JP2005017921A - Auxiliary light projecting device and camera system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auxiliary light projecting device projecting appropriate auxiliary light to a photographic lens attached to a camera, and a camera system using the same. <P>SOLUTION: In the auxiliary light projecting device 5 projecting auxiliary light for detecting a focus to a subject based on the level of the luminance or the contrast of the subject and detecting the auxiliary light reflected from the subject by the focus detection means 17 of the camera 1, the focus detection means 17 is constituted of a line sensor 181, and the auxiliary light is made to perform scanning to cross with the arranging direction of the line sensor 181 several times or made to perform scanning while flickering in the arranging direction of the line sensor 181. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an auxiliary light projector for automatic focus detection and a camera system using the same.
[0002]
[Prior art]
Conventionally, in the auxiliary light projector used for automatic focus detection of a camera, when the subject is dark or the contrast is low, an auxiliary light scanning spot is scanned on the subject to ensure the contrast of the subject. There is a light projection device (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-90592
[Problems to be solved by the invention]
In the case of a camera with an interchangeable photographic lens, the photographic angle of view varies depending on the focal length of the photographic lens attached to the camera. In general, the focal length of an interchangeable lens is several mm to several hundred mm, and the shooting angle of view changes accordingly. In the conventional auxiliary light projector, if the irradiation angle of the auxiliary light for focus detection is determined in accordance with the shooting angle of view of the telephoto lens, the automatic focus detection of all the shooting angle of view of the wide angle lens when the wide angle lens is attached. There is a problem that it becomes impossible to project auxiliary light to the area.
[0005]
Also, if the illumination angle of the auxiliary light for focus detection is determined according to the shooting angle of view of the wide-angle lens, the resolution of the projection angle of the auxiliary light will deteriorate when the telephoto lens is attached, and the shooting angle of view of the telephoto lens There is a problem that it is difficult to finely control the projection angle of the auxiliary light throughout.
[0006]
The present invention has been made in view of the above problems, and an object thereof is to provide an auxiliary light projector that projects auxiliary light suitable for a photographing lens attached to a camera, and a camera system using the auxiliary light projector. And
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, auxiliary light for focus detection is projected onto the subject based on the brightness or contrast of the subject, and the auxiliary light reflected from the subject is detected by the focus of the camera. In the auxiliary light projecting device to be detected by the means, the focus detection means is composed of a line sensor, and the auxiliary light is scanned so as to cross a plurality of times with respect to the arrangement direction of the line sensors, or Provided is an auxiliary light projecting device which is scanned while blinking along a line sensor arrangement direction.
[0008]
In the auxiliary light projecting apparatus according to the present invention, it is preferable that the transverse interval or the blinking interval of the auxiliary light is changed according to the pixel pitch of the line sensor.
[0009]
According to the present invention, in the camera system including the camera and the auxiliary light projector, the camera has an auxiliary light target angle calculation unit and focus detection unit information, and the auxiliary light target angle calculation unit is the camera. Auxiliary light projection position is calculated based on photographing lens information from a photographing lens attached to the auxiliary lens, and the auxiliary light projection device uses auxiliary light consisting of continuous light or blinking light based on the calculation result and the focus detection means information. There is provided a camera system characterized in that light is projected onto a subject and reflected light from the subject is detected by a focus detection means of the camera.
[0010]
In the camera system according to the present invention, it is preferable that the photographing lens information is at least one of focal length information or subject distance information of the photographing lens.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 shows a configuration diagram of a camera system equipped with an auxiliary light projector according to an embodiment of the present invention. FIG. 2 shows a schematic configuration example of the focus detection means of the camera system shown in FIG. FIG. 3 is a schematic configuration diagram of exposure amount detection means (AE detection) of the camera system shown in FIG. FIG. 4 shows an enlarged schematic view of the AE sensor shown in FIG. FIG. 5 is a schematic configuration diagram of the auxiliary light projector according to the embodiment of the present invention. FIG. 6 is an explanatory diagram of the auxiliary light projection position of the auxiliary light projector according to the embodiment of the present invention, and FIG. 7 is a schematic diagram illustrating the projection state of the auxiliary light in the finder. FIG. 8 is a schematic diagram showing a projection state of auxiliary light according to the embodiment of the present invention. FIG. 9 is an auxiliary light projection processing flowchart when the AF area is manually selected in the camera system shown in FIG. FIG. 10 is a flowchart of auxiliary light projection processing at the time of automatic AF area selection in the camera system shown in FIG.
[0013]
In FIG. 1, a camera system according to an embodiment of the present invention includes a camera body 1 (hereinafter referred to as a camera), a replaceable shooting lens 3 attached to the camera 1, and focus detection (AF). And an auxiliary light projecting device 5 for projecting auxiliary light used for detection.
[0014]
Light from a subject (not shown) is reflected by the quick return mirror 6 through the photographing lens 3 and forms an image on the finder screen 7, and can be observed by the photographer through the pentaprism 9 and the eyepiece lens 11. A part of the reflected light is guided to the AE sensor 13 and the amount of incident light is measured.
