JPS62215248A - Focus detecting device with auxiliary lighting device - Google Patents

Abstract

PURPOSE:To eliminate unnecessary distance measuring operation, inhibit light from being emitted fruitlessly, and to save electric power by inhibiting subsequent searching operation from performed and auxiliary light from being emitted when a search means decides that focus detection is impossible. CONSTITUTION:In case a conversion coefficient K for converting the quantity of defocusing of a zoom lens into the rotating speed of a motor is large, the gradient is small as shown by a straight line A3 and the quantity of focus movement of the lens per time is small, so overlap parts among distance measurement ranges DFE1-DFE3 of distance measurement at points tc1-tc3 of time become large. Namely, the distance measurement range DEF2 is not necessary specially and a object is never missed even when a measurement of distance is not taken at the point tc of time. When the conversion coefficient is large, the focus of the lens is moved by a constant quantity and next distance measuring operation is started. Consequently, the number of times of the emission of the auxiliary light can be decreased without forming any area where the distance measuring operation is impossible, power consumption due to lighting is reduced, and the number of times of giving a person as the object a glare is reduced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a focus detection device that performs focus detection based on the output of an integral type light receiving element, and is particularly suitable for focus detection on a subject with low brightness or low contrast. The present invention relates to a focus detection device including an auxiliary illumination device that projects auxiliary light onto a subject.

[Prior art] Automatic focus adjustment device, so-called autofocus (hereinafter referred to as
A camera equipped with an AF (abbreviated as AF) is equipped with an auxiliary light illumination device, and by emitting this auxiliary light and performing focus detection, it is possible to perform AF even on low-brightness or low-contrast subjects. Detection devices have already been put into practical use. For example, AF according to JP-A No. 60-1.56029
In i-configuration, the number of times the fill light is emitted is limited to two times, and if it is detected that the focus of the subject cannot be detected in fill light mode,
No search is performed to detect whether focus cannot be detected at another lens position, and the auxiliary light is emitted only when the motor is stopped.

[Problem to be Solved by the Invention 1] However, with the API structure described above, no search is performed in order to suppress the emission of the auxiliary light, which has the disadvantage of reducing the possibility of in-focus detection. there were.

[Means for solving the problems] A focus detection device equipped with an auxiliary illumination device according to the present invention has the following features:
A focus detection device that performs focus detection using the output from an integral type light receiving element having multiple pixels includes an auxiliary illumination device that projects auxiliary light for focus detection onto a subject with low brightness or low contrast, and a an auxiliary light mode setting means for setting an auxiliary light mode in which auxiliary light is projected by the auxiliary illumination device; and when the auxiliary light mode setting means is in the auxiliary light mode, the focus detection device determines that the focus of the subject cannot be detected. a search means for detecting whether focus detection is impossible at another lens position; and a search prohibition means for prohibiting the search operation when the search means determines that focus detection is impossible. The present invention is characterized in that the search operation prohibited by the search prohibiting means prohibits emission of the auxiliary light.

1 Effect 1 With the above configuration, when the search means determines that focus cannot be detected as a result of a predetermined search in the auxiliary light mode set by the auxiliary light mode setting means, the search inhibiting means prohibits the search and the auxiliary light mode is set. Emission of light is prohibited.

[Example 1 First, the principle of autofocus will be explained.

The first of the photographic lenses is symmetrical with respect to the optical axis.
The subject light beams that have passed through the first and second regions are respectively re-imaged to create two images, and the mutual positional relationship of these two images is determined to determine the amount of deviation of the imaging position from the expected focal position, and the A focus detection device has already been proposed that determines whether the image position is in front or behind the expected focal point position, and FIG. 10 shows the configuration of its optical system.

A condenser lens 6 is disposed at a predetermined focal plane 4 behind the photographic lens 2 or at a position further rearward from this plane 4, and reimaging lenses 8 and 10 are disposed symmetrically with respect to an optical axis 18 at a position further rearward. However, one-dimensional image sensors 12a and 12b each having an image pickup device COD as a light receiving element are disposed on the imaging plane of each of the re-imaging lenses 8 and 10, for example. FIG. 11 is a diagram schematically showing a focus detection method using this optical system.

In addition, in FIG. 11, the light receiving element is shown as one one-dimensional image sensor.

In the case of so-called front focus, in which the image of the object to be focused is formed in front of the planned focal plane 4, the image sensor 12
The upper images B and ②+ both approach the optical axis 18, and the distance between them becomes smaller. Conversely, in the case of a rear bin where the image of the object is formed behind the predetermined focal plane 4, the images 1 ++ and B ++ on the image sensor 12 are both far from the optical axis 18,
When the mutual distance becomes large and the images are in focus, the mutual distance between the images on the image sensor 12 becomes a specific distance defined by the configuration of the optical system of the focus detection device. Therefore, by detecting the distance between the two images on the image sensor 12, the state of focus on the object can be determined.

Next, the calculation of the lens movement amount, ie, the defocus amount DF, required to move the focusing lens at the expected focus position will be explained.

FIG. 12 shows each pixel constituting the image sensor 12, and the image sensor 12 is
Assuming that the distribution of image 1 thus formed corresponds to pixels A and -An, each pixel A is adjusted according to the illuminance distribution of the image. -A
Suppose that pixel signals Iao to Ian are output from n, and similarly, the re-imaging lens 10 causes the distribution of the image (2) on the inno-syn sensor 12 to be pixel B. −B corresponds to n+s,
Il] o ~ Ibn ten. is the pixel signal from each pixel.

Pixel A. -An and B. -Bn+s as image sensor 1
If we call the standard part and reference part of 2, the image I on the standard part
By detecting which part of image 1 on the reference part and image 1 on the reference part match best, and finding the interval between the matching parts, the image 1. The image interval between I1 is known, and the defocus amount, which is the amount of lens movement until the photographing lens 2 is brought into focus, is determined.

Specifically, a total of nine sets of n+1 consecutive pixels in the reference part (Bo-Bn), (B1-Bn+t), -(
88 to Bn+6), and the pixel signals from each set of pixels (■1].-I bn), (I b, -I b
pixel A in the reference portion. The pixel signals 1ao to Ian from -An are sequentially compared, and the output with the highest degree of coincidence is detected. To detect this - political change, for example, find Σl ■)] i 1 J - ■ ai 1 1 = 0 for nine combinations F'' O+ 1 +...8) and find the minimum value among them. What you can do is go away.

For example, the one that best matches ■ao~Ian is T1
1. - I Iin+4, then the set of pixels (B
, -B old 4) and pixel A. The distance -An is the image interval between the image I and the image ① on the image sensor, and the distance is the pixel ＼. Let be the a-th pixel of image sensor-2, and pixel B.

If this is the 5th pixel, the number of pixels is (+] + 4-a
), and if the pixel pitch is d, the image interval ρX is
It is found as x=(b+4-a)Xd...(1).

Now, the designed image interval between image I and image ■ at the time of focusing is ρ. Then, the defocus amount DF at this time is DF=KXI(b+4-a)Xd-L! ol
− It is determined by (2). Here, K is a constant specific to the focus detection optical system. This defocus amount DF1 also includes information on the direction of defocus,
If DF is positive, it is a rear pin, and if DF is negative, it is a front pin. Note that the range of the defocus amount DF that can be detected by this calculation is KX ((b-a)Xd Nol≦DF≦KXI(
1] + 8 a) Xd Nol −(3),
In the distance measurement calculation, the defocus amount DF can be detected within the range shown by equation (3). Hereinafter, the range expressed by this equation (3) will be referred to as the defocus coverage range.

