JPS59220709A - Automatic focus detector - Google Patents

Abstract

PURPOSE:To save electric power and to increase a detection speed by deciding on focusing speedily when the integral value of output of a photodetecting element attains to a focus detectable level within a specific projection time. CONSTITUTION:When an image is in focus, light projected from a projecting element 3 is reflected irregularly by an object to strike two areas 6A and 6B of the photodetecting element 6 equally, and the integral values VA and VB of output from the areas have no difference. When the image is not in focus, there is some difference, so the photodetecting element 6 is moved until the difference is eliminated to move a lens associatively. For the purpose, a means which detects the integral values attaining to the specific level and a means which detects the elapse of the specific projection time are provided, and a decision on focusing is made immediately when either detecting means operates.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic focus detection device that automatically detects the focus of an imaging optical system.

Conventionally, as an automatic focus detection device for an imaging optical system, as shown in FIG.
, a light receiving element FD having an FB receives the light and detects the distance from the light receiving position to the object OB, or a focus adjustment state of the imaging optical system is detected.

That is, in the first factor, the object OB is at the position S.

, the projected light spot image projected from the light projecting element LT toward the object OB hits the object OB and is reflected, and the reflected light projected spot image is reflected between the photosensitive areas FA and FB of the light receiving element FD. Assume that it is formed exactly in the middle position.

Then, an object O located at a position S2 far away from the position S1
For B2, the larger the distance between position S1 and position 82, the closer the reflected light from the projected spot image is to the photosensitive area PA side of light receiving element FD (in the upward direction of arrow A in FIG. 1). It is formed. On the other hand, for an object OB5 located at a position S1 (position S1) and a position S3 which is nearer to the target object OB5, the reflected light of the projected spot image is
It is formed in a state closer to the photosensitive area FB side of D (in the downward direction of arrow A in FIG. 1). Therefore, by detecting the position of the reflected light projection spot image formed on the light receiving element FD, it is possible to estimate the current distance state of the object. Specifically, the photosensitive area FA of the light receiving element FD
If you compare the outputs of FB and FB, the photosensitive areas PA and FB will output an output corresponding to the amount of light they receive, so you can see the position where the reflection/projection block (&) is formed.
As shown in the figure, in a system that has an imaging optical system that images the object on the predetermined focal plane FM, if the distance state of the object is known as described above, the imaging optical system Since the focus of the system can be adjusted, the light receiving element FD can be adjusted to the photosensitive area F.
A,! : Move toward the larger output of P and B as shown by arrow A, and when the reflected light projection spot image comes to the exact midpoint between the photosensitive areas FA and FB of the light receiving element FD, the imaging optical system is in focus. The light receiving element F should be focused so that
The focus of the imaging optical system can be adjusted by moving the imaging optical system in the direction of arrow B, that is, in the direction of the optical axis X in conjunction with the movement of D. In other words, FiW, the above light receiving element F
If the difference in output between the photosensitive areas FA and FB of D is zero, the focus is achieved.If the output of the photosensitive area FB is larger than the output of the photosensitive area FA, then the front bin (towards the front of the expected focal plane) If the output of the photosensitive area FA is larger than the output of the photosensitive area FB, then the focus position of the imaging optical system is on the rear side of the planned focal plane. In the case of the front bin, move the imaging optical system to the intended focal point 1fiTFM direction (to the right of arrow B).
In the case of rear focus, if you manually or automatically move the imaging optical system in the opposite direction to the planned focus thTFM (to the left of arrow B),
This allows the imaging optical system to be brought into focus.

By the way, in the above-mentioned device that determines front focus, focus, and rear focus based on the output state of the light receiving element, the above focus detection is generally not possible unless the integrated value of the output of the optical element reaches a certain V level. It is generally known that this cannot be done with high precision. Taking the above device as an example, at the moment when the projected light spot image hits the light receiving element PD, the outputs of the photosensitive sections FA and FB are both close to the noise level, and at which position on the light receiving element FD the projected light spot image is located. I don't know if it's formed. By integrating the output of the photosensitive element PD, the signal level increases, and the ratio S/N of the signal S to the noise level N increases, so that the output levels of the photosensitive elements FA and FB can be compared. However, this makes it possible to accurately detect the focus position.

That is, the focus detection that is performed in accordance with the output of the light receiving element FD as described above cannot be performed with high accuracy unless the projected light spot image is continued to be projected onto the light receiving element FD for a certain period of time and the light reception signal is integrated. .

For this reason, conventional automatic focus detection devices of this type generally continuously project the above-mentioned light spot image for a predetermined period of time, integrate the amount of received light, and then compare the outputs to perform focus detection.

However, the intensity of the light spot image incident on the light-receiving element varies greatly depending on the distance and reflectance of the object, so if the projection time of the light-emitting spot image is constant as described above, the light intensity of the light-receiving element Even though the integrated value of the output has reached a level that allows focus detection, the projected light spot image continues to be projected for the predetermined time.

Therefore, a large amount of wasted power is consumed, the time required for focus detection is long, and because of miniaturization, only a small capacity power supply can be incorporated. This has been a very serious problem in devices such as cameras that require a high focus detection speed.

The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide an automatic focus detection device that is efficient in power consumption and has a high detection speed.

The feature is that the light receiving element receives the reflected light of the projected light spot image projected onto the target object and outputs a signal according to the light receiving position. An automatic focus detection device of an imaging optical system that forms an image of the projected light spot image on a predetermined focal plane necessarily includes a time detection means for detecting that the light emitting time of the light emitted spot image has reached a predetermined time, and the light receiving means. and level detection means for detecting that the integrated value of the output of the element has reached a predetermined level, and further, when either the time detection means or the level detection means detects the predetermined time or the predetermined level. The automatic focus detection device is provided with a determination means for determining the focal box state of the imaging optical system based on the integral value of the output direction of the light receiving element, so that the integral value of the output direction of the light receiving element is determined as the focal point. This is intended to save power consumption and improve focus detection speed by quickly determining focus when the level reaches a detectable level.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 2 shows an automatic focus detection device (hereinafter referred to as A? device)
This diagram schematically shows the overall configuration of the . In the figure, 1 is the imaging lens group involved in focusing operation in the photographing lens as an imaging optical system, and 2 is the imaging surface of the image sensor, and here the imaging surface of the imaging tube is shown. , the imaging plane of a solid-state image sensor, or the #'i film plane. Reference numeral 3 denotes a light projecting element for projecting a beam of light onto the field of view (generally the area to be suppressed), and is composed of a laser diode, an infrared light emitting diode, or the like. 4 is a light projecting lens, and a light projecting element 3 is placed on a subject 5 (generally a distance measuring object) as a target object.
A projected spot image is formed. 6 is a light receiving element,
It is possible to emit output by dividing into two photosensitive areas 6A and 6B, and the area 6A is arranged on the light projecting element 3 side and the area 6B on the opposite side. The light receiving element 6 is composed of, for example, a two-area P-N photodiode or a Ki charge-coupled device. FL is a visible light cut filter, which allows as much of the light from the infrared light emitting diode 3 as possible to pass through and suppresses external light components.

Reference numeral 7 denotes a light-receiving lens, which forms a projected light spot image on the subject 5 onto the light-receiving element 6 . Reference numeral 8 denotes a motor for driving the photographing optical system, which drives the lens group 1 and the light emitting element 3 via a cam or the like.
and the light receiving element 6. Reference numeral 9 denotes an automatic focus detection circuit (hereinafter referred to as F%AP circuit) which moves the motor 7 according to the output of the light receiving element to move the lens group 1 to the in-focus position.

Next, to explain the operation Mb of the apparatus it shown in FIG. Suppose that the same amount of light is received by two areas 6A' and 6B on the optical sensor. In this case, in the light receiving element 6, the area 6A
The difference VA-VB between the integral value VA of the output from the area 6B and the integral value vB of the blade from the region 6B becomes zero. In short, the light emitted from the light projecting element 6 passes through the optical path b1, hits the subject, is diffusely reflected, and further passes through the optical path b2, forming an image on the light receiving element 6. Therefore, assume that the lens group 1 is at the in-focus position at this time and the subject 5 has moved to a distance of 11. Then, as a matter of course, the focus position of lens group 1 shifts to the rear, resulting in a rear bin state. On the other hand, assuming that the light emitting element 6 and the light receiving element 6 remain in the same position, the optical path 1lSl:
bl hits the subject and is diffusely reflected and passes through the optical path a6 to form an image on the light receiving element 6, but as shown in FIG. No.

