JP2506344B2 - Auxiliary illuminator for focus detection - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an auxiliary lighting device used for focus detection on a subject having low brightness.

[Prior Art and Problems Thereof] FIG. 13 is a diagram for explaining the principle of an automatic focus adjustment device that calculates the defocus amount of the taking lens and automatically adjusts the focus, so-called autofocus (AF). A semi-transmissive mirror 602 located between the taking lens 601 and the film surface Z, and a reflective mirror 603 provided on the semi-transmissive mirror 602.
Thus, the light passing through the taking lens 601 forms an image on the image sensor 604 including a plurality of pixels. The focus shift amount is calculated from the positional relationship of the formed image or the contrast, and the photographing lens is driven according to the calculated shift amount to adjust the focus. Also, for a subject with insufficient light intensity, an auxiliary light source provided on the camera side
An active focus detection is performed by projecting light onto a subject with a light projecting lens 606 by 605. in this case,
In order to facilitate the focus detection, a method is used in which a pattern having a transparent portion and an opaque portion is provided immediately before the auxiliary light source and the pattern is projected onto the subject.

Here, when there is one focus detection area on the film surface, this focus detection area is generally spread with the optical axis of the taking lens as the center, and in this case, the focal length of the taking lens changes. Then, although the size of the focus detection area on the subject changes, the center position of the focus detection area is on the optical axis of the taking lens and does not change.
Therefore, in such a case, the auxiliary light source may illuminate the subject area including the optical axis of the photographing lens regardless of the focal length of the photographing lens.

However, in a multi-point focus detection device having a plurality of focus detection areas on the film surface, the focus detection area may be provided on the film surface at a position deviated from the optical axis of the photographing lens. In this case, when the focal length of the photographing lens changes, the size of the focus detection area on the subject changes and the center position of the focus detection area on the subject also changes. However, in the conventional auxiliary light source, since the irradiation direction or the irradiation angle is fixed, it is not possible to illuminate the focus detection area that changes with the change of the focal length. It is necessary to illuminate a subject at a wide angle using a light source having a large area or a plurality of light sources, but the power consumption is large and it is difficult to incorporate the camera.

Note that the following disclosure examples are given as examples in which a plurality of auxiliary light sources are provided.

In Japanese Patent Application Laid-Open No. 58-201015, a plurality of light fluxes are projected onto an object and the reflected light from the object is detected by a plurality of light receivers to measure the distance in a plurality of areas. This is because when a spot light is projected onto an object and distance measurement is performed, a predetermined amount of reflected light cannot be obtained depending on the subject condition, or
Since the distance measuring field of view is narrow, for example, in the case of shooting two people side by side, the distance measuring field of view falls between people, which makes it impossible to perform distance measurement or erroneous distance measurement. Is.

Further, in Japanese Patent Laid-Open No. 60-16811, a plurality of light emitting elements are lit in time series and projected toward each focus target, and reflected light from an object in each focus target is received by a light receiving element. , The number of light emitting elements to be turned on according to the change of the focal length of the taking lens by controlling the focal position of the taking lens based on the signal output from the light receiving element and the lighting state of the light emitting element. Are in control. In this disclosure example,
Both the light projecting system and the light receiving system are composed of optical systems separate from the taking lens, and are fixedly provided on the camera body. If the light emitting element that is turned on and the reflected light on the light receiving element at that time are known, , It is configured so that the distance to the object is always uniquely obtained. Here, it is necessary to switch the number of light-receiving elements according to the focal length of the shooting lens, because if you set multiple focus areas based on the shooting range of the short focus lens, you can shoot when using the long focus lens. This is to avoid that an object outside the angle of view is also targeted for distance measurement. As described above, these disclosed examples do not take into consideration that the projected light flux can effectively and efficiently irradiate the focus detection area even when the photographing lenses having different focal lengths are used.

[Object of the Invention] The present invention has been made in order to eliminate the above-mentioned problems, and is an auxiliary illuminating device for focus detection that can cope with a change in the focus detection area outside the optical axis due to a change in the focal length. The purpose is to provide.