[0015]
The central portion of the quick return mirror 6 is a half mirror, and the light passing through the quick return mirror 6 is reflected by the sub mirror 15 and enters the focus detection means 17.
[0016]
The quick return mirror 6 is driven by a drive unit (not shown), is flipped up from the optical axis at the time of exposure, and the shutter 19 is opened and closed, and all the light from the subject is guided to the film or the image sensor 21 (the following description is imaging) The case where an element is used will be described).
[0017]
The camera CPU 23 incorporated in the camera 1 processes an image signal from the image sensor 21, an AE signal processing unit 25 that processes the signal from the AE sensor 13, an AF signal processing unit 27 that processes a signal from the focus detection means 17. And a display control unit 35 that controls a display unit 33 that displays an AF area in the finder.
[0018]
Also, the camera CPU 23 receives signals from the release button half-press SW 37, full-press SW 39 of the camera 1, the AF mode SW 41 provided in the camera 1, the AF selector SW 43, etc., and performs predetermined sequence control. Is called.
[0019]
In the half-pressed state, the brightness of the subject is detected by the AE sensor 13 to calculate the optimum exposure amount, and the focus detection by the focus detection means 17 is performed, and the focusing operation on the subject drives the photographing lens 3. Done. In the fully pressed state, the quick return mirror 6 is flipped up from the optical axis, the shutter 19 is opened and closed, and the subject image is exposed to the image sensor 21.
[0020]
The AF mode SW 41 performs AF mode selection such as manual, single, and continuous. When manual mode is selected, the auxiliary light emission and focus detection functions do not work. When the single mode is selected, a series of focus detection operations described later are performed in conjunction with the half-pressing operation of the release button. When the continuous mode is selected, the focus detection operation described later is continued during the half-press operation of the release button.
[0021]
The AF selector SW 43 is used by the photographer to input whether the AF area is manually selected by the photographer, is automatically selected, and which AF area is selected in the case of manual selection. Based on the AF area selection information of the photographer, the display control unit 35 displays the AF area on the display unit 33 in the finder.
[0022]
In addition, the camera CPU 23 communicates various information with the photographing lens 3 and the auxiliary light projector 5 via a contact (not shown).
[0023]
The photographic lens 3 has a focal length encoder 51 for obtaining lens focal length information and a subject distance encoder 53 for obtaining a current distance value to the subject, and numerical values of each encoder are transmitted to the camera CPU 23 via the lens CPU 55. Sent. The lens CPU 55 has a ROM (not shown) that stores the photographing magnification β. The photographing magnification β is calculated based on the numerical values of the focal length encoder 51 and the subject distance encoder 53, and the value is transmitted to the camera CPU 23.
[0024]
The photographic lens 3 performs a focusing operation by driving a focus lens group 57 by a lens driving motor 59 (for example, a known ultrasonic motor) based on defocus information based on the focus detection unit 17 from the camera CPU 23. The amount of rotation of the drive motor 59 is detected by the encoder 61. For the encoder 61, for example, an MR (magnetoresistive) sensor or the like is used. The signal from the encoder 61 is sent to the AF control unit 63 in the lens CPU 55. The AF control unit 63 calculates the target drive amount of the focus lens group 57 based on the defocus information sent from the camera CPU 23, and controls the lens drive motor 59 to move the focus lens group 57 to the target position. In this way, feedback control for focusing is performed. The taking lens 3 may be a lens having an image stabilization mechanism.
[0025]
The auxiliary light projecting device 5 includes an auxiliary light projecting unit 81 that is rotatably supported, and a strobe light emitting unit that emits light when the brightness of the subject is insufficient (hereinafter referred to as an SB light emitting unit). 83. In addition, an SBCPU 89 including an auxiliary light control unit 85 that controls the light projecting unit 81 and an SB control unit 87 that controls the amount of light emitted from the SB light emitting unit 83 is provided. Information is transmitted through
[0026]
FIG. 2 shows an example of the AF sensor area (Af detection area) of the focus detection means 17. In the present embodiment, area 1 in which a cross sensor is arranged at the center of the finder, area 2 and area 4 in which horizontal sensors are arranged in the upper and lower areas in the center, and vertical sensors in the left and right areas in the center. There are five detection areas in total, that is, the arranged area 3 and area 5. Each sensor has a width of about 1 mm and a length of about 2 to 5 mm. The arrangement of the AF sensor area is appropriately changed depending on the design of the camera 1.
[0027]
FIG. 3 illustrates an AE detection system and its control. The light beam that has passed through the photographing lens 3 reaches the eyes of the photographer through the quick return mirror 6, the finder screen 7, the pentaprism 9, and the eyepiece lens 11. On the other hand, a part of the light beam diffused by the finder screen 7 reaches the light receiving element 13 through the pentaprism 9 and the photometric lens 101. The light receiving element 13 is a storage type light receiving element such as a CCD element.
