JP2006003523A - Display device in finder and camera with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate display brightness differences caused by optical length differences, without taking account of the disposition of a light source. <P>SOLUTION: A display device in a finder includes: a light transmissive member having a plurality of display sections on it and inserted into a finder optical path; and an illuminator for throwing rays of light from the light source to the plurality of display sections. The finder internal display device provides superimposition display within a finder image plane in such a manner that the rays of light from the illuminator are reflected by the display sections and guided to an eyepiece section. In the finder internal display device, the optical path lengths of the rays of light thrown from the illuminator to the display sections differ between the display sections. The longer the optical path length of the light thrown by the illuminator is, the larger the amount of light thrown by the illuminator is. The amount of light thrown is altered, for example, by altering a duty ratio assigned to duty-drive the light source. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device in a viewfinder that performs superimpose display on a viewfinder screen, and a camera having the display device.

  A light transmitting member in which a plurality of display units are formed is inserted into the finder optical path, and an illuminating device that projects light toward each display unit of the light transmitting member is provided, and reflected light from each display unit is provided to the eyepiece unit. There are display devices that perform superimpose display within the viewfinder screen by guiding them. For example, in the display device described in Patent Document 1, the light transmitting member is disposed below a pentaprism that constitutes a finder optical system, and an illumination device having a plurality of light sources (LEDs) is disposed in front of the pentaprism. Display is performed by irradiating each light source light obliquely to each display unit via a pentaprism. By using such a display device, for example, a specific area of a plurality of focus detection areas set in the screen can be illuminated and notified to the photographer.

JP 2003-107560 A

  In the display device as described above, a plurality of display units are provided scattered on the light transmitting member, whereas a plurality of light sources corresponding to the display units are concentrated in one place. However, even if light sources having the same luminance are used, the apparent brightness varies depending on the position of the display unit. Specifically, when the light transmitting member and the illumination device are arranged as in Patent Document 1, the upper display of the screen inevitably appears brighter than the lower display, and particularly when the upper and lower displays are simultaneously performed. Give the person an unpleasant impression. There is no problem if the light sources are arranged so that the light projecting optical path lengths are all the same, but this is difficult and is not practical in consideration of space and assemblability.

An in-finder display device according to the present invention includes a light transmission member formed with a plurality of display units and inserted into a finder optical path, and an illumination device that projects light from a light source to each of the plurality of display units. The light from the apparatus is reflected by each display unit and guided to the eyepiece unit, so that the present invention is applied to an in-finder display device that performs superimpose display on the finder screen. The projecting optical path length from the illumination device to the display unit varies depending on the display unit. When the light projecting light path length becomes longer, the amount of light reaching the display unit decreases, so the light projecting light quantity of the illumination device is set according to the light projecting light path length.
In particular, in the invention according to claim 2, the light projection light quantity is set to be larger as the light projection optical path length is longer.
According to a third aspect of the present invention, the amount of light to be projected is made variable by changing the duty ratio when the light source is duty driven.
According to a fourth aspect of the present invention, a plurality of light sources are provided corresponding to each of the plurality of display units, and one or a plurality of display units are displayed in a superimposed manner by controlling lighting of the plurality of light sources.
The invention according to claim 5 is an indicator in which the plurality of display units indicate a plurality of focus detection areas set in the finder screen, and an indicator corresponding to any one or a plurality of selected focus detection areas. Is displayed as a superimpose.
According to the sixth aspect of the present invention, the projected light quantity is calculated so that the projected light quantity increases as the subject brightness increases, and the actual projected light quantity is given by weighting the calculated projected light quantity according to the projected light path length. The amount of light is determined, and the light source is controlled to be turned on with the determined amount of projected light.
A camera according to the present invention includes the above-mentioned display device in the viewfinder.

