JP2007017695A - Display device and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of performing an easily visible in-finder display. <P>SOLUTION: In the display device where an in-display is superposed on asubject image and displayed, illumination light rays are diffracted by a diffractive optical element using a holographic liquid crystal panel, and the in-finder display is displayed. The luminance of the in-finder display can be changed by controlling the on-off of a voltage to be applied to a transparent electrode provided at a hologram display part in a diffractive optical element. AS for AF area display 803, 808, 809 in a dark patient area 72, the ratio between the off and on of the voltage to be applied is reduced, so as to reduce luminance. On the contrary, regarding AF area display 804, 805, 810 in bright patient areas, the ratio between the off and on of the supply voltage is increased, so as to increase luminance. Thus, the visibility of the AF area display is improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device that displays a viewfinder display superimposed on a subject image in the viewfinder field, and a camera provided with the display device.

A so-called superimpose display technique is known in which a selected AF area is displayed over a subject image in the viewfinder field in a camera having a plurality of automatic focus detection areas (hereinafter referred to as AF areas). (For example, refer to Patent Document 1). In this conventional camera, a display unit is configured by a fine prism formed on a focusing screen or on a reflecting plate disposed in the vicinity of an intended image plane of a subject image, and the display unit is illuminated by an LED through a penta prism. The reflected light from the display unit is observed with an eyepiece together with the subject image.
Japanese Patent Laid-Open No. 7-244317

  Incidentally, a relatively dark area and a relatively bright area are mixed in the viewfinder field. However, in conventional cameras that perform superimpose display, the brightness of each display is the same, so the AF area display displayed in a bright area is darker than the surroundings and is difficult to see, and conversely in a dark area. The displayed AF area display may be too bright and dazzling compared to the surrounding area. Therefore, there is a problem that the AF area display is difficult for an observer to visually recognize.

The invention of claim 1 is applied to a display device that displays a subject image in the viewfinder field of the photographing device so as to overlap the viewfinder display, and according to the subject brightness in a predetermined area including the viewfinder display in the viewfinder field, A display luminance control means for controlling the luminance of the display in the finder within the predetermined area to an optimum luminance for visual recognition is provided.
The invention of claim 2 is applied to a display device that displays a subject image in the viewfinder field of the photographing device so that the display in the viewfinder is superimposed, and a refractive index anisotropic region layer including a liquid crystal with refractive index anisotropy and a refractive index. A diffractive optical element having at least one liquid crystal hologram display part in which a liquid crystal multilayer structure part formed by alternately laminating isotropic region layers is sandwiched between a pair of transparent electrodes, and a light source for making illumination light incident on the diffractive optical element A display control means for controlling on / off of the display in the finder by the diffracted light diffracted by the liquid crystal hologram display unit by controlling the voltage applied to the pair of transparent electrodes, and a predetermined display including the display in the finder within the finder field of view Display luminance control means for changing the on / off ratio by the display control means in accordance with the subject brightness in the area and controlling the brightness of the display in the finder in the predetermined area to the optimum brightness for visual recognition. Characterized by comprising a.

  According to the present invention, the brightness of the in-finder display in the predetermined area is controlled to the optimum brightness for visual recognition in accordance with the subject brightness in the predetermined area including the in-finder display. Even in a subject image, display in the viewfinder that can be easily recognized can be performed.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention, and is a schematic diagram showing a schematic configuration of a single-lens reflex camera equipped with a display device according to the present invention. The camera shown in FIG. 1 is an electronic camera that captures a subject image with an image sensor 10 such as a CCD or CMOS. Of course, the present invention can also be applied to a camera that performs imaging using a silver salt film.

  A main mirror 2 and a sub mirror 7 are disposed on the optical axis 8 between the photographing lens 1 and the image sensor 10, and a shutter 9 is disposed in front of the image sensor 10. The main mirror 2 is formed of a half mirror. Part of the subject light that has passed through the photographing lens 1 is reflected upward in the figure by the main mirror 2, and a subject image is projected onto a finder screen 3 disposed at a position optically conjugate with the image sensor 10. A subject image projected on the finder screen 3 can be observed through a finder optical system including a pentaprism 4 and an eyepiece lens 5.