” A method for more accurately determining the image interval by detecting the degree of coincidence between images I and II on two consecutive image sensors was disclosed by the applicant in Japanese Patent Laid-Open Nos. 59-126517 and 60-491.4. However, since the gist thereof is not the subject of this application, it will not be described in detail here.

Next, the contrast value C9 correlation level value YM and pixel signal peak value P used for determining the reliability of the defocus amount DF and determining the emission of auxiliary illumination will be explained.

The pixel peak value P is defined as the maximum value of the pixel signals (ao to Jan) of the reference portion used for calculating the defocus amount DF. That is, P = maxl I a
o, -I anl - (4) Furthermore, the fund trust value C is defined by the following equation.

The correlation level signal YM is 1! =1.2. ..., 9 When we define the −political change function, Hmin(+2)=+n1n((H(1), H(2),
−1((9)l −(7)) It is defined as the value obtained by normalizing the minimum value of H(ρ) by the contrast value C.

YM=Hmin(β)/C・(8) Standardized by contrast value C is −political change function H(ρ
) depends on the contrast value.

Note that the correlation level value YM obtained here is obtained in units of pixel pitches, or in fact, the coincidence function is often minimized at an intermediate position between pixels. Therefore, interpolation calculation can be performed to find the position ρmin where the minimum value Hmin(p) of H(ri) is truly minimum.

Note that the correlation level value YM expressed by equation (8) becomes more accurate if the value at this true minimum position/min is determined.

Regarding this interpolation calculation method, please refer to Japanese Patent Application Laid-open No. 5
9-1265], No. 7, so it will not be discussed here.

Here, either the pixel peak value P is below a predetermined value and the subject is dark, the foundation value C is below a predetermined value and the subject is low contrast, or the correlation level value YM
is greater than or equal to a predetermined value, the reliability of the distance-measuring defocus amount DF is low. These cases are called low contrast.

Next, an embodiment of an autofocus camera to which the present invention is applied will be described.

Figure 1 shows the overall configuration of the camera. In the figure, the part surrounded by a dashed line is the camera body BD, and the part located on the left side of the camera body BD is a replacement part that can be attached and detached from the camera body BD. A zoom lens LZ is shown as an example of a lens, and the upper part of the camera body BD is an electronic flash device FS with an auxiliary illumination device AL built therein.

Camera body BD and zoom lens LZ are connected to clutch 10.
6 and 107, and electrically connected via contact group A. In addition, electronic flash device F
S is electrically connected to the camera body BD via a contact group B.

Focus adjustment lens group FL of zoom lens LZ.

A portion of the light beam that has passed through the zoom lens group ZLJ and the master lens group R ML is reflected by the main mirror 110 and advances to a portion of the finder, and the rest is reflected by the main mirror 110.
It passes through a part of the half mirror in the center of the sub mirror 111.
Autofocus (AP) sensor module 1 via
The optical system is configured to be guided to 21.

The AF sensor module 121 includes an interface circuit 1
The lens circuit 1 is electrically connected to the AF switch roller 128 via 22 and provided within the zoom lens LZ.
25 is connected to the controller 128 via the contact group A and the signal line 5SL2. The AP control roller 128 calculates the amount of defocus based on information from the AF sensor module 121. Also, the lens circuit 125
Based on the lens information sent by and the focal length value set by the photographer by rotating the zoom ring
The F control roller 128 converts the calculated defocus amount into the number of revolutions of the lens drive motor required to move the focus adjustment lens group FL to the in-focus position.

Next, the configuration of power transmission for performing focus adjustment will be explained.

A motor drive circuit 124 that drives the motor 109 and an encoder 123 that monitors the speed and number of rotations of the motor are also connected to the AF switch roller 128, and the motor 109 is driven and controlled according to the number of rotations determined by the above calculation. Ru. The power of this motor 109 is from the camera body BD.
The drive mechanism 108, the clutches 107, 106. The light is transmitted to the large gear 103 provided on the outer periphery of the focus adjustment member 102 of the focus adjustment lens group PL via the transmission mechanism 105 and small gear 104 on the zoom lens LZ side.

A female helicoid is formed on the inner periphery of the focus adjustment member 102, and a fixing part 101 integrated with the lens mount
A male helicoid is formed to screw into the female helicoid. The focus adjustment lens FL is moved back and forth by the power transmitted to the large gear 103, and focus adjustment is performed.

In addition, the electronic flash device is connected to the AF switch roller 128 through the contact group B by the signal line 5SLI, and the controller 128 controls the light emission and stop of light emission with the flash discharge tube 130 and the auxiliary lighting device AL. It is configured to be

FIG. 2 shows a control circuit in the autofocus camera.

MC0M is an 8-bit microcomputer that performs sequence control of the entire camera such as automatic focus adjustment and exposure.
(hereinafter abbreviated as microcomputer), and the controller 128
corresponds to

S is a switch that is turned on in the first step of pressing the shutter release button halfway, and when this switch Sl is turned on, power is supplied to this circuit from a power supply circuit (not shown), and automatic focus adjustment, which will be described later, is performed. Then, a series of photometry operations is started. S2 is a switch that is turned on at the second stage of pressing the shutter release button to the fully pressed state, and when this switch S2 is turned on, the exposure operation is started. The negative ends of these switches S, , S2 are each grounded, and the other ends are pulled up to the voltage ■ through the resistors RllR2, and are connected to the inverters INV1 . The signals are input via INV2 to interrupt input terminals lNTl and INT2 of the microcomputer MCOM, respectively.

FLM is a CCD image sensor corresponding to the AF sensor module 121, and includes a reference signal generation circuit R3 and a brightness monitor circuit MC. The brightness monitor circuit MC generates a brightness signal AGCO3 indicating the degree of integration of the CCD image sensor, and the reference signal generating circuit R
3 is a luminance signal AGCO3 and a CCD image sensor F
A reference signal DO8 is output as a reference for the video signal O8 from the LM. IF1 to IF6 and OR1 indicate the interface circuit 122 in block form, and the operations in these circuits are explained by the CCD image sensor FLM.
The explanation will be based on the operation.

First, the CCD image sensor FLM is a microcomputer MC0.
Terminal P of M. By outputting a high-level pulse as an integration clear signal ICG from step 3, it is initialized (1) and starts integration. At the same time, the reference signal generation circuit R3 and the brightness monitor circuit MC are also initialized, and in synchronization with the start of integration of the CCDC image sensor LM, the reference signal generation circuit R3 outputs the reference signal DO8, and the brightness monitor circuit MO outputs a luminance signal AGCO3.

The AGC controller circuit IP2 monitors the subject brightness based on the difference between two input signals, the brightness signal AGCO3 and the reference signal DO8, and controls the COD image sensor FL.
When determining whether to end the integration of M, if the difference between the two signals reaches a predetermined value, the AGC controller circuit 1i8IP2 connects the terminal P of the microcomputer MC0M to stop the integration. 1 and S via OR circuit ○R1
An integration stop signal TINT is sent to the H pulse generation circuit IF3 and the sensor drive pulse generation circuit IF4.

When the integration stop signal TINT is input, the SH pulse generation circuit IF3 outputs an integration end signal SH to end the integration to the COD image sensor FLM. Further, the sensor drive pulse generation circuit IF4 synchronizes the clock pulse φout: outputted from the terminal CI- of the microcomputer MC0M with the integration stop signal TTNT, and generates sensor drive pulses φ1. It is converted into φ2 and sent to the CCD image sensor FLM.