[0028]
The AE detection system includes a light receiving / accumulating unit (light receiving element) 13, a transfer unit 103, a voltage converting unit 105, an accumulating gate unit 107, and various control units. As shown in FIG. 4, the light receiving / accumulating unit 13 has a plurality of light receiving segments arranged in a matrix of 20 horizontal and 12 vertical, and accumulates electric charges generated in each segment. In addition, the light receiving and accumulating unit 13 is configured to measure the object scene corresponding to the photographing screen. FIG. 4 shows a state when the divided state of the photometric area is collated on the object scene. Clock pulses necessary for charge transfer are supplied from the timing circuit 109 to the transfer unit 103, and the charges accumulated in the light receiving accumulation unit 13 are transferred to the voltage conversion unit 105 pixel by pixel. The voltage converter 105 converts the 240 charge signals sent from the pixels into the same number of voltage level values, and outputs them to the A / D converter 111 from the output terminal. The accumulation gate unit 103 is a gate that receives a signal from the accumulation time setting unit 113 and commands the light receiving and accumulation unit 13 to start and end charge accumulation. By sending a pulse signal to this gate, the start and end of charge accumulation are performed. I do. The accumulation time setting unit 113 calculates the optimum accumulation time at the next accumulation based on information from the luminance calculation unit 115 and the exposure calculation unit 117 and adjusts the accumulated charge amount. The A / D conversion unit 111 converts the voltage signal from the light receiving element 13 into a numerical signal that can be recognized by the computer, and outputs the numerical signal to the luminance calculation unit 115. The luminance calculation unit 115 uses information regarding the photographing lens 3 input from the in-lens ROM 119, the storage time t input from the storage time setting unit 113, and the signal V (m, n) from the A / D conversion unit 111. Thus, 240 luminance values BV (m, n) are obtained by the following equation.
[0029]
BV (m, n) = log (V (m, n) .k (m, n) / t) / log (2)
However, BV (m, n) indicates the mth region from the left and the nth region from the bottom of each of the plurality of matrix-shaped photometric regions in FIG. The reason why the logarithm with the base of 2 is taken on the right side is to convert it into a luminance value based on the Apex method, and the unit of BV (m, n) is (EV) or (BV). k (m, n) is a correction coefficient unique to each photometric area in the photographic lens 3 attached, and is obtained by experiment or simulation from the open F value, exit pupil position, vignette information, etc. input from the in-lens ROM 119. .
[0030]
When performing the exposure calculation, the exposure calculation unit 117 receives 240 luminance signals from the luminance calculation unit 115, performs the exposure calculation, and calculates an appropriate exposure value.
[0031]
Thus, a camera system equipped with the auxiliary light projector according to the embodiment of the present invention is configured.
[0032]
Next, the auxiliary light projector according to the present embodiment will be described in detail with reference to FIG.
[0033]
In FIG. 5, the auxiliary light emitting unit 81 includes a cylindrical housing 130 in which a substrate 133 that holds an LED element 131 that emits auxiliary light (IRED or LD may be used) is fixed to one end. A movable cylinder 137 formed with a collimator lens 135 fixed is provided at the other end. A fixed diaphragm 139 is provided between the LED element 131 and the collimator lens 135 to limit the luminous flux of the emitted light. In the lower part of the outer periphery of the movable cylinder 137, a recess 143 that abuts the needle-like support member 141 with a sharp tip supported by the housing 130 is provided to support the movable cylinder 137. The movable cylinder 137 is supported so as to be movable up and down and left and right with the depression 143 as a fulcrum. An elastic body 145 that is supported by the housing 130 and presses the movable cylinder 137 in the direction of the fulcrum is provided substantially directly above the recess 143 with which the support member 141 contacts, so that the movable cylinder 137 does not come off the fulcrum due to vibration or the like. It is configured. The movable cylinder 137 is supported by a support member 141 and an elastic body 145 in the vicinity of the center of gravity, and is held in the housing 130 so as to be capable of rotating vertically and horizontally.
[0034]
The movable cylinder 137 is rotated vertically and horizontally by a voice coil motor (VCM) 147 provided on the light emitting element 131 side on the outer periphery of the movable cylinder 137. The VCM 147 in the figure is for turning in the vertical direction (pitching), but a VCM for turning in the left-right direction (yawing) (not shown) is also provided.
[0035]
The amount of rotation of the movable cylinder 137 is detected by the angle detection unit 149 provided at the position facing the VCM 147 on the LED element 131 side of the outer periphery of the movable cylinder 137. A left-right yawing amount detection unit (not shown) and a driving VCM are provided to face the outer peripheral portion of the movable cylinder 137 in a direction substantially perpendicular to this axis in a plane including the axis formed by the VCM 147 and the angle detection unit 149. It has been.
[0036]
In the light emission control of the LED element 131, the LED drive unit 151 controls the drive current of the LED element 131 to control the light emission amount.