  Near the upper portion of the finder screen 3, a diffractive optical element 6 is provided for performing in-finder display regarding shooting information such as an AF area and camera information such as a remaining battery level. In the present embodiment, a holographic liquid crystal panel is used as the diffractive optical element 6, and the display in the finder can be turned on / off by the drive circuit 18. Illumination light from the light source 22 is incident from the side surface of the diffractive optical element 6. An LED or the like is used for the light source 22. Display light such as AF area display diffracted by the diffractive optical element 6 is reflected by the pentaprism 4 toward the eyepiece lens 5 and is observed as an in-finder display together with the subject image via the finder optical system.

  Part of the subject light transmitted through the main mirror 2 is reflected by the sub mirror 7 and guided to the AF sensor 14 via the field lens 11, the AF mirror 12 and the imaging lens 13. The output signal from the AF sensor 14 is input to the AF calculation unit 20, and the defocus amount with respect to the planned focal plane of the photographing lens 1 is calculated by the phase difference detection method.

  Part of the light from the subject image projected on the finder screen 3 is taken into the photometric sensor 16 via the photometric lens 15, and the subject luminance based on the output signal of the photometric sensor 16 is calculated by the luminance calculation unit 17. Is done. As the photometric sensor 16, an area sensor in which CCD elements are arranged in a matrix is used, and the luminance of the entire area in the finder field can be measured. Of course, it is also possible to use a divided photometric sensor in which the viewfinder field is divided into a plurality of regions and a detection unit is provided for each region.

  At the time of shooting, the main mirror 2 and the sub mirror 7 are retracted from the optical path including the optical axis 8 and the shutter 9 is opened, and the subject luminous flux reaches the image pickup surface of the image pickup device 10 to perform exposure for a predetermined time. The imaging signal output from the imaging device 10 is read into the image processing circuit 19 where various image processing is performed. The luminance calculation unit 17, the drive circuit 18, the image processing circuit 19, and the AF calculation unit 20 are connected to a CPU 21 that comprehensively manages control of the entire camera. The CPU 21 drives the focusing lens of the photographing lens 1 by a focus adjustment motor (not shown) based on the defocus amount calculated by the AF calculation unit 20 to perform a focusing operation.

[Description of Diffraction Optical Element 6]
Next, the diffractive optical element 6 that performs display such as AF area display will be described. Hereinafter, an AF area display will be described as an example. FIG. 2 is a diagram schematically showing a cross section of the diffractive optical element 6 composed of a holographic liquid crystal panel. The diffractive optical element 6 includes a pair of glass substrates 61 and 62 facing each other, and a transparent isotropic polymer material 63 exists as a base member in a gap therebetween. The side surface of the diffractive optical element 6 is sealed with a transparent sealing material 67.

  In the hologram display section 60 that performs AF area display, a refractive index isotropic region layer made of a polymer material 23 that is a refractive index isotropic material and a liquid crystal droplet rich layer that is a refractive index anisotropic material ( In the following, a liquid crystal multilayer structure 64 is formed in which 640 are alternately stacked. In addition, transparent electrodes 65 and 66 having the same shape as the AF area display are formed on the hologram display section 60 of the glass substrates 61 and 62. A voltage is applied to the transparent electrodes 65 and 66 by the drive circuit 18 shown in FIG.

  In FIG. 2A, the voltage applied to the transparent electrodes 65 and 66 is in the ON state, and the liquid crystal molecules in the refractive index anisotropic region layer 640 are aligned in the vertical direction in the figure. In the present embodiment, the effective refractive index neff of the liquid crystal droplets when the liquid crystal molecules are aligned in the vertical direction with respect to the illumination light 68 from the side surface of the diffractive optical element 6 is the refractive index of the isotropic polymer material 63. It is configured to be approximately equal to np. Therefore, when the applied voltage is on, the incident illumination light 68 is transmitted through the liquid crystal multilayer structure 64 and emitted from the opposite side surface. As a result, the display light is not emitted from the diffractive optical element 6, and the AF area display is not displayed. The subject light from the finder screen 3 disposed on the lower side of the diffractive optical element 6 passes through the diffractive optical element 6 and travels to the finder optical system.

  On the other hand, FIG. 2B shows a case where the voltage applied to the transparent electrodes 65 and 66 is turned off. When the applied voltage is turned off, the direction of the liquid crystal molecules in the refractive index anisotropic region layer 640 becomes random, and the refractive index of the liquid crystal droplets and the refractive index of the polymer material 63 have different values. As a result, the liquid crystal multilayer structure 64 functions as a Bragg diffraction grating in which a layer having a high refractive index and a layer having a low refractive index are arranged in a stripe pattern.