Therefore, this amount of shift is calculated as the amount of movement of the subject 5, that is, J2 11
The lens group 1 is moved to the in-focus position in accordance with +. That is, the AF circuit 9 rotates the motor 8 in the forward or reverse direction according to the sign of VA - VB (including its magnitude in some cases), thereby camming the projecting element 5, the light receiving element 6, and the lens group 1. etc., so that VA-VB=0, that is, the light is projected.

When the pot image comes to the middle position between areas 6A and 6B on the light receiving element 6, the image of the object at a distance of 1 is sharply focused 421 on the image forming plane 2. As a result, the light projecting element 6 moves to the position 3', the light receiving element 6 moves to the position 6', and the lens group 1 moves to the position 1' with eight ribs. In this case, the projection optical path b1,
The reflected optical path is indicated by a2'. - When the force plate object 5 moves to the 130th position Uλ, the lens group 1 moves in the opposite direction to the above and performs a focusing operation so that #bL,'VA-yB=Q. In this case, the projection optical path is 01, and the reflected optical path is C2.
It is indicated by.

Figures 4 to 7 show other embodiments of an automatic focus detection circuit that performs distance measurement based on the same principle as the device in Figure 2. It's different. Hereinafter, the same members as those in the device shown in Fig. 2 will be given the same numbers and will be briefly explained.

Figure 4 shows a type of so-called half-TTL distance measurement in which a light spot image from a light projecting element is projected through a photographing lens, and the light is received by a light receiving device installed outside the camera. It is something. 10 is a half mirror 2 having a reflective surface 10a configured as a cold mirror, and is disposed between a lens group 1 and an image forming surface 2 of a photographing lens, which is moved especially for focus adjustment. 4' is a light projecting lens, and 3 is a light projecting element.It is desirable that the light projecting element 5Ij is arranged at a position optically conjugate with the image forming surface 2. The movement of the photographic lens 1 is performed in mechanical conjunction with the light receiving element 6.

Figure 5 shows a so-called TTL f system in which light is emitted from a light emitting element and light is received by a light receiving element through a photographing lens.
It is an automatic focus detection device of the iii-distance type. 10'
is a half mirror placed at the same position as 10 in Figure 5.
14' is a light projecting lens; 3 is a light projecting element arranged at a position optically conjugate with the focal plane 2 of the photographing lens 1; It is made to pass. 7' is a light-receiving lens, and 6 is a light-receiving element arranged at a position optically conjugate with the photographing lens 10 and the image plane 2. It is designed to pass through a slumped position.

Note that the light projecting element 6 and the light receiving element 6 are fixedly installed, and are not mechanically interlocked with the photographic lens.

FIG. 6 is a modification of FIG. 5, in which the projected light beam is aligned with the photographing optical axis.

FIG. 7 shows an automatic focus detection device that uses the same light projection system as in FIG. 4 and uses an image sensor 15 provided on the focal plane as a light receiving element for focus adjustment and imaging. It is. The image signal received by the image sensor 13 is divided by the distribution circuit 11 to the ALT' circuit 7 and the image sensor 12.

FIG. 8 shows the photosensitive surface of the image sensor 13 of the device shown in FIG. 7, and when used for focus detection, 15A, 1
The signals from the two zones of 3B are sent to A through the distribution circuit 11.
Send to P circuit 7. In addition, in the case of the one shown in FIG. 1, it is necessary to devise a method to allow infrared light to pass through the image pickup device 13 during distance measurement, and to remove the infrared light during image pickup.

By the way, among the above embodiments, in the type shown in FIG. 2, the light projecting lens 4 and the light receiving lens 7 are located outside the photographing lens 1, so it is possible to increase the size of the projecting and light receiving lenses 4 and 7. This is advantageous in terms of reach, but on the other hand, it has the disadvantage that it cannot be compactly assembled as a whole. On the other hand, the type shown in FIG. 4 has advantages and disadvantages opposite to those of the type shown in FIG. Furthermore, since there is no need for mechanical interlocking between the imaging lens 1 and the projection/reception system, which requires precision, there is also the advantage that the structure is simple. The type shown in Figure 4 has intermediate properties between those in Figures 2 and 5.

The type shown in Figure 5 has a shorter baseline length of the light emitting/receiving system than the one shown in Figure 4, and is disadvantageous in terms of distance measurement accuracy.
Like the one shown in the figure, it has the advantage that the projected light beam remains at the center of the finder even when out of focus. Incidentally, in all of the above types, the light spot image formed on the subject 5 by the light projecting element B is formed on the optical axis of the photographing lens when in focus. In other words, the distance measurement zone of any of the above devices is
There is a reed in the center of the viewfinder.

It becomes an automatic focus detection device without para/Ftx.

In addition, in the device shown in FIG. 7, the light receiving aperture of the light receiving cable 16 is approximately equal to the F number of the photographing lens, so compared to other types of devices, the area of the light receiving aperture can generally be made larger, and the reaching distance can be reduced. It is advantageous in that respect. In addition, in the device shown in FIG. 6, the signal from the camera 16 is distributed to the AF1 path 9 and the imaging circuit 12, but this is because it is practical to distribute it in a time-division manner. This is suitable for systems such as still video cameras that use photons to measure distance prior to shooting.

Next, the structure of the electrical circuit in the above device will be explained with reference to FIG. Each region 6A, I of the light receiving element 6 mentioned above
The reflected light projection spot image received by the SE is supplied to an amplifier circuit as photoelectrically converted optical information at an amount of 101 a + 101 bA, and is sufficiently amplified. At this time, the amplifiers 101a and 101b have a sufficient degree of amplification for the modulation frequency of the infrared light that becomes the projected light spot, and have a sufficient degree of amplification for the frequency of the modulated light from unnecessary sunlight or commercial power. It is desirable to use an amplifier circuit with frequency characteristics that keep speed down. The output of this amplifier is the synchronous detection circuit 10
2a and 102b, and synchronous detection is performed. At this time, the synchronization signal has the same frequency as the light emission drive signal of the light projecting element 3, and maintains a constant phase relationship. The output of this synchronous detection circuit is integrated by integration circuits 103a and 105b, and increases moment by moment at an increase rate proportional to the signal intensity of the reflected light spot image. By the above signal processing, the integrating circuit 103a
, 103b independently from the integral voltage VA +V
B is processed and summed by an arithmetic circuit, which will be explained below, and converted into several bits of digital information.

That is, the integrated voltages vA and vB are converted into a difference signal YA-VB by a subtracter 104 on the one hand, and are converted into a difference signal YA-VB by an adder/R-device 105 on the other hand.
Therefore, the error signal VA + vB is obtained. Difference signal VA-
vB is added to the e-to-French circuit 106, and l vA-vB
get l. This value lvA-vBl is compared with a comparison value Vn in a comparator 107 serving as a comparison means, and the magnitude relationship thereof is output. On the other hand, the sum signal 'VA+vB is compared with the comparison value vL+VH in comparators 108 and 109 as level detection means, respectively, and the magnitude relationship of each is outputted. Furthermore, in the comparator 110, the integrated voltage - and VB
are directly compared in terms of size. The four digital signals obtained from the above are comparators 107, 108,
The outputs of 109 and 110 are applied to a jl order control circuit 111 as an N constant means, and the operation of the entire system is determined.

Reference numeral 112 denotes a light emission driving circuit, which supplies current to the light projecting element 6 in synchronization with a synchronization signal from the control circuit 111 to control the light emission of the light projecting element 2.

A motor drive circuit 113 controls the rotational direction and rotational speed of the photographing optical system drive motor 8 using signals from the control circuit 111.

FIG. 10 shows a further embodiment of the circuit configuration shown in FIG. 9.

