JPS59228211A - Automatic focus detector - Google Patents

Abstract

PURPOSE:To stabilize operation and improve precision, and to reduce power consumption by varying a dead zone area. CONSTITUTION:A comparing means 107 detects the difference between the output integral values of photodetection areas 6A and 6B of a photodetecting element exceeding a specific level, and a time detecting means detects the projection of a projection spot image being continued for a specific time. A deciding means 111 decides that an image formation optical system is in focus when the means 107 detects the difference exceeding the specific level, and decides on its in-focus state when the time detecting means detects the specific time. The specific time of the time detecting means is varied to a shorter time when it is decided that the means is in focus to stabilize the operation and improve the precision, and also reduce the power consumption.

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.

In Japanese Patent Application No. 57-175485, the present applicant disables the display system, lens drive system, and other operations in the area where the automatic focus detection device JT is considered to be in focus, and prevents problems such as hunting. The present invention discloses an invention intended to improve the accuracy of the automatic focus detection device with regard to providing a so-called dead zone region that prevents stable operation.

That is, although the stability of the above-mentioned device can be achieved by providing one dead zone, the width of the dead zone directly becomes the width of the decrease in accuracy. Therefore, in the above application, a comparison signal for determining whether the signal detected by the automatic focus detection device is within the range of the signal indicating the in-focus state is used to form a narrow dead zone area. A second comparison signal is provided to form a wide dead zone area with the first comparison signal, and after the in-focus state is determined based on the first comparison signal,
The in-focus state is determined based on the second comparison signal, thereby achieving both stabilization of operation due to the dead zone and prevention of deterioration in accuracy.

However, in the device shown below that integrates the received light signal to determine focus/out-of-focus, the device of the above application has an extremely large waste of power consumption, and it is difficult to make the camera etc. more compact. This is a very serious problem for automatic focus detection devices for devices that require high performance and can only be equipped with small-capacity batteries.

This will be explained in detail below.

Conventionally, as an automatic focus detection device for an imaging optical system, as shown in FIG. 1, a light spot image is projected from a light projecting element LT toward an object OB, and the reflected light is divided into two photosensitive areas PA;
There is one in which the light is received by a light receiving element PD having a PE and the distance from the light receiving position to the object OB is detected 717, or the focus adjustment state of the imaging optical system is detected.

That is, in FIG. 1, when the object OBm is at the position S1, the projected light spot image projected from the light projecting element LT toward the object OB hits the object OB1 and is reflected, and the reflected projected light is Assume that the spot image is formed at a position exactly midway between the photosensitive areas FA and FB of the light receiving element FD. Then, for an object OE located at a position S, and a position S2 that is far away, the reflected light of the projected spot image is at a position S, and a position S
2, the photosensitive area FA of the light receiving element FD increases.
It is formed in a state closer to the side (in the upward direction of arrow A in FIG. 1).

On the other hand, the object O is located at position S3, which is much closer to position S1.
For B, the reflected light of the projected spot image is closer to the photosensitive area FB side of the light receiving element FD as the distance between position S1 and position S is larger, and the - state (in the downward direction of arrow A in Fig. 1) ) is formed. Therefore, by detecting the position of the reflected light projection spot image formed on the light receiving element FB, it is possible to know the current distance state of the object. Specifically, if you compare the outputs of the photosensitive areas PA and FB of the photodetector FD, the photosensitive areas FA and P'B will output an output with a size corresponding to the received field, so the reflected light spot image will be different. You can see where it is formed. Furthermore, as shown in Fig. 1, in the case of an imaging optical system that forms an image of the object on the predetermined focal plane FM, if the distance state of the object is known as described above, the Since the focus of the imaging optical system can be adjusted with When the image forming optical system reaches a position exactly in the middle of the arrow B, the image forming optical system is moved in the direction of arrow B, that is, the optical axis, in conjunction with the movement of the light receiving element PD, in order to adjust the focus so that the image forming optical system is in focus. By moving it in the X direction, the focus of the imaging optical system B can be adjusted. In other words, if the difference between the outputs of the photosensitive areas FA and FB of the photosensitive element FD is zero, it is in focus, and if the output of the photosensitive area FB is larger than the output of the photosensitive area PA, then the front is in focus. If the output of the photosensitive area FA is larger than the output of the photosensitive area FB, then the focus position is rearward (the focus position of the imaging optical system is on the front side of the planned focal plane). Indicates that the image forming optical system is in the focused position (with a focus position of the imaging optical system), and in the case of front focus, the image forming optical system is moved in the direction of the planned focal plane 7M (to the right of arrow B), and in the case of rear focus, the focus position is By manually or automatically moving the imaging optical system in the direction opposite to the intended focal plane FM (to the left of arrow B), the imaging optical system can be brought into focus.

By the way, in the above-mentioned device that determines front focus, focus, and back focus based on the output state of the light receiving element, the above-mentioned focus detection is generally not possible unless the integrated value of the output of the optical element reaches a certain level. It is generally known that this cannot be done with high precision. Taking the above device as an example, at the moment the projected light spot image hits the light receiving element FD, 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 is formed. By integrating the output of the light receiving element FD, the signal level increases and the ratio S/N of the signal level/l/S to the noise level/l/N increases.
By making it possible to compare the output levels of the PB, it becomes possible to accurately detect the focus position. RI + n, the focus detection performed according to 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 PB for a certain period of time and the received light signal is integrated. be.

Therefore, in this type of automatic focus detection device, the photosensitive area PA.

Focus detection is performed by comparing the integral value of the output of PE, but specifically, if the difference in the integral value of the output of photosensitive parts PA and FB is 0, it is in focus, otherwise it is out of focus. becomes. If a dead zone region is provided in the in-focus state, it may be determined that the in-focus state is established if the difference in the integral values is within a certain range including O. At this time, in the above-mentioned application, the defined area is simply expanded.

That is, the integral value of the outputs of photosensitive parts FA and FB is ΣPA・ΣB
E, and the comparison signal in the narrow dead zone region is nl n2(n
t <"t), the comparison signal in a wide dead zone area is
2r ml < nl ), then in the above application, the narrow dead zone % m2) is determined to be in focus when the condition of ΣPA-ΣPB (n2) is satisfied in the town area, and flll, <Σ in the wide dead zone area.
PA-ΣP B (When the condition of +12 is satisfied, it is determined that the object is in focus. However, with this method, since the dead zone area is widened, it takes more time to exit the dead zone area. The circuit must be driven extra for the projection of the light emitting element, etc. Therefore, the power consumption is large.
This is a serious problem for automatic focus detection devices for cameras and the like, which are required to be compact and can only be equipped with a small-capacity power source.

The present invention has been made in view of the above circumstances, and aims to provide an automatic focus detection device that stabilizes operation and improves accuracy by making the dead zone region variable, and at the same time consumes less power. It is.

The gist of this is based on the magnitude relationship between the integral values of the output of a light-receiving element that projects a light spot image onto an object and outputs at least two types of signals depending on the light-receiving position that receives the reflected light. Yes, in the automatic focus detection device of the imaging optical system that forms an image of the object on a predetermined focal plane, the magnitude relationship between the integral values of the outputs of the light receiving elements has become equal to or higher than a predetermined level. and time detection means for detecting that the projection time of the projected light spot image has reached a predetermined time, and further, when the comparison means detects that the projection time of the projected spot image has reached the predetermined level or more. determines that the imaging optical system is out of focus, and determines that the imaging optical system is in focus when the time detection means detects that the predetermined time has elapsed; The automatic focus detection device is characterized in that the device includes means for changing the predetermined time detected by the time detection means to a shorter time after the determination means determines that the focus is in focus. Below, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows the entire configuration of an automatic focus detection circuit (hereinafter referred to as an AP device) in a one-piece format. 1 in the diagram
2 is the imaging lens group involved in the focusing operation during imaging, and 2 is the imaging element's imaging element 1. Although it shows the image plane i,
4. J body 'A> may be the imaging plane of the 1i# element or the film direction. 31C is a light projection confectionery for projecting a light beam onto the object field (generally the area to be measured), and is composed of a laser diode or an infrared light emitting diode. Reference numeral 4 denotes a light projecting lens, which forms a light projecting spot image of the light projecting confectionery 30 on a subject 5 (generally a distance object 6111) as an object. 6 is a light-receiving element that can take out the output by dividing it into two photosensitive chain rings 6A and 6B.
6B is arranged to be on the opposite side. Note that this light-receiving element 6 is composed of a 2-area PIN photodiode or a charge-coupled device (for example, θ11), and the OFL is a visible light cut filter), which allows the light from the infrared light emitting diode 3 to pass through as much as possible, and blocks external light components. It is meant to suppress.