[0037]
The auxiliary light control unit 85 in the SBCPU 89 is provided with a light emission amount calculation unit 153 that instructs the LED drive unit 151 to emit light, and transmits information to the camera CPU 23 via the SBCPU 89 to calculate an appropriate light emission amount. Then, an appropriate light emission amount is instructed to the LED driving unit 151.
[0038]
The VCM 147 for rotationally driving the movable cylinder 137 is supplied with a current for rotational driving whose duty is controlled by a pulse width modulation driver (PWM driver) 155, and the movable cylinder 137 is appropriately driven.
[0039]
As the movable cylinder 137 rotates, the angle signal detected by the angle detection unit 149 is sent to the follow-up control unit 159 of the auxiliary light control unit 85 via the LPF & amplifier unit 157. The cutoff frequency of the LPF provided to eliminate the high frequency noise component from the voltage output of the angle detection unit 149 is set to an appropriate value in consideration of the stability of the tracking control unit 159. Further, the amplifier unit has a configuration in which the amplifier gain can be changed in accordance with the change of the dynamic range (detection width) of the angle detection unit 149 described later. The follow-up control unit 159 performs a control calculation for driving the movable cylinder 137 based on a target angle calculation result, which will be described later, sent from the camera CPU 23. Calculation is performed by known PID control or the like based on the output of the angle detection unit 149 and the target angle from the target angle calculation unit 31. The follow-up control calculation output is output to the PWM driver 155 as a drive duty.
[0040]
The auxiliary light target angle calculation unit 31 acquires the focal length information, shooting magnification information, and subject distance information of the photographing lens 3 acquired from the lens CPU 55, and the AF mode SW information, AF selector information, and AE luminance signal information acquired by the camera CPU 23. Based on the AF defocus information, the height L (see FIG. 6) information of the light projecting unit 81 acquired from the SBCPU 89, and the like, the light projection target angle of the auxiliary light is calculated. The calculation result is sent to the auxiliary light control unit 85 in the SBCPU 89.
[0041]
With the above-described configuration and feedback control, auxiliary light can be projected to a target position according to the characteristics of the photographic lens 3, the light beam emitted from the auxiliary light is narrowed down, and only the necessary area is irradiated. Thus, it is possible to increase the light projecting efficiency and obtain the auxiliary light projecting device 5 having the effect of reducing the power consumption.
[0042]
Next, the auxiliary light target angle calculation will be described in detail.
[0043]
Based on the focal length information, photographing magnification (β) information, subject distance information, and AF selection area information of the photographing lens 3 mounted on the camera 1, the projection light target angle of the auxiliary light is calculated. The camera 1 has the AF area arrangement information shown in FIG. In FIG. 2, there are five focus detection areas. Each area is identified as area 1, area 2,... Area 5.
[0044]
In the case of a 35 mm film camera, the size of the focus detection sensor is about 2 to 5 mm in the longitudinal direction and about 1 mm in the width direction when converted to the screen size. In order to calculate the target projection angle of the auxiliary light, it is necessary to define the in-screen coordinates of the focus detection area and its detection direction. In FIG. 2, the center of the screen is the origin (0, 0), and the coordinate values at both ends of each area are stored in the camera CPU 23 as AF area arrangement information. The coordinate scale is about half of the width of the detection area. As described above, when the width is 1 mm, the coordinate scale is 0.5 mm. For example, when the arrangement of area 2 in FIG. 2 is 6 mm high and 4 mm wide with respect to the center of the screen in the horizontal direction of the screen (vertical contrast detection), the arrangement information is (−8, 12), (8, 12), H It is expressed. In the case of area 1, since there are two detection directions, the arrangement information also includes information in both the vertical direction and the horizontal direction. Based on this AF area arrangement information, the swing angle of the auxiliary light is calculated.
[0045]
As shown in FIG. 6A, when the optical axis 171 of the auxiliary light from the auxiliary light projector 5 is emitted in a state substantially parallel to the optical axis 173 of the photographing lens 3, the subject distance R of the subject 175 is short. Since the auxiliary light can be irradiated to a desired position due to the influence of the parallax, it is necessary to correct the projection angle θ of the auxiliary light according to the distance to the subject 175. The correction requires the auxiliary light emission height L from the optical axis 173 of the photographic lens 3. The auxiliary light emission height L is a height CL from the contact point of the camera 1 to the optical axis 173 of the photographing lens 3, and a height SL from the contact point of the auxiliary light projector 5 to the optical axis 171 of the light projecting unit 81. The sum of The camera CPU 23 has the CL, and the SB CPU 89 has the SL. Information on the shooting magnification β and shooting distance R is communicated from the lens CPU 55, and information on SL is communicated from the SBCPU 89 to the camera CPU 23. Based on these pieces of information, the auxiliary light target angle calculator 31 calculates the light projection angle θ of the auxiliary light.
[0046]
When the photographer selects, for example, area 1 in the AF area shown in FIG. 6B, the initial emission angle θini (1) is obtained from FIG.