Figure 10 shows the part (A) of the circuit in Figure 9.
A low-noise operational amplifier is installed at the first stage of the amplifiers 101a and 101b.
& 201 a T 201 b, and a bypass characteristic is provided by setting the feedback circuits 202 a and 202 b. In the energy of the infrared light actually projected from the light projecting element 3, the external light component can have a considerably thick value compared to the energy returned to the light receiving element 6. The visible light cut filter PL and this circuit tend to have a relatively effective effect of suppressing external light components, and depending on the settings, can be put to practical use for most subjects. Furthermore, capacitor 203
a.

Direct current components such as sunlight are almost completely cut off by the beam 203b. Reference numerals 204a and 204b are AC amplifiers, which sufficiently amplify components near the same wave number as the compliment, and then supply the signals to the next-stage synchronous detection circuit.

The synchronous detection circuits 102a and 102b shown in FIG. 9 include inverters 205a and 205b, an analog switch 206a,
206b, 207a, and 207b, and analog switches 206a, 206b, and 207a.
, 207b by the synchronizing signal 5YNO and alternately selecting the non-inverted signal and the inverted signal.

In another embodiment, a four-phenomenal analog multiplier ° is used, and the input signal and the synchronization signal 5YNC! There is also a method of finding the product of AC components of (not shown).

The synchronously detected signal becomes a DC (pulsating current) component and is supplied to the next-stage integration circuits 103a and 103'b.

This integrating circuit 103a, IDi is an operational amplifier 20
8a.

2081), resistors 209a and 209b, and capacitors 210a and 210b. A current proportional to the synchronous detection output voltage flows through the synchronous detection circuit 102a.
, 102b, flow into capacitors 21 Da and 210b through resistors 209a and 209b f, respectively.
It is accumulated, becomes an integrated voltage, and is applied to the operational amplifiers 208a, 2.
Output is available from 021b. This jK pressure is the VA
+VB. Note that 1211a and 211b are analog switches for initializing the charges stored in the capacitors 21'Oa and 210b.
The Ff (load) accumulated in 0b is cleared by the OLR signal from the control circuit 111 in preparation for the next accumulation.

FIG. 11 shows the integral voltage vAt VB to l vh v
9 shows part (B) of the circuit of FIG. 9 which generates Bl and compares it with the comparison voltage -. Integrating circuit 105a, 1
The integral "I" pressure VA t "IB output from 03b is applied to the operational amplifier 212 and the resistors 216 to 2 with the same resistance value R.
16 to obtain -vA+vB. This direct line is the next stage absolute value circuit 1
Added to 06. The absolute value circuit 106 is an operational amplifier 21
7. Diodes 218, 219, resistor 2 with resistance value 2R
20 to 222, and a resistor 223 having a resistance value R. Operational amplifier 217, diodes 218, 219
, resistor 220.221 configuration of the diode 219
The cathode has a high impedance when a negative input is applied, and a potential that is 11 times the input 1d pressure when a positive input is applied. As a result, the negative input of comparator 224 becomes -0,s I VA V
A voltage of B + is applied. Adding a voltage of 10 -5vn to this positive input is ζ'p, l vA vBl
and vD are compared. Let this comparison value be DD.

In addition, #iIP in FIG. 12 shows the (re) part of the circuit in FIG.
27.22B is added to the positive input. 0.5 VL% U, 5 vH are added to the negative input of each comparator, (vA + VB): vll, (VA + VB
): Comparison of VH is performed, and the comparison values LL and BIB are
Output.

Furthermore, FIG. 13 shows the circuit CD) portion of FIG. 9, where the circuits M, and - are directly compared by a comparator V-Y229K, which outputs the comparison 1ii A B.

FIG. 16 shows another example for obtaining the comparison value DDf: from vA and vB. vA and vB are comparators 230 and 2
51 positive inputs. Also, resistor 2 with resistance value R
62.255 to the negative input. Also,
The negative input is also connected to the current source 234°235, and as a result, the negative input has vB+iR,
α pressure of vA and iR is applied. However, soil is 254.25
5, the output of comparators 230 and 231 is O
It is added to R circuit 266 to obtain output DD. Output D
D Id vA-vB> iR= VD or vB-v
When A> iR= vD, it becomes true logic '1vA-vB
1> Apply VD logic.

FIG. 15 shows a part of the order control circuit 111 implemented in hardware. Clock C is If! The minimum period of the order control circuit 111 is determined, and the light emission modulation of the light emitting element 4 and the synchronization of the synchronous detection circuits 102a and 102b are performed.
It becomes the source of NO. 236 is n kakunta, and the period of this output ON determines the distance measurement period and the maximum integration time iJl. The 7 rods and 70 tabs 257 and 238 are each set by the signals DD and HH, and are reset every distance measurement cycle by the signal On.

The output DDQ of each of the Noritub flops 237.2i.

HHQ is an integration termination signal, which is input to the 7-lip 70-tub 240 via the OR circuit 269 and held at the period of the signal Cu. The inverted output Q of the flip 70 tube 240 becomes the infinite signal FAR. Signals FAR and DDQ are OR circuit 2
41, the 7 lip 70 knob 242 is set, and the motor rotation signal MO is output. This clip flop 2
42 is also reset by the focus signal HHQ, and prohibits the output of the motor rotation signal MO during focusing.
to stop. The signal AE is updated in the clip frog 245 by a signal DDQ representing out-of-focus AB.
It becomes Q. Here, when the Fi front pin, that is, vA>VB, is true logic. Signal EQ and signal FAR are OR
Via circuit 244, a signal F representing the direction of rotation of the motor is supplied.
It becomes N. Final motor ・The drive signals FF (towards infinity) and NN (towards the closest direction) are the output statements Fi of the AND circuit 245 whose inputs are the signals FN and MO, and the signal FN is NOT.
The selection is made by the output of an AND circuit 247 which receives the output obtained through the circuit 246 and the signal MO.

Same JSJ signal 5YNC! is the signal DDQ, and the 111 n
When HQ and both are doubtful and negative, the signal is sent to the OR circuit 259,
AND lLi1 % 2 via ZJOT circuit 248
49 is input to the AND circuit 249. It is output in synchronization with the output OLK of clock C. Integral initialization signal OL output from OR circuit 250
R becomes true logic from when the end of integration is determined based on the output of the OR circuit 269 input to the OR circuit 250 and the signal On until the start of the next integration.

FIG. 16 shows the waveforms observed as each signal in FIG. 15 when the state changes from front focus to rear focus to focus to infinity.

At the front pin, DD rises first, and AB is at a high level at this time. In the rear bin, DD stands up first, but AB
is at a low level. When in focus, JlfB rises. At infinite time, the maximum integration time is reached before any rise occurs.

FIG. 17 shows a part of the apparatus in which a microcomputer is used as the sequence control circuit 111 and the apparatus is controlled by software. This figure also shows the light emitting drive circuit 112 and motor drive circuit 113 of the light projecting element 3. Reference numeral 251 is a microcomputer (for example, it has an internal structure as shown in FIG. 18), and input terminals receive the aforementioned signals DD and AB.

LL and HH are input, and the aforementioned signals 8YNO, OLR, FF, and NN are also output from the output terminal.

Further, it is easy to add a signal bow or the like for controlling the rotational speed of the motor.

The current flowing through the light emitting element 2 is transmitted through the transistors 252 and 25.
5 by the signal 5yNa.

The current flowing through the motor 8 is switched by the signal FF and the signal NN via the transistors 254 to 257, and flows in the forward or reverse direction.

The circuit configuration including the transistors 258, 259 and the diode 260 is a voltage control circuit, and the α pressure applied to the shimotor is switched in two stages by the shi, r, and ow signals. 261
, 262 are a close-range switch and an infinity switch, which are closed when the photographing optical system hits the close-range end and the infinity end, respectively.
This prevents driving beyond the limit.

FIG. 19 shows the trench signal waveforms at various parts of the circuit shown in FIG.

The synchronous signal 5YNO is the synchronous detection circuit j02a.