[Configuration of Invention] The present invention is used for a camera that performs focus detection on a plurality of focus detection areas, at least one of which is on the optical axis and one of which is off the optical axis, using light that has passed through a replaceable photographing lens. In an auxiliary lighting device for projecting auxiliary light for focus detection to a low-brightness subject, a light emitting means for emitting auxiliary light without passing through the taking lens and a change in focus detection of the taking lens A projection lens arranged in front of the light emitting means so as to project the auxiliary light in an irradiation range having a spread in the movement direction of the off-optical axis focus detection area on the subject.

[Embodiment] FIG. 1 shows the appearance of a camera incorporating an active automatic focus adjusting device according to the present invention.

Reference numeral 1 denotes a camera body, 2 is an interchangeable photographing lens, 3 is a relay button 3 for shutter release, and 4 is an auxiliary for a low-brightness subject at the time of focus detection. The projection window for projecting light is shown. The camera 1 to which the present invention is applied is a so-called TTL type camera that performs focus detection using light passing through the taking lens 2.

FIG. 3 (A) shows an example of a focus detection optical system having a plurality of focus detection areas.

Reference numeral 100 denotes a taking lens, and patterns 100a, 100b, 100c, 100d on the pupil plane of the lens in the figure show regions through which the focus detection light flux passes. Reference numeral 101 denotes a focus detection area mask arranged immediately after a planned focal plane (not shown). The area mask 101 has three rectangular openings 101a, 101b, 101c.
Is provided, so that 3 on the shooting screen
There are two focus detection areas. The opening 101b is located substantially in the center of the photographing screen with the longitudinal direction being the horizontal direction. On the other hand, the openings 101a and 101c are located in the left and right areas of the photographic screen with the longitudinal direction thereof being up and down, and symmetrically with respect to a straight line passing through the optical axis of the photographic lens 100. It should be noted that this arrangement shows only one embodiment and is not limited to this.

102a, 102b, 102c are condenser lenses arranged immediately after the openings 101a, 101b, 101c of the area mask 101, respectively, and connect aperture mask openings 103a to 103f described later on the exit pupil plane of the taking lens 100. It acts to make you image. Reference numeral 103 denotes an aperture mask arranged behind the focus detection area mask 101, and the aperture mask 103 is provided with the aperture mask openings 103a, 103b, 103c, 103d, 103e, 103f described above. The openings 103a and 103b are formed by the condenser lens 102b in the area 1 on the exit pupil plane of the photographing lens 100.
Imaged on 00a and 100b respectively, and aperture mask openings 103c and 1
03d is imaged by the condenser lens 102a on regions 100d and 100c on the exit pupil plane of the taking lens 100, respectively, and the aperture mask openings 103e and 103f are formed by the condenser 102c on the exit pupil plane region 100d of the taking lens 100. And 100c, respectively. In this way, the aperture mask openings 103a to 103f serve to determine the focus detection light flux area in the exit pupil plane of the taking lens 100. Reference numeral 104 denotes an image-forming optical member provided immediately after the diaphragm mask 103. The image-forming optical member 104 has openings 104a to 103f, as shown in FIG. 3B. Correspondingly, imaging lenses 104a, 104b, 104c, 104d, 104e, 104f are formed. These imaging lenses 104a to 104f are for re-imaging the image formed near the focal plane on the AF light receiving element surface. Reference numeral 105 denotes a substrate arranged further behind the imaging optical member 104, and this substrate 105 has one-dimensional sensors 106a, 10a.
6b and 106c are provided respectively, and the sensor 106a receives the image formed by the image forming lenses 104a and 104b, and the sensor 106b forms the image formed by the image forming lenses 104e and 104f. In order to receive light, the sensor 106c is
The lenses are arranged so that the images formed by the image forming lenses 104c and 104d can be received. That is, these sensors 106
a, 106b and 106c are aperture mask openings 103a and 103b and 10a, respectively.
3e and 103f, 103c, and 103d are arranged in the direction in which the images are formed, for example, by taking a correlation between the image formed through the aperture mask opening 103a and the image formed through the aperture mask opening 103b. The focus state of the lens is detected. The arrangement direction of the aperture mask openings 103a and 103b is arranged along the longitudinal direction of the opening 101b of the focus detection area mask 101, and the orientation direction of the aperture mask openings 103c and 103d is the focus detection area mask. Since it is arranged along the longitudinal direction of the opening 101a of the 101, the direction of the sensor 106a and the sensor 106b
And 106c differ by 90 °. The sensor 106a is
Since it is arranged in the left-right direction, it has focus detection capability for a subject having a horizontal contrast, while the sensors 106b and 106c are arranged in a vertical direction, so that a subject having a horizontal contrast is obtained. It has a focus detection capability. The focus detection area on the shooting screen by these sensors 106a, 106b, 106c is shown as 200a, 200b in FIG.
Shown at 200c.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 4 shows a focus detection area when auxiliary light is emitted to a plurality of focus detection areas to perform focus detection by a camera incorporating the focus detection auxiliary illumination device of the present invention shown in FIG. , Shows the relationship with auxiliary light.