θini (1) = Arctan (L / R), (R′≈R)
Given in. When area 2 is selected, the initial angle θini (2) is obtained using the shooting magnification β and the area arrangement information (h2).
θini (2) = Arctan ((L−1 / β * h2) / R), (R′≈R). Since R ′ and R are substantially equal, there is no problem in calculation even if R is used in the above formula.
[0047]
Although the initial emission angle θini in the vertical (pitching) direction has been described here, the initial emission angle in the horizontal (yawing) direction is similarly calculated.
[0048]
As a result of the above calculation, the projection position of the auxiliary light is optimized according to the photographing lens 3 attached to the camera 1, so that the target AF area on the subject 175 (for example, as shown in FIG. , It is possible to project auxiliary light to area 1 (white arrow).
[0049]
Furthermore, in the auxiliary light projector 5 according to the present embodiment, the scanning range and the minimum scanning step amount of the auxiliary light are changed based on information such as the focal length of the photographing lens 3 attached to the camera 1. Details will be described below.
[0050]
Since the shooting angle of view changes depending on the focal length of the shooting lens 3 mounted on the camera 1, the swing angle (scanning range) of the auxiliary light for focus detection is changed. The longer the focal length, the narrower the angle of view. For example, in a 35 mm system, when the focal length is 300 mm, the diagonal is about 8 degrees. On the other hand, the shorter the focal length, the wider the angle of view. For example, when the focal length is 18 mm, the diagonal is about 100 degrees. For this reason, it is necessary to optimize the swing angle of the auxiliary light according to the angle of view. When the angle of view is narrow, the swing angle of the auxiliary light may be small, but the accuracy (scanning step) required for the swing angle is small. When the angle of view is wide, the swing angle of the auxiliary light increases, but the required accuracy may be low. The control accuracy of the swing angle depends on the angle detector 149 of the auxiliary light. If the maximum swing angle of the angle detection unit 149 is set to 100 degrees, when the 10-bit A / D circuit is quantized, the control accuracy is approximately 0.1 degrees / LSB, and the auxiliary light swing angle accuracy is also determined to be 0.1 deg or more. It becomes difficult. When used as it is with an imaging lens having a focal length of 300 mm, the image plane resolution is about 0.5 mm from 300 mm × tan 0.1 deg. This means that the auxiliary light can only be shaken with a minimum interval of 0.5 mm.
[0051]
On the other hand, as described above, the width of the AF sensor CCD when converted into the image plane is only about 1 mm wide, and it can be seen that the resolution is clearly insufficient when the scanning step of the auxiliary light is at intervals of 0.5 mm.
[0052]
In the present embodiment, the angle detection output 149 and the movable cylinder 137 are rotated so as to change the swing angle of the auxiliary light and the minimum scanning step amount according to the focal length information and the subject distance information sent from the photographing lens 3 as needed. The minimum rotation step amount of the VCM 147 is also changed.
In this way, by changing the maximum swing angle and the minimum scanning step amount according to the photographing lens 3, it becomes possible to project the auxiliary light for focus detection suitable for the photographing lens 3 onto the subject.
[0053]
The swing angle is calculated based on the focal length information. For example, the swing angle (dynamic range) is set to twice the calculated view angle, and the amplifier of the LPF & amplifier unit 157 provided at the subsequent stage of the angle detection unit 149 is used. Change the gain. Further, the feedback gain of the follow-up control unit 159 is also changed with the change of the amplifier gain of the LPF & amplifier unit 157. By changing the amplifier gain and feedback gain as described above, it is possible to secure an appropriate dynamic range and minimum scanning step amount (resolution) according to the focal length (angle of view) of the photographic lens 3, and optimal auxiliary light irradiation is possible. It becomes.
[0054]
Next, scanning of auxiliary light for the focus detection area will be described.
[0055]
In FIG. 7, focus detection sensors (for example, CCD elements) 181 (hereinafter referred to as line sensors) in area 2 and area 4 are formed by arranging a plurality of light receiving elements 181a in the horizontal direction, and line sensors in area 3 and area 5. Is formed by arranging a plurality of light receiving elements 181a in the vertical direction. In the central area 1, a plurality of light receiving elements 181a are arranged in the vertical and horizontal directions to form a cross-shaped line sensor.
[0056]
FIG. 8 is a diagram illustrating an example of a scanning state of auxiliary light in the present embodiment. When the line sensor 181 arranged in the focus detection area (for example, area 2 in FIG. 7) is scanned from the left side to the right side in the figure while blinking the auxiliary light (flashing scanning) 183, the auxiliary light is continuous. An example of a case where scanning is performed so as to cross the line sensor 181 while making it emit light (wave-shaped scanning pattern) 185 is shown in a single figure.