On the other hand, after sending out the integral clear signal CG, the microcomputer MC0M starts counting a predetermined time while monitoring the terminal Po+. Now, if the subject is of low brightness, that is, even if the predetermined time count ends, the terminal P. If the integration stop signal TINT is not input to terminal P of the microcomputer MC0M. From 2, the OR circuit ○R1
A high-level pulse signal as an integration stop signal MSH is sent to the SH pulse generation circuit IF3 and the sensor drive pulse generation circuit IF4 via the SH pulse generation circuit IF3 and the sensor drive pulse generation circuit IF4, thereby terminating the integration of the CCD image sensor FLM.

As described above, when the subject is of high brightness, the AGC controller circuit IP2 is used, and when the subject is of low brightness, the microcomputer MC0M is used to control the COD image sensor FL.
The integration of M is terminated.

After completing the integration in 1., the CCD image sensor FLM
The previously described Shisuko sensor drive pulse φ1. In synchronization with φ2, the signals accumulated in each pixel are sequentially output as the video information signal O8.

The subtraction circuit IF1 takes the difference between the video information signal O8 and the reference signal DO8 and outputs it to the amplifier circuit IF5. This amplifier circuit IF5 amplifies the output of the subtraction circuit IFI so that it becomes an appropriate signal level for the next stage A/D conversion circuit IF6, and this amplification factor is determined by the AGC at the end of integration.
Based on the difference between the reference signal DO3 input to the controller circuit IF2 and the luminance signal AGCO3, the signals xl, , x2 . x4. An amplification factor of x8 is selected.

Integration stop signal TI from AGC controller circuit IP2
When the integration is finished by NT, it is multiplied by x1, and when the integration is finished by the integration stop signal MS+ (from the microcomputer MC0M, xl, , x2, x4 depending on the brightness).
．． An amplification factor of x8 is selected. Below, this amplification factor is A
It is called GC data.

Further, the signal is taken into the microcomputer MC0M via the output cover from the AGC controller circuit IF2 or the terminal group BS2.

Each pixel information from the CCD image sensor FLM, which has been analog-to-digital converted by the A/D conversion circuit IF6, is input to the microcomputer MC0M via the terminal group BS.

The above is a description of the part corresponding to the ink face circuit 122 in FIG. 1, but a detailed description is omitted since it was disclosed in Japanese Patent Application Laid-Open No. 125817/1988, which was previously filed by the present applicant.

Next, a circuit for driving and controlling the photographing lens will be explained.

Mol is a motor that drives the photographic lens, and the first
Focusing lens group FL connected as explained in the figure
move. MDRI is a drive circuit for the motor Mol, and is connected to the terminal P I 01 P l of the microcomputer MC0M.
Signals AFMTB, AFMTR from l l P + 2
, AFMTF, the focusing lens group FL is stopped, retreated, and advanced. ENC is an encoder pulse generation circuit, which is activated by the signal AFPEN from the terminal P11 of the microcomputer MC0M, and the motor M○1 is activated.
The microcomputer MC0M sends a pulse signal AFP according to the amount of rotation of the
Sends to the interrupt terminal ■NT3. In this embodiment, 16 pulses are output for each revolution of the motor MO1.

By inputting this pulse signal AFP, the microcomputer MC0
M detects the amount of rotation of motor Mol and connects terminal P101p.
Signals AFMTB, AFMTR, AFMT from HIP+2
F is output, and the motor Mo1 is controlled as described above.

Table 1 shows the states of signals AFMTB, AFMTR, AFMTF and motor Moj.

L E C corresponds to the lens circuit 125 in the zoom lens LZ in FIG. 1, and connects the terminal P 201 P 2 + I
Lens data is serially transferred to the microcomputer MC0M by the start signal C8 and synchronization signal SCK from 22. This lens circuit LEC converts the defocus amount of the zoom lens LZ into a conversion coefficient for converting the number of revolutions of the motor Mol, an infrared correction amount ΔIR that corrects the focal position according to the wavelength of the zoom lens LZ, and an infrared correction amount ΔIR of the camera. The starting aperture value Av of the lens necessary for determining the exposure control value is output.

Pulse signal AF from encoder pulse generation circuit ENC
Let the count number of P be N, and the CCD image sensor FLM
If the defocus amount of the zoom lens LZ calculated by the microcomputer MC0M from the video information is DF, then the conversion coefficient has the following relationship.

N=KXDF Also, if the defocus amount of the zoom lens LZ in daylight is DFd, and DF7oo is the focus amount of the zoom lens LZ with the wavelength of the auxiliary light of 700 nm, then the infrared correction amount ΔIR is as follows. There is a relationship between

DFd=DF, oo-ΔIR Lens data is transmitted to the terminal P7 of the microcomputer MC0M.
．． 'Ii: The lens circuit LEC becomes active by the start signal C8 sent by setting it to H level, and the lens circuit LEC sends the serial data SIN to the microcomputer MC0M in synchronization with the synchronization signal SCK.

As described above, the microcomputer M COM calculates the motor rotation amount based on the defocus amount DF calculated by the image information taken from the CCD image sensor FLM and the conversion coefficient from the lens circuit LEC, and performs automatic focusing operation. At the same time, the end result of the operation is sent from the terminal group BS3 to the focus state display circuit DDC and displayed.

MDR2 is a drive circuit for driving the motor MO2 for film winding, winding and rewinding, and receives signals MM from terminals P401 and P41 of the microcomputer MC0M.
Controlled by MN. Table 2 shows the relationship between the signals MM and MN and the operation of the motor MO2.

LMC is a photometry circuit for exposure control, and the photometry data is
After being digitally converted by the A/D converter AD2, it is input to the terminal group BS of the microcomputer MC0M.

EDO is an exposure control setting input circuit that inputs the film sensitivity and the exposure control mode set by the photographer to the microcomputer MC.
It is sent to the 0M terminal group BS.

The photometric circuit 1-MC is controlled by the microcomputer MC0M.

An exposure control value is calculated based on data input from the lens circuit LEC and the exposure control setting input circuit EDO,
This calculation result is sent to the exposure control circuit EX via the terminal group BS5.
By sending the signal to C, predetermined exposure control is performed, and the result of this calculation is displayed by the exposure display circuit EXD via the terminal group BS6.

S3 is a shooting mode selection switch for selecting frame shooting or continuous shooting, and S4 is an automatic focusing operation (AF
) or release, and S5 is a one-shot switch that locks the AP once the lens is in focus.) A
This is an A/F mode selection switch that selects between F mode and continuous AF mode, which continuously performs automatic focusing.

One end of each of these switches S 3 + S 41 S 5 is grounded, and the other end is connected to resistors R3, R4, R
5 to the voltage V, and are connected to the terminals P 6o+P 611P 62 of the microcomputer MC0M, respectively. Table 3 shows the control details for each state of the switches S, S, S5.

FLS, AL, and C are the electronic flash device FS in Figure 1.
Corresponds to the strobe circuit 126 and auxiliary light emitting circuit 127 in
5o-P53.

ST2 and ST5 are a charging completion signal and an auxiliary light attachment signal sent from the strobe circuit FLS to terminals P50 and PSol, respectively, and ST3 is a dimming signal for controlling the light emission time of the electronic flash device FS. Circuit FLB
This is a light emission stop signal that is sent to the strobe circuit FI-S via the strobe circuit FI-S. ST, connects the auxiliary light emitting circuit A from the terminal P52 to control the light emission and stop of light emission of the infrared light emitting diode LED used as the auxiliary light for focus detection.
This is an auxiliary light control signal sent to the LC. S× is
This is a synchro switch of the camera, and the state of this switch SX is taken into the strobe circuit PLS as a signal ST.