7 is a light receiving lens, which emits light spot 1 on the photographic object 5;
The image is formed on the light receiving element 6. Reference numeral 8 denotes a motor for driving the photographing optical system J, which is interlocked with the lens group 1% light projecting element 3 and light receiving element 6 via a cam or the like. Reference numeral 9 denotes an automatic focus detection circuit (hereinafter referred to as A2 circuit) which moves the motor 7 in accordance with the output of the light receiving element to move the lens group 1 to the in-focus position.

Next, to explain the operation of the device shown in Fig. 2, the subject 5 forces;
At a distance of 6 mm from the image plane, the reflected light of the projected light spot 1ωP is received by two areas 6A and 6BI/C equal to each other on the optical sensor as shown in FIG. 3(a). In this case, in the light receiving element 6, the integral value of the output from the on-vehicle 68 is 1, and the integral value of the output from the area 6B is V.
The difference between V and B, -VB, becomes O. On the optical path 9, the light emitted from the light projecting element 3 travels along the optical path b1 7, hits the object, is diffusely reflected, and further passes through the light ii3be and falls on the light receiving element 6. Therefore, assuming that the lens group l is at the in-focus position at this time, it is tentatively assumed that the subject 5 has moved to a distance l. Then, as a matter of course, the bit position of lens group 1 shifts to the rear and becomes a rear bottle-shaped head. On the other hand, if the light emitting element 3 and the light receiving element 6 remain in the same position, the light path hits the subject and is diffusely reflected, and the light 1'lr
The light receiving element 6 kCiA l& is passed through ay, but I
■As shown in Figure 3 (b), the image of the 1st red is greatly admired (
i Shifted to 13iii1.

The above VA-vB does not become O.

Adjust this amount of shift by adjusting the amount of shift of subject 5.
)l! , −/, and moves the lens 7ip 1 to the in-focus position IMh. Chisel 11 i;) Said V, -V
The Ak' circuit 9 rotates the motor 8 in the forward or reverse direction according to the sign of B (including its size in some cases), and in turn rotates the light emitting element 3, the light receiving element 6, and the lens agitator l by a cam or the like. 1 person - Vn = 0, that is, the projected spot image is at the middle position between areas 6A and 6B on the light receiving element 6. Make sure to tie it sharply on the 9th side and 2nd. The projection element 3 goes to the 3' digit, the light receiving element 6 goes to the 6th digit rt, and the lens group 1 goes to the 1' digit +It. will be moved to. In this case, the projection optical path b1% reflection optical path is indicated by a;. On the other hand, when the subject 5 moves to position 13, the lens group 1 and the like move in the opposite direction to the above, and perform a focusing operation so that VA-VB=o. In this case, the projection optical path is 'l, the reflection optical path 6, and C7.
It is indicated by.

Figures 4 to 7 show other embodiments of a self-excited focus detection device that performs distance measurement based on the same principle as the binding shell in Figure 612. They have different forms. Hereinafter, the same members as those in the apparatus shown in FIG. 2 will be given the same numbers and will be briefly described.

Figure 4 shows the projection of light from one light projecting element (projection slit)+J,
This is a so-called half-TTI, distance measuring type in which light is passed through a photographic lens and received by a light receiving element provided outside the camera. Reference numeral 10 denotes a half mirror having a reflective surface 10a configured as a cold mirror, and is disposed between the lens group 1 and the imaging plane 2, which move for the purpose of focusing particularly on the focal point rAm of the taking lens. 4 is a light projecting lens, 3 is a light projecting element, and it is preferable that the light projecting element 3 is arranged at a position optically conjugate with the image forming surface 2.0 Movement of the photographing lens 1 means that the light receiving element This is done mechanically in conjunction with 6.

Fig. 5 shows a so-called T beam projection from a light emitting element and a light receiving element using a shadow lens k, nM on the light receiving metal fitting.
TL distance measurement type automatic focus detection device [O]. to
The half mirror 14' placed at t is a projection lens, and 3 is placed at a position conjugate with the focal plane 2 of the photographic lens 1 and the optical f't'. It is a light projecting element, and its light projecting spot image is I:X of the photographing lens l.
It is designed so that the outer circumference of # is near;
' is the fluorescent lens, and 6 is the image formation i'(tr
A light receiving element t4 is disposed at a position optically conjugate with 2, and its luminous flux is near the outer periphery of the 1st post of the shadow lens 1, and
Throw) "r; -) Y, It is designed to pass through a slumped position.

Note that the light emitting element 3 and the receiving YS element 6 are fixedly installed.
There is no occasional movement with the photographic lens.

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

In FIG. 7, the same light projection system as in FIG.
This figure shows an automatic focus detection device that is used for both unused and imaging purposes. The image signal received by the image sensor 13 is sent to the distribution circuit 11 to the A, F'li2 circuit 7 and the image sensor 12.
It is divided into minutes.

Figure 8 shows the photosensitive surface of the image sensor 13 of the apparatus shown in Figure 7, and when used for focus detection, 13A, 1
Signals from two zones 3J and 3 are input to the AP circuit 7 via the distribution circuit 11. Furthermore, in the case of the model K shown in FIG. 7, it is necessary to devise a method to allow infrared light to pass through the image pickup device 13 during sidecar operation, and to remove the infrared light during operation.

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 l, so it is possible to increase the size of the projecting light receiving lens 4.7. Although it is advantageous in terms of reach, it is contrary to J! I
The problem is that the entire i1 cannot be compactly assembled. On the other hand, the type shown in FIG. 4 has a disadvantage in length t9r% opposite to the type shown in FIG. Furthermore, since there is no need for mechanical interlocking between the photographing lens l and the projection/receiving system, which requires only one element, there is also the advantage that the number of sensors can be reduced to 11. The type shown in Figure 4 has an intermediate character between Figures 2 and 5.

The type on the 5th day has a shorter baseline length of the emitting and receiving threads than the one shown in Fig. 4, which is disadvantageous in terms of distance measurement accuracy;
Like the one in Figure J↓3, it has the advantage that the emitted light beam is centered in the finder even when out of focus. Incidentally, in all of the above types, the light spot image formed on the photographic subject 5 by the light projecting element 3 is formed on the optical axis of the chromatic lens when in focus. That is, in any of the above-mentioned devices, the distance measurement zone is located at the center of the focusing point, and the distance measurement zone becomes a self-excited heating point value due to parallax.

In addition, in the case of the one shown in FIG. 7, the light receiving aperture of the light receiving element 13 is approximately equal to the F number of the superior lens, so compared to other types of m IM, the area of the light receiving aperture is generally larger, and the reaching distance is shorter. It is advantageous in this respect. In addition, in the device shown in FIG. 6, the signal from the focusing image element 13 is distributed to the AF circuit 9 and the 4-acid 11 path 12, but since it is practical to distribute this in a time-division manner, this type of device is used. This is suitable for systems such as still video cameras that change the distance before shooting.

Next, the arrangement of the air circuit in the device 6 will be explained based on FIG. 9. The 6th region of the light receiving element 6 is the same as above! 6A, 6
Each of the reflected light projection spots received by B is supplied to amplifier circuits 101a and 101b as optical i-converted optical information and is sufficiently amplified. At this time, this increase @ device IQla,
101b has a sufficient amplification factor of 5<j for the modulation frequency of the infrared light that forms one beam spot, and has a sufficient amplification degree (5 < j It is preferable to use an M-width circuit with a frequency characteristic that suppresses 1w, where V is the engineering width and 1w.The output of this amplifier is the synchronous detection circuit bη10
2a, 102b) L1 synchronous test e vomit. This (iA 1ljj J off signal has the same frequency as the t shift element 30 end light drive signal, and maintains a constant position a relation. The output of this same 'IυJ' , 103b, reflected light projection spot 1
Strong signal in the east! L'', which was compared to 9IJ at the same time, is processed by h!XV by signal processing of 0 or more,
The amount obtained independently from the responsibility distribution circuits 103a and 103b is divided into two parts: pressure V and VB are the functions explained below. , -1li
! It is processed, determined, and converted into digital 1#t'k.