Reference numeral 1 denotes a single-lens reflex camera body equipped with the TTL type focus detection device described above. The focus detection device (not shown) inside has three focus detection areas as shown in FIG. 3 (A). Have. For example, on a subject at a distance D, M, R, L
Similarly, the focus detection area becomes M ', R', L'at the distance D '(D'> D),
Further, at the distance D ″ (D ″> D ′), M ″, R ″, and L ″. When the subject is bright and has contrast,
Focus detection is performed using light from the subject in the focus detection area, but when the subject is dark and has low contrast, auxiliary light is emitted to the subject through the projection window 4 of the camera body 1. It This auxiliary illumination light illuminates any one of m, r, and l at the distance D, and the distance D ′.
At the position of, illuminate any range of m ', r', l ',
At the position of the distance D ″, one of m ″, r ″, and l ″ is illuminated. As is clear from FIG. 4, the illumination ranges m, r, l by the auxiliary light illuminate the focus detection areas M, R, L on the subject, respectively. Here, the illumination range r of the auxiliary illumination light
Has a spread in the center movement direction (horizontal direction) of the focus detection area R from the photographing lens optical axis, and the illumination range 1 of the auxiliary illumination light is the center movement direction (horizontal direction) of the focus detection area L from the photographing lens optical axis. Direction). The reason will be described with reference to FIG.

FIG. 5 is a plan view on the subject at the distance D in FIG. 4, and shows changes in the focus detection area due to changes in the focal length of the taking lens 2.

The focus detection areas M, R, L are when the focal length of the taking lens 2 is f, and the focus detection areas when the focal length is f / 2 are M2, R2, L2, respectively. When the focal length is 2 × f, the focus detection areas are M3, R3, and
It becomes like L3. That is, in the focus detection area M having the optical axis O of the shooting lens 2 at its center, the size of the focus detection area changes according to the change in the focal length of the shooting lens 2, but the sensor position does not change. However, with respect to the focus detection areas R and L, not only the size of the focus detection area changes with the change in the focal length of the taking lens 2, but the center positions of the focus detection areas R and L from the optical axis O, respectively. In the direction of. Here, since the focal length of the photographing lens 2 and the irradiation angle of the auxiliary illumination light are irrelevant, that is, the illumination areas m, r, l are constant. Therefore, even if the focal length of the photographic lens 2 changes and the focus detection area changes like R2 and R3, in order to cope with this, in the illumination area r, the center of the focus detection area R from the optical axis O can be accommodated. It has a spread in the direction of movement. The same applies to the auxiliary illumination range l, from the optical axis O to the focus detection area L.
It has a spread in the moving direction of the center.

Next, a method of setting the illumination areas m, r, l as described above will be described with reference to the auxiliary illumination device in FIG.

FIG. 6 shows an embodiment of the projection optical system of the auxiliary lighting device inside the projection window 4 in FIG. 1, and is a sectional view in the VW direction.

Reference numeral 5 denotes a light projecting lens provided to face the projection window 4, and 6 denotes a pattern surface for providing contrast to the illumination light flux, which is provided at the focal position of the light projecting lens 5. 7 is an LE having three light emitting diodes (LED) a, b, c
It is a D package, and in front of this LED package 7,
A spherical lens 8 is provided at the center, and cylindrical lenses 9 and 10 which are located on the left and right of the spherical lens 8 and have a curved surface only in the up-down direction without a curved surface in the left-right direction. FIG. 7 is a front view of the lens portions 8, 9 and 10 as seen from the front.