Next, the control operation in the autofocus camera described in item 1 will be explained according to the flowchart of FIG.

When the switch SI is turned on by pressing down the shutter release button in the first step, an interrupt is generated to the microcomputer MC0M by the interrupt 1) input terminal lNTl.Figure 3 (A)
- Step well 101 of the main flowchart shown in (C)
Subsequent programs such as automatic focusing operation and automatic exposure are executed.

In step #102, the image sensor FLM is initialized by initialization, but the details thereof are disclosed in Japanese Patent Application Laid-Open No. 60-241007, so the details thereof will be omitted. Next, in step well 105, various seven lags are initialized. Table 4 shows the flags initialized here and the functions of each flag. Next, the program advances to the integration routine CDINTA after step 106.

Steps #108 to #109 are a routine for determining whether or not to emit auxiliary light. In step #108, if the auxiliary light is to be emitted and the auxiliary light mode flag is 11.
If the flag is set to 11+, the process proceeds to step #109, where the low con search prohibition flag is determined.

To explain the meaning of low contrast search here, even if low contrast is detected as a result of distance measurement calculation, it is only within the defocus coverage range shown by equation (3) above for a certain lens position. However, at lens positions outside the defocus coverage range, results that are not low contrast may be obtained. Therefore, it is necessary to repeat distance measurement (1) while driving the lens from the closest point to the infinity point, and determine whether or not the contrast is low within the large distance range for all shooting. Therefore, when low contrast is detected, the process of repeating distance measurement without driving the lens until detecting low contrast is called low contrast search.

Now, in step #109, if the low contrast search is permitted and the low contrast search prohibition flag is reset to "°0", the process proceeds to step #110, and the longest integration time Tmax of the COD image sensor FLM is set to 50 m5ec.
, and in step #111, the auxiliary light control signal ST,
to H level. As a result, the auxiliary light emitting circuit ALC
operates and the light emitting diode LED starts emitting light. In step #112, after waiting for 5 m5 ec to recover the time responsiveness of the CCD image sensor FLM to changes in subject brightness after the start of light emission, step #114
Integration starts at .

On the other hand, if the auxiliary light mode flag is cleared to O in step #108, or if the low contrast search prohibition flag is set to 1 in step #109, the auxiliary light is not emitted and the step In Step 113, the maximum integration time T max is set to 20 m5ec, and step #1
At step 14, integration of the CCD image sensor FLM is started.

When the integration is started, in step #115, the integration stop signal TINT from the AGC controller circuit IF2 is monitored, and the process proceeds to step #110 or step #1.
It is determined whether the maximum integration time T max set in step 13 has elapsed. If the integration is completed within the maximum integration time T max and the integration stop signal TINT becomes H level, the process proceeds to step #118. However, if the maximum integration time T max elapses before the integration is completed, the step #118 is reached. 117
At step #118, the microcomputer MC0M sends an integration stop signal MSH to stop the integration.

In step #118, the auxiliary light control signal ST is set to L level to stop the light emitting diode LED.

Next, in step #119, the AGC controller circuit I
After importing AGC data from F2 and starting the integration of the next cycle in step #120, photometry is started in step #121, and further, in step #122, the CCD image obtained in steps 114 to #117 is The 8-bit data of each pixel in the sensor FLM is taken into the microcomputer MC0M. This operation is called a data dump, and in parallel with this data dump, the pixel peak value P explained in equation (4) and the contrast value C explained in equation (5) are calculated.

In the next step #123, communication is made with the zoom lens LZ, and the aperture value Av and the infrared correction amount Δ are added to the conversion coefficients described above.
In addition to taking in the IR, information on whether or not the auxiliary lighting device AL is installed is also taken in. In step #124, the defocus amount DF is calculated from the obtained data of each pixel as shown in equation (2).

In steps #125 to #127, photometric calculations are performed. First, in step #125, the above step #1
Import the photometry data started in step 21 and proceed to step #1.
At step 26, the exposure control settings and the auto7 orcus mode explained in Table 3 are taken in, and flags indicating each mode are set.

Exposure calculation is then performed in step #127, and the calculation result is displayed in step #128.

In the next steps #129 and #130, by determining the auxiliary light mode flag and the low contrast search prohibition flag,
It is determined whether or not the auxiliary light is emitted during the integration of the CD image sensor FLM. The case where the auxiliary light mode flag is 1 and the low contrast search prohibition flag is O is when the CCD image sensor FLM is performed by emitting the auxiliary light. The outer correction amount ΔIR is corrected, and the next step #132. Well 133. The reliability of distance measurement is investigated in #134. That is, in step #132, it is determined whether the maximum value P of the pixel output shown in equation (4) is greater than the predetermined value P1, and in step #133, the contrast value C shown in equation (5) is determined to be greater than the predetermined value C1. Further, in step #134, it is determined whether the correlation level value YM expressed by equation (8) is smaller than a predetermined value YM.

The larger the pixel peak value P and contrast value C,
Furthermore, the smaller the correlation level value YM, the higher the reliability of distance measurement. If all of P>P, C>C+, and YM<YM are satisfied, it is determined that the distance measurement is reliable, and the process proceeds to step #135, where the low contrast search prohibition flag and the number of end detections are set. The LS flag shown is reset to O. If P≦P, C≦C1, or YM≧YM, the reliability of distance measurement is considered to be insufficient, and the focus flag is reset to O in step #136, and then the measurement is performed in step #137. Proceed to the unreachable processing routine.

On the other hand, if the fill light is not emitted, step #1
29 or proceeding from step #130 to step #138, it is determined whether the pixel output is abnormal based on the maximum value P or a predetermined value P2, and in step #139 it is determined whether the contrast value C is larger than the predetermined value C2. Step well 1
．． At step 40, it is determined whether the correlation level value YM is smaller than a predetermined value YM2. P>P2, C>C2, YM<YM
If both of 2 are satisfied, it is determined that the distance measurement is reliable and the process proceeds to step #135. However, if either P≦P2, C≦C2, or YM≧YM2,
Since the distance measurement is unreliable, step #141. i
Go forward. In step #141, the auxiliary light attachment signal ST5
It is determined whether the auxiliary lighting device AI- is at level I], that is, whether the auxiliary lighting device AI- is installed. If the auxiliary lighting device AL is installed, the process proceeds to step 142, and the magnification is set by the AGC controller circuit IP2. If the magnification is 2x, 4x, or 8x, it is determined that the subject is dark, and the step well 143 switches on the auxiliary light mode '7.
After the lag is set to 1, step #144 advances to the integration routine CDINTA.

On the other hand, if the auxiliary lighting device AL is not installed in step #141, or if it is determined that the subject is bright in step #142, the process proceeds to step #132, where the maximum value P, contrast value C, and A correlation level value YM is determined. Here, the above P, ,C, ,
YM, and P2. C2°Yl'+4. is P, <P2.
C, <C2, YM, >YM2, and step #138° #139. How to judge the reliability of distance measurement in #140?Step well 132. #1.3
3. The reliability judgment is stricter than the one in 134 (Koori).

This is because the criterion for distance measurement reliability is set high when the auxiliary light is not emitted (step #138).
~ #140) If the above criteria are not met, the process proceeds to the auxiliary light mode from step #141, but in this auxiliary light mode, if the auxiliary lighting device AL is not installed or the subject is However, if the distance measurement reliability is low, the auxiliary light cannot be emitted, so the process proceeds to step #132, and the distance measurement is performed again in steps 132 to #134, where the distance measurement reliability criterion is lowered by one step. Reliability is being determined.