  According to the present invention, since the respective light projection amounts of the illumination device are set according to the respective projection light path lengths from the illumination device to the plurality of display units, without paying attention to the arrangement of the light sources. Differences in display brightness due to differences in optical path lengths can be eliminated.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a side view of a finder portion of a single-lens reflex camera according to the present embodiment, and reference numeral 1 denotes a camera upper cover. Part of a subject light beam that has passed through a photographing optical system (not shown) is reflected by a movable main mirror (half mirror) 3, and includes a focusing screen 11, a display plate 12, a pentaprism 13, eyepiece lenses 5 and 6, and an eyepiece lens. Observed through the protective glass 7. Part of the light passing through the pentaprism 13 enters the photometric element 9 via the photometric lens 8, and the photometric element 9 outputs a signal corresponding to the amount of incident light as a subject luminance signal. On the other hand, a part of the light beam transmitted through the main mirror 3 is reflected by the sub mirror 23 and received by the focus detection module 24. The focus detection module 24 performs focus detection based on the received light beam and outputs the result.

  When shooting is instructed, the main mirror 3 jumps up and retracts from the subject optical path together with the sub mirror 23, and then the shutter 25 is opened and closed. The subject luminous flux passes through the shutter opening and reaches the film 2, and the film 2 is exposed. In the case of a digital still camera, the light receiving surface of an image sensor (for example, CCD) is positioned at the position of the film.

Next, focus detection of the camera and superimpose display of the focus detection area will be described.
As shown in FIG. 2, nine focus detection areas ARa to ARi are set in the screen of the camera of this embodiment. Fr is a frame for displaying each area, and is formed on the display board 12 as described later. The focus detection module 24 can independently detect the focus adjustment states of these nine areas.

  The photographer can select one of nine areas using a focus detection area selection operation member (not shown). There is also a mode in which the camera automatically selects one of the areas based on the focus detection result of each area. In either case, focus adjustment (focusing) is performed based on the focus adjustment state of the selected area. Further, there is a mode in which all areas are divided into several groups in advance, and when the photographer selects any group, only the areas belonging to the selected group are effective.

  One selected focus detection area or a plurality of focus detection areas belonging to the selected group is displayed superimposed on the subject image on the finder screen and notified to the photographer looking through the finder. Such superimpose display is realized by the display plate 12 provided below the pentaprism 13 and the illumination device 100 provided in front of the pentaprism 13.

The display plate 12 is composed of a light transmitting member, and a frame Fr (display unit) representing the focus detection area is formed on its surface by a number of fine prisms, and the subject luminous flux reaching this portion from the lower side of FIG. Refracts and deviates from the eyepieces 5 and 6, and that portion appears darker than the surroundings. Thereby, the photographer can confirm the position of each focus detection area. On the other hand, when the oblique light L is incident on the frame Fr from the illumination device 100, the light is sequentially reflected by the small triangular slopes P1 and P2 toward the pentaprism 13 in the fine prism portion. Further, the light incident on the non-prism portion around the frame Fr and inside passes through the focusing screen 11 without being reflected and falls downward. As a result, only the illuminated frame Fr appears to shine brightly in the screen, and the photographer can recognize that it is the selected area.
Since the incident angle of the illumination light differs depending on the frame, it is necessary to change the angles of the slopes P1 and P2 depending on the frame so that all the reflected light from each frame part is directed to the eye point.

  In FIG. 1, an illuminating device 100 that illuminates a frame portion includes a chip type light emitting diode (hereinafter referred to as a chip type LED) 16 fixed to a hard substrate 15, a first light shielding member 17, a lens array 18, and a second light shielding. The member 19, the diffusion plate 20, the aperture mask 21, and the light projecting prism 14 are included. These elements are held by the holder 22, and the holder 22 is fixed to the camera body.

  FIG. 4 is an exploded perspective view of the lighting device 100, and the light shielding members 17 and 19 and the diffusion plate 20 are not shown. The chip-type LED 16 has nine LEDs 16 a to 16 i corresponding to the nine focus detection areas ARa to ARi, and is soldered to a land (not shown) of the hard substrate 15. The lens array 18 has nine hemispherical lens portions corresponding to the LEDs 16a to 16i, and the irradiation light of each LED 16a to 16i is condensed by each lens portion and travels toward the aperture mask 21 side. Due to the light condensing action of the lens portion, it is possible to suppress a decrease in luminance as compared with a lens mold type (cannonball type) LED. A surface light source can be created by combining with the aperture mask 21. The illumination light that has passed through the aperture mask 21 is reflected twice by the light projecting prism 14 and irradiated obliquely, and the irradiated light is irradiated to each frame portion of the display plate 12 via the pentaprism 13.