The light projection will be described. The light projected by LEDa is
The light passes through the spherical lens 8, passes through the center of the pattern surface 6, and is projected by the light projecting lens 5 toward the subject.
This projection light illuminates the illumination range m in FIG.
Further, the light projected from the LEDb enters the cylindrical lens 9. Here, the light is condensed in the vertical direction, but is not condensed in the horizontal direction, so that the light has a certain amount of spread in the horizontal direction, and the light having the spread in the horizontal direction passes through the pattern surface 6 and then is projected. The light lens 5 projects the light toward a subject. The side wall 10 of the LEDb is a reflecting mirror, and the light projected from the side surface of the LEDb is reflected in the direction of the pattern surface 6 and projected by the light projecting lens 5 toward the subject. With this configuration, it is possible to irradiate the pattern surface 6 at a position farther from the optical axis S of the light projecting lens 5. The projection light by the reflected light from the LEDb and the side wall 10 illuminates the illumination range l. Similarly,
The projection light of the LEDc and the projection light from the side wall 11 illuminate the illumination area r. It should be noted that the pattern surface 6 is arranged at a position where the light beams from the respective LED light-emitting portions overlap each other little by little, and as shown in FIG. 5, the illumination light is emitted between the regions r and m and the regions m and r. The dead zone that does not reach is eliminated. With such a configuration, the illumination areas m, r, and l shown in FIG. 5 can be obtained, and the focus detection areas R and L located outside the optical axis of the taking lens 2 have a predetermined focal length of the taking lens 2. Even when the area moves due to a change, the illumination areas r and l spread in the moving direction, so that focus detection can be performed on a focus detection area outside the optical axis regardless of the focal length of the taking lens 2. The focus detection areas R and L in FIG. 5 can be arranged in the same direction (meridional direction) as the focus detection area M on the optical axis.

FIG. 8 shows a second embodiment of the auxiliary lighting device of the present invention.

Here, the number of LED chips of the LED package 7 in FIG. 6 is set to 5, and LEDs d and e are further provided in the lateral direction of the LEDs b and c located on the lateral sides, respectively. The illumination range by LEDs a to e is shown in FIG. LEDa illuminates the illumination range m, LEDs d and b refer to the illumination ranges r ₁ and r ₂ , respectively, and LEDs e and c illuminate the illumination ranges l ₁ and l ₂ , respectively. Here, FIG. 9 is a sectional view on the object plane common to FIG. 5, and the focus detection areas M, R, L and the like are common to FIG. As is clear from FIG. 9, when the taking lens 2 has a short focal length, the illumination range
It suffices if the LEDs d, e, a that illuminate r ₁ , l ₁ , m emit light, and if the focal length is long, the LEDb, which illuminates the illumination range r ₂ , l ₂ , m,
It suffices to emit light from c and a. In this way, the focus detection area can be illuminated more efficiently by changing the illumination area according to the focal length of the taking lens 2. still,
The pattern surface 6 is arranged at a position where the light beams from adjacent LEDs slightly overlap each other, and as shown in FIG. 9, the illumination ranges r ₁ and r ₂ , r ₂ and m, m and l ₂ , l ₂ The dead band area where the illumination light does not reach is eliminated between ₁ and l ₁ .

Next, a third embodiment of the present invention will be described with reference to FIG.

In FIG. 10, common members to those in FIG. 6 are designated by common reference numerals. There are 3 LEDs, a, b, and c.
The reflecting mirror V is formed so that not only the front emission light of the light emitting portion but also the side emission light is efficiently projected forward.
Further, a spherical lens W is provided at the front of each light emitting unit, and plays the role of condensing the respective projected light beams. The illumination range in this case is as shown in FIG. FIG. 11 is a sectional view on the object plane common to FIG. 5, and the focus detection areas M, R, L and the like are common to FIG. The illumination range of LEDa is m, and the illumination ranges of LEDs b and c are 1 and r, respectively. Here, the illumination ranges r and l are set to a size that can sufficiently cover the focus detection area that moves from R2 to R3 or L2 to L3 according to the change in the focal length of the taking lens 2. Auxiliary illumination is possible for the focus detection area outside the optical axis of the taking lens. Also in this case, the pattern surface 6
Are arranged at positions where the luminous fluxes from the respective LEDs are slightly overlapped with each other, and as shown in FIG. 11, a dead band region where illumination light does not reach between m and l and m and r is eliminated.