102b, it is also used for current driving of the light projecting element 3, and a light-emitting RED is obtained. light receiving element 6a,
The electrical signal obtained is obtained by superimposing the reflected light component of the projected infrared light and the external light component of the sun or artificial light, and has a waveform like the signal SPO. This signal is sent to an amplifier 101a with high-pass characteristics.

The signal Amp is obtained by applying the signal Amp to the signal Amp. When the OLR signal is released almost at the same time as the start of light emission, the outputs of the synchronous detection circuits 102a and 102b are integrated, and an integrated waveform like a signal generator nt appears at the output of the integrating circuits 103a and 1053). This integral waveform increase rate is proportional to the amount of emitted light component of the emitted infrared light. Even with very weak human power, a large S/N ratio can be obtained by integrating a sufficient number of times (time).

Next, the operation of the present apparatus will be explained based on FIG. 9 and according to the numbers in the flowcharts shown in FIGS. 20 to 24. Here, it is assumed that a microcomputer (hereinafter referred to as microcomputer) 251 is used as the control circuit 111.

■ When the AF operation switch (not shown) is closed, the control circuit 1
11 starts operating.

(2) First, it is determined whether or not the 8ffiN8 input terminal kl of the control circuit 111 is at a high level. When the 5ENS input terminal is at a high level, the system operates in the adjustment mode shown in FIG. 25, and distance measurement is not performed. In the adjustment mode, the infrared light emitting diode 3 is turned on and off and the output of the light receiving element 6 is set to T. A time-integrating and offset adjustment amplifier circuit 101a.

101b, synchronous detection circuit 102a, 1 (12'b%
By adjusting the integration circuits 103a and 103b or by an adjustment mechanism (not shown), the infrared light emitting diode 3 or the light projection lens 4,
The positional relationship of the light receiving element 6, the light receiving lens 7, etc. is adjusted. Therefore, the normal control circuit 1110HENB input terminal is in a low level state. When the AFfF-excitation switch is closed, the device first operates in the following normal ranging mode.

■ When entering the normal ranging mode, first reset the oo7 lag. The contents of the ■ flag will be described later. Also, as the Ω memory for this ■ flag, microcontroller 2
51 Memo in RAM area! jM(1) shall be used.

(2) After this, the control circuit 111 starts the distance measuring operation. That is, the ff1iJ# circuit 111 first drives the light emission drive circuit 112 and the synchronous detection circuits 102a and 102b in synchronization with the synchronous signal 5YNO, and also drives the integration circuit 1.
Release the clear state of 05a + 105b. As a result, a projected spot image of infrared light is projected from the light projecting element 3 toward the subject in synchronization with the synchronization signal 5YNO.
The reflected light is detected by the light receiving element 6. The light-receiving element 6 receives fc'i! from the two photosensitive areas 6A and 6B according to the amount of light received according to the position of the light-receiving spot image of the reflected light projection spot. A signal is output, which is amplified by amplifiers 101a and 101b, and synchronously detected by synchronous detection circuits 102a and 102b. The optical information obtained in this manner is sequentially integrated by the integrating circuits 105a and 103b, and the output thereof becomes the integrated '4 voltage -1 vB.

This integral magnetic pressure -9VB#i As mentioned above, it is shown below.
The control circuit 111 is arithmetic-processed into the four digital information of
is input. That is, the subtracter 104 adds the difference signal vA-vB to the absolute value circuit 106, and the digital output from the comparator 107 that compares the magnitude relationship between the absolute value lvAvBl and the comparison value VD, DD. The sum signal -+vB from the adder 105 and the comparison value V1. The digital output from the comparator 10B, LL, which is compared in magnitude with the sum signal -+v from the adder 105, and the comparison value vH (
A digital output from the comparator 109 that compares the magnitude relationship between vH>vL and HH ■ A comparator 110 that compares the magnitude relationship between the signal and vB.
On the other hand, in the control circuit 111, the time detection means in the microcomputer determines the integration time of the signal in the integration circuits 103a and 103b, that is, the projection time of the light projecting element.
If this is t, then the maximum integration time is T. The size relationship between the two is compared. Therefore, when these pieces of information are given, the control circuit 111 outputs a signal such that I VA VB l≧or -+
It is determined whether vB≧vH or t≧To. When any one of these five conditions is met, the control circuit 111 determines that distance measurement is complete. Second
Figure 5 shows the reflected light projection spot image P and the integral signal VA when in focus.
r This shows the state of VB, and as shown in FIG. The photosensitive areas 6A and 6B of No. 6 both provide substantially equal large single-shift outputs. For this reason, the integral signal vA,
As shown in FIG. 25 (2), the values of VB are almost the same and increase rapidly. For this reason, as shown in FIG. 25 (2), the signal vA+VB also increases rapidly with time t, while the signal 1vA-vBl hardly increases as shown in FIG. 250. Therefore, for comparison value - IVD% maximum integration time T, vA+vB≧v11, 1vA-vBl<vD and t
<To, it is determined that the image is in focus.

On the other hand, Fig. 26'' shows the state of the reflected light projected spot image and the integral signals vA and ■B when out of focus.When the lens group 1 is in the front focus or rear focus state, the reflected light projected spot image PFi
As shown in FIG. 26, the photosensitive area 6 of the photosensitive element 6
Generally, one of the output signals of A and 6B has a larger value. Therefore, as shown in FIG. 26 (2), one of the integral signals -1VB increases rapidly with time t, but the other integral value hardly increases. Therefore, Figure 26■,
As shown in (2), until the signal vA+vB becomes larger than the comparison value VH, the integration time t reaches the maximum integration time T. By the time it reaches , the signal IVAVBl becomes 1vA-vBl≧chi. Therefore, l VA vys 1≧vD is detected, and if v, +vB<vH and t(To), it is determined that the subject is in the front focus or rear focus state.
This shows the state of the reflected light projection spot image P and the integral signal VA p 'VB when the object 50 is far away or the reflectance of the subject 50 is extremely low. In this case, the reflected light projection spot image P is
Either it is not formed on the light receiving element 6, or even if it is formed, the amount of light received is extremely weak. Therefore, the output signals of the photosensitive regions 6A and 6B of the light receiving element 6 are both small values, and the integral signals vA and VB do not increase gradually as shown in FIG. 27 (2). Therefore, the integration time t is the maximum integration time T. Even if the signal is vA+VB.

l vAVBl are both 1+ as shown in No. 274yl■■
vB≧Vn l ”IAVB l≧VD does not hold.

Therefore, t≧Ti, , vA+vB<vTll vA−
If VB l <vD, it is determined that the subject 5 is far away or in a state where distance measurement is difficult.

As above (% VA + vB≧VH or 1vA-vB
If 1≧VD or t≧T is the condition for determining the completion of distance measurement, when the values of the integral signals vA and VB reach a level that allows distance measurement, automatic focus detection operation can be started immediately and m Wasteful consumption of cargo is prevented. In particular, as will be described later, this device can measure distances with a maximum integration time of 1°. If the time is within the maximum integration time, the maximum integration time T is set within the microcontroller in order to keep the time for one distance measurement cycle constant. Count the time until it reaches T. After the time has elapsed, the next distance measurement cycle is started in order to measure the distance again, so it is T after the distance measurement is completed.

There is no unnecessary consumption of electric charge until the time elapses, and the effect of power saving is extremely high.

FIG. 24 specifically shows the contents of ■ as a subroutine. It will be established in the following order.

(2) The light projecting element 6 and other 6111 distance circuits start operating as described above.

@ Release the clear foreshadowing of the integration circuits 105a and 103b.

θ The light projecting element 3 emits light.

O After that, by stopping the synchronization signal 5YN (:!), the light emitting motion circuit 112 is stopped, and therefore the 36 of the light emitting element 3 is stopped.
Stop light. At the same time, the synchronous detection circuits 102a and 102
The drive of b is also stopped.

(2) Determine whether distance measurement has been completed according to the distance measurement completion determination conditions described above.

○ When the above-mentioned condition for distance measurement completion r is not satisfied, the light emitting element 6 emits light again and the distance measurement is repeated.

