converted optical path length from the focusing screen 5 to the eyepiece lens 8, and the diopter is normally set to −1 diopter. The eyepiece 8 may be constituted by a lens system in which the principal point position is variable or the focal length is variable by a plurality of movable lenses, instead of the fixed single lens shown in FIG.
[0012]
The light flux from the subject is imaged on the focusing screen 5 through the photographing lens 1 and the quick return mirror 4 that is retracted from the photographing optical path during photographing. An image on the focusing screen 5 is formed on the pupil e through the penta roof prism 6, the optical member 7, and the eyepiece 8.
[0013]
The condenser lens 9 has a conjugate imaging relationship between the light source 2 and the photographer's pupil e, and functions as a so-called condenser lens for the display light beam to be efficiently incident on the pupil e by the liquid crystal panel 10. In order to reduce the size of the apparatus, it is desirable that the distance between the light source 2 and the condenser lens 9 is short. However, if the distance is reduced, the power of the condenser lens 9 is increased accordingly, and the pupil e and the light source 2 are reduced. We must keep the conjugate relationship.
[0014]
Therefore, in this embodiment, by using a Fresnel lens as the condenser lens 9, the lens is thinned and the apparatus is downsized. Strictly speaking, the imaging relationship between the light source 2 and the pupil e of the photographer is set by the condensing power of the condensing lens 9 and the projection lens 12 combined. The light beam condensed by the condensing lens 9 enters the liquid crystal panel 10, and information including characters and pictures superimposed on the finder image is formed by the liquid crystal panel 10 shown in FIG. Arbitrary characters and information are formed on the liquid crystal panel 10 in advance, but may be formed in an arbitrary shape at the time of display with fine dots.
[0015]
In any case, the liquid crystal panel 10 allows light transmission through an area having the same shape as the information to be superimposed on the finder image when displaying information, and light shielding at other times. At the time of information display, the liquid crystal panel 10 is illuminated by the light source 2, and at this time, the liquid crystal panel 10 transmits light only in a region having a shape to be displayed. Note that a sheet having light diffusion characteristics may be added in the vicinity of the liquid crystal panel 10 in order to improve visibility.
[0016]
The light beam transmitted through the liquid crystal panel 10 is reflected by the optical member 11 and collected by the projection lens 12. Then, the optical member 7 is combined with the viewfinder image from the focusing screen 5, reaches the photographer's pupil e through the eyepiece 8, and is observed. In this case, the condensing power of the projection lens 12 and the eyepiece 8 is combined, and the photographer enlarges and observes the liquid crystal panel 10. The focal length of the projection lens 12 and the projection lens 12 are set so that the virtual image formed on the focusing screen 5 by the eyepiece 8 and the virtual image by the projection lens 12 of the liquid crystal panel 10 and the eyepiece 8 are formed at the same distance. It is necessary to set the distance between the liquid crystal panel 10 and the liquid crystal panel 10.
[0017]
Further, when the focal length of the eyepiece lens 8 is fs and the focal length of the projection lens 12 is ft, it is desirable to satisfy the following expression.
fs / 5 <ft <fs
[0018]
If the focal length fs of the projection lens 12 exceeds the upper limit of the above formula, the distance between the projection lens 12 and the liquid crystal panel 10 increases, and at the same time, the effective area of the liquid crystal panel 10 must be increased, resulting in an increase in the size of the apparatus. At the same time, the illumination efficiency of the illumination system including the light source 2 and the condenser lens 9 is lowered.
[0019]
However, if the lower limit of the equation is exceeded, the pattern to be produced on the liquid crystal panel 10 becomes small, making the production difficult, and the F.V. No. , The configuration with a single lens becomes difficult, and there is a possibility that the quality of the display image is seriously lowered. In the present embodiment, an aspherical lens is used as the projection lens 12 in order to reduce the size and performance of the apparatus. As a result, it is possible to obtain good performance with little image distortion and diopter shift over the entire display area.
[0020]
Many methods for detecting the line of sight have been proposed in the past. In this embodiment, the line of sight is detected from the relationship between the reflected image of the cornea of the light source and the pupil, which is already disclosed in this embodiment and is practically used in a single-lens reflex camera or the like. The method is used. That is, the illumination light source 14 is composed of an LED that emits a longer wavelength than visible light. The light emitted from the illumination light source 14 illuminates the photographer's pupil e, which is a detection target in the line-of-sight direction, and the illuminated pupil image is transmitted through the eyepiece 8 and reflected by the optical member 7, and the projection lens 12 and the optical member 11. And forms an image on the sensor 3 through the imaging lens 13. On the sensor 3, a pupil image and a virtual image due to corneal reflection of the illumination light source 14 are formed. From the positional relationship between the pupil image and the virtual image of the illumination light source 14, the line-of-sight direction can be detected by a predetermined algorithm. .
