JPS59201007A - Automatic focus detecting device - Google Patents

Abstract

PURPOSE:To save a power consumption, and to increase a focus detecting speed by detecting a fact that a projection time of a projecting spot image has reached a prescribed time, or an integral value of an output of a photodetector has reached a prescribed level, and executing a focusing decision. CONSTITUTION:An electric signal is outputted in accordance with a photodetecting position of a reflected projecting spot image from photosensitive areas 6A, 6B of a photodetector. Voltage VA, VB are outputted from integration circuits 103a, 103b through amplifiers 101a, 101b and synchronous detecting circuits 102a, 102b, and an output from a comparator 107 which has compared ¦VA, -VB¦ and a comparing value VD, an output from comparators 108, 109 which have compared VA+VB and comparing values VL, VH (VH>VL), and an output from a comparator 110 which has compared VA and VB are inputted to a controlling circuit 111. In the controlling circuit 111, a projection time (t) of a projecting element and the maximum integral time T0 are compared, and when one condition among three conditions of ¦VA-VB¦>=VD, or VA+VB>=VH, or (t)>=T0 is satis fied a completion of photometry is decided.

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. 34, 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 a device in which the light is received by a light-receiving element PD having a PB, and the distance from the light-receiving position to the object OB is detected, or the focusing state of the imaging optical system is detected. In the figure, it moves in conjunction with the light receiving element PD and the imaging optical system. That is, as can be easily understood from FIG. 34, the projected light spot image projected from the light projecting element LT now hits the object/OB at the position S1 and is reflected, and the reflected light is exposed to the light of the light receiving element PD. It is assumed that the area is formed exactly between areas PA and PB. At this time, considering a state where the object OB is at a position S2 further away, the object OB
The projected light spot image reflected from the light receiving element PD is formed at a position closer to the photosensitive area PA side of the light receiving element PD. Further, assuming that the object OB is located at a nearby position S3, the projected light spot image reflected from the object OB is formed at a position closer to the photosensitive area PB of the light receiving element PD. Therefore, when the subject OB is at position S1, if the focal position of the imaging optical system is on the expected focal plane FM (in-focus state), then the subject OB is at position S2 or S.
Even if it is out of focus in 3, the photodetector PD
By comparing the light reception outputs of the photosensitive parts PA and PB, it is possible to know which side the focal position of the imaging optical system is shifted from the expected focal plane FM. Therefore, by applying this principle, when the imaging optical system is in an out-of-focus state, the photosensitive area PA of the photodetector PD.

Depending on the magnitude of the output of the PB, the imaging optical system is moved manually or by a motor or the like along the optical axis in the direction of the in-focus position. As the imaging optical system moves, the light emitting element L
When the projection direction of T and the light reception direction of the light receiving element PD are changed, and the above-mentioned projected light spot image is formed exactly between the photosensitive areas PA and PB of the light receiving element PD, the focal position of the imaging optical system is at the planned focal plane. If it is set so that it is located above, the focus of the imaging optical system can be detected by detecting that the difference in the received light output between the photosensitive areas PA and PB has become zero. As a result, the photosensitive areas PA, P of the photodetector PD
If the difference in the outputs of B is zero, it is in focus, and the photosensitive area PB
If the output of the photosensitive area PA is thicker than the output of the photosensitive area PA, then the front focus (a state in which the focus position of the imaging optical system is placed in front of the expected focal plane) and the output of the photosensitive area PA is greater than the output of the photosensitive area PB. If the beam is also thick, the image is rear focused (the focus position of the imaging optical system is behind the planned focal plane). Depending on the magnitude of the outputs of the photosensitive areas PA and PB, the imaging optical system can be manually or automatically moved backward for front focus, or forward for rear 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 integrated value of the output of the light receiving element is generally set at a certain level. If the distance is not reached, it will be difficult to perform the focus detection with high accuracy. That is, 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 parts PA and PB are both close to the noise level, and it is difficult to determine where on the light receiving element PD the projected light spot image is located. Since the formation of the photosensitive portions PA and PB is different, it becomes possible to compare the output levels of the photosensitive portions PA and PB9, and it is only through this that it becomes possible to accurately detect the focus position. In other words, it is difficult to accurately perform focus detection according to the output of the photodetector PD as described above unless the projected light spot image is continuously projected onto the photodetector PD for a certain period of time and the received light signal is integrated. It is.

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 detect the focal position. Since the intensity of the light of the projected spot image that enters the light receiving element changes greatly depending on the distance and reflectance of Even though the value has reached a level at which the focal position can be detected, the projected light spot image continues to be projected for the predetermined time.

Therefore, wasted power is consumed by large leaves, and the focus detection time becomes longer.In order to downsize, only a power supply with a small capacity can be incorporated.Furthermore, the focus detection speed is This has been an extremely serious problem in devices such as cameras, which require improved performance.

The present invention has been made to solve the above-mentioned problems, and its main features are to provide an automatic focus detection device that is efficient in power consumption and has a high detection speed.

The feature is that the image of the object is determined by the integral value of the output of the light receiving element which receives the reflected light of the projected light spot image projected onto the object and outputs a signal according to the receiving position. An automatic focus detection device for an imaging optical system that forms an image on a predetermined focal plane, the device comprising: a time detection means for detecting that the projection time of the projected light spot image has reached a predetermined time; and an output of the light receiving element. level detection means for detecting that the integral value of has reached a predetermined level; The integrated value of the output of the light-receiving element is at a level at which focus can be detected by an automatic focus detection device including a determination means for determining the focusing state of the imaging optical system based on the integral value of the output of the light-receiving element. When this occurs, focus determination is quickly performed to save power consumption and improve focus detection speed.

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

Figure 1 shows an automatic focus detection device (hereinafter referred to as AF device)
This diagram schematically shows the overall configuration of the . In the figure, 1 is the lens group involved in the focusing operation in the photographic lens, 2 is the imaging plane of the image sensor, and here the imaging plane of the image pickup tube is shown, but the imaging plane of the solid-state image sensor, It's good to see Orui on film. Reference numeral 3 denotes a light projecting element for projecting a light beam onto a field of view (generally a distance measurement area), and is composed of a laser diode, a near-infrared light emitting diode, or the like. 4 is a light projecting lens which forms a light projecting spot image of a light projecting element 30 on a subject 5 (generally a distance measuring object). The light can be divided into 6B and the output direction can be determined (1), and the area A is arranged on the light projecting element 3 side, and the area B on the opposite side. The light-receiving sensor 6 is designed to pass as much light as possible from the near-infrared light emitting diode 3 (1), for example, and to suppress external light components. A light spot image is formed on the light receiving sensor 6. Reference numeral 8 denotes a photographing optical system driving motor, which is interlocked with the lens group 1, the light projecting element 3, and the light receiving sensor 6 via a cam or the like.

Reference numeral 9 denotes an automatic focus detection circuit (hereinafter referred to as AF open circuit) which moves the motor 7 in accordance with the output of the light receiving sensor to move the lens group 1 to the in-focus position.

Next, to explain the operation of the apparatus shown in Fig. 1, the subject 5 is from the imaging plane! When the distance is , the reflected light of the projected spot image P is divided into two areas 6 on the optical sensor as shown in Fig. 2 (1m).
Suppose that the same amount of