■ What are the conditions for distance measurement brother r? i: If 4 is added, signal DD
,AB,LIJ,J(H(JjiJ CH ratio*a 107
．． 108.109゜110 output) is the RAM of the microcomputer
It is stored in memory M (0) within the area. After that, by stopping the synchronization signal IJYNC, light emission wM, @circuit 1
12 is stopped, and therefore the light emitting element 6 stops emitting light.

At the same time, a synchronous detection circuit 102a.

The drive of 102b is also stopped.

(2) Then, by setting the CIJAR output of the control circuit 111 to high 7 bells, the integration circuit 103a.

106b is brought into a clear state in preparation for the next distance measurement operation.

Note after performing the above series of control aII! J.M. (
The 4-bit data stored in 0) performs an automatic focus detection operation and a shift to another distance measurement mode, which will be described later. The subroutine shown in FIG. 24 is also used in other distance measurement modes, which will be described later, by changing the condition for determining the completion of distance measurement in step (2).

Returning again to FIG. 20, when vA+VB≧VH is detected, it is determined that the object is in focus, as described above.

(2) When the focus is determined, a stop signal (Fp=NN=Q) from the control circuit 111 is supplied to the motor drive circuit 113 to stop the motor 8.

■ After the integration time t reaches the maximum integration time T0,
A transition is made to a normal focus distance measurement mode suitable for normal focus, which will be described later, and distance measurement is performed again.

(2) On the other hand, if h vh + VB≧Va does not hold, it is either out of focus or the value of the integral signal -9VB is small, and it is determined here whether this is the case. l VA--1≧
If it is not -, the distance measurement is completed at t≧To, so in this case, as mentioned above, since the level of the integral "signal -9VB is low, the low-level integral signal" IAr V
Perform distance measurement suitable for B. (Support) Transition to low level distance measurement mode as described below.

(2) When 1vA-vBl≧VD, it is determined that the lens group 1 is in an out-of-focus state, and then a determination is made as to whether the focus is from the front or the rear. When vA>VB, it is determined that it is necessary to drive the motor 8 to move the lens group 1 to the nearest side with the rear focus.

(2) Next, the speed control for driving the motor 8 is carried out. In this embodiment, the motor speed is controlled in two steps, and by switching the speed to a low speed when approaching the in-focus state from the out-of-focus state, the lens group 1 is brought to the in-focus position. 1. Preventing overrun. It seems to stop smoothly. Incidentally, this motor speed may be reduced in any number of steps as necessary. Here, the level of the comparison value VL is used as a fixed reference (21') in order to judge whether it is close to the in-focus condition or has deviated greatly. When out of focus, when the distance measurement is completed, that is, 1vA-vB1= At the time when vD is reached, if the signal -+vB is VA+ vB≧vL, the speed is low, vA
When +VB<vI, high speed is used as a general rule. This situation is shown in FIGS. 26 and 28, with FIG. 26 showing the high speed and FIG. 28 showing the low speed.

As can be seen from FIGS. 26 and 28, the closer the focused state is, the closer the reflected light projection spot image P approaches the intermediate position between the photosensitive areas 6A and 6B of the light receiving element 6, so that the integral signals vA and VB The difference in levels will become smaller. Therefore, the closer the lens group 1 is to the in-focus position, the longer the time t at 7 until l VA VB l≧VD becomes 1+v.
The value of B increases. Therefore, the degree of out-of-focus can be determined by the magnitude of 1+vB.

The speed control of the motor 8 and the reflected light spot image P described above
Figure 29 shows the relationship between the positions on the light receiving element 6.
■It is. This increases the amount of light received by the photosensitive areas 6A and 6B when the reflected projected image P moves from the position Pl (rear focus) to the position P5 (front focus) via P2 (coupling bin). I understand. The middle part (2) in Figure 29 is within the low speed range and is represented by the shape ε. The value of ko is set directly depending on the conditions such as the speed of the motor and the inertia of the system. This will cause a problem.
'Here, in this device, the determination of whether or not the distance measuring light is completed when the object is out of focus is controlled by l'A-VB + "'D" constant pressure. In the embodiment of the present application, vL=-vL'
This value is typically set to v, but other values may be set.
Now, let's go back to the flowchart in Figure 20. After being out of focus and being determined to be in focus, V E+v
It is determined whether B≧vL. When large-10-≧vL, the control circuit 111 outputs multiple signals 1 to drive the lens group 1 at low speed as described above.
is controlled by the closest side.

After the time elapses until i;=To is reached, the process returns to step (2) and the distance measurement is performed again in the normal distance measurement mode.

On the other hand, when 40vB<vL in the phase shown in Fig. 20, the motor 8 should be rotated once at high speed in principle as described in -, but here it is further driven to the nearest side at this speed. A determination is made as to whether or not the determination to be made has been made n2 times in a row while the normal probe code is turned over n2 times. When n2 times or less,
Moving to (2), the motor 8 is driven at low speed to the close side.

If it is determined that the motor 8 should be driven toward the closest side at high speed two or more consecutive times, the motor 8 is thereafter driven toward the closest side at high speed. On the other hand, if the judgment that should be made when moving towards the closest position at high speed is not performed n times in a row, for example, if the focus judgment etc.
2. The motor 8 does not become high speed until it is determined that it should be driven continuously at high speed toward the closest side.

As mentioned above, the reason for controlling the speed of the motor 8 is to always excite it at a low speed when starting the motor 8. This improves the starting feel and reduces noise in the integral signals v, , 'WB. This is to prevent the lens group 1 from performing hunting or other operations due to the positioning of the lens.

Regarding the operations of @ to [phase], the operations are exactly the same as those of [phase] to ■ except that the driving direction of the motor 8 is reversed, so a description thereof will be omitted.

Next, the normal focus distance measurement mode will be explained.

It is determined that the focus is on at O■, and at the time of integration I
Jj t is the maximum integration time T. When the distance is reached, distance measurement is performed again in the normal focus distance measurement mode suitable for distance measurement from an in-focus state. This is because there is a possibility that the distance of the subject changes from time to time even after the subject is in focus.
Here, the maximum integration time is T. This is because it is necessary to remeasure the distance every ) to check whether the lens group 1 is in focus. In the normal focus distance measurement mode, the conditions for determining the focus state are from 1 + vB ≧ - to vA + vB ≧ in the normal distance measurement mode.
vL('I, <VH). The reason why the condition for determining completion of distance measurement is changed from 1+vB≧vH to vA+VB≧vI is to widen the range in which it is determined that the focus state is reached. Secondly, the range where it cannot be determined to be out of focus, the cine sensitivity zone, is widened to make it difficult for the lens group 1 to move from the position where it was previously determined to be in focus. For example, if Vl is set to "%-", as shown in FIG. 30, an effect equivalent to doubling the comparison value VD can be obtained, and l v
Since it is difficult to determine that AvBl≧-, h0 is unlikely to be in an out-of-focus state. Therefore, it is possible to reduce malfunctions due to noise superimposed on the integral signal VA*VB.

Also, by lowering the comparison value, the light emitting element 50
It goes without saying that it is possible to shorten the time it takes to emit data, and that it is also advantageous in terms of energy consumption in devices like this device, where one distance measurement cycle takes a fixed amount of time. do not have.

Note that other conditions for determining completion of distance measurement are the same as in the normal distance measurement mode, and subsequent operations proceed in the same manner as in the normal distance measurement mode.

Start distance measurement, and 1vA-vBl≧- or -10VB
When one of the three conditions ≧vL or t≧To is satisfied, the control circuit 111 completes distance measurement, and the comparison signals DD, AB, LL, HH at that time are stored in the memory M(0)Gl(
Remember again.

[Phase] Here, in ■, note jJM, based on the data stored in (0), whether l vAvBl≧vD,
Determine whether the lens is out of focus. l vAvBl
≧vD! When the value is constant, there is no out-of-focus, and distance measurement is performed again in the normal distance measurement mode.