As a result, if the auxiliary light device AL is installed,
By raising the criterion for the reliability of distance measurement using steady light, it is possible to appropriately emit the fill light without performing unreliable distance measurement, and when the fill light is emitted or If the auxiliary light cannot be emitted, the probability of ranging operations for various objects can be increased by lowering the reliability standard.

Step #129. Well 130. Well 138. #139, #
1.40. #141. The auxiliary light mode is determined in step #142, but the determination in step #138 and step #139, that is, the pixel peak value P and contrast value C
The determination is made in parallel with the data dump of the reference section of the CCD. As a result, since the pixel peak value P and contrast value C have been obtained at the time of step #122, it may be determined at this time whether or not to enter the auxiliary light mode ''.

For this reason (this is a step from step well 121).

It is sufficient to follow the flowchart 1 shown in Fig. 4 for the flow up to #123. First, after starting photometry at the step well 121, in step #1201, only the reference portion of each pixel output of the CCD image sensor FLM is detected. In addition to data dumping, pixel peak value P and contrast Y
Calculate the value C.

In step $1202, the contrast value C and the above-mentioned C2 are compared, and if C>C2, the pixel peak value P and the above-mentioned P2 are compared in step #1208. Here P>
In the case of P2, both the contrast t and the peak data are sufficient, so in step #1209, data dump of the reference section of the CCD image sensor is performed, and in step #123
Proceed to.

On the other hand, if it is determined in step #1202 that C≦C2 or in step #1208 that P≦P2, the process advances to step #1203. In step #1203,
If the auxiliary light mode flag has already been set, the process advances to step 1209; however, if the auxiliary light mode flag has been reset, the AG
The AGC data from the C controller circuit IP2 is determined, and if the AGC data is 1, it is determined that the subject is bright, and the process proceeds to step #1209. If the AGC data is not 1, the process advances to step #1205, where the level of the auxiliary light installation signal ST5 is determined, and the auxiliary lighting device AL
If the auxiliary lighting device AL is not attached and the auxiliary light installation signal ST5 is at the H level, the auxiliary light mode is set at step #1206. The flag is set to 1, and in step $1207, the program proceeds to the integration routine CDINTA.

That is, if it is not the auxiliary light mode, C≦C2 or P≦
If it is P2 and the AGC data is not 1, if the auxiliary illumination device AL is attached, the auxiliary light mode is set and the process proceeds to the next integration routine. Furthermore, the auxiliary light mode may be determined based on the pixel peak value P, contrast value C, and AGC data at the time when the data dump of the reference section is completed.

Also, in the step well 1201, the contrast value C is calculated in parallel with the data dump of the reference section, but it is also possible to calculate the contrast value C after the data dump of the COD is completed. It's obvious.

That is, as shown in FIG.
Perform the D data dump, calculate the contrast value C in step #1211, and then calculate the contrast value C9 pixel peak value P, auxiliary light mode flag, AGC data, and auxiliary light in the same way as shown in FIG. Mounting signal ST5
It may be determined whether or not to enter the auxiliary light mode by determining.

Based on the above results, the reliability of the heat was determined to be good.
Proceeding from step #135 to step #145, the defocus amount D obtained in step 124 is converted into a conversion coefficient.
F is converted into the encoder pulse count number N, and the process proceeds to step #146.

Since this defocus amount DF is at the time of integration in steps #114 to #117, step #1 calculates the number of encoder pulses from this time of integration.
The value obtained by subtracting the rotational speed NM of the motor up to the time point 45 from the encoder pulse count number N is set as the drive encoder pulse count number N. Note that when the motor is stopped, the value of NM is O.

Through the above operations, find the drive encoder pulse count number N required for focusing! ), then step #14
The program advances to the motor control routine MPULS from 7 onwards.

Step well 148 L trowel, the high speed flag is determined, the high speed flag is set on the bow, and the motor is set to 1.0. When the motor is driven at a high speed of OOOrpm, the motor control routine MSS after step #149
ET, and the focus flag is reset to O in step #150. In the next step #151, the encoder pulse count number N obtained in step #146 and the preset near zone pulse count number NZON are determined.
Compare 3. This near zone pulse count number N
ZON is used to determine the switching of the motor rotation speed, and when the lens is close to the in-focus position and the encoder pulse count number N is near zone pulse count number N 2O
If it is smaller than N, the rotational speed of the motor is set to a low speed of 1 OOOrpm in step #152.

When such control is performed, accurate control can be performed without the lens exceeding the in-focus position due to inertia. After the high speed flag is reset to 0 in step #153, motor control is started in step #154, and the program proceeds to the integral routine CDINT in step #155.

On the other hand, at step #151 the encoder pulse callan)
If IN is equal to or greater than the near zone pulse count number NZON, the process advances to step #156, and the motor rotation speed is set to 10+ in order to shorten the driving time of the lens to the in-focus position.
A high speed of 000 rpm is set. Step #157
After the high speed flag is set to 1 at step 154, the process proceeds to step I54.

On the other hand, if the high speed flag is reset to 0 in step #148, that is, the motor is 1, . 000r
If the pm is slow or stopped, step well 15
Go to step #1. ,! Encoder pulse count number N obtained in 1.6 and in-focus pulse count number N INF indicating the range of the preset focusing state
are compared. If the encoder pulse count number is less than or equal to the in-7 orcus pulse count number NINF, it is determined that the lens is in the in-focus position, and in this case, in-focus is displayed in step #159. Then, in step #0, it is determined whether the one-shot AF flag is present, and once the lens is in the appropriate position, the one-shot AF flag is locked.If the AP mode is selected and the flag is set to 1, proceed to step #161. Waits for an interrupt from interrupt terminal INT3 or INT2. That is, if the encoder pulse count number N obtained from the distance measurement result is smaller than the encoder pulse count number NJNF when the motor is driving at a low speed, the count from the encoder pulse generation circuit ENC is performed without performing distance measurement again. The motor is driven by a number of N, and the lens is locked in the in-focus position.

On the other hand, if the one-shot AF flag is reset to 0 and continuous AP mode is set, in which automatic focusing is always performed, CDIN is set from step #160.
Proceed to T routine. Also, in step #158, if the encoder pulse count number N is greater than the in-focus pulse count number NjNF, step #16
At step #3, the focus display is turned off, and at step #164, the program proceeds to the motor speed control routine MSSET.

As is clear from the above explanation, the integration of the CCD image sensor FLM and the emission of auxiliary light are performed not only when the motor is stopped, but also while the motor is driving.
You can measure the speed of autofocus operation.

Next, the distance measuring routine CDINT starting from the step well 200 shown in FIG. 3(A) will be explained. In this routine, "renormalization integration", which will be described later, and external light monitoring in the auxiliary light mode are performed.

Here, this renormalization integration and the ambient light monitor in the auxiliary light mode will be explained in detail with reference to FIG.

FIG. 8 shows the integration of the CCD image sensor FLM, the emission of the auxiliary light, the photometry, the data dump of the CCD, the contrast calculation performed in parallel with this, the distance measurement calculation, the auto 7 orcus (AP), and the exposure control (AE). It shows the timing of taking in AGC data from the AGC controller circuit IF2, and becomes active when each reaches the T level.

The period TA in the figure indicates the operation in the auxiliary light mode,
As explained in steps #108 to #118, first,
At time t1, the lighting of the auxiliary light is started, and at time t2, after 5 m5ec has elapsed, the integral (T
I■) is started. When the integration time, which is within 50 +n5ec, ends at time t3, the auxiliary light is turned off and AGC data (AGC■) is taken in. This AGC data acquisition = 40- At time t, immediately after the end of the scan, the CCD integral (T1
■) and start photometry at the same time. In parallel with this photometry operation, the data of CCV' in the multilayer I■ is dumped (DUM■), and a fund trust calculation is performed. At time t when this data dump and contrast calculation are completed, distance measurement calculation, AP control, and A
E operation (DFC■) is started.