[0021]
FIG. 3 is a spectral transmittance characteristic diagram of a half mirror used as the optical member 7. This half mirror has a characteristic of an average transmittance of about 70% in a wavelength region of wavelengths of 400 nm to 700 nm and infrared of 700 nm or more. As a result, 70% of the finder light beam from the subject image formed on the focusing screen 5 passes through the optical member 7 and reaches the photographer's pupil. The optical member 11 uses a dichroic mirror that reflects visible light and transmits infrared light as shown in FIG.
[0022]
Most of the light beam emitted from the light source 2 and transmitted through the liquid crystal panel 10 is reflected by the optical member 11, then 30% is reflected by the optical member 7, and is superimposed on the viewfinder image from the focusing screen 5. Reach pupil e.
[0023]
By such an action, the finder image and the information display are superimposed and can be observed at the same time, and display using a free color expression is performed in the finder using the light source 2 of any color or the transmission wavelength of the liquid crystal panel 10. be able to.
[0024]
On the other hand, in the line-of-sight detection system, the light emitted from the illumination light source 14 is reflected by the pupil e and transmitted through the eyepiece lens 8, and 30% of the light is reflected by the optical member 7 and transmitted through the projection lens 12 and the optical member 11. An image is formed on the sensor 3 through the image lens 13.
[0025]
Further, a dichroic mirror can be applied as the optical member 7, and FIG. 5 shows a spectral transmission through a dichroic mirror having an incident angle of 45 ° when the dichroic mirror is applied to the optical member 7 of the finder optical system as a second embodiment. It is a rate characteristic figure. This dichroic mirror can be manufactured by forming a dielectric multilayer film on a glass substrate. In the dichroic mirror, the wavelength dependence of the spectral transmittance is always different depending on the polarization direction except that the incident angle is 0 °, that is, light is incident on the dichroic mirror perpendicularly.
[0026]
In this case, as shown in FIG. 5, it has a transmittance of about 90% in the visible region in the latter half of the wavelength range of 400 to 600 nm for forming a finder image, and S-polarized light in the visible light at the 600 nm level, which is a red component. The component has a characteristic that the transmittance is about half value at about 660 nm, and the transmittance is about half value at about 680 nm for P-polarized light. By applying the dichroic mirror having such characteristics to the finder system and using the light source 2 having an emission center of about 660 to 680 nm, most of the luminous flux from the display optical system is reflected by the dichroic mirror, and the eyepiece 8 Through the pupil e of the photographer.
[0027]
On the other hand, about 90% of the finder beam from the subject image formed on the focusing screen 5 passes through the dichroic mirror and is guided to the photographer's pupil e through the eyepiece 8. At this time, the display efficiency can be increased by increasing the reflection efficiency of the display light beam by changing the polarization direction of the light beam from the display optical system incident on the dichroic mirror to S-polarized light by the action of the liquid crystal panel 10. Even if this is not perfect S-polarized light, the object can be achieved, and with such a configuration, red information can be displayed freely in the viewfinder.
[0028]
On the other hand, most of infrared light from the illumination light source 14 used for line-of-sight detection is also reflected by the dichroic mirror, so that it can be guided to the sensor 3 efficiently.
[0029]
FIG. 6 is a spectral transmittance characteristic diagram of the dichroic mirror at an incident angle of 45 ° when the dichroic mirror is applied to the optical member 7 of the finder optical system as the third embodiment. The dichroic mirror has a transmittance of about 90% in the visible region where the finder image is formed at a wavelength of 450 nm or more. In the visible light, the S-polarized component is about 450 nm and the transmittance is half value, and the P-polarized light is about 420 nm. It has a characteristic that the transmittance becomes half value. In addition, the reflectance is increased in the infrared wavelength region used for line-of-sight detection.
[0030]
In this way, by applying the dichroic mirror to the finder optical system shown in FIG. 1 and making the light source 2 have a light emission center characteristic of about 450 nm, most of the luminous flux from the display optical system is reflected by the dichroic mirror, The eyepiece 8 guides the light to the photographer's pupil e. On the other hand, about 90% of the finder light beam from the subject image formed on the focusing screen 5 passes through the dichroic mirror and is guided by the eyepiece 8 to the pupil e of the photographer.