■ When l vp, vn l≧VD, it is in focus or when sufficient signal cannot be obtained because the object is far away or the object's reflectance is low jl), vA+ VB≧vXJ
Depending on whether the focus is on or not, the superposition state of the residual signals vA and vB is determined, and based on that state, it is determined whether or not focus is achieved. When vA+-≧VL, distance measurement is completed at t≧To, and since the integrated signal Vh*VB is extremely low, it is determined that the object is far away or the reflectance of the object is low, and the level is low. Switch to time distance measurement mode and perform distance measurement again.

〇 On the other hand, when -+vB≧vI, it is determined that the camera is in focus, and then the camera counts up to the maximum integration time T0 in the same way as described in ①.

[Phase] Next, it is determined how many times the normal focusing and ranging mode has been repeated. If the number of repetitions is n (no), the camera returns to the normal focus distance mode again, and continues normal focus distance measurement until it reaches n = n or moves to another 6111 distance mode with [phase] or ■. Perform distance measurement in mode. Normal focus distance measurement mode n. After repeating the rotation, when n=no, the mode returns to the normal distance measurement mode, and the arrow O distance measurement is performed in the normal distance measurement mode and in the normal dead zone.

As mentioned above, by returning the dead zone to the normal state every time, a decrease in distance measurement accuracy can be prevented. As a result of the valgus effect, the distance measurement accuracy decreases. Therefore, by returning to the normal distance measurement mode every time, focusing and non-focusing are determined in the normal dead zone, and the distance measurement accuracy decreases. Therefore, by doing this, we aim to achieve both stability during focusing and distance measurement accuracy.
and Vl.

It is necessary to set it to an appropriate value for the above purpose.

Next, the operation in the low level ranging mode will be described based on FIG.

[Phase] As mentioned above, in the normal distance measurement mode or the normal focus distance measurement mode, if both the integral signals vA and VB are at a low level, -is is determined, or in the ω time distance measurement mode described later. When the level of the integral signals vA and VB rises to a certain level and distance measurement becomes possible, the integral signal VA +
``Distance measurement is performed in a low level distance measurement mode suitable for distance measurement when the VB level is low. In the low level ranging mode, the integral signal V is calculated in the same way as in the normal ranging mode.
When A and VB are obtained, completion of distance measurement is determined based on 1+vB≧VH or t≧To. It should be noted that, as a condition for determining completion of distance measurement, --vB≧V yo is excluded here, which is different from the case of the normal 6111 distance mode. This is because in the low level distance measurement mode, the level of the signal detected on the light receiving element 6 is low because the subject 5 is far away or the reflectance of the subject 5 is low, and therefore the integrated signal VA * S of VH
/N is not very good, for example, the magnitude relationship between the levels of the integral signals vA and vB may be opposite to the original values, and this is to prevent erroneous tracking distances from occurring. In other words, if signals in the near direction and infinity direction are output repeatedly, if these are detected as they are, out-of-focus signals in different directions will be output alternately, leading to unstable operation. . Figure 51 is an example of such an integral signal with poor s/ii.As shown in Figure 31 (■), the 1 signal and the VB signal alternate, so the signal shown in ■0 in Figure 31 is At the point <'(I), tvA-vBt≧vDvB>V
If A, it is determined that the front pin state is present, and the control circuit 111 sends a control signal to drive the motor 8 in the infinite direction.
Output. Also, by chance (in terms of probability n(1) -
〉-, there is #:t, but as shown in (I)' (l vA-v
If Bl < vD, distance measurement is not determined at point (I) and 'VA>'VB+ at point (II).
l "Ih VB l > VD is determined by φ. This results in outputting an out-of-focus signal to the motor 8 in the direction completely opposite to that in the above case. The indeterminacy described above is minimized. In order to reduce the distance measurement at low level, in the distance measurement mode, l vA-vBl≧vD is not used as a judgment condition for completion of distance measurement, and after continuing integration until vA+v, teT when J3≧vH is not judged, 1vA-vBl≧Vn. Judgment of
[Stocks] We are planning to do so. By switching between a plurality of modes in this manner, it is possible to achieve both the advantages of the normal ranging mode (power saving, etc.) and the reciprocal nature of the low-level ranging mode.

[Phase] Returning to the flowchart of the distance measurement mode at low level in Fig. 21, when the distance measurement is completed in [Phase], the next time the distance measurement is completed is v.
If A+VB≧−, it is determined whether or not the transfer has been performed. When vA+vB≧VH, it is considered that the signals V and vB are sufficiently large, and it is determined that there is no need to perform distance measurement in the low-level distance measurement mode, and the process returns to the normal distance measurement mode. Fig. 62 shows the signal vA and signal Vn + signal - + VB r signal 1v when returning from low level mode to normal ranging mode.
, - indicated the state of vBl. As shown in ■〈1v, -v
Even if Bl>vD, the distance measurement is not completed and is continued. As shown in ′■
When the condition H is satisfied, distance measurement is completed and the mode returns to normal distance measurement mode.

If VA + vB≧vH, distance measurement is completed at t=T
It means that it was carried out under oO inspection. Continue +vB
The level of the distance is determined, and it is determined whether it should be determined to be infinite or whether it is within a finite distance and a 1 lill distance possible region. 77, +VB≧v1. When (vl<vIi) is not the case, the levels of the integral signals vA and vB are extremely high.

Since the distance is low, it is determined that the object is in an infinite state, and subsequent distance measurement is performed in the infinite time distance measurement mode, which will be described later. Figure 33 shows the signal when entering infinite distance measurement mode.
FIG. 6 is a diagram showing the state of the VA+VB% signal vA+vB. To the result of distance measurement up to t='l'o + v, <
Since the values of the integral signals VA t and VB are both extremely low, it can be determined that the object is in an infinite state, and in this case, the values of lv and -vBl are l VA
-VB Even if l≧VD, l VAVn l < v
Even if it is D, this is ignored. Note that even when the object is not far away and the reflectance of the object is low, the light-receiving confectionery 6 will not be able to obtain sufficient reflected light, so such a situation will occur in this case as well. By the system (l
With ill distance measurement, it is very difficult to distinguish whether an object is far away or has low reflectance. For this reason, assuming that the former is the case, the control circuit 111 sends a control wholesale signal (IFF=j, N
N-0) is output to the motor drive circuit 116. As a matter of course, (if another distance measurement signal is obtained before the liquid lens 1 reaches the ■ end, a stop or reversal signal will be added to the motor drive circuit 115 at that point.) @ vA + When vn≧vL , when the 1+- signal after integrating T0 time is vII≦vA+vB<-, next it is determined whether 1vA-vBl≧-, and 1vA
When vn l < vn, in principle, it is determined that the focus is at a low level. As shown in Fig. 34 (lvA-vBl≧vD
When this happens, it is determined that the focus is out of focus at a low level, and the motor is, in principle, rotated at a low speed in the direction of focus.

[Phase] Now, as stated above (, l vA+ vB l≦
During VD, the control circuit 111 outputs a simulator stop signal as low level focusing, but as an exception c-)
When the flag=1, this stop signal is not output. The flash 72g is set to 1 when shifting to the distance measurement mode at the time ①, and is reset to 0 in the normal distance measurement mode as described above. ■When the flag is set to 1, the control circuit 11
From 1 onwards, the same control signal as before is sent to the motor drive circuit 116.
Output to. If oo7 lag = 1 in the low-level ranging mode, (1) only when transitioning from the hour mode to the low-level ranging mode, and from the ψ hour mode to the low level mode. When shifting to the time distance measurement level mode, a signal to drive the motor in the infinite direction is output as will be described later. Therefore, when oo7 lag=1, the motor 8 continues to move the lens group 1 in the infinite direction even if it is determined that focusing is at a low level.

The reason why we set up the outside of the shrine for flag -1 in this way is that when focusing on a subject that is far away or has a reflectance that is so far that a low-level focus signal is output, there is a large shift from the in-focus state to the close side. It has been experimentally confirmed that when distance measurement is started from a position that is out of focus, the output of the in-focus signal is lost due to leakage current of the light-receiving element 6 while the focus is still in the process of being out of focus. Therefore, if the motor 8 is stopped with such a false focus signal, it will stop in a state where it is largely out of focus.