That is, the integral pressure V, , VB is, on the other hand, tail: 'F'J
-1'j 104 becomes the difference signal V, -VB,
On the other hand, the adder 105 produces the phase signals VA+VB.

Difference No. 1 V input - vBtfie pair (+fi circuit 1061v
7JO error, obtain 1vA-vBl. This jla
1 VA-VB 1 outputs the comparison value VD and the ratio φ2, 2 and 1 in comparison 5107 as a comparison measure. On the other hand, the sum signal ■10VB has a ratio γλ at comparison t=108 and 109 as a level checking means, respectively.
They are compared with the values vL and VI (and their magnitude relationships are output.Furthermore, in the comparator 110, the state voltages V and VB are directly compared for their magnitude relationships.From the above, the four digital information, i.e. comparators 107.108.
The outputs of 109 and 110 are ``j3'' order f as a judgment means.
The power is applied to the ttil u circuit Ill, and the operation of the entire system is energized.

112 is a light emitting circuit, W is also a working circuit, and ib'l groaning circuit 11
The synchronization signal from 1 is applied to the light emitting element 3, and the light emission from the light emitting element 2 is increased to 0113.
is the motor drive direction, and the rotation direction and rotation of the photographing optical system driving motor 8 is determined by the signal from the electric circuit Ill. l
;11: % y”r In Figure 9, the box (1) of this circuit is
This is a more detailed version.

Figure io is the same as that of (A) in 85 of Figure 59. , 4S minutes, using the tiffl boost amplifiers 201a and 201b of the Eibato sound at the beginning > 22 of the amplifiers 101a and 101b,
Feedback times = 202a, 202b ty) Set>ff4'! : ! Tutehaiha x confrontation f'D'Jl'#
Light is emitted to the outgoing laser beam, and the light is emitted from the f-element 3.
Compared to the energy returned to [7], it can be a fairly large value. The visible light cut filter FL and this circuit are
It has the effect of suppressing external light components compared to 40%, and can be used practically for most subject conditions depending on the settings. Furthermore, capacitor zo3a.

203b cuts most of the direct current components such as sunlight. 204a and 204b cut the AC J'#' with a filter, and after sufficiently amplifying the components near the modulation frequency, send the signal to the next stage synchronous detection circuit. supply

The four-period habituation circuits 102a and 102b shown in FIG. 9 are composed of inverters 205a and 205b, an analog switch 206a,
206b, 207a, 207b K, and analog switches 206a, 206b, 207a
, 207b is switched by the synchronous I/A 5YNC, and the non-inverted signal and the anti-inverted signal are alternately selected.

As another example, there is a method of using 4 x 9 analog risers and calculating the product of the input signal and the alternating current component of the same fE\5YNC (shown in Figure 11M1).

Synchronous side? The reflected signal becomes a DC (pulse 6t) component,
It is supplied to the next stage integration circuits 103a and 103b.

These t4 division circuits 103a and 103b are operational amplifiers 2
08ae208b, resistance 209a, 209b, -x
It is composed of capacitors 210a and 210b. Then, a current proportional to the synchronous detection output voltage flows from the synchronous man wave circuits 102a and 102b to the resistors 209a and 102b, respectively.
209b, flows into the capacitors 210a and 210b, is accumulated, becomes an integrated nail pressure, and is applied to the operational amplifier 2.
08a and 208b. These IE pressures are the V input and VB, respectively. In addition, 211a and 211b are the initial sources of the charges accumulated in the capacitors 210a and 210b.
capacitor 210a.
, the charge accumulated in 210b can be kept in the next charge +f
The CLI from the ill elevation circuit 111 is also cleared by the signal.

1st tldti, jA min'Ji It ”Al vB
Created Kara I VA 'B 1, and the relative soft ore pressure v
The h output from the zero division circuits 103a and 103b, which shows the (LS) part of the circuit in FIG. 9 for comparing D.
i (min sHr, IEVh+ Vn is the operational amplifier 212 and each 'equal resistance j+7.j 14 resistors 213 to 216
Calculated horizontally by the Seishin circuit 104 configured by,
-v, 0 to obtain 10 vB This 1:1t is added to the absolute value circuit 106 of the next stage o +! :i':'! pair ((i circuit 106 is operational amplifier 217, diode 218, 219
, resistance value 2H resistance 220-222, resistance value II (,
It is constituted by a resistor 223. Operational amplifier 21
7. Diodes 218, 219, resistors 220, 221
Due to the 0 behavior, the cathode of the diode 2190 has an impedance when a negative input is applied, and a potential that is -1 times the input surface pressure when a positive input is applied. As a result, H
Voltages of -0,51v and -yBl are applied. By adding a part of the pressure of 5 Vl) to this positive input,
tV enters - Vl31 and VD's sexual intercourse shows the woman. Let this comparison value be l)D.

Also, Figure 12 is the episode I of Figure 9! This shows part (C) of 1~, where vA and VB are added by the resistor 225.226 with a low value ratio, and 0.5 (V, +VB) is added to the comparator 2.
It is added to the multiple inputs of 27 and 228. 0.5■LsO,5Vll is added to the negative power of each comparator, and the theory is (VA+VB): vL, (VA+
VB) : V)I is compared, and the comparison value LL,
Output 1-u-i.

Further, FIG. 13 shows the circuit (1)) of No. 91 No. 1, in which ① and VB are directly compared by a comparator 229 to output a ratio It value AI3.

Figure 13 shows the different percentages for obtaining the comparison value DD from VB.
1M4 examples. v,, Vl3 is the comparator 23
A positive input Vζ of 0.231 is added. Also, the resistance value f
(is applied to the negative human power through the resistors 232 and 233 of
.

235 is also connected, and as a result, VB+ is connected to negative human power.
s, a voltage of VA + tR is applied. However, 11
ri234.235 voltage (Af, value ゛1 comparator 2
The outputs of 30 and 231 are added to the OR circuit 236, and the output 1) IJ is 4G 6 t'L ro Output DD i
'j V4 VB) I R= vD or 1i VB-
Otori) When iR = vH, it becomes true logic and 1 mu VBI
>Represents the logic of VD.

FIG. 15 shows a part of the ordering system Ill implemented in hardware. Clock C has It= ordinal 1
Determine the minimum id of the circuit Ill,
Element 40 mostly modulated and synchronized isometric wave circuit 102a, 10
It becomes the source of synchronization signal 5YNCO of 2b. 236 is an n counter, and the period of this output ON determines the distance measurement period, 2, and the maximum time. flip flop 237.23
8 are respectively set by the signals DD, ) output and the signal C
It is reset every sub-range period by n.

The output of each of the flip-flops 237, 238 1) DQ
.

The I side Q is an integral abort signal, and the inverted output Q of the 0 flip-flop 2400, which is input to the flip-flop 240 via the OR circuit 239 and held at the cycle of the signal Cu, becomes the black eye 4R center, f(. Signal FAf(, and DDQ are 0
) through the circuit 241 to the flip-flop 242 ′t
1-set, and the motor rotation number MO is output. This flip 70 toggle 242 is reset by the focusing signal H1 (Q signal) to stop the output of the motor rotation signal MO at the time of focusing and stop the motor 8. A signal DDC representing
It is updated by J and becomes ABQ. Here (Fushizen Bin,
In other words, when vA>VBO, it is in the A group. The signal A13Q and the signal phkL are passed through the oit circuit 244 to become a signal FN representing the rotational direction of the motor. The final motor drive signals F F (toward infinity) and NN (towards close proximity) are the output of the AND circuit 245 which inputs the signal F N and No. 13 MO, or the signal FN is N0TLL! circuit 246
ANI whose inputs are the output obtained via
) is selected by the output of circuit 247.

Synchronous signal SYNC is for signal 1) L) Il and signal G 1
Q together? :When the signal is logic, the signal is 014 times f5239
．． By being input to the AND circuit 249 via the NOT circuit 248, the signal is input to the NIKE circuit 249. The same JRJ is output as the output CLK of the clock C. OR
The integral initialization signal CLF output from the circuit 250 is
After the end of integration is determined based on the output of the circuit 239 and the signal Cn, 01 input to the OR circuit 250 becomes true logic at 1 at the start of the next integration.