  FIG. 5 is a block diagram of a camera control system. The microcomputer (hereinafter referred to as the microcomputer) MCU that controls the camera includes a half-press switch SW1 that is turned on when a release button (not shown) is half-pressed, a release switch SW2 that is turned on when the release button is fully pressed, and the AF selection described above. A focus detection area selection switch AFS that is switched by operation of the operation member is connected. The AF selection operation member is operated when a desired focus detection area or group is selected as described above.

  In the microcomputer MCU, a photometric unit AEC that detects the subject brightness using the photometric element 9, a distance measuring unit AFC that detects the focus adjustment state of each area using the focus detection module 24, and LEDs 16 a to 16 i are lit. A light emission control circuit LEDD to be driven, a drive unit DRV that drives the shutter 25 and the mirror 3 to perform a photographing operation, and a memory MRY such as an EEPROM that stores various information are connected.

  FIG. 6 shows details of the light emission control circuit LEDD. The current control circuit IDR decodes the control signal from the microcomputer MCU and controls the current value of the constant current circuit. The nine LEDs constituting the chip-type LED 16 have the anode side connected to the row changeover switch HSW and the cathode side connected to the column changeover switch VSW. Each of the row changeover switch HSW and the column changeover switch VSW is composed of three switches, and the microcomputer MCU performs switching control of these switches via the row changeover control circuit HDR and the column changeover control circuit VDR to supply power to a desired LED. Can be turned on. The current control circuit IDR may be individually provided for each individual LED or each group divided into a plurality of groups.

  In the camera configured as described above, when the half-press switch SW1 is turned on by a half-press operation of the release button, the microcomputer MCU has one LED corresponding to the selected area or a plurality of areas corresponding to the area belonging to the selected group. The LED is turned on and the area is superimposed. FIG. 7 shows an example of the group display. In this example, a cross-shaped group including five areas ARa to ARd and ARg is selected, and the LEDs 16a to 16d and 16g corresponding to these five areas are turned on. The frame Fr corresponding to the area is displayed in a superimposed manner. Similar superimpose display is also performed when the photographer selects a desired area or group using the focus detection area selection switch AFS.

  Note that the LED lighting time (display time) is about 100 ms from the viewpoint of LED light affecting photometry and energy saving. Further, in the case of group display, the corresponding LEDs are not lit at the same time, but are lit in order one by one, the details of which will be described later.

  By the way, if the LEDs are always turned on in the same manner, the display is too bright when the scene is dark, and conversely, the display is difficult to see when the scene is bright. Therefore, in this embodiment, the apparent brightness of the display is changed by duty-controlling each LED with a duty ratio corresponding to the subject brightness. The duty ratio is a ratio between the lighting time and the light-off time of each LED. The duty control is performed by the microcomputer MCU by controlling the row switching control circuit HDR and the column switching control circuit VDR shown in FIG. This can be realized by ON / OFF control of the column selector switch VSW. Specifically, the subject brightness is divided into several stages in advance, and a table in which the duty ratio is assigned to each stage is stored in the memory MRY. Then, the duty ratio is obtained from the table according to the detection result of the subject brightness, and the LED is duty-driven based on the duty ratio. The numerical values in the table are set so that the lighting time in one duty cycle becomes shorter as the subject luminance is lower. As a result, the darker the object scene, the darker the apparent brightness of the superimpose display becomes, and an easy-to-view and not too bright display becomes possible regardless of the lightness or darkness of the object scene.