For this reason, ■ flags are used to identify false focusing signals, and as mentioned above, if the flash flag is 1, the control circuit 111 outputs the infinite direction signal and continues distance measurement in the low-level distance measurement mode. I am planning to do so.

When ooo79g=0, in principle, multiple motor stop signals are output from the control circuit 111, and the motor 8 is stopped.

[Phase] On the other hand, when l vAvBl≧Vp at O, it is determined that the lens is out of focus at a low level. At this time, after it is recognized that the object is out of focus at a low level, a determination is made as to the direction of out-of-focus, that is, a determination is made as to whether p VA > vB.

@ vA > vB (When 0, it is in the rear focus state, and the control circuit 111 determines that it is necessary to activate the motor 8 to move the lens group 1 to the nearest side. Distance measurement at low level In principle, the motor speed rotates at a low speed in the low-level ranging mode.The reason is that in the low-level distance measurement mode, the values of the integral signals VA * 'FB are both small, so the S/N is low and the direction signal is not sufficiently reliable. This is to reduce the instability of the lens group 1, such as hunting.

■ Next, after defocusing at a low level, the focus state continues n
It is determined whether the fourth edition has been determined. n411 When a constant direction signal is obtained continuously, the signals vA and VB
It is judged that the S / N of is sufficiently high, and usually 6 (
Return to 1j distance mode. In this way, the normal distance measurement mode saves t6 hours (1'vAVn l≧VD't' distance measurement is completed and rests until T) and the stability of the range mode for η at low level (T
This makes it possible to make a judgment after integrating at ot.

[Yes] Returning to RI again, when vA>VB is not the case, the ■ flag is displayed as in the case of low-level focusing as described above.
A determination is made as to whether it is 1 or not.

■■When the flag is 1, the motor 8 is rotated at high speed in order to move the lens group 1 to the closest position U.

The reason for the high speed here is that, as with low-level focusing, the motor 8 temporarily slows down near the false focus signal even though it is out of focus due to a false focus signal. This is to prevent

(3) On the other hand, when the flag is 0, the motor 7 is driven at the excessively low speed as described above.

0 For the same reason as @, if the direction signal is output 5 times or more in a row, it returns to normal distance measurement, otherwise it performs distance measurement again in the low level distance measurement mode.

On the other hand, in step (2), when the low level focusing state is determined and a signal to stop the rotation of the motor 8 is output, the mode shifts to the low level focus distance measurement mode and distance measurement is performed again.

In the low level focusing 611j distance mode, the condition for determining distance measurement completion is vA+VB≧vL (Vl, <Vn) or t≧
T, (T, <To) is different from the condition for determining distance measurement completion in the bell time distance measurement mode -+-≧- or t≧To. This is the same as the normal focus distance measurement mode explained in FIG. 20. In addition to shortening the dead zone, the dead zone is widened as shown in FIG. 35, and the lens group 1 is stably stopped at a position determined to be in a combined heat state. In particular, in a low-level focused state, the level of the signal -1VB is low and <S/N is poor, so stabilizing the focused state by widening the dead zone is extremely effective.

The reason for setting VA+vB≧VL (VL<Va) is to enable focus determination even in the normal 611j distance mode in accordance with the maximum integration time T.

[Phase] When distance measurement is completed, first, 1 of vA+vB≧vL
'Perform the seven determinations. When vA+VB≧vI, ld: Even though the integration time has become shorter, the integrated signal is above the predetermined level, so it is determined that the signal has become large enough to enable distance measurement in normal distance measurement mode, and the normal Return to distance measurement mode and perform distance measurement.

o When vA+VB≧vL, it is determined whether 1vA−vB1≧VD. When 1vA-vBl≧'VD, it is determined that the signal has become sufficiently large, similar to [phase], and the mode returns to the normal ranging mode.

@VA-1-vB<VL and 1vA-vBl<VD
When -, it is determined that the object is in focus, and counting is continued until t==To is reached.

Determine whether distance measurement in the focus distance measurement mode at low level has been repeated n3 times, and if n6 times, return to distance measurement mode G at low level j9. n. If the number of cycles is small, switch back to the focus and distance measurement mode at low level. As in the case of the normal focus distance measurement mode, this returns to the low level distance measurement mode every n5th time, and determines whether the distance measurement has been completed by vA + v, ≧Vn or t≧T.
By setting it to 0, the dead zone is returned to its original state and a decrease in distance measurement accuracy is prevented. As described above, by changing the distance measurement mode from the low-level focus distance measurement mode to the low-level distance measurement mode, it is possible to simultaneously ensure stability of focus at low levels, power saving, and maintenance of accuracy. It becomes possible to do small things.

Next, the ω wait mode will be explained with reference to FIG.

(1) When shifting to the time distance measurement mode, as described above, in the [phase] of FIG. 20, vA+vB<vL and -Fu are determined. That is, as explained in the flowcharts of FIGS. 20 and 21, if both the distance measurement integrated signals vA and VB are extremely low, it is determined that the distance measurement is in the range direction, and is suitable for distance measurement when the subject 5 is in an infinite state. At ω, the camera enters distance measurement mode.

o In the distance measurement mode at 00, it has already been determined that there are an infinite number of subjects 5, so first the motor 8 is driven at high speed in the direction of infinity.

@ Next, the ω flag is set to 1 to indicate that infinite g has occurred. As previously explained in the flowchart of FIG. 21, the 7 lag is used to distinguish false focus signals and is reset to 0 in distance measurement mode.

@Next, n6 is set to use M(6) from the RAM area in the microcomputer as a kakunta for counting a predetermined number of times n6.

@ ■In time distance measurement mode, vA+VB≧V□ or t:T2
1, it is determined that distance measurement is complete. Here, one of the conditions for determining distance measurement completion in normal distance measurement mode is IVA vnl≧v
The reason why there is no D is because the value of l vAvBl is unreliable because both the integral signals vA and VB are extremely low values in the flash ranging mode as well as in the case of D at low level. .

Furthermore, the maximum distance measurement time T2 (T
2<To), the maximum integration time is shortened even in low-level distance measurement mode, as will be described later.If vA+vB>vL, the direction is determined based on the magnitude relationship of vA and vB, with vA+vB=vL as the boundary, as will be described later. .

If +vB<vL, it is determined that the direction is infinite regardless of the magnitude relationship of vA and VB, so vA+VB-4=vI
This is to prevent the completely opposite direction determination from occurring due to the influence of noise superimposed on the signals vA and VB at the time of . In this apparatus, the integration time T is changed as shown in FIG. 36 by changing the value of <vL. T2
A similar effect was obtained by changing to .

When i vA+vB≧VH, it is determined that distance measurement is possible in the normal distance measurement mode, and distance measurement is performed in the normal 6j11 distance mode.

D When vA+vB≧-, ylJil distance complete 1d
, t = T2C (therefore, To-
Count T2 time.

[Phase] Determine whether -10VB≧vL. V.A.
+Vn≧V1. In this case, as described in FIG. 21, distance measurement should be performed in the low level distance measurement mode, so the mode is returned to the low level distance measurement mode and the next distance measurement cycle is entered.

■ At this point, continuously n6 after the distance measurement mode starts at ω
Determine whether the number of times has elapsed. If it has not reached the n6th time, it returns to @ again and distance measurement is performed at the maximum integration time T2.

That is, this means that the maximum integration time is T2 (T2<To
), but as described below, < Ts (Tl < T2
<To) is not performed.

The reason for this is that infinity is determined because, as mentioned above, the signal is small because the object is actually far away or the reflectance is low, so it is okay to judge it as infinity, or The object's reflectance is unavoidably low, and the object is at a distance that can be measured, but the size of the object is finite.
・Since the distance of the object and the current position of the distance measuring system are greatly different, the spot image P or the light receiving element 6 may be deviated from the subject 5, and initially it will be driven in the infinity direction due to the infinity judgment, and the reflected light will be emitted. When the spot image P starts to be formed correctly on the light receiving element 6, it is possible to drive the spot image P to the in-focus position by a distance of 1 (1j) depending on the magnitude relationship of VA #VB times the signal.