Figure 16 shows the state of front bin → back bin → union → infinity! This is the waveform observed as each signal in FIG. 15 when there is a change in /.

)jJ Hi:/ Te is D L) Kamost &c rises, when AB is at h level, DD rises first in the 0 bin, but AB is at a low level. When in focus, HH rises. Infinite time increases to the maximum time before it rises.

FIG. 17 shows a part of the apparatus in which the 1:81 pressure control circuit iii is controlled by software using a microcomputer. In this figure, a light emitting element 30 element light drive circuit 112 and a motor distance υ circuit 1 are shown.
13 f'4 is also shown. 251 is a microcomputer (for example, it has an internal structure as shown in Fig. 18), and inputs each of the above-mentioned signals Z)D, AB.

LL and HI4 are output by one person, and FF and NN are output from the output terminal for this and each of the aforementioned signals 5YNC1CLL. Therefore, it is easy to remove the number LOVfJ for the motor rotational speed 1 (↑I+! J Lab 1).

The i current flowing through the light emitting element 2 is transmitted through the transistors 252 and 2.
53 by the signal 5YNC.

f flowing to the motor 8; (the fourth flow is the transistor 254-2
57, the signal 1i' F and the signal N N & are switched and rotated in the forward or reverse direction. The circuit I blue is formed by the transistor 258, 259 and the diode 260. Yes, LOW
The signal causes the 11°C pressure applied to the motor to be divided into two levels. 261 and 262 are the nearest switch% respectively
It is a %lqp% switch, which closes when the Yakata optical system hits an impending illness or an infinite delay, and prevents driving beyond the limit.

FIG. 19 shows electrical signal waveforms at various parts of the circuit shown in column 9.

The synchronous signal 5YNC is the synchronous detection circuit 102a.

102b, but also used to drive the current of the 8-part Rokuko 3, and a light-receiving element 6a that provides the light emission output IRBD;
The E substitution signal obtained from 6b is obtained by superimposing the reflected light component of the projected infrared light and the external light component of thick M+ or artificial light, and has a waveform like the signal SPC. No. 451 Anlp is obtained by multiplying this No. 43 by an amplifier 101a9101bK having a rotary pass characteristic. When CLl and L I@ are divided by 1 almost at the same time as the light emission starts, the outputs of the synchronous detection circuits 102a and 102b are integrated, and
An integral waveform like signal Int appears at the outputs of 3103a and 103b. This integral waveform increase is 1 minute of the emitted light of the infrared light! proportional to size. Even for extremely weak inputs, a large 8N can be achieved by integrating a sufficient number of times (time).
Next, the operation of the bookstore will be explained in accordance with the flowchart numbers shown in Figures 201 to 24 with reference to Figure 9. Here 1
Assume that a microcomputer (hereinafter referred to as a microcomputer) 251 is used as the "u1" control circuit lll.

(0) When the AF operation switch (not shown) is closed, the control circuit 111 starts operating 1iJ.

(2) - First, it is determined whether or not the 818 terminals of the 161j circuit 111 are in a high level disorder. 5
When the EN8 input terminal is at the quotient level, # is shown in Figure 23.
,] is operated in regular mode, and the sub-rectangle is not f′i. In the adjustment mode, infrared light emitting diode 3 is ON -0F.
li' and the direction of the light receiving element 6 are T. Time, integration and IC offset adjustment amplifier circuit 101a.

101b, synchronous wave io1'1s102al102b
% + & Minute rM103a, 103b Le94 adjustment,
or +-j'A when f > 4 Due to an emergency, infrared light emitting diode 3 or useless lens 4, light receiving element 6, light receiving lens 7 Q, (, :, position II! relationship adjustment is performed .

Therefore, normally the lN8 input terminal of the 81i11 control switch 111 is in a low level state, and the AF' operation switch is turned to 1.
! Once installed, the main unit will first operate in the normal ranging mode shown below.

■ When entering the energization ranging mode, first reset the ■ flag as a prohibition means. Note that an example of the contents of this ω flag will be described later. Also, as a memory for this ω flag, the microcomputer 2511'LA (memory M(1 in the area)
) shall be used.

■ After this s f'6! The I control circuit 111 starts the distance measuring operation from 1 to 4. That is, the 1υ1'' collar circuit 111 first includes the light emission drive circuit 112 and the synchronous detection circuits 102a and 10.
2b is activated in synchronization with the synchronizing signal 5YNC, and the +J key is pressed, and the clear state of the integrating circuits 103a and 103b is released.

As a result, a suffix spot image of infrared light is projected from the light projecting element 3 into the photographic field in synchronization with the synchronization signal 5YNC, and the reflected light is detected by the light receiving element 6. Light receiving element 6
Then, the two photosensitive areas 6A and 6B receive the reflected light according to the light receiving position of the projected spot image, and the output signal is outputted to the amplifiers 101a and 101b.
The signal is amplified by the auxiliary detection circuits 102a and 102b and subjected to the same waveform. The optical information obtained in this manner is sequentially integrated by the integrating circuits 103a and 103b, and the output becomes <tributary 'ijj pressure V,, VB.

As mentioned above, these integrated voltages vA and VB are shown below.
@4 digital information has been processed by 4F and 1n11
The subtracter 104 generates a difference signal V,, -VB, which is added to the pairwise value circuit 106, and its absolute l1rfIVA-VB+
The magnitude relationship between the digital output from the comparator 107 which has been completely compared and the comparison value VD. Digital output from comparator 108 LL @ Kasumi, sum signal MA + VB and ratio bite value V from comparator 105
H (VH>VL) (!: ) Big and small! +i 4A'
e Ratio+i'y L, ris+Digital output from softener 109, HI-4 ■ Signal ■ Digital output from ratio ii9 device 110 comparing the magnitude relationship of A and VB, An On the other hand, in the control circuit Ill The time detection means in the microcomputer measures the time of integration of the signal in the 14 integration paths 103a and 103b (1fj, klr:), and the projection time of the light projecting element is t, the maximum time is 46 minutes T.

(for example, 28 m=m).

So, given these information, mitllWm 1
11 Teu, 4t4'ryji l VA -VB I
≧V1) or MA + VB≧VH or t≧r1+o
It is determined whether or not. If any one of these three conditions is met, the control circuit 111 determines that the distance to light has been reached. FIG. 25 shows the reflected light spot image P and the integral signal vN when in focus.

s', n As shown in Figure 25, in the focused state, the reflected light spot image P is formed at approximately the midpoint between the photosensitive areas 6A and 6B of the light receiving element 6. Therefore, substantially equal large f-direction outputs can be obtained from the +1 areas 6A and 6B of the photodetector 1 of the photodetector 9Z element 6.For this reason, ηi
The values of the minute signals V, , VB are both 1 as shown in Fig.
・? : l''<I'U: Bubbles and bubbles increase in the same state. Therefore, as shown in No. 251A■, the signal VA + V
D also increases rapidly with time j)>]1, while the signal I
VxVBl hardly increases as shown in FIG. 25 (2). 9ε, compare (i & vH, vDh 1Fft dog t'i'4 minute hour i81 'l'o VA 10V
BFsvHI I VA -VBI < VO cut
(To tear l'f It is determined that the state is i<A. On the other hand, FIG. 26 shows the state of the reflected light projection spora I-11 and the integral signals V, , and VB when out of focus Dj4k When the lens Rt is in the front focus or rear focus state, the reflected light projected spot image P is as shown in FIG. The output signals of the photosensitive areas (5A and 6B generally depend on which one is thicker).

Therefore, as shown in FIG. 26 (2), one of the li integral signals vA and VB increases rapidly with time 1t41t, but the other integral 11α does not increase at all.

Therefore, as shown in FIG.