[0031]
At this time, the polarization direction of the light beam from the display optical system incident on the dichroic mirror is changed to S-polarized light by the action of the liquid crystal panel, and the display efficiency can be increased by increasing the reflection efficiency of the display light beam. If not, the goal can be achieved. With such a configuration, a blue-violet information display can be freely displayed in the viewfinder. On the other hand, most of the infrared light of the illumination light source 14 used for line-of-sight detection is reflected by the dichroic mirror, so that it can be guided to the sensor 3 efficiently.
[0032]
FIG. 7 is an explanatory diagram for a method of correcting a hue change depending on the finder observation direction caused by using the dichroic mirror in the second and third embodiments. L0, L1, and L2 indicate three light beams having different directions that pass through the finder optical system. The respective light beams L0, L1, and L2 are transmitted through the photographing lens 1, reflected by the quick return mirror 4 and imaged on the focusing screen 5, and reach the photographer's pupil e through the penta roof prism 6, the dichroic mirror, and the eyepiece lens 8. . Here, attention is paid to the incident angles of the light beams L0, L1, and L2 on the quick return mirror 4. If the incident angles of the light rays to the quick return mirror 4 are θ0, θ1, and θ2, respectively, θ1 <θ0 <θ2.
[0033]
Generally, the quick return mirror 4 is set to 45 ° with respect to the optical axis of the photographing lens 1, so that θ0 is 45 °. On the other hand, looking at the incident angles of the light beams L0, L1, and L2 to the optical member 7 that is a dichroic mirror, if the incident angles are ω0, ω1, and ω2, respectively, ω2 <ω0 <ω1.
[0034]
Since the incident angle to the dichroic mirror varies depending on the upper and lower observation directions of the finder image, it is desirable that the spectral transmittance is constant regardless of the incident angle to the dichroic mirror. However, the dichroic mirrors of the second and third embodiments obtain the spectral transmittance characteristics shown in FIGS. 5 and 6 by depositing a dielectric multilayer film on a glass substrate. In such a dichroic mirror, it is extremely difficult to eliminate the angle dependency of the spectral transmittance, which is not preferable because the hue of the finder image changes in the vertical direction.
[0035]
Specifically, in the second embodiment, the spectral transmittance characteristics of the dichroic mirror of FIG. 5 will be described. When the incident angle of the dichroic mirror increases, the wavelength at which the transmission and reflection characteristics are reversed as shown by large ← is a short wavelength. Shift to the side. Conversely, when the incident angle is decreased, the wavelength at which the transmission and reflection characteristics are inverted shifts to the longer wavelength side, as indicated by → small. As a result, when considering only the characteristics of this dichroic mirror, when looking at the top of the viewfinder image, that is, when viewing the light beam L1 in FIG. 7, the long wavelength side cut wavelength at which the incident angle to the dichroic mirror can be transmitted is short wavelength side. As a result, the viewfinder image appears blue to the photographer.
[0036]
On the contrary, when looking under the finder image, that is, when viewing the light beam L2 in FIG. 7, the cut wavelength on the long wavelength side where the incident angle to the dichroic mirror is small and transmitted is shifted to the long wavelength side, and the red component increases. As a result, the viewfinder image appears red to the photographer.
[0037]
In order to prevent such a hue change in the vertical direction, the quick return mirror 4 is constituted by a dielectric multilayer film, and the hue change due to the angle dependency of the reflectance cancels the hue change caused by the dichroic mirror. It is desirable to do so. In this way, in the second embodiment, as a characteristic of the quick return mirror, the light component L1 having a small incident angle reflects more red component on the longer wavelength side, and the light beam L2 having a large incident angle. Many blue components on the shorter wavelength side are reflected.
[0038]
In general, it is desirable that a quick return mirror used in a single-lens reflex camera is set so as to have a substantially flat reflection characteristic with respect to a wavelength in the visible range, and has a smaller angle dependency. However, the quick return mirror 4 is configured by a dielectric multilayer film as described above, and a good finder system with little hue change is obtained through a finder system including a dichroic mirror by utilizing the incident angle dependency of the reflectance. be able to.