In such a case, the maximum integration time Tl(T, ('r2<
If it is set to (To), the dead zone will widen, the response will be delayed, and as a result, the correct control of the motor 8 will be delayed.
This will overrun the in-focus position. In order to eliminate such defects, the maximum integration time is set for n6 times in order to distinguish between a true infinite state and a short-term infinite state during the focusing process, as described above. The distance measurement is performed without changing T2 to Tl (T2<To). Incidentally, as long as distance measurement is being carried out in the 61i1 distance mode at time (3), a signal for driving the motor 8 in the infinite direction is always outputted from the control 4 circuit 111. However, when the lens 1 reaches the infinite end, the infinity switch 262 turns ON.
Motor 8 is stopped.

o After the 6th time, the maximum integration time Ts (Tl
<72). The judgment of rangefinder completion is 1+vB
≧vL or t≧T5. This means that the maximum integration time is Ts (
By setting T5<T2), the dead zone is widened and stability and power saving are achieved at the same time.

If OvA+VB≧vL, the maximum integration time T, (T,
< T2 ) was shortened (comparison value vIJ despite C
Therefore, it is determined that the signals vA and VB are large enough to enable distance measurement even in the normal distance measurement mode, and the mode returns to the normal distance measurement mode.

[Stock] When vA+ 'VB < VL, the distance measurement result is that the level of the integral signal VA rVB is still extremely low, so it is determined that the subject 5 is again in an infinite state, and To-1
Count 3 hours.

■ Next, at the maximum integration time T3, it is determined whether or not distance measurement has been performed n7 times, and if n7 times have not been reached, the [
Go back to [phase].

When the seventh distance measurement is completed, the maximum integration time is set to T2 and the distance measurement is performed once again.

Here, the reason why the integration time is returned to T2 every predetermined number of times (n1) is to prevent a decrease in distance measurement accuracy, as in the above-described low level focus distance measurement mode. In addition, in order to perform distance measurement n6 times in a row with the maximum integration time T2, M (6)
= n6, but here it is only once, so M(<
5)=1.

Above are 10 normal distance measurement modes Z normal focus 61i 1 distance mode 3, low level 11 distance mode 4 low bell focus jlil distance mode 5, oo distance measurement mode 05 I+1 distance modes Figures 20 to 22
A detailed explanation has been provided based on the flowchart in the figure.

As is clear from this explanation, the automatic focus detection device R according to the present invention achieves highly reliable and stable operation by appropriately switching the distance measurement modes 1 to 5 above to perform distance measurement. obtained,
In addition, it has become possible to achieve both power saving and power saving.

In the above embodiment, the determination of in-focus or out-of-focus is determined from the magnitude relationship of the absolute value of the difference between the minute signals VA + Vn + vA - vB +, which indicates the light receiving position of the projected spot image P. It goes without saying that it may be determined from a ratio such as vA/vB, but the present invention can be applied to any Jq as long as the magnitude relationship of the signal -9VB is determined. or,
Instead of determining the signal level from 1+vB as in the above embodiment, the signal level may be determined from either - or Vn. That is, the present invention can be applied to any device as long as the level state of the signal -2VB can be known.

Furthermore, it goes without saying that the present invention is applicable even if the light receiving element has three or more photosensitive areas.

As described above, according to Kinei 8Acc, the integral value of the output of the light receiving element that receives the reflected light of the projected spot image projected onto the target object and outputs a signal according to the light receiving position) An automatic focus detection device for an imaging optical system that forms an image of an image on a predetermined focal plane, the device comprising: a time detection means for detecting that a light projection time of the light spot image has reached a predetermined time; and a light receiving element. and level detection means for detecting that the integral value of the output of has reached a predetermined level, and further when either the time detection means or the level detection means detects the predetermined time or the predetermined level, Since the integrated value of the output of the light receiving element is determined from the focal position [(Q output Since the focus position is detected immediately when the focus position reaches a possible level, there is no waste in power consumption or focus detection time, and an automatic focus detection device with high power saving effect and fast detection speed is provided. Therefore, the present invention is particularly suitable for automatic focusing of cameras, etc., which cannot incorporate a large-capacity power supply due to miniaturization, and where the quality of focus detection speed may lead to missing a momentary photo opportunity. It is very effective for the detection device.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional example, Figs. 20 to 24 are operational flowcharts of the automatic focus detection device according to the present invention, and FIGS. 25 to 56 are operational flowcharts shown in FIGS. 20 to 24. Supplementary explanatory diagram. 1...Photography] Cedar lens 2...Planned focal plane 6...Light emitter 4...Light emitter lens 5...Subject 6...Light receiving element 7...Fluorescent lens 8... Motor 9...AF circuit No. 7 Fig. 1Δ) MZ Dal SYNC No. 30 (r'') Procedural amendment (voluntary) Commissioner of the Patent Office Kazuo Wakasugi 1. Indication of the case!,'''I2. (,I dor bar',,, (,(i). Patent application filed on May 30, 1988 (2) 2, Title of invention Automatic focus detection device 3, Relationship with the amended person case Patent Applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
) Canon Co., Ltd. Representative Ryu Kaku 3 Department 4, Agent address: Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo 146 (telephone: 7513-2111) 5, Specification subject to amendment 6, Contents of amendment (1) In the 5th line of page 29 of the specification, ``First of all, ■Hula'' is corrected to ``First of all, ■Hula as a prohibited means.'' (2) In the odd line on page 31 of the specification cylinder, "minute time T. and" is changed to [
Correct it to ``with the minute time T0 (for example, 28 m5ec)''. (3) In the 6th line of page 42 of the specification, "wide range" is corrected to "wide range". (4) Page 42, line 8 of the specification: “In other words, widen the dead zone.”
is corrected to "widen the so-called dead zone." (5) Specification, page 54, line 15'(T+<To) J to r (T, < To, for example, Tl = 1.78
Corrected to m5ecJ. (6) In the second line of page 55 of the specification, ``It is designed to make it look like this.'' is corrected to ``It makes it look like it does and also reduces power consumption.'' (7) In the third line of page 58 of the specification, r(T2<To)J is “
T2<T. 9 For example, T2 = 1!3.3m5ec)
Correct to J. (8) r in the third line of page 61 of the specification (T3 < T2
) J to "(T3<T29 e.g. T3 = 1.78m
5ec) Correct to J.

Claims (1)

[Scope of Claims] (1) The above-mentioned An automatic focus detection device for an imaging optical system that forms an image of an object on a predetermined focal plane, the level detection means for detecting that the integrated value of the output of the light receiving element has reached a predetermined level; a comparison means for detecting that the magnitude relationship between the integral values of the outputs of the light receiving elements has exceeded a predetermined level; and a time detection means for detecting that the projection time of the projected spot image has reached a predetermined time. the imaging optical system based on the integral value of the output of the light receiving element when at least one of the level detection means, the comparison means, or the time detection means detects the predetermined level or the predetermined time; 1. An automatic focus detection device characterized by comprising determining means for determining a focus adjustment state of. (2. In the device described in claim (1),
An automatic focus detection device characterized in that the level detection means is a detection means for detecting whether the sum of integral values of each output of the light receiving means has reached a predetermined level. (6) In the device according to claim (1),
The automatic focus detection device is characterized in that the comparison means is a comparison means for detecting whether the difference between the integral values of the respective outputs of the light receiving means has reached a predetermined level or more. (4)! The apparatus according to claim (1), (2), or (6), further comprising a drive means for moving the imaging optical system to a focusing position based on the output of the determination means. An automatic focus detection device characterized by: (5) In the device according to claim (4),
It has a state detecting means for detecting a level state of the integral value of the output of the light receiving element, and the determining means operates the driving means at a low speed when the level of the integral value detected by the state detecting means is low. . An automatic focus detection device characterized in that when the level of the integrated value is high, the driving means is operated at high speed. (6) In the device according to claim (4),
The automatic focus detection device is characterized in that when the determining means operates the driving means, the driving means operates at a low speed for a certain period of time from the start, and thereafter operates at a high speed. (C) The automatic focus detection device according to claim (6), wherein the determining means is a microcomputer.