The signal l MA-VB l td l VA -4o l ≧
vD to fx ro be) tel VA-VB I ≧VH
I)"CJ Kawashu, MA 10Vn < VBkatsut(
If 'I' is 0, it is determined that the front pin or rear pin state is present. Figure 27 shows a reflected light projection spot image P when the subject 5 is far away or the probability of reflection from the subject 5 is low.
This shows the states of Vλ and VB of the trouble Iha issue. In this case, the reflected light projection spot image P is not formed on the light receiving element 6, or even if it is formed, the amount of received light is extremely weak. . For this reason, the photosensitive areas 6A and 6B of the light receiving element 6
The output signals of both have small values, and as shown in FIG. Therefore, when the integral 4th quadrant t is the maximum integral, 1i4j 'l'. Even if the signal V/, +VBS I VA 'B'
Both are shown in Figure 27 @ ■ < Vx + Va ≧ Frost 1 ■
A-VBI≧VDtoiJ:Nara1i□Kttet≧
To, VA+VB<VHI vA-yvBl<VD
If so, it is determined that the subject 5 is in the north or in a situation where the -j distance is difficult.

As mentioned above, VA + V (3?, VH, 1 or u l
By setting VA VB l ≧VD or t≧l1lo as the condition for determining completion of distance measurement, automatic focus detection operation can be started immediately when the value of the integral signal V person, VB slows down to a level that allows distance measurement. At the same time, wasteful consumption of TD cargo is prevented. In particular, with this device, as will be described later, if distance measurement is completed within 1 minute (Ill), the maximum signal time T within the microcontroller is required to keep the time for one distance measurement cycle constant. .The time until K is reached is counted, and the next distance measurement cycle is started to perform distance measurement again after the time has elapsed, so there is no waste ↑a and load from the completion of distance measurement until T. Time elapses. There is no history of consumption, and the effect of saving '14L is extremely good.

FIG. 24 specifically shows the contents of (4) as a subroutine. jl will be explained below.

(2) The light projecting element 3 starts operating like the other ntll circuit water circuits.

@ Clear state 4 of the integrating circuits 103a and 103b is canceled.

θ The light projecting element 30 emits light.

[Phase] After that, the light emitting drive circuit 112 is stopped by stopping the signal 8YNC, and therefore the light emitting element 3
0 Stops light emission. At the same time, the synchronous detection circuit 102a,
The drive of 102b is also stopped.

(2) -F4J determination is made as to whether the distance measurement is a photon or not according to the above-mentioned distance measurement completion determination condition.

6 When the distance measurement completion condition 711 is not completed, flash the light emitting element 3 again and 64! Repeat l distance.

■ If the condition for distance measurement completion is satisfied, signals DD, AB
, LL, f-II ((, jll ratio 4 & !107.1
08.109.

110 output) is the memory M in the RAM area of the microcontroller.
(0). After that, synchronize signal B YNC.
By stopping the light emission/light drive circuit 112,
Therefore, the light emitting element 3 stops emitting light. At the same time, a synchronous detection circuit 102a.

102b's commotion is also stopped.

■ And + & Ij both 1m road ut o CLEAf
By setting the LtB force to kAV Bell, the integration circuit 10
3a.

103b is set to clear state 1 to prepare for the next distance measurement operation.

After performing the above series of fill (if!l), the 4-bit data stored in the memory M (0) is used to perform automatic focus detection operation and move to another distance measurement mode to be described later. The subroutine shown in the figure can also be used in the other distance measurement modes described below by changing the att+saikoryo judgment condition in (2).

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

(2) When the focus is determined, a stop signal (1"F=NN=0) from the control circuit 111 is supplied to the motor drive circuit 113 to turn the motor 8 on and off.

■ And the g minute time t is the dilation integration time 1゛. When he reaches this point, he switches to the Shinjo Aiguma distance measurement mode, which is suitable for normal situations described below, and performs distance measurement.

■ On the other hand, when vA 10 V mouth ≧ VH, 1.
This is when the values of the i-integrated signals vA and VB are small, and it is either one of them! Let's do the rl separation here. 1h-V81
When ≧VD is not present, a distance of 41 is completed when t≧′1゛o, so as mentioned above, in this case, the integral signal F, VB
Because the level of is in a low state.

Distance measurement suitable for low-level integrated signals V and V6 is performed. Transition to low level distance measurement mode, which will be described later.

(2) When IvA-VBI≧VD, it is determined that the lens group l is in an out-of-focus state, and it is then determined whether the lens group is in the front focus or the back focus. When vA>VB, it is the rear bin, and the motor 8 is set to bμ in order to eject the lens group l to the nearest piece.
It is determined that assistance is required.

[Phase] Next, the speed at which the motor 8 should be operated is determined. Book'-)! In this example, the motor speed jt is controlled in two stages, and by switching the speed to a low speed when approaching the in-focus state from the out-of-focus state, the lens 4k
This prevents the lens from overrunning the focus position and allows it to stop smoothly. The motor speed may be changed to any number of speeds as necessary. Here, the level of the comparison value VL is used as a determination standard to determine whether the focus is close to the in-focus state or whether it is significantly out of focus. When out of focus, turn the knob when distance measurement is complete b I VA Vn I =
V1) K4 L, at the time of It-1i VA +
VB 75E MA + VB ≧vL(7) Time t/
'r i, [k i'M, When VA+VB < VL, as a general rule, use SjJ route. This state is shown in Fig. 26 and Fig. 2g28) Fig. 26 shows the state at high speed, and Fig. 28 shows it at low speed.

As can be seen from the lens 281A in FIG. 26, the reflected light projection spot image P approaches the intermediate position between the photosensitive areas 6A and 6B of the light-receiving element 6 as it approaches the in-focus state. The difference in level between VB and VB becomes smaller.Therefore, the time t from when lens group 1 is close to the in-focus position to -1 and IVA-VBI≧VD becomes longer, and the time t until IVA-VBI≧VD becomes longer. Therefore, the degree of focus shift can be determined by the magnitude of VA + V[,.

Speed Ki side 9 of the motor 8 described above. FIG. 29 (■■) shows the relationship between the positions of II and the reflected light projection spot image P on the light receiving element 6. In this case, the reflected light projection image P is at the 16th position (rear bin) of PI.

You can see the magnitude of the amount of light received in the photosensitive areas 6A and 6B when moving to position iQ (riil bin) of P through the (joint bin). It is expressed as and. The first shift of ko is set to an appropriate value depending on conditions such as the speed of the motor and the inertia of the system. This results in:

Here, in this device, when out of focus, sub 111 complete + s + J
cn is performed. In the example of the actual capacity of the water head, vL=Vl: is closed, but other pistons may be set.

Now, we return to the flowchart of FIG. 20 again.

After being in an out-of-focus state and being determined to be the rear bin, vA+vB≧
vL is determined.

■ When vA+vB≧vL, the motor 8 should be driven at low speed as described in +iiJ (+1lllll A signal is output from the Fn circuit Ill, and the lens group l is moved to the closest side ii3!I.

Time axis if4'4 until reaching e 1 = Il10
After that, return to step (3) and ail distance measurement is performed again in the normal distance measurement mode.

e On the other hand, Fig. 20 QQ LC ite VA + VB
(At the time of VL (D), in principle, the motor 8 should be rotated at a high speed as mentioned above, but here, the determination that the motor 8 should be driven at this high speed at close range is made nt times to create the normal trace 1 distance mode. It is determined whether the return itl has been repeated n2 times in succession. If it is less than n2 times, the process moves to (2), and the motor 8 is driven at a low speed to the main direction f111.

If it is determined that the target should be moved closer to the target position Q nt times or more consecutively, the Tanabata 8 will be driven closer to the target at high speed. On the other hand, it was close at high speed! The judgment that should be α in if is 0
If it is not performed twice in a row and, for example, a judgment such as focusing is made in the middle, j4 and n.

The motor 8 does not become active until it is determined that it should ring at a high speed in the vicinity twice in a row.

As mentioned above, the reason why the speed of the motor 8 is set to 'h'lJ@I is that when starting the motor 8, it always moves at a low speed, which improves the feel at the time of starting and also increases the 4" Jj minute signal.
The operations are exactly the same except that the direction in which the lens 511 performs hunting or the like is reversed due to the addition of noise to VB, so a description thereof will be omitted.

I will briefly explain the normal focus distance measurement mode.