  Therefore, the illumination light incident from the side surface is diffracted by the liquid crystal multilayer structure 24, is emitted as display light 69 from the glass substrate 62 toward the pentaprism, and is observed through the eyepiece lens 5. In this case, display light 69 having the same shape as that of the transparent electrode 66 is emitted, the AF area display is in the display state, and the AF area display is observed on the subject image. Further, since the display light is guided to the finder optical system by Bragg diffraction, the illumination light can be efficiently used as the display light.

  FIG. 3 shows the diffractive optical element 6 in the case where a plurality of hologram display parts 60 provided with the liquid crystal multilayer structure part 64 are arranged. A common transparent electrode 65 is formed on the glass substrate 61, and transparent electrodes 66a and 66b are formed on the other glass substrate 62 for each of the liquid crystal multilayer structures 64A and 64B. As described above, by forming the two hologram displays 60A and 60B on the diffractive optical element 6, two AF area displays can be displayed. In this case, the on / off control of the two AF area displays is performed by holding the potential of the transparent electrode 65 at a constant potential (for example, ground potential) and individually controlling the voltage application to the transparent electrodes 66a and 66b on the opposite side. Can be performed independently.

  The illumination light 68 emitted from the light source 22 is introduced into the diffractive optical element 6 through a light guide 61 made of a transparent resin or the like. The illumination light 68 incident on the diffractive optical element 6 is diffracted by the liquid crystal multilayer structures 64A and 64B, and display lights 69a and 69b are emitted from each of them. In FIG. 1, the display of the light guide 61 is omitted, and the display of the light guide 61 and the light source 22 is omitted in FIG.

[Control of display brightness]
Next, luminance control for AF area display will be described. In the present embodiment, the brightness of the AF area display is individually made brighter or darker by controlling the voltage application to the transparent electrodes 66a and 66b. When the amount of light from the light source 22 is constant, the brightness of the AF area display can be changed by controlling the lighting time per unit time of the AF area display, that is, by voltage application control.

  FIG. 4 is a diagram for explaining luminance control by controlling the lighting time, and shows an on / off pattern of the applied voltage. When the AF area display is turned on, the applied voltage is repeatedly turned on and off as shown in patterns A to C. The display brightness at this time can be controlled by changing the ratio of the off (lighting) time to the on (light off) time. In the case of the pattern A, the pulse width t1 is the on time, and the pulse is generated with the period t3. Therefore, the ratio between the off time and the on time is expressed as (t3-t1) / t1.

  On the other hand, in the case of the pattern B, since the pulse having the width t1 is generated with the period t4 (= t3 / 2), the ratio of the off time to the on time (t4-t1) / t1 becomes smaller than that of the pattern A, and AF The brightness of the area display decreases. On the contrary, if the period t3 is made longer than that in the case of the pattern A without changing the pulse width t1, the ratio between the off time and the on time is increased and the luminance is increased. In the pattern C, the cycle t3 is the same as that in the pattern A, and the pulse width t5 is twice as long as t1. Therefore, the ratio of the off time to the on time is the same as that of the pattern B, and the same luminance as that of the pattern B is obtained. Note that the periods t3 and t4 are preferably set to about 20 Hz to 200 Hz in consideration of display flicker and influence on the liquid crystal.

  FIG. 5 is a diagram showing an example of the display form of the AF area display. FIG. 5A is a diagram showing the AF area display position within the viewfinder field, and 15 AF areas 701 to 715 in three columns and five columns are set. When a plurality of AF areas are set in this way, a plurality of AF areas of an area that the photographer wants to focus are displayed in a group, and a desired AF area is selected from the plurality of AF areas and AF is selected. There is a mode to do.

  For example, when the area 71 in the upper right of the screen is an area to be focused, AF area displays 803 to 805 and 808 to 810 corresponding to the six AF areas 703 to 705 and 708 to 710 in the area 71 are displayed. . At this time, as shown in FIG. 5B, the subject in the area 72 including the AF area displays 803, 808, and 809 is relatively dark, and the subject in the area including the AF area displays 804, 805, and 810 is relatively bright. The AF area displays 803, 808, and 809 decrease the brightness, and the AF area displays 804, 805, and 810 increase the brightness and improve the visibility of each AF area display.