[0039]
FIG. 8 shows a configuration diagram of the fourth embodiment, and the same reference numerals as those in FIG. 1 denote the same members. In the fourth embodiment, a line-of-sight detection system is arranged in the transmission direction of the optical member 11, and an information projection system is provided in the reflection direction.
[0040]
The dichroic the optical member 11 consisting of dichroic mirror, by providing a property of reflecting infrared light and transmitting the light in the visible region, as shown in FIG. 9, the optical axis of the optical axis X1 and visual axis detection system of the display system X2 is separated. Other operations are the same as those in the first to third embodiments.
[0041]
【The invention's effect】
As described above, the finder of the single-lens reflex camera according to the present invention inserts the first optical member having a suitable wavelength characteristic immediately before the eyepiece, and displays various photographic information in the finder with good finder characteristics. By realizing the display device and providing the second optical member, a compact line-of-sight detection means can be realized at the same time.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment.
FIG. 2 is a pattern diagram of a liquid crystal panel.
FIG. 3 is a half mirror spectral transmittance characteristic diagram of a first optical member.
FIG. 4 is a spectral transmittance characteristic diagram of a second optical member.
FIG. 5 is a spectral transmittance characteristic diagram of the first optical member used in the second embodiment.
FIG. 6 is a spectral transmittance characteristic diagram of the first optical member used in the third embodiment.
FIG. 7 is a diagram illustrating the principle.
FIG. 8 is a configuration diagram of a fourth embodiment.
FIG. 9 is a spectral transmittance characteristic diagram of a second optical member used in the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shooting lens 2 Light source 3 Sensor 4 Quick return mirror 5 Focus plate 6 Penta roof prism 7, 11 Optical member 8 Eyepiece 9 Condensing lens 10 Liquid crystal panel 12 Projection lens 14 Illumination light source

Claims (8)

A first optical member disposed immediately before the eyepiece lens in the finder optical path, a second optical member disposed in the optical path separated by the first optical member, and the finder optical path by the first optical member Information projection means arranged so as to guide information made up of characters, figures and the like to the photographer's pupil, illumination means for illuminating the photographer's cornea and pupil, and the photographer's illumination illuminated by the illumination means Line-of-sight detecting means for guiding reflected light from the cornea and pupil and separating from the finder optical path by the first optical member to detect the observation direction of the photographer, and the information projection by the second optical member a finder of a single-lens reflex camera for separating the optical path from the optical path and the photographer's pupil to reach the pupil of the photographer from the means in the sight line detecting means, the first optical member reflecting the wavelength incident It is a dichroic mirror whose transmission characteristics change, and the dichroic mirror is installed so that its normal vector is in a plane defined by the normal vector of the finder optical path and the quick return mirror provided in the single-lens reflex camera. , single lens, characterized in that to offset the change in hue finder caused by the difference of the angle of incidence of the finder light to the dichroic mirror, the quick and hue change caused by the difference of the incident angle of the light flux from the photographic lens to return mirror Ref camera finder . The normal vector of the first optical member, single-lens reflex camera viewfinder according to claim 1 the angle between the horizontal plane including the optical axis of the finder optical path is 45 ° to 30 °. 2. The single-lens reflex camera according to claim 1 , wherein the dichroic mirror has a characteristic in which a transition point between reflection and transmission characteristics is in a wavelength range of 400 to 500 nm with respect to an incident angle of finder light, and has a characteristic of transmitting a visible light flux. finder. Single-lens reflex camera viewfinder according to claim 3, wherein the LED light source equipped with short emission wavelength than the characteristic transition point of the dichroic mirror in the information projection means. The dichroic mirror has a reflection and transmission characteristic transition point between wavelengths of 600 to 700 nm with respect to the incident angle of the finder light, transmits light in the visible range, and reflects infrared light having a wavelength of 700 nm or more. The finder of the single-lens reflex camera of Claim 1 which has. 6. A finder for a single-lens reflex camera according to claim 5 , wherein the light source provided in the information projection means is an LED having an emission wavelength longer than a characteristic transition point of the dichroic mirror. The illuminating means emits infrared light having a wavelength longer than that of visible light, the second optical member reflects light having a wavelength in the visible range, and transmits light having a wavelength emitted from the illuminating means. single-lens reflex camera viewfinder according to claim 1 is. The illuminating means emits infrared light having a wavelength longer than that of visible light, the second optical member transmits light having a wavelength in the visible range, and reflects light having a wavelength emitted from the illuminating means. single-lens reflex camera viewfinder according to claim 1 is.

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