0 (Normal focus U11 suitable for distance measurement from the focused state when the in-focus state is determined and the integration time t reaches the maximum integration time 1r0)] Distance measurement is carried out. This is because the subject generally has a chronological property that changes the distance from time to time even after the combination.
This is because it is necessary to measure the distance at every interval (maximum integration time in this case) and to confirm whether or not the lens group l is in focus. ] In the δ focus ruff distance mode for river use, the condition for determining the focus state is 4. Ill'j4
Mo) "ノ"i' enter + Vll Q2 VH Ka II)
VA + VB > vL (vL < VH). The reason why the condition for determining completion of distance measurement is changed from v,1+vB≧1 to ■10VB≧vL is to widen the range in which it is determined that the focus state is reached. In other words, when in an out-of-focus state, the dead zone (so-called ζp), which cannot be increased by 4 (1 + As shown in Fig. 30, 5 (qualitatively, the same effect as when the comparison value VD is doubled can be obtained, and 1 v input - vB1 Therefore, it is possible to reduce the erroneous operation due to the noise superimposed on the integral signals VA and VBVC.In addition, by lowering the comparison value, the integral time, that is, the light emission can be reduced. It is possible to shorten the time during which the element 3 is emitting light, and it is also advantageous in terms of power consumption in devices where one distance measurement cycle is a fixed time, such as this device. There's no need to fix it.

Same, other conditions for completion of distance measurement are usually IF! 1ff
The operation after that is the same as in the case of - mode, and the subsequent operation is the same as in the normal distance measurement mode, starting 0 square distance measurement that progresses by 1C,
1■-■B1≧VD or vA+vB≧■L or t≧'v
When one of the three conditions o is satisfied, the control circuit 111 completes the distance measurement, and the comparison value at that time is
! 3. LL, l-11 (is stored in memory M(0) again i
I play Q7 myself.

[Phase] Here, in (8), based on the data stored in the memo IJM (0), it is determined whether 1v input-vB1≧VD and whether or not there is an out-of-focus state.olV*-
If vB1≧VD, it is out of focus and 6 (11 distances) are performed again in the normal distance measurement mode.

@ When IVA-VB+≧VD, it is a time when sufficient signal cannot be obtained due to focus or because the object is far away or the amount of reflection from the object is low, and the integral No. 18 depends on whether 40vB≧VL. ■^, Determine the level state of VB and determine whether it is gold steel based on the state. ■Mu+
When VB≧vL is not k 6111 Distance completion is performed when t≧T0, and since the integral signals vk and VB are extremely low, it is determined that the object is far away or the reflection of the object is low, and when the level is low. Shift to distance measurement mode and perform distance measurement.

[Phase] On the other hand, when in focus when VA+VB≧vLO, -11
4", and then set the maximum integration time T in the same way as described in ①.

Count up to.

0 Next, determine how many times the >Ifl fK focus d4ij distance mode has been turned over. Number of combing n〈
If no, return to normal focus di11 distance mode and n
= noK reached or other ranging mode v with [phase] or @
The distance measurement is performed in the normal focus distance measurement mode until the focus moves to c. Repeat the normal focus distance measurement mode n0 times, and when n = n0, return to the normal 1i1i1 distance mode again, and the next M11 distance is the normal 1ntJ distance mode, tlI1 in the normal dead zone.
1 distance is done and it is inoreru.

As stated above, it is possible to prevent the range Xi'+' from decreasing by returning the dead zone to its normal state every oth time. , the stability increases, but its valgus effect causes a decrease in distance measurement accuracy.Therefore, by returning to the normal distance measurement mode every time, the focus/μ focus is determined in the normal dead zone. , compensates for the decrease in distance measurement accuracy.Therefore, by doing this, we aim to achieve both stability during focusing and distance measurement h'l JK. Therefore, it is necessary to set it to an appropriate value.

Next, the operation in the low level ranging mode will be described based on FIG. 421.

[Phase] As mentioned above, in the normal ranging mode or normal focus ranging mode, both integral signals V, , VB are determined to be at a low level, or the integral signals are determined to be low in the ω time ranging mode, which will be described later. Rod 1 with the level of signal V,, VB becomes il+lI i? When it is announced that tj is possible, distance measurement is performed in a low level distance measurement mode suitable for ill distance when the level of the integral signals vA and VB is low.

In the low-level distance mode, do the same thing as in the normal distance measurement mode.
■1 Determine the completion of distance measurement by . Note that (1) vA-VB≧vrt is excluded as the 441-tail condition for distance measurement completion, unlike in the normal S distance mode. The level of the signal detected on the light-receiving element 6 is low because the distance to the body 5 is in the distance or the reflection of the subject 5 is 1 thicker, and therefore the integrated signal V
,,The S/N of VB is not very good, for example, the 88 minute signal v people, the magnitude relationship of the VB level may be opposite to the original value, and this is to prevent erroneous distance measurement from occurring. If signals in the direction of 1 to 1 and the direction of no 1 are repeatedly output, if these are detected as they are, out-of-focus signals (Ff) in different directions will be output alternately.

Operation may become unstable. )? f< 31 Figure shows θ・1 of such an integrated signal with poor S/N, and the 31st
As shown in Figure ■, the VA double signal and the word name are alternately replaced, so the T code shown in ■@ in 131LJ is < (1
) OA Tel VA-VB l ';? -VD, VB)
If it becomes VA, then if it is in s 1fil bin state -
f'(I) and outputs a control signal to drive the motor 8 in an infinite direction from the control circuit 111. Also, although by chance (certainly) Va>Vi at the point (I), (I )'4C shows f Ko(!: < I V, V-Yo l < VDteattat, then (I) 7, then distance measurement "FIJ 't
:i is not done (11) Vx>Vn, 1Vx
-vs l>Vn The judgment is YES. This is n
- Agetani and Jiku mentioned in J〈An out-of-focus signal in the opposite direction will be output to the motor 8. In order to reduce the instability mentioned above, in low level distance measurement mode (IVA-VBI and VD are not used as a contract condition for H1 distance completion)
For G who cannot determine that input+VB≧vH, the integration is continued until t=T0. By being able to switch between numerical modes in this way, it is possible to combine the advantages of the normal ranging mode (power saving, etc.) with the stability of the low-level ranging mode.0 [Phase] Again, Returning to the flowchart of the distance measurement mode at low level in the Jrt21 diagram, when the distance measurement is completed in [phase], it is then determined whether the distance measurement has been completed based on V, +VB≧vH. When Vmu + VB 2 vll, signal ■A.

” means that B is large enough, 1f (at level - ff
It is determined that there is no need to perform distance measurement in the ill distance mode, and the process returns to the normal distance mode. Fig. 32 shows the signals vA, signal VB, signal V, +VB, and signal 1v when returning from low level mode to construction 11TIJ distance mode.
The state of person-VB+ is shown as 0@ and <IVA-V
Even if s I > XrD...1j distance is not completed and distance measurement is performed with a thin string. As shown in ■, at 1 o'clock when the condition <I<To-V input +VB≧VH is satisfied! The lJ distance is completed and the mode returns to normal distance measurement mode.

c3 When VA+VB≧2, distance measurement is completed at t=
This means that it was carried out under the conditions of T0. Continue ■ Enter +
Determine the level of VB: Should it be determined as 8th period? 4 (1 foot & 1 row) to determine whether it is a measurable area within a finite distance.
Woo VA+VB2VL (When VL<Vl(), t, t Since the levels of the integral signals vA and VB are extremely low, it is determined that the object is in the infinite shape 31η, and subsequent distance measurement is performed by infinite time distance measurement, which will be described later. Figure 3 shows the state of the signal ■ON?VB% signal VA + vB when entering the infinite distance measurement mode.Distance measurement was performed until t=T. Result ■Enter + ■Exit<V
Since the integral signal and the value of VB are both extremely low, it is difficult to judge that the object is in an infinite state.'f: CDm l VA 'B l nof1u
id l VA-VB 1vλ-V even if l≧VD
Even if n l < VD, this is ignored.

Note that even when the object is not far away and the reflection range of the object is low, the light-receiving element 6 cannot receive sufficient reflected light, so this kind of arm occurs in this case as well, but when projecting like this device, - In systems that measure distance using a light-receiving system, it is very difficult to distinguish whether an object is far away or has low reflection. Assuming that all of these heights are the former, the control circuit 111 generates the f'jj control signal (FF
=11NN=0) is output to the motor drive circuit 113.

Naturally, if another distance measurement signal is given before the shadow lens l reaches the end of .1L>, a stop or reversal signal is applied to the motor drive circuit 113 at that point.