In the first to third embodiments described above, the photographing lens whose focal length changes is explained. However, when the photographing magnification is largely changed at a fixed focus such as a macro lens, the position of the focus detection area other than the center is detected. It is also effective when moving.

FIG. 2 is a block diagram showing an example of a system control circuit of a camera to which the auxiliary illumination device for focus detection described above is applied. In addition, here, the second having five LEDs
The example of is applied. The configuration will be described below.

Reference numeral 300 denotes a focus detection sensor, which is a one-dimensional sensor 106.
Three CCD image pickup devices a, 106b, and 106c are used, and these outputs are output in time series by a signal from the CCD drive circuit 301. 301 is a CCD drive circuit for driving the CCD element 300, and internally converts an analog signal into a digital signal.
Includes A / D conversion circuit. A digital memory circuit 302 stores the digital signal output from the CCD drive circuit 301. Reference numeral 303 denotes a control arithmetic circuit, which controls the system and also stores the C stored in the digital memory 302.
The data of the CD element 300 is processed according to a predetermined algorithm, and the defocus amount and the defocus direction of the taking lens are output. 304 is a subtraction circuit, and the control arithmetic circuit 303
The defocus amount and defocus direction calculated in
The correction data (C) regarding the spherical aberration of the taking lens output from the register 313 is input, and the correction data (C) is input.
The defocus amount obtained by subtracting and the defocus direction are output. Reference numeral 305 denotes an adder circuit, and the defocus amount and the defocus direction from the control arithmetic circuit 303 and the register 31.
The correction data (C) regarding the spherical aberration of the taking lens, which is output from 3, is input, and the defocus amount and the defocus direction in which the correction data (C) is added are output.
306 is a selector circuit, to which the output signals of the subtraction circuit 304 and the addition circuit 305 are input, and further, a signal indicating either positive or negative is input as a selector signal from the register 313. If this signal is a negative signal, The output data and signal of the subtraction circuit 304 are selected, and if it is a positive signal, the output data and signal of the addition circuit 305 are selected. The defocus data selected by the selector 306 is input to the display comparison circuit 307 and the multiplication circuit 310. The multiplication circuit 310 includes a register 31
From 4, the conversion coefficient (K) for focus adjustment is input as a multiplication value. The conversion coefficient (K) includes information on the mechanical configuration of the lens movement system necessary for obtaining the lens movement amount corresponding to the defocus amount, for example, information on a helicoid lead, and the like. The required number of rotations (N) of the motor is obtained by multiplication with the conversion coefficient (K). The calculated motor rotation speed (N) and a signal indicating the rotation direction of the motor determined by the defocus direction are input to the motor drive circuit 311. On the other hand, the display comparison circuit 307 receives the defocus amount and the focus width data from the focus width data circuit 308, and outputs data indicating a focus or a non-focus by comparing both data. . A display circuit 309 receives a signal from the display comparison circuit 307 and a signal in the defocus direction output from the selector circuit 306 to display in-focus or out-of-focus, or to display out-of-focus. When it is in focus, the direction of displacement is also displayed.

As described above, the motor rotation speed (N) and the signal of the rotation direction are input to the motor drive circuit 311, and the motor M is rotated according to these input data. The rotation of the motor M is performed by the gear train GT and the slip mechanism SL indicated by broken lines.
Is transmitted to the drive axis DA that drives the lens via.
In addition, at the position after passing through the slip mechanism SL, a photocoupler PC
The encoder is provided, and the photo coupler PC monitors the rotation of the drive shaft DA and feeds it back to the motor drive circuit 311 to rotate the motor by a predetermined number of revolutions.