  In addition, in this embodiment, the duty of the LED is controlled in consideration of the distance (light projection optical path length) from the illumination device 100 to the frame Fr (display unit). That is, as can be seen from FIGS. 1 and 3, among the nine focus detection areas ARa to ARi (FIG. 2) described above, the upper three areas ARd to ARf, the middle three areas ARa to ARc, and the lower three areas. The optical path length from the illuminating device 100 is different from ARg to ARi, and becomes longer in the lower stage. For this reason, when all the LEDs are turned on in the same manner, the display appears brighter in the upper stage, and the photographer feels uncomfortable particularly in the group display in which a plurality of stages are displayed simultaneously.

In order to solve this problem, the duty ratio obtained from the above table is weighted according to the position of the focus detection area. For example, the lower LED is the reference (weight Wled = 1), the middle is Wled = 0.9, and the upper is Wled = 0.8. Thereby, the lighting time in 1 cycle of a duty becomes long, so that the lower stage with long projection light path length. This means that the longer the projected light path length is, the larger the projected light quantity of the illumination device 100 is. It is possible to eliminate the difference in brightness due to the optical path length and make the apparent brightness the same in all stages. It becomes.
The numerical value of the weight Wled is not limited to the above, and may be set as appropriate according to the difference in the optical path length.

8 to 11 show flowcharts for realizing the superimpose display in software.
When the half-push switch SW1 is turned on by half-pressing the release button, the program shown in FIG. 8 is started by the microcomputer MCU. First, in step S1, photometry is performed by the photometry unit AEC to obtain subject brightness. In step S2, it is determined whether or not the superimpose display in the half-press operation has already been completed. If completed, the process proceeds to step S6, and if not completed, the process proceeds to step S3.

  In step S3, the AF mode is determined from the state of the focus detection area selection switch AFS. If it is the group AF mode, the process proceeds to the group display process in step S4 to display the selected group in a superimposed manner, and if not, the single display process in step S5 is performed to display the selected one area in a superimposed manner. move on. Details of steps S4 and S5 will be described later.

  In step S6, it is determined whether the release switch SW2 is on or off. If it is off, it is determined in step S7 whether the half-press switch SW1 is on or off. If the half-press switch SW1 is off, the process is terminated, and if it is on, the process returns to step S1. If the release switch SW2 is on, the photographing process is performed in step S8. The photographing process includes mirror up, narrowing down, shutter opening / closing, mirror down, and the like.

Details of the group display processing in step S4 will be described with reference to FIG.
In step S401, the selected group is determined, and if it is a cross-shaped group shown in FIG. 7, the process proceeds to step S402. Here, only the processing for the cross-shaped group will be described as a representative, but the basics are the same when another group is selected.

  In step S402, the duty ratio Duty1 corresponding to the subject brightness (the detection result in step S1) is acquired from the table described above. In step S403, a weight Wled corresponding to the optical path length is set for the five LEDs 16a to 16d and 16g in the display group. Wled is “1” for the LED 16g corresponding to the lower area, “0.9” for the LEDs 16a to 16c corresponding to the middle area, and “0” for the LED 16d corresponding to the upper area. .8 ".

In step S404,
Duty2 ＝ Duty1 × Wled
Thus, the actual duty ratio Duty2 of each LED is obtained, and LED lighting control by Duty2 is performed in step S405 and thereafter.

  Here, when all the corresponding LEDs are turned on simultaneously during group display, a large-scale power source capable of flowing a large current at a time is required. Therefore, a method is used in which a plurality of LEDs are sequentially turned on one by one at short time intervals, and are displayed as if a plurality of frames Fr are simultaneously displayed due to the afterimage phenomenon of human eyes. Here, the five LEDs 16a to 16d and 16g to be lit are represented by LEDs 1 to 5 in the order of lighting.

  First, only LED1 is turned on (step S405) and waits until a predetermined lighting time T2 elapses (step S406). When T2 elapses, LED1 is turned off and LED2 is turned on, and after time T2, LED2 is turned off and LED3 is turned on. This process is repeated (steps S407 to S414). After the LED 5 is turned on, the operation is performed from the LED 1 again. Each lighting is performed according to the above Duty2. Then, when a predetermined time T1 has elapsed from the start of lighting of the first LED1, the process proceeds from step S415 to step S416 to stop the timer, and then in step S417, all the LEDs are turned off and the process returns. Here, T1 is about 100 ms, T2 is about 4 ms, and one cycle of the duty is about 50 μs. Since T2 is extremely short in this way, even if the LEDs are turned on one by one, it appears that the display is made simultaneously due to the afterimage phenomenon.