As already explained, photometry is performed at the time t when the auxiliary light is turned off.
Since the measurement starts at time t after 3, no photometry error occurs due to the illumination of the auxiliary light. Distance calculation and A in DFC■
At the time t6 when the P control and the AE calculation are completed, the integrator I2 is ended. In other words, after the completion of integrator I■, the next cycle of integrator I■ is started, and during the integration of TI■, the CCD data dump and huntrust operation (DtJM■) for the previous integrator I■ are performed. Measurement 1 [performance W and AF control.

Processing with AE calculation (DFC■) is performed, and the integration of TI■ is completed at time L6 when this process is completed.

As explained above, when the integration of the COD image sensor FLM is completed, the next cycle of integration is started, and the control in which the previous integration data is processed in parallel is called renormalization integration. By performing this renormalization integration, the integration of the CCD image sensor FLM can be performed efficiently, and the distance measurement cycle is shortened, thereby enabling autofocus that responds at high speed.

In this example, the processing time required from the end of the -th integration until the end of the control necessary for AF and the start of the next integration is constant at approximately 20 m5ec, and the renormalization in TI■ The integral is approximately 20 m5ec. Further, as is clear from the chart 70 in FIG. 3, the auxiliary light is turned off during the renormalization and integration. In other words, in the renormalization integration in TI■, the integration is performed without the auxiliary light being emitted, and by monitoring the AGC data (AGC■) and contrast during this renormalization integration, the original image of the subject without the auxiliary light being emitted is determined. brightness and contrast can be obtained.

Further, in the renormalization integration in the auxiliary light mode, distance measurement calculation is not performed, and only AGC data acquisition and CCD data dumping are performed. Therefore, both the reference part and the reference part are not required for CCD data dumping, and only the reference part is performed. Therefore, the CCD data dump (DUM■) during renormalization integration in this auxiliary light mode V is different from the normal CC data dump (DUM■).
The processing time is approximately half that of the D data dump (DUM■). In addition, since the contrast calculation is performed in parallel with this data dump, the brightness and contrast of the subject can be obtained quickly, making it possible to determine whether it is better to perform the next integration using steady light or whether it is better to use auxiliary light. Judgments are made quickly.

Here, when the subject brightness is bright, that is, when the AGC data is 1 and the contrast value C is greater than or equal to the predetermined value C3, the fill light mode is canceled and the AGC data is 2.
．． 4.8, but if the contrast value C is 03 or less, the auxiliary light mode is maintained and the auxiliary light is emitted in the next cycle as well. Note that the value of C3 and its meaning will be described later. The integral numerator I■ is the AGC data (AGC■) and contrast of the renormalization integral in TI■
(DUMP■) indicates that the auxiliary light mode is maintained and integration is performed with the auxiliary light emitted.

Next, the operation when the auxiliary light mode is canceled will be explained.

If the AGC data (AGC■) of the renormalization product I■ is 1 or the contrast value C in DUM■ is smaller than C3, the auxiliary light mode is reset, and in the next cycle of the product I■, the auxiliary light will not be emitted. Not done. The period TB in the figure indicates the case when the auxiliary light mode is not in effect. In this case, all CCD data in the renormalization integration of TI■ is data dumped (DUM■), distance measurement calculation, AP control, AE calculation (DFC■) will be carried out.

Period TO indicates a case where the subject brightness becomes even brighter.

The integration of the CCD image sensor FLM is terminated by the AGC controller circuit IF2 before the longest integration time is reached. Immediately, the processing time for integration becomes shorter than 20 m5ec, and the renormalization product I2 ends before DFC2, which is the integration process of TI2, ends. In this case, the data of the renormalization product I■ is ignored, and the DFC
After the process (2) is completed, a new multiplication element I (2) is started.

Now, returning to chart 70 in FIG. 3, 1) the distance measuring routine CDINT for performing the above-mentioned renormalization integration and mode determination in the auxiliary light mode will be explained.

First, in step #201, the auxiliary light mode flag is determined, and if it is set to 1, that is, in the auxiliary light mode, the process proceeds to step #202, where the integration stop signal TINT is set.
is determined, and if it is at H level, the process advances to step #208, and after the auxiliary light mode flag is reset to O, the process jumps to step #106, the integration routine CDINTA. That is,
If it is determined that the integration has already been completed within 20 m5ec required for the previous integration process and the subject is sufficiently bright, the fill light mode flag is cleared and the fill light mode is canceled.

On the other hand, in step #2o2, the integration stop signal TIN
If T is 1-level, CCD at step well 2゜3.
The integration of is completed, and AGC data is taken in step #204. Then, in step #205, the AG
If the C data is determined and the subject is bright and the AGC data is a bow, proceed to step #208. On the other hand, if the AGC data is not 1, contrast is calculated in parallel with the data dump of the CCD reference section in step #206. will be done. Next, in step #207, the contrast value C is determined, and if it is larger than the predetermined value C3, it is determined that the contrast of the subject itself is sufficient, and step #20
At 8, the auxiliary light mode flag is reset to 0, and on the other hand,
If the contrast value C is less than or equal to C3, the integration routine CDI in step #106 is performed while the auxiliary light mode is maintained.
Fly to NTA.

Here, the value of C3 is set so that C3>C2 with respect to the value C2 in the step well 139 described above.

In other words, by making the conditions for leaving the fill light mode stricter than the conditions for entering the fill light mode, once the fill light mode is selected, the fill light mode is prevented from being cleared due to a slight change in contrast. . This prevents the distance measurement from becoming unstable due to a difference between the distance measurement using the auxiliary light and the distance measurement using the constant light due to entering or not entering the auxiliary light mode.

In this way, in 1) integrated integration in auxiliary light mode, the auxiliary light does not emit light, and the constant light is used for integration.
Capturing of AGC data, data dumping of the reference portion of the CCD, and contrast calculation are performed. This AGC
The brightness and contrast of the subject are determined based on the data and contrast, and a determination is made as to whether to continue the auxiliary light mode.

As is clear from the following explanation, in the renormalization integration during fill light mode, the fill light is not emitted, the mode is determined only by AGC data and fundus, and distance measurement calculations are not performed. The brightness and contrast of the object can be determined in a short time, and the end result is a high-speed determination of whether or not to emit auxiliary light in response to changes in the subject.

Here, step well 205 or well 207 (here, if it is determined that the subject is bright or has contrast, there is a high possibility that distance measurement can be performed using constant light, so the distance measurement can be performed using the data of this renormalization integral. In other words, in step #205, if the AGC data is 1, the auxiliary light mode is reset and the process proceeds to step #120, and in step #207, it is determined that C>C3. In this case, the auxiliary light mode is cleared and data dumping of the reference section has been completed, so the process may proceed to step #122 to perform data dumping of the reference section, and then proceed to step #123.

In steps #132 to #134, if it is determined that distance measurement is impossible due to low contrast, that is, the reliability of distance measurement is low, the process proceeds to the low contrast processing routine shown in FIG.

First, in step #602, it is determined whether the lens is at the end position of the infinity point or the closest point. This end detection is determined when an encoder pulse accompanying movement of the lens is not output within a certain period of time. If the lens is not in the end position, step #603
The process proceeds to , and the low-con search prohibition flag is determined. Low con search is prohibited and the low con search prohibition flag is set to 1.
If the low contrast search is set to , the process advances to step 620 and jumps to the distance measurement routine CDINT. However, if low contrast search is permitted, the process advances to the low contrast processing routine LCONS starting from step #604.