Reference numeral 324 is a trigger circuit, which sends a focus detection start signal to the control calculation circuit 303 in response to turning on / off of the shutter button or an additional switch. Reference numerals 312, 313, and 314 denote register circuits, respectively, which are focal length information (F) of the photographing lens read by the reading circuit RD, correction data (C) regarding aberration of the photographing lens, and a conversion coefficient (K) for focus adjustment.
Have been entered respectively. A decoder circuit 315 decodes the signal output from the register circuit 312 and sets one of the output terminals p to q to a high level. Reference numerals 316 and 317 denote AND circuits, respectively. A lighting control signal (g) for controlling the lighting of the light emitting diode from the control arithmetic circuit 303 is input to one of the input portions of each, and the decoder is input to the other input portion. Output terminal p, q of circuit 315
The signals output from each are input. Transistors 3 are connected to the output terminals of these AND circuits 316 and 317, respectively.
20,321 are connected and these transistors 320,32
By controlling the ON / OFF of 1, the transistor 32
Light-emitting diode LD ₂ , LD ₃ or L connected to 0,321
Blink D ₄ and LD ₅ . The transistor 322 is controlled by the lighting control signal (g) from the control arithmetic circuit 303 to light the light emitting diode LD ₁ . Here, LD ₁ corresponds to LEDa in FIG. 8, LD ₂ and LD ₃ correspond to LEDs b and c, and
LD ₄ and LD ₅ correspond to LEDs d and e, respectively. Reference numeral 325 is a photometric circuit that measures the brightness of the subject, and sets the signal line g to a high level when the measured subject brightness is darker than the constant lens.

The configuration on the camera body side has been described above. Next, the configuration on the interchangeable lens side will be described.

In FIG. 2, a portion separated by a one-dot chain line shows an interchangeable lens EL, and a zoom lens is used as the interchangeable lens EL here. ZR is a zoom ring for zooming, and a brush BR that is rotatable by an external operation and is rotatable integrally with the zoom ring ZR is attached. Corresponding to the brush BR of the zoom ring ZR, a code plate CD is provided on the lens barrel fixing part (not shown), and the digital corresponding to each focal length is provided according to the rotation of the zoom ring ZR, that is, the setting of the focal length. It is configured to generate a code signal. The code signal is provided on the lens and is connected so as to be input to the lens information output circuit LID including a ROM (Read Only Memory). The ROM included in the lens information output circuit LID has an address specified by a digital code signal, and according to the start of reading from the reading circuit RD on the camera body side, the above-mentioned focal length information (F) of the taking lens and correction data regarding aberration ( C) and the rotation speed conversion coefficient (K) of the motor are updated in accordance with the zooming of the taking lens and output from the reading circuit RD.

The connector CN that electrically connects the camera body and the interchangeable lens EL has a power supply terminal. A synchronous clock pulse terminal, a read signal terminal, a serial data terminal and a ground terminal are provided. Also, to drive a focusing lens (not shown) for focus adjustment. The driven shaft FD is in mesh with the ring FR of the focusing lens.

The above is the description of the configuration, and then the control operation will be described.

When the interchangeable lens EL is attached to the camera body, the lens information output circuit LID on the interchangeable lens EL side and the reading circuit RD on the camera body side are connected via the connector CN, and both earth lines are simultaneously connected. Further, mechanical engagement for driving the focusing lens is made by the unevenness between the drive shaft DA and the driven shaft FD.

When the release button 3 is first pressed lightly, the trigger circuit 32
The focus detection start signal from 4 is output to the control circuit 303,
As a result, the contents of the ROM are read by the reading circuit RD from the lens information output circuit LID via the power supply terminal of the connector CN from the reading circuit RD, and the focal length information (F) is stored in the register 312 and the correction data (C) relating to the aberration. ) Is register 3
At 13, the rotation speed conversion coefficient (K) of the motor is loaded into the register 314. The acquisition of these data is
After that, it is performed at a predetermined timing, and the data is sequentially updated. The content of the ROM to be read depends on the address specified by the digital code of the code plate CD which is determined by the position of the brush BR which moves according to the setting of the zoom ring ZR. Therefore, even if the focal length of the zoom lens changes in accordance with zooming, the focal length information (F) corresponding to this focal length is read from the ROM at any time and loaded into the register 312.