FIG. 10 shows the single display process in step S5. In this case, the same processing as in FIG. 9 is performed on one LED corresponding to the selected area. That is, the duty ratio Duty1 corresponding to the subject brightness is acquired from the table (step S501), the weight Wled corresponding to the optical path length is set for the LED (step S502),
Duty2 ＝ Duty1 × Wled
Thus, the actual duty ratio Duty2 of the LED is obtained (step S503), and the LED is turned on for the lighting time T1 with the Duty2 (steps S504 to S506).

  The above is the control accompanying half-pressing of the release button, but FIG. 11 shows the processing when the focus detection area selection operation member is operated. When the focus detection area selection switch AFS is turned on, this program is started. First, a selection area corresponding to the operation is determined (step S11). Next, photometry is performed (step S12), and group display processing or single display processing is performed according to the operation of the switch AFS (steps S13 to S15). These group / single display processes are as described with reference to FIGS.

  In the above, the amount of emitted light is changed by duty control of the light source, but the amount of emitted light may be changed by adjusting the current to the light source, or a neutral density filter is placed in front of the light source with a short optical path length. By doing so, a method of reducing the amount of light emitted may be used. The number of focus detection areas is not limited to nine, and the present invention can also be applied to superimpose displays other than the focus detection areas. Further, although an example in which the optical path length is different in the vertical direction of the screen has been shown, the present invention can also be applied when the optical path length is different in the horizontal direction of the screen. In addition, if the light amount control is performed according to the subject brightness, the display can be more easily viewed.

The figure which shows the finder structure of the camera in one Embodiment of this invention. The figure which shows the focus detection area of a finder screen. The figure explaining the display principle of a superimpose display apparatus. The exploded perspective view of an illuminating device. The block diagram of the control system of a camera. The figure explaining the detail of the light emission control circuit. The figure which shows an example of a group display. The flowchart which shows the process started by half-press operation. The flowchart which shows the detail of a group display process. The flowchart which shows the detail of a single display process. The flowchart which shows the process started by area selection operation.

Explanation of symbols

12 Display board 14 Projection prism 16a-16i LED
DESCRIPTION OF SYMBOLS 100 Illuminating device ARa-ARi Focus detection area Fr Frame which shows focus detection area LEDD Light emission control circuit MCU Microcomputer SW1 Half press switch SW2 Release switch

Claims (7)

A plurality of display units formed and inserted into a finder optical path; and a lighting device that projects light from a light source to each of the plurality of display units, and the light from the lighting device is transmitted to each display unit. In the viewfinder display device that performs superimpose display in the viewfinder screen by being reflected by the eyepiece and guided to the eyepiece,
The in-finder display device characterized in that each light projection light amount of the illumination device is set according to each light projection optical path length from the illumination device to the plurality of display units. The in-finder display device according to claim 1, wherein the projected light quantity is set to be larger as the projected light path length is longer. The in-finder display device according to claim 1, wherein the light projection amount is set by changing a duty ratio when the light source is duty-driven. 2. The plurality of light sources are provided corresponding to each of the plurality of display units, and one or a plurality of display units are displayed in a superimposed manner by controlling lighting of the plurality of light sources. The display apparatus in a finder in any one of -3. The plurality of display units are indices indicating a plurality of focus detection areas set in the finder screen, and superimpose display of indices corresponding to any one or a plurality of selected focus detection areas. The in-finder display device according to claim 4. The projected light quantity is determined so that the projected light quantity increases as the subject brightness increases, and the actual projected light quantity is determined by giving a weight according to the projected light path length to the obtained projected light quantity, The in-finder display device according to any one of claims 1 to 5, wherein the lighting of the light source is controlled with the determined amount of projected light. A camera comprising the in-finder display device according to claim 1.

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