[Phase] ■When 10vB≧■L, that is, +p0shi? while,
The V input + VB signal after 111 minutes is ■L≦V input + VB
When < Vvt, l VA-Va 1≧VD Kato9 dl)'f' (If wo line fx i, l VA-V
When B l <"r>, as a general rule, focus at a low level and perform 4 (IQ). % 34 V (as shown in C < I
When %-VBI≧VD, it is determined that the lens is out of focus at a low level, and as a general rule, the motor is rotated at low speed in the direction of aligning scissors.

[Phase] Now, as stated above, when IVA 1≦VD, a motor stop signal is output from the expansion circuit 111 as a low level focus, but as an exception, ■ flag;
When 1, this stop signal is not output. ■The flag is 0 above
This is set when the mode is changed to the time distance measurement mode. In the IT ranging mode, it is reset to KO as described in 61. (2) When the flag is set to 1, the a++ control circuit 111 outputs the same control signal as the previous time to the motor jump circuit 113. ■ In ranging mode at low level
If the flag is set to 1, it is only when transitioning from ω standby mode to low level ranging mode, and ■ when transitioning from standby mode to low level ranging level mode.
i As will be described later, a signal to move the motor in the infinite direction is output. For this reason, when the ■ flag = 1, even if it is determined that the focus is at a low level, the motor 8 will move the lens group l.
continues to move in an infinite direction.

The reason why the φ flag = 1 was set as an exception to this rule is that when focusing on a subject that is far away or on a reflection so that a low-level focusing signal is output, it is necessary to (1+: t: It has been experimentally shown that when the mll distance is started from a shifted position, the in-focus signal J is output due to the leakage of the light receiving element 6 while it is still in the process of being out of focus. Therefore, when the motor 8 is stopped with such a false focus signal, it will stop in a state that is largely out of focus t9.

Therefore, the ω flag is used to identify a false focus signal, and if the flag = 1 as described above, the discount f output circuit 111 tI
'i Distance measurement is continued in the low level distance measurement mode with the full output of the infinite direction signal.

[Phase] When the flag = O, the motor stop signal is sent as a general rule.
No. is output from the sub-m11u path 111, and the motor 8 stops.

[Phase] On the other hand, in some cases, when IVAVBI≧VD, it is assumed that the object is out of focus at a low level. After determining that the lens is out of focus at a low level at this time, a determination is made as to whether or not the direction of the focus shift is greater than v.

When 0.mu.>VB, it is in the continuous bin state, and the s i't control circuit 111K determines that it is safe to drive the motor 8 to extend the lens #l to the full length 11+l. In the low-level ranging mode, the motor speed rotates at a low speed in principle.The reason is that in the low-level ranging mode, the values of the minute signals V, VB are both small, so the S/N is low.
This is to prevent unstable movement of the lens group l, such as hunting, since a sufficiently reliable direction (i) cannot be obtained.

[Phase] Next, it is determined whether the low-level, unfocused acid pin state has been added n4 times in a row. When a constant direction signal is obtained n4 times in a row, the signal V,,V
It is determined that 87N of B is sufficiently high, and the mode returns to normal distance measurement mode. In this way, the power saving by the normal distance measurement mode (the distance measurement light is completed when 1~・λ-Val≧VD and rests until T) and the cheapness of the 11 distance mode at low level (judgment is made after integrating up to To) In other words, it is possible to achieve both

[Phase] Returning to [Phase] again, when vk>VB is not satisfied, that is, when it is the previous bin, it is determined whether the ■ flag = 1 as in the case of low level focusing described above.

[Phase] ■When the flag = 1, move the lens group l to the close side (rotate the motor 8 at speed ^).

The reason for the high speed here is to prevent the motor 8 from temporarily slowing down near the false focus signal due to a false focus signal while going out of focus. On the other hand, when the ■ flag is O, the motor 7 is driven at a low speed in accordance with the above-mentioned principle.

[Phase] Next, for the same reason as [Phase], ns 1-71
If the direction signal is output continuously, return to normal distance measurement.
If not, low level! Perform distance measurement again in temple distance measurement mode.

■ On the other hand, when the in-focus state is determined at a low level in [phase] and a signal is output to stop the rotation of the motor 8,
When the level is low, the mode shifts to focus distance measurement mode and distance measurement is performed again. In the focus distance measurement mode at low level, the 44j constant condition for distance measurement completion is VA+VB≧VL ('/L<VH) or 1d t≧
T, ('l”, (T, example Eva T.

= 1.76 mx), and the condition for determining distance measurement completion in low level distance measurement mode is VA + VB≧VH or t≧T.
, is different from . This is similar to the normal focus distance measurement mode explained in Fig. 20, by making 'r shorter than +1 + o, s e + 'p widens the dead zone as shown in Fig. 35.
This is to stably stop the lens 8 to a position of 1θ that is determined to be in focus, and to reduce power consumption. In particular, the signal v
Since the levels of k and v8 are low < S/N is poor, stabilizing the in-focus state by widening the dead zone is extremely effective. In addition, ■+vB≧vL (VL < VH)
The reason for this is to correspond to the maximum integration time TI and enable focus judgment even in normal ranging mode. 0 [phase]
When distance measurement is completed, first, 114 pairs of v, +vB≧■L are matrixed. When v,7+vB≧VL, the integrated signal is above the required level even though the acquisition time has become shorter, so the signal has become large enough to perform distance measurement in normal distance measurement mode.tlJ disconnect, return to normal distance measurement mode, and perform distance measurement.

(i!ri Vx + VB ≧ML te'l '/'
When olvA-Vnl≧VD, it is determined that the signal has become sufficiently large, and the mode returns to the normal distance measurement mode.

e vA+Vs<VL and IVA-VBt<Vo O
At time #i, it is determined that the camera is in focus and counts until t=ToKJ.

■ Determine whether distance measurement in focus distance measurement mode has been repeated nfi times at low level, and if n, once, return to i)'+lt distance mode at low level s ns times. If so, repeat 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 nth time, and the distance measurement completion judgment condition is set to V^+VB≧
By setting vFK or t≧″r0, the dead zone is returned to its original state and the deterioration of ranging accuracy is prevented.As described above, the ranging mode is changed from the low level focus ranging mode to the low level ranging mode. 41 makes it possible to simultaneously ensure focusing stability at low levels, '1JfiEi power generation, and 4N ash maintenance.

Next, the co mode will be explained with reference to FIG. 22. The transition to the d111 distance mode at ω is when it is determined that ζ+VB<VL in the [phase] of FIG. 20, as described above. That is, as explained in the flowcharts of FIGS. 20 and 21, if both the iM product signals vAs and vB for distance measurement are extremely low, it is determined that there is a head, and the distance measurement is performed when the subject 5 is in an infinite state. The camera enters 0 o'clock distance measurement mode, which is suitable for

(2) In the 0 o'clock distance measurement mode, it has already been determined that there are an infinite number of temporary objects 5, so the motor 8 is first driven in the infinite direction at high speed.

@ Next, the ω flag is set to l to indicate the hand in which the infinite signal was generated. As explained above in the flowcharts of FIGS. 20 and 21, the ■ flag is used to distinguish the V$ focus signal, and is reset to OK in the normal distance measurement mode.〇@Next B? Set n6 to use M(6) from the INAM area in the microcomputer as a counter for counting the number of times the machine has run.

@ In ooiQ ranging mode, VA + VB≧v(I
Also, Fi, t = 'l'.

It is determined that distance measurement is complete. Here, one of the conditions for determining distance measurement completion in normal distance measurement mode is 1Vx-%'nl≧VD
The reason why there is no is in the low level distance measurement mode and in the stud ∎ time distance measurement mode, both the integral signals VA and VB are extremely low values, so the value C of lv person - v131 is unreliable. It is from.

In the equation, the maximum 1i1i1 distance time Tt (Tt < To e.g. Tt = 19.3 m
5-c) As for -low level a+++ y+i, the time is shortened by the maximum +jt minute than the mode, as will be described later, with the border of ■+vB-■L as "CVA + VB) VL"
Naraha v, I vB (7) Large and small Ia Section I'm J:
Rutameni, who performs the direction judgment and determines that if v person Jujimo < VL, it is Otori, ■ 8 is an infinite direction regardless of the magnitude relationship.
VA +Vs: Vl, time (i% - VAI
This is to prevent hunting from occurring due to the influence of noise such as Vo V'-k x<, which would result in a completely opposite direction determination. The equipment cost is as shown in Fig. 36.
Instead of adjusting the value of vL, the same effect is obtained by changing the time period To to T.