At step #605, a low contrast search flag indicating that low contrast control is in progress is set to 1, and at step #606, the maximum value MAX is set to the drive encoder pulse count hN. This maximum value M
AX is the maximum value that can be set for the encoder pulse number (N), and is expressed as FFFF in hexadecimal, for example.

In the next step 607, the display is turned off, and
The auxiliary light mode flag is determined in step #608,
If it is set to 7lagka bow in fill light mode,
Proceed to step #609.

In steps #609 to #613, the (±, te) orcus amount DF is converted into the rotation amount of the motor using the conversion coefficient K.
The motor drive speed and the distance measurement cycle in the auxiliary light mode are switched, and the control at this point will be explained using FIGS. 9(A) to 9(C).

FIG. 9(A) shows a state in which the low-contrast search is being performed appropriately. The vertical axis is the focal position of the lens,
The horizontal axis represents the time axis. Distance measurement is at time Lc,,Lc
2. This is done at the time indicated by tc3.

If the rotational speed of the motor is constant, the change in the focal position of the lens is determined by the conversion coefficient K, and changes with time as shown by the straight line A1 shown in the figure.

The range of DFEI is used for distance measurement at time tel, the range of DFE2 is used for distance measurement at time tc2, and the range of D is used for distance measurement at time tc3.
This indicates that distance measurement can be performed in the range of FE3, and these distance measurement ranges D FEI, D FE2. D
FE3 is the range of the defocus amount DF shown by equation (3). As is clear from Fig. 9(A), the distance measurement range DF
Since E1 and DFE2 or DFE2 and DFE3 are set to overlap, it is possible to detect the distance by either distance measurement, regardless of the distance to which the object corresponds to the focal position of the lens.

FIG. 9(B) shows the case where the value of the conversion coefficient is small,
As shown by straight line A2, compared to FIG. 9(A),
The outer area is large, and the amount of lens focus movement per hour is large. Therefore, time LC1+Lc2+LQ3
Each distance measurement range DFEI, DFE2. DF
There are areas where distance measurement cannot be performed, such as E31i continuous access, DZl, and DZl. Therefore, in this embodiment, the conversion coefficient K
This means that the rotational speed of the motor is reduced to prevent areas where distance measurement is not possible such as DZl and DZ2 from occurring.

In addition, Fig. 9(C) shows the case where the conversion coefficient K is extraordinary (i), and as shown by straight line A3, the slope is smaller than that in Fig. 9(A), and the value per hour is The amount of focus movement of the lens is also reduced. Therefore, the time te++Lc2+
Each distance measurement range DFEI by TCS distance measurement.

DFE2. There are many overlapping parts in DFE3. In other words, the distance measurement range DFE2 is not particularly required,
Even if distance measurement at time tc2 is omitted, the subject will not be overlooked. Therefore, in this embodiment, if the conversion coefficient is too large, the focus of the lens is moved by a certain amount before starting the next distance measurement, thereby reducing the number of times the auxiliary light is emitted without creating an area where distance measurement is not possible. As a result, power consumption due to light emission is reduced, and the number of times the subject is exposed to glare is also reduced.

Returning again to chart 70 in FIG. 6, the low contrast search in the above-mentioned auxiliary light mode will be explained.

In step #609, the size of the conversion coefficient is determined,
If the set value KALI is exceeded, the rotational speed of the motor is set to 1.0 in step well 610. OOOrpm, and in step well 611, the conversion coefficient K is now set to the set value K.
It is compared with AL2 (KAL2>KALl). If the value of K is smaller than KAL2, KAL1≦K<KAL2
This case corresponds to FIG. 9(A). This process proceeds to step #614, where motor control is immediately started, and then, at step #620, the distance measurement routine CDI
Proceed to NT. Also, if the value of K is greater than KAL2, then K
≧KAL2, which corresponds to FIG. 9(C) in this case,
As mentioned above, unnecessary distance measurement will be performed, so after starting motor control in step #612,
In step #613, the drive encoder pulse count (N) set in step #606 is the maximum value MA.
After driving the lens by NS pulses from X to MAX-NS, the process proceeds to step #614.

On the other hand, in step #609, the conversion coefficient K is set to the set value KAL.
If it is smaller than 11, it corresponds to Figure 9 (B),
As explained, an area where distance measurement is not possible will occur, so step #
At 613, the rotational speed of the motor is set to 5. After reducing the speed to OOOrpm, the process proceeds to step #614.

Further, if the auxiliary light mode is not set according to the determination in step #608, the magnitude of the conversion coefficient is determined in step #615, and is smaller than the set value KAL 3 (
If so, the rotational speed of the step well 6161 trowel motor5. On the other hand, if the value of KAL is 3 or more, the rotational speed of the motor is set to 10.0 in step #617. Set to OOOrpm, then step #6
Proceed to step 14.

In addition, the value of K A L 3 is K A I-3< K A
It is set to be I-1. This is because the distance measurement cycle in auxiliary light mode is longer than that in steady light, and the conversion coefficient K is large in steady light, so as shown in Figure 9 (C), unnecessary Even if distance measurement is performed, there is no problem of increasing power consumption or giving a shadow to the person as with fill light, so K≧
In the case of KAL3, the motor is driven at 1.0.000 rpm and distance measurement is repeated.

As shown in ``2'', if the defocus force of the lens on the subject or the view is too large and is not within the defocus coverage range,
Repeat distance measurement without driving the lens. Furthermore, by switching the motor drive for the low-contrast search operation depending on the value of the conversion coefficient, 1) accurate and efficient distance measurement can be performed;

In other words, in the auxiliary light mode, even if the K value is small, the drive speed of the motor is reduced to eliminate areas where distance measurement is impossible, and if the K value is extraordinary, a certain number of pulses from the encoder is counted. By waiting until the end, the emission of the auxiliary light can be kept to a minimum, thereby reducing power consumption and improving the usability.

Next, the case where the termination is detected in step #602 will be described.

The motor is immediately stopped in step #618, and the low contrast search prohibition flag is set to 10 in step #619. Depending on the setting of the flag, if low-contrast search is prohibited, proceed to the next cycle's distance measurement routine CDINT in step #620, or if low-contrast search is permitted, low-contrast search is performed in step #621. If the medium flag is determined and low contrast search is not in progress and the flag is reset to O, that is, if the lens starts low contrast search from the end position, step #
At step 629, the LSF flag indicating the first end detection during low-con search is reset to 0, and after reversing the motor at step #630, step #63
At step 1, the process advances to the low-consult search processing routine LCONS.

On the other hand, a low con search is in progress at step #621,
If the flag is set in the bow, that is, if the end is found during the loaf search, the LSF flag is determined in step #622, and the flag is set to 1 at the -th end detection. The process proceeds to step #629 and later, and if the low-contrast search is continued as described above, or if the end detection is the second time and the flag has been reset to O, the low-contrast search is performed in step #623. The search prohibition flag is set to zero, and the low-contrast search flag is reset to O in step #624. and,
In step #625, low contrast display is performed. Next, in step #626, once the focus is achieved, the lens is locked and automatic focusing operation is prohibited (one shot)
The state of the AP flag is determined, and if it is AP mode and the flag is set to 1, the interrupt terminal NT1 or TN is set again in step #627.
Either wait for an interrupt to occur in T2 or use one shot A
If the mode is not F mode and the flag has been reset to 0, the process proceeds to the distance measurement routine CDTNT in step #628.