[0057]
In the blinking scanning, scanning is performed on the line sensor 181 while blinking auxiliary light, so that even when there is no contrast difference in the subject itself, a contrast difference is generated and focus detection becomes possible. The flashing interval of the auxiliary light suitable for focus detection varies depending on the arrangement pitch of the light receiving elements 181a. When the pitch is fine, the flashing interval is shortened to provide auxiliary light suitable for the line sensor 181. The auxiliary light turn-on interval or light extinction interval is preferably 3 to 6 times the pitch of the light receiving elements 181a. In order to avoid generation of a false detection signal, the lighting interval may be aperiodic.
[0058]
Further, when the auxiliary light is continuously emitted and the auxiliary light is scanned so as to cross a plurality of positions of the focus detection sensor 181, the auxiliary light is applied to the light receiving element 181a of the line sensor 181 as shown in FIG. A contrast difference occurs between a place where the light hits and a place where the light does not hit, and the focus can be detected.
[0059]
The auxiliary light scanning control as described above is performed on the target line sensor by the SBCPU 89 synchronizing and driving the LED driving unit 151 and the PWM driver 155 based on the arrangement information of the line sensor 181 from the camera CPU 23. It becomes possible to perform flashing scanning or wave scanning.
[0060]
Next, the focus detection step in the camera system using the auxiliary light projector according to the present invention will be described in detail with reference to FIGS.
[0061]
When the photographer turns on the power of the camera system, the camera CPU 23 obtains various information such as focal length information and subject distance information and stands by.
● (Step 1 (S1)): AE output reading When the photographer takes a shooting posture on the subject and presses the release button halfway down, the AE detection element 13 detects the amount of light from the subject and reads it into the camera CPU. .
(Step 2 (S2)): Based on the information in the auxiliary light necessity determination step S1, it is determined whether or not auxiliary light projection is necessary. When auxiliary light is unnecessary, the auxiliary light emission sequence is ended (END), and a focus detection sequence (not shown) is executed.
(Step 3 (S3)): When the luminance or contrast is insufficient to receive the AE arrangement information receiving auxiliary light, the SBCPU 89 of the auxiliary light projecting apparatus receives the AF detection area arrangement information from the camera CPU 23. Receive. Since the AF detection area varies depending on the camera, it is possible to accurately radiate auxiliary light to the AF selection area by receiving the AF detection area arrangement information. Further, the AF detection area arrangement information includes information on whether the AF detection area is arranged vertically or horizontally. Thereby, the irradiation direction of AF auxiliary light can be changed. When the AF detection area is arranged in the vertical direction, the auxiliary light is irradiated so as to form a horizontal stripe on the AF detection area, and when the AF detection area is arranged in the horizontal direction, a vertical stripe is created. Control to emit auxiliary light.
(Step 4 (S4)): Based on the output from the AF auxiliary light drive control start angle detector 149, feedback control for projecting the auxiliary light to the target position is performed. The auxiliary light projection target angle is set to the aforementioned initial position θini, and the fixed position control of the auxiliary light projection position is started. The initial position θini at this time is performed at the center position of the auxiliary light angle detection unit 149.
(Step 5 (S5)): Judgment whether or not AF area is manually selected. Reads whether AF area selection is manual or automatic. If it is automatic, when automatic selection is described later. The processing of the flow (after S23) is performed. Here, the case of manual selection will be described.
(Step 6 (S6)): Reading of focal length information and subject distance information The camera CPU acquires respective information from the focal length encoder 51 and the subject distance encoder 53 provided on the photographing lens 3 via the lens CPU 55. .
(Step 7 (S7)): The shooting angle of view changes depending on the focal length of the photographic lens 3 mounted on the dynamic range setting camera 1 of the angle detection unit 149, and accordingly, the swing angle of the auxiliary light and the minimum scanning step amount Changes. The dynamic range of the LPF & amplifier unit 157 provided at the subsequent stage of the angle detection unit 149 is set to an optimal value according to the focal length of the photographing lens 3.
(Step 8 (S8)): Read AF selection area The AF selection area information selected by the photographer is read into the camera CPU 23.
(Step 9 (S9)): The auxiliary light target angle calculation unit 31 calculates the auxiliary light target angle based on the output of the auxiliary light target angle changing focal length encoder 51, the information of the distance encoder 53, and the AF selection area information, and the SBCPU 89. , The projection angle of the auxiliary light is set. The output of the subject distance encoder 53 is used for parallax correction. When this process is first performed, the focus is usually not achieved, and this process increases the certainty every time the process is repeated. The reason for changing the target angle toward the AF selection area is that there is a high possibility that there is a subject near the selection area.
(Step 10 (S10)): After the light emission angle of the auxiliary light is set to the target angle in the calibration light emission step 9, the calibration light emission is performed. In calibration light emission, the rough irradiation position and light emission amount of auxiliary light are adjusted from the AE luminance value information. The light emission time is set based on the AE element accumulation time.
(Step 11 (S11)): The AE output reading camera CPU 23 acquires AE luminance value information from the AE sensor 13 after the calibration light emission in Step S10.