@ VA + VB -ip VHcD Q B i
*'M 1ifll VM Mote IC Templ It is determined that distance measurement is possible, and distance measurement is performed in the local distance mode.

@V, 1+VB≧V [("?' When no, distance measurement is completed Hat = Tt Because it is done by To-Il
l. Count time.

@ V person + 0 ■ person + who identifies whether VB≧vL
When VB≧vL, as described in Fig. 21, the 6111 distance should be performed in the tltil distance mode at low level, so it returns to the low level distance measurement mode and enters the next claw 1'' distance cycle. .

@06 continuously since the distance measurement mode started at ω
Take advantage of the number of times that have passed. If it has not reached the 06th time, it returns to @ again and performs distance measurement at the center of the maximum integration time + aj'. In other words, this means that the predetermined time after starting distance measurement in ω mode (times n6 times) is the maximum time Tz (Tt
< TO), but as described below (iJ yo < Ts
(Ts < Tt < To) Do not make any changes.

The reason for this is that infinity is judged because, as mentioned above, the signal is small because the object is actually powerful or the amount of reflection is low, so it is okay to judge it as infinity. Objects with low reflection are unavoidable, and objects are
! ! ] The distance ν is equal to the distance ν; At first, it is moved in the direction of the silent limit by infinity judgment, and when the reflection light emitting slot) 1w P starts to form correctly on the light receiving Yonago 6, the distance of 1 illll becomes possible, and ■
, depending on the magnitude of the VB signal, the F'A #
This is the case when it is done.

and C) 6Rs4 combination, maximum 4'jt minutes! ifl
k Ts ('I's < Tt. For example, Ts =
If it is set to 1.76 m5x= ), the discontinuity band will be widened, the response will be delayed, and as a result, the correct control of the motor 8 will be delayed, resulting in overrun of the in-focus position. In order to eliminate such defects, we need to distinguish between the infinite state of the soldier and the short-term infinite state during the focusing process, as in the case of Kohobe.

During the session, the maximum operation time is T without changing to T3.

Distance measurement is performed with ('l''t<To) maintained.

fx > , 00 o'clock Jii 5 (tri in i-mode
ll As long as you run the distance, always 1 jil 1 circuit 1
11 outputs a signal to cause the motor 8 to move in an infinite direction.

However, when the shi/zu l reaches the infinite end, the infinite switch 2
62 is turned on, and the motor 8 is stopped.

[Stocks] n After the 6th time, the maximum 4i' is applied to the minute time Ts (
Distance measurement is carried out at vA+VB≧■1 or t≧゛r. This is due to the low level focus Jul Ir mentioned in h11.
Same as 4i mode, the maximum time is 4.4 minutes 7゛I's (T
By making s <'i'*), the dead zone is widened,
We are striving to achieve both safe living and economic efficiency.

($ V4 + VB ≧VL (1) 'm case,
It, large+'a minute 1ii3 '1', (T,
(T,) short<1. Despite fc, the ratio IPλja
'Vr, so 1R vAs vB is normally σ,
It is sufficient even in 11 set mode (if it is thick enough to allow H11 distance, return to ++J, ljZ L, JTI normal distance measurement mode.

[Stocks] When VA +VB < V2O, the secondary fruit is the integral signal vA.

Since the VB level is still extremely low, it is determined that subject 5 is again in an infinite state 1zs II, -1゛3 o'clock [
Count the rivers.

[Phase] Next, a 1'JJ determination is made to determine whether the 1tiil distance has been performed n7 times at the maximum integration time Ts, and if n7 times have not been reached, it is again determined as [Stand].

(2) When the n7th djU distance is completed, next distance measurement is performed once with 4' and the maximum integration time set to T.

Here, the number of rectangles is 7 times per month (tt minutes). Returning the time to T2 is the same as the low-level focusing roll distance mode described in IJ. .At @, the maximum time is reached 06 times in a row! O minute time T
, fvl (6) = no was set in order to measure the distance at , but here it is only once, so m4 (6) =
Set to 1.

Above is 1. Mowing distance mode 2, normal focusing mode 3, low level ranging mode 4.11 and level combination 6]+1 distance mode 5, oO mode l
This is a detailed explanation of the five distance measurement modes based mainly on the flowcharts shown in FIGS. 20 to 22. As is clear from this explanation, the automatic focus detection device according to Mokupomei is reliable and easy to use by switching the distance measurement modes 1 to 5 above as appropriate to perform distance measurement. In addition, in the above embodiment, it is possible to achieve both good operation and power saving.In addition, in the above embodiment, it is possible to achieve both in-focus and out-of-focus. Signal.

It is calculated from the magnitude of the absolute difference between VB and VB1, but this can also be calculated from a ratio such as VA/VB, which is as much as 6 degrees. That is, the signal V, v8
The present invention can be applied to anything as long as the size relationship between the values is innovated. Father, v as in the above example, 10V
Instead of determining the signal level from B, the signal level may be determined from either VB or VB. In other words, the present invention can be applied to any device as long as the level state of No. Needless to say, it can be applied.

As explained above, the present invention projects a light spot image onto an object, and outputs at least two types of E signals depending on the light receiving position where the reflected light is received. According to the relationship, in the automatic focus detection device of the imaging optical system that forms an image of the object on a predetermined focal plane, the magnitude relationship between the integral values of the output direction of the light receiving element is equal to or higher than a predetermined level. and time detection means for detecting that the projection time of the projected light spot image has reached a predetermined time. (1) Determine that the imaging optical system is in an out-of-focus state, and determine that the imaging optical system is in focus when the time detection means detects that the predetermined time has been reached. A determining means is provided, and after the determining means determines that the focus is in focus, the predetermined time detected by the time detecting means is changed to a shorter time, so that the dead zone region is variable. It is possible to stabilize multiple operations and improve accuracy, and at the same time, it is possible to extremely reduce power consumption, and the effect is extremely high, especially in devices such as cameras that require compactness.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a conventional example, FIGS. 2 to 8 are schematic diagrams showing an optical system of an automatic focus detection device according to the present invention, and FIGS. 9 to 19 are automatic focus detection according to the present invention. An explanatory diagram of the electric circuit of the device, FIGS. 20 to 24 are operation flowcharts of the automatic focus detection device according to the present invention, and FIGS. 25 to 36 are supplementary to the operation flowcharts shown in FIGS. 20 to 24. Explanatory diagram. 1'...Taking lens 2...Planned focal plane 3...Light emitter 4...Φ light emitter lens 5...Subject 6...Light receiving element 7...Light receiving lens 8...Motor 9φ fist/AF circuit No. q Fig. 76 S YNC No. Z'7 Fig. 2 B! Figure 22 Figure 5 Figure 24 Figure 25 ■ Figure 26 (Figure X ■ Figure 35 TI 乃 L7z T
ot

Claims (1)

[Claims] (1) A light receiving element that projects a light spot image onto a target object and outputs at least two types of signals depending on the light receiving position that receives the reflected light. An automatic focus detection device for an imaging optical system that forms an image of the object on a predetermined focal plane, wherein the magnitude relationship between Tagata's integral values of the light receiving element is equal to or higher than a predetermined level. and a time detection means for detecting that the projection time of the projected spot image has reached a predetermined time,
Further, when the comparison means detects that the F-fr has reached the predetermined level or higher, the imaging optical system is determined to be in an out-of-focus state, and the time detection means determines that the predetermined time has been reached. A determination means is provided for determining that the imaging optical system is in focus when the above-mentioned imaging optical system detects the focus, and after the determination means determines that the focus is in focus, the above-mentioned imaging optical system detected by the time detection means is provided. An automatic focus detection device characterized by changing a predetermined time to a much shorter time. (2. In the device described in claim (1),
An automatic focus detection device characterized in that the determination means is a microcomputer. (3) In the device described in claim (2),
An automatic focus detection device characterized in that the time detection means is included in the microcomputer.