  In this case, a predetermined area including the AF area display is set in advance for each AF area display, and an EV value corresponding to the subject luminance is calculated for each predetermined area by the luminance calculation unit 17 in FIG. Then, the brightness of each AF area display is controlled so that the EV value of each AF area display is larger by about +1 to +3 than the calculated EV value of each subject. This + α is a coefficient for optimizing the AF area display for visual recognition, and is preferably set according to the photographer's preference. As shown in FIG. 5B, six AF area displays 803 to 805 and 808 to 810 are displayed, and when a desired AF area is selected from them, the selected AF area is displayed as shown in FIG. An area AF area display 804 is displayed.

  In this way, by controlling the brightness of each AF area display individually according to the brightness of the subject that is the background of each AF area display, even if the subject is a mixture of bright and dark areas, the visibility Excellent AF area display can be performed. In the present invention, the brightness of the display in the finder is individually controlled according to the brightness of the subject image that is the background of the display in the finder for easy visual recognition. The present invention can also be applied to a display device that displays by reflecting with a microprism formed in the above. That is, an LED is provided for each display composed of microprisms, and the light quantity of each LED is controlled according to the luminance of the subject image.

  However, when the diffractive optical element 6 composed of a holographic liquid crystal panel is used as in the present embodiment, the applied voltage of each transparent electrode is controlled on and off while the luminance of the light source 22 is kept constant. The brightness can be changed for each display. Therefore, it is not necessary to provide a light source for each display, and there may be one as in this embodiment, and the light source portion can be reduced in size. On the other hand, when the LED is provided for each microprism, the light source portion becomes large, and when there are 15 AF area displays as shown in FIG. 5A, it is almost difficult to store the light source in the camera. It becomes.

  In the display device described above, the brightness of the display in the finder is changed by changing the on / off pattern of the applied voltage. However, the display brightness may be changed by using the light amount control of the light source 22 together. In the embodiment described above, the display device related to the display in the viewfinder of the camera has been described as an example. However, the present invention is not limited to the camera and can be similarly applied to the display in the viewfinder of the photographing apparatus.

1 is a diagram illustrating an embodiment of the present invention, and is a schematic diagram illustrating a schematic configuration of a single-lens reflex camera including a display device according to the present invention. It is a schematic diagram which shows the cross section of the holographic liquid crystal panel 6, (a) shows an OFF state, (b) shows an ON state. It is a figure which shows the diffractive optical element 6 at the time of arrange | positioning multiple liquid crystal multilayer structure parts 64. FIG. It is a figure which shows lighting pattern AC. It is a figure explaining AF area display in a finder visual field, (a) shows arrangement | positioning of AF area, (b) shows grouped AF area display, (c) shows selected AF area display. Show.

Explanation of symbols

1: photographic lens 3: finder screen 4: pentaprism 5: eyepiece 6: diffractive optical element 10: imaging element 16: photometric sensor 17: luminance calculation unit 18: drive circuit 21: CPU
22: Light source 60, 60A, 60B: Hologram display part 64, 64A, 64B: Liquid crystal multilayer structure part 65, 66, 66a, 66b: Transparent electrode

Claims (3)

In a display device that displays a finder display superimposed on a subject image in the viewfinder field of the photographing device,
Display luminance control means for controlling the luminance of the display in the finder in the predetermined area to the optimum luminance for visual recognition according to the subject luminance in the predetermined area including the display in the finder within the finder visual field. Display device. In a display device that displays a finder display superimposed on a subject image in the viewfinder field of the photographing device,
A liquid crystal hologram display portion in which a liquid crystal multilayer structure portion formed by alternately laminating a refractive index anisotropic region layer and a refractive index isotropic region layer containing a liquid crystal having refractive index anisotropy is sandwiched between a pair of transparent electrodes, Having at least one diffractive optical element;
A light source that makes illumination light incident on the diffractive optical element;
Display control means for controlling the voltage applied to the pair of transparent electrodes to control on / off of display in the finder by the diffracted light diffracted by the liquid crystal hologram display unit;
The on / off ratio by the display control means is changed in accordance with the subject brightness in the predetermined area including the in-viewfinder display within the viewfinder field, and the brightness of the in-finder display in the predetermined area is controlled to the optimum brightness for visual recognition. A display device comprising display brightness control means. Photometric means for detecting subject brightness in the viewfinder field;
A display device according to claim 1 or 2,
The display brightness control means controls the brightness of the display in the finder in the predetermined area according to the subject brightness in the predetermined area detected by the photometry means to an optimum brightness for visual recognition. .

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