(Step 12 (S12)): From the AE luminance value information in the auxiliary light confirmation S11, it is confirmed whether or not the auxiliary light is projected within a predetermined range. Compared with the AE luminance value information read before the light emission, it is confirmed whether or not the luminance output considered to be auxiliary light is obtained.
● (Step 13 (S13)): Change target angle to a different AF area If there is no difference between the AE luminance output before emission and the AE luminance output after calibration emission in step S11, there is no subject in that AF selection area Another possible cause is that the subject in the AF selection area is far away. In that case, calibration light emission is performed again by changing the target angle to an area different from the selected AF area. If the auxiliary light output cannot be obtained even when the entire AF area is irradiated, the photographer is warned and the auxiliary light emission is stopped.
(Step 14 (S14)): The auxiliary light projection approximate position is detected based on the determination AE output whether the auxiliary light projection position is within the predetermined range. The irradiation position is detected by comparing the AE luminance output read before light emission with the AE luminance output read this time. If the auxiliary light irradiation position is within the predetermined range, it is possible to capture the AF area during subsequent main light emission. If it is not within the predetermined range, the auxiliary light target angle is reset (S9) based on the AE luminance output, and the calibration light emission (S10) is performed again.
(Step 15 (S15)) When the defocus amount estimation auxiliary light projection position is not within the predetermined range, the following causes are considered.
[0062]
(A) AF is not in focus and the value of the subject distance encoder 53 is not at the subject distance. For this reason, the parallax correction is not appropriate, and the irradiation position is deviated.
[0063]
(B) There is a deviation in the angle between the optical axis 171 of auxiliary light and the optical axis 173 of the photographing optical lens 3 at the output center position of the auxiliary light angle detector 149.
[0064]
The approximate position to the subject can be calculated from the factor (a). From the auxiliary light irradiation angle θ, the height L of the auxiliary light projector 81, the in-screen auxiliary light confirmation position h2, the shooting magnification β, etc., the subject distance Rt is
Rt = (L−h2 / β) / tan θ
It is represented by However, the photographing magnification β is a function of the subject distance R and the focal distance f. The approximate subject distance Rt can be estimated from the auxiliary light confirmation position thus observed.
(Step 16 (S16)): Determining whether or not the defocus amount is within the predetermined range The defocus amount is obtained from the subject distance estimated as described above and the value of the subject distance encoder 53 sent from the photographing lens 3. If the defocus amount is within the predetermined range, the steps after the auxiliary light target angle changing step (S9 to S13) are executed so that the irradiation position falls within the predetermined range in order to correct the factor (b). If the defocus amount is outside the predetermined range, the defocus amount is sent to the lens, AF driving is performed (S17), and the steps after the auxiliary light target angle changing step (S9 to S13) are executed again. Thus, by estimating the defocus amount, the approximate focus position can be specified even for a blurred image that cannot be detected by focus detection, so that the AF speed can be improved.
(Step 18 (S18)): When the auxiliary light projection position is within the predetermined range in the determination routine of the auxiliary light target angle changing step 14 to the selected AFCCD, the AF area sensor ( The auxiliary light target angle is changed toward the CCD, and the change contents are instructed to the SBCPU 89.
● (Step 19 (S19)): Auxiliary light SCAN
The auxiliary light is scanned and emitted in a predetermined pattern, and the auxiliary light is scanned at the AF sensor position in the AF selection area. An auxiliary light target angle is instructed to the SBCPU 89 as needed in accordance with the shape of an AF sensor (CCD) stored in a ROM (not shown) of the camera CPU 23. By instructing the scan pattern from the camera 1, it is possible to accurately detect the focus in accordance with the AF sensor.
(Step 20 (S20)): AF signal processing Focusing on the subject is performed by a known focus detection process.
● (Step 21 (S21)): Determining whether or not the Defocus is within the Predetermined Range If the defocus amount is within the predetermined range, the AF is terminated and the auxiliary light control is stopped and terminated (END). When the focus amount is not within the predetermined range, the defocus amount is transmitted to the lens.
(Step 22 (S22)): AF driving is performed on the defocus data lens according to the defocus amount. The camera 1 side again executes the steps (S5 to S21) after the AF area manual selection step.
[0065]
The above is the drive sequence at the time of manual selection.
[0066]
Next, the drive sequence (after step 23) at the time of automatic selection will be described with reference to the flowchart of FIG. Processing steps equivalent to those in the manual selection flowchart of FIG. 9 are denoted by the same reference numerals, description thereof is omitted, and only different steps will be described.
(Step 24 (S24)): Step corresponding to step S8 in FIG. 9 to the center of the AF selection area, where the first light projection position of the auxiliary light automatically selects the center of the AF area. Note that the first light projection position is not necessarily limited to the center of the AF area, but generally the center of the AF area is most easily understood. Henceforth, step group SG1 from S9 to S17 is the same as that at the time of manual selection. If the auxiliary light irradiation position is within the predetermined range in S14, the process proceeds to the next S25.
(Step 25 (S25)): Change the AF area The AF area is automatically changed, and the step group SG2 from S9 to S13 is repeated. Thus, all the AF areas are scanned.