In this embodiment, in the above steps #618 to #622,
Once the end of the low-contrast search is detected, the emission of the auxiliary light is also prohibited at the time the low-contrast search is prohibited. This is because even if the auxiliary light is emitted and distance measurement is performed even after the low-contrast search has been completed, the probability of focus detection is not only low, but also the power consumption is prohibitive, increasing discomfort for the person. Immediately, during low-contrast search, if distance measurement becomes impossible even after one end detection, the next low-contrast search operation is prohibited, and the emission of the auxiliary light is also prohibited, resulting in meaningless auxiliary operation. Eliminating light emission reduces power consumption and improves usability.

Next, the rotation amount of the motor is determined by the encoder pulse generation circuit EN.
When a predetermined pulse signal AFP is input to the interrupt terminal INT3, the interrupt shown in FIG. 7 occurs.

First, in step #702, the drive pulse (N) is subtracted by 1 and a new drive pulse is counted. Step #
The value of the drive pulse count N is determined in step 703, and if it is equal to or greater than the set value N ZON, the motor is currently in the region where the motor is driven at high speed. If N is smaller than N ZON, step #70
After the high speed flag is reset to 0 in step 4, the motor rotation speed is set to 1 in step #705. OOOr
pm. This allows the driving speed of the motor to be appropriately controlled and prevents the lens from overrunning the in-focus position. Then, in step #706, the value of the driving pulse (curran)H is determined again, and the set value NINF
If this is the case, it is determined that the focus is not in focus, and the process proceeds to step #713, where the motor continues to be driven.

On the other hand, if it is smaller than the set value N INF, it is assumed that it is within the in-focus state range, and the in-focus 7 lag is set to 1 in step #707, and in-focus is displayed in step #708. By setting the focus 7 lag here,
If the camera is in the AF priority mode, the release operation is permitted, and if the focus 7 lag is reset, the release operation is prohibited.

In step #709, it is determined whether the drive pulse count N is O. If not, the process proceeds to step #713 and the motor continues to be driven at 1,000 rpm. If so, step #71
The motor is stopped immediately at 0, and then step #7
At step 11, the state of one-shot AF7 lag is determined.

One-shot) If the AF mode is set and the flag is 1, the next distance measurement is not performed, and the process waits for an interrupt from lNT1 or lNT2 in step #714, and if it is not one-shot AF mode V, the process proceeds to step #712. and return.

As is clear from the above explanation, when the auxiliary light mode flag in this embodiment is set at step #143 in the INT routine, the auxiliary light mode is set at step #208.
This will continue until the flag is reset. That is, in the one-shot AF mode, when the auxiliary light mode is entered in step #143, distance measurement using the auxiliary light is performed until focus is achieved unless the 7 lag is canceled in step #208.

Also, in the continuous AP mode, accurate distance measurement with good responsiveness is similarly possible in the auxiliary light mode.

The decision to cancel this auxiliary light mode is made using the renormalization integral AGC.
Since this is done using data and contrast values, efficiency is improved and mode determination can be made without lengthening the ranging cycle.

Furthermore, in the loaf search, by changing the motor speed and the auxiliary light emission interval in the auxiliary light mode using the conversion coefficient K, reliable distance measurement can be performed and low power consumption can be achieved. By prohibiting the emission of auxiliary light during the low contrast search prohibition period, it is possible to eliminate unnecessary emission of auxiliary light and reduce the discomfort caused to the person to be photographed.

Although the auxiliary light emitting device in the above embodiment is described as being built into the strobe device, the auxiliary light emitting device may be provided outside the camera body, or as described in Japanese Patent Laid-Open No. 59-208512. As disclosed in the above publication, the auxiliary light may be provided in the camera body behind the photographic lens, and the auxiliary light may be emitted through the photographic lens.

As explained above, if the end of one degree is detected by low-contrast search, it is determined that distance measurement is impossible, and the next low-contrast search operation is prohibited, as well as the emission of the auxiliary light. It has become so. This eliminates wasteful ranging operations with low probability of focus detection, and also suppresses power consumption by prohibiting meaningless emission of auxiliary light. It should be noted that the low-contrast search may be inhibited by detecting the end once.

Table 1 8FMTB 8FMTRAFMTF Motor Mo
l status 100 Brake 0 1 0 Right rotation 0 0 1 Left rotation 0 0 0 Stop table 2 MM MN Motor MO2 status 0 1
Brake 1 0 Rotation to the right 0 0 Rotation to the left 1 1 Stop table 3 Only exposure 83 is on Quick shooting Continuous while switch S2 is on
P6o4-I - Exposure 84 is off all together, F priority Even if switch S2 is turned on, Piil←H becomes in focus. Exposure is prohibited in main S, on Release switch S2 is turned on, focusing P61←L priority If exposure is started regardless of the point status, the lens will be locked and automatic focusing operation will be prohibited. Effect 1 According to the present invention, when the search means determines that focus detection is impossible, subsequent searches are prohibited and the emission of the auxiliary light is prohibited, so that useless distance measurement with a low possibility of focus detection is performed. By eliminating the operation and prohibiting the emission of meaningless auxiliary light, power consumption can be reduced, and the discomfort caused to the person being photographed can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the configuration of a camera to which the present invention is applied, FIG. 2 is a block diagram showing a control circuit in FIG. 1, and FIGS. 3 (A), (B), and (C). . 4 to 7 are flowcharts showing the operation of the control circuit shown in FIG.
Figures (A), (B), and (C) are diagrams showing the distance measurement range at each point in time for autofocus; Figures 10 and 11 are schematic diagrams to illustrate the principle of auto-7 orcus;
The figure is a diagram showing each pixel of the ranging element in FIGS. 10 and 11. LZ...zoom lens, AL...auxiliary lighting device, F
Brush: Electronic flash device, MC0M: Microcomputer, FLM: CCD image sensor, IFI...
・Subtraction circuit, IF2...AGC controller circuit, 1
F3...SH pulse generation circuit, IF4...Sensor drive pulse generation circuit, IF5...Amplifier circuit, IF6...
A/D conversion circuit, Mol...motor, MDRI...
Motor drive circuit, ENC encoder pulse generation circuit, L
EC...lens circuit, DDC...focus state display circuit, S, , S, , S,, S,, S5... switch, MC
2... Motor, MDR2... Winding motor drive circuit, LMC... Photometering circuit, AD2... A/D conversion circuit, EXC... Exposure control circuit, EXD... Exposure display circuit, EDO.・・Exposure control setting input circuit, ALC
...Auxiliary light emitting circuit. Patent Applicant: Minolta Camera Co., Ltd. Agent, Patent Attorney: 2 people including the above-mentioned 'iN Opening Ro RG2-215248 (21) Figure 4'' - Figure 5, Top

Claims (1)

[Claims] (1) In a focus detection device that performs focus detection using the output from an integral type light receiving element having a plurality of pixels, an auxiliary illumination device that projects auxiliary light for focus detection onto a subject with low brightness or low contrast; an auxiliary light mode setting means for setting an auxiliary light mode in which the auxiliary illumination device projects an auxiliary light at the time of focus detection; and a auxiliary light mode setting means for setting an auxiliary light mode in which the auxiliary illumination device projects an auxiliary light; a search means for detecting whether or not focus detection is impossible at another lens position when the determination is made; and when the search means determines that focus detection is impossible, prohibiting the search operation; What is claimed is: 1. A focus detection device equipped with an auxiliary illumination device, comprising: a search prohibition means; and when a search operation is prohibited by the search prohibition means, emission of an auxiliary light is prohibited.