When the acquisition of the lens data is completed, a CCD drive pulse is sent from the control arithmetic circuit 303 to the CCD drive circuit 301 via the signal line e. As a result, a CCD drive start signal is sent from the CCD drive circuit 301 to the CCD element 300, which is a focus detection sensor, and focus detection is performed. The analog signal detected by the CCD element 300 is converted into a digital signal by the A / D conversion circuit of the CCD drive circuit 301 and stored in the digital memory circuit 302. On the other hand, from the photometric circuit 325, information on the brightness of the subject is output to the control arithmetic circuit 303 via the signal line f, and when the photometric value is darker than the preset level, it is output from the CCD 300. At the same time when the integration of the signal is started, the control arithmetic circuit 303 sends a high level signal to the AND circuits 316 and 317 via the signal line g. As described above, the focal length information (F) of the photographing lens is stored in the register 312, and this focal length information (F) is decoded by the decoder 315, and the decoder 315
One of the output terminals p and q is at high level. Therefore, when the signal line g of the control arithmetic circuit 303 goes high, the output of either AND circuit 316 or 317 goes high. For example, when the output terminal p of the decoder 315 is high level, the output of the AND circuit 316 becomes high level and the transistor 320 is turned on, so that the LEDs b and c are turned on. In this way, the LEDs of the LED package 7 are switched and turned on according to the focal length of the photographing lens. Note that the transistor 322
Is directly connected to the signal line g, the light emitting diode LD ₁ lights up regardless of the focal length information (F).
This is because the LED light emitting unit a is arranged so as to measure the focus detection area m at the center of the photographing screen.

The projection light emitted from the LED package 7 is reflected by the object and then enters the CCD element 300 through the photographing lens. When the incident light on the CCD element 300 reaches a certain level, the control arithmetic circuit 303 from the CCD element 300 via the signal line h.
A high level signal is sent to. As a result, a signal for stopping the integration operation of the CCD drive circuit 301 is sent from the control arithmetic circuit 303 through the signal line e, and the signal line g is set to the low level to turn it on. The circuit is turned off, and the light emitting diode that was lit turns off. When the integration operation of the CCD element 300 is completed, it is converted into a digital signal by the A / D conversion circuit of the CCD drive circuit 301 and transferred to the digital memory circuit 302 and stored therein, as described above. When the memory for the digital memory circuit 302 is completed, the control arithmetic circuit 303 processes the input data according to a predetermined program, and calculates the defocus amount and the defocus direction signal at that time from the phase difference of the correlation signal of the CCD line. To do. When there are a plurality of focus detection areas, it is necessary to perform processing to determine which area of data is to be used. This is not the purpose of the present application, so a description thereof will be omitted. -146028, etc.

The calculated defocus amount ΔL and the defocus direction are input to the subtraction circuit 304 and the addition circuit 305. on the other hand,
The correction data (C) from the register 313 is input to the subtraction circuit 304 and the addition circuit 305, and the subtraction circuit 304 outputs the defocus amount obtained by subtracting the correction data (C) and the defocus direction. The addition circuit 305 outputs the defocus amount obtained by adding the correction data (C) and the defocus direction. Then, in the selector circuit 306, if the selector signal from the register 313 is a negative signal, the signal from the subtraction circuit 304 is selected, and conversely, if a positive selection signal is input, the addition circuit 305 is selected. The signal from is selected. The data and signal selected by the selector circuit 306 are given to the multiplication circuit 310 and the display comparison circuit 307. In the multiplication circuit 310, the rotation speed conversion coefficient K of the motor M from the register 314 is multiplied, and together with the calculated motor rotation speed N, the defocus direction signal from the selector circuit 306 gives the motor rotation direction signal. It is given to the drive circuit 311. On the other hand, in the display comparison circuit 307,
The defocus amount data and the data from the focusing width data circuit 308 are compared, and if the defocus amount data does not fall within the predetermined focusing width, a shift of the defocus amount is detected according to the signal in the defocus direction from the selector circuit 306. The left and right display portions 309b or 309c of the display circuit 309 are used to indicate the direction.
Either lights up.

In this way, in the case of out-of-focus, the display circuit 309 displays the out-of-focus state, and the motor M 311 is rotated by the motor drive circuit 311. The rotation speed at this time is detected by the photocoupler PC, so that the motor M rotates exactly N times and stops. The rotation of the motor is transmitted to the drive shaft DA via the gear train GT and the slip mechanism SL, and is further transmitted to the focusing ring FR via the driven shaft FD of the exchange lens EL, and a focusing optical system (not shown). The system is moved along the optical axis by the defocus amount.

Thereafter, the same control as described above is performed, the defocus amount is again compared with the data from the focus width data circuit 308, and if the defocus amount data is within the predetermined focus width, the display circuit 309 displays. Center display 3 for focusing
09a lights up and the release operation is permitted, and then the shutter button is released by pressing the release button 3 further.

As described above, the LED light emitting unit is switched and the illumination range is switched according to the change in the focal length of the photographing lens, so that the illumination is performed corresponding to the focus detection area that moves with the change in the focal length. Therefore, it becomes possible to detect the focus even in the focus detection area deviated from the optical axis of the photographing lens. Further, since the wide area is not illuminated but only the necessary area is illuminated, the power consumption can be suppressed and the focus detection can be performed efficiently.

[Advantages of the Invention] The auxiliary lighting device according to the present invention has a wide illumination range of the auxiliary lighting device so as to cope with the amount of movement of the focus detection area off the optical axis due to the change in the focal length of the taking lens. Therefore, the focus detection area deviated from the optical axis can be illuminated, and the focus detection can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of the appearance of a camera equipped with the auxiliary lighting device for focus detection of the present invention, and FIG. 2 is applied to a camera equipped with the auxiliary lighting device for focus detection of the present invention. A block diagram showing one embodiment of the control circuit, FIG.
1 of the focus detection optical system applied to the focus detection device of the present invention
FIG. 3 (B) is a front view of the imaging optical member in FIG. 3 (A), and FIG. 4 is a subject when an auxiliary lighting device in the camera of FIG. 1 is used. The figure which shows the relationship between the focus detection area and the illumination range by auxiliary light in the above, FIG. 5 is the top view on a certain subject in FIG. 4, FIG. 6 is the auxiliary illumination device for focus detection of this invention. 7 is a view showing an embodiment of the optical system in FIG. 7, FIG. 7 is a front view of the lens portion in FIG. 6, and FIG. 8 is a second embodiment of the optical system in the auxiliary illumination device for focus detection of the present invention. FIG. 9 is a diagram showing the relationship between the focus detection area on the subject and the illumination range by auxiliary light when the light projecting system of FIG. 8 is used, and FIG. 10 is the focus of the present invention. FIG. 11 is a diagram showing a third embodiment of the optical system in the auxiliary illuminating device for detection, FIG.
FIG. 10 is a diagram showing a relationship between a focus detection area on a subject and an illumination range by auxiliary light when the projection system of FIG. 10 is used, and FIG. 12 shows a focus detection area on a photographing screen by the focus detection device. FIG. 13 and FIG. 13 are views for showing the principle of active focus detection. 1 ... Camera body, 2 ... Shooting lens, 3 ... Release button, 4 ... Projection window, 300 ... CCD element, 301 ... CCD drive circuit, 302 ... Digital memory circuit, 303 ... Control arithmetic circuit , 304 ... subtraction circuit, 305 ... addition circuit, 306 ... selector circuit, 307 ... display comparison circuit, 312 to 314 ... register, 315.6 ... decoder, 316, 317 ... AND circuit, 320 to 322 ... … Transistors, LD ₁ to LD ₅ ……
Light emitting diode.

Claims (1)

(57) [Claims] 1. A low-luminance camera for use in focus detection for a plurality of focus detection areas, at least one of which is on the optical axis and one of which is off the optical axis, using light that has passed through an interchangeable photographing lens. In an auxiliary lighting device for projecting auxiliary light for focus detection on a large subject, a light emitting means for emitting auxiliary light without passing through the taking lens, and an off-axis focus due to a change in focus detection of the taking lens An auxiliary lens for focus detection, comprising: a light projecting lens arranged in front of a light emitting means for projecting auxiliary light in an irradiation range having a spread in the moving direction of the detection area on the object. Lighting equipment.