(Step 26 (S26)): End of all areas SCAN When scanning of all AF areas is completed, the process proceeds to step 27.
● (Step 27 (S27)): All AF areas were scanned in the step before AF area selection in which auxiliary light was confirmed by AE, and among these AF areas, the position where the auxiliary light was projected was confirmed by the AE sensor. After selecting and executing S18 to S20 and SCAN of all areas with AE output is completed (S28), target AF area selection S29 is executed to select an AF area used for focus detection. Subsequent processing is the same as that for manual selection, and thus description thereof is omitted. Through the above steps, focus detection at the time of automatic selection is executed.
[0067]
The above-described embodiment is merely an example, and is not limited to the above-described configuration and shape, and can be appropriately modified and changed within the scope of the present invention.
[0068]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an auxiliary light projector that projects auxiliary light suitable for a photographic lens mounted on a camera, and a camera system using the auxiliary light projector.
[Brief description of the drawings]
FIG. 1 shows a configuration diagram of a camera system equipped with an auxiliary light projector according to an embodiment of the present invention.
2 shows a schematic configuration example of focus detection means of the camera system shown in FIG.
3 shows a schematic block diagram of exposure amount detection means (AE detection) of the camera system shown in FIG. 1. FIG.
4 shows an enlarged schematic diagram of the AE sensor shown in FIG. 3;
FIG. 5 is a schematic configuration diagram of an auxiliary light projector according to an embodiment of the present invention.
FIG. 6 is an explanatory diagram of an auxiliary light projection position of the auxiliary light projection apparatus according to the embodiment of the invention.
FIG. 7 is a schematic diagram illustrating a projection state of auxiliary light in the finder.
FIG. 8 is a schematic diagram showing a projection state of auxiliary light according to the embodiment of the present invention.
9 is a flowchart showing an auxiliary light projection processing flow when AF area is manually selected in the camera system shown in FIG.
10 is a flowchart showing an auxiliary light projecting process flow at the time of automatic AF area selection in the camera system shown in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Camera 3 Shooting lens 5 Auxiliary light projector 6 Quick return mirror 7 Finder screen 9 Penta prism 11 Eyepiece 13 AE sensor 15 Submirror 17 Focus detection means 19 Shutter 21 Imaging element (film)
23 Camera CPU
25 AE signal processing unit 27 AF signal processing unit 29 Video signal processing unit 31 Auxiliary light target angle calculation unit 33 Display unit 35 Display control unit 37 Half-press SW
39 Fully pressed SW
41 AF mode SW
43 AF mode selector SW
51 Focal Length Encoder 53 Distance Distance Encoder 55 Lens CPU
57 Focus lens group 59 Lens drive motor 61 Encoder 63 AF control unit 81 Projecting unit 83 Strobe light emitting unit (SB light emitting unit)
85 Auxiliary light controller 87 SB controller 89 SBCPU
DESCRIPTION OF SYMBOLS 101 Photometry lens 103 Transfer part 105 Voltage conversion part 107 Accumulation gate part 109 Timing circuit 111 A / D conversion part 113 Accumulation time setting part 115 Luminance calculation part 117 Exposure calculation part 119 ROM in lens
130 Housing 131 LED element 133 Substrate 135 Collimator lens 137 Movable cylinder 139 Fixed aperture 141 Support member 143 Depression 145 Elastic body 147 VCM for rotation
149 Angle detection unit 151 LED drive unit 153 Light emission amount calculation unit 155 Pulse width modulation driver (PWM driver)
157 LPF & amplifier unit 159 Tracking control unit 171 Auxiliary light optical axis 173 Shooting lens optical axis 175 Subject 181 Line sensor 181a Light receiving element 183 Flashing scanning 185 Wave scanning

Claims (4)

In an auxiliary light projector that projects focus detection auxiliary light on the subject based on the brightness or contrast level of the subject and causes the focus detection means of the camera to detect the auxiliary light reflected from the subject.
The focus detection means is composed of a line sensor,
The auxiliary light is scanned so as to cross a plurality of times with respect to the direction in which the line sensors are arranged, or scanned while blinking along the direction in which the line sensors are arranged. apparatus. The auxiliary light projecting device according to claim 1, wherein a transverse interval or a blinking interval of the auxiliary light is changed according to a pixel pitch of the line sensor. In a camera system consisting of a camera and an auxiliary light projector,
The camera has an auxiliary light target angle calculation unit and focus detection means information,
The auxiliary light target angle calculation unit calculates an auxiliary light projection position based on photographing lens information from a photographing lens attached to the camera,
The auxiliary light projecting device projects auxiliary light consisting of continuous light or blinking light to a subject based on the calculation result and the focus detection unit information,
A camera system, wherein reflected light from the subject is detected by a focus detection means of the camera. 4. The camera system according to claim 3, wherein the photographing lens information is at least one of focal length information and subject distance information of the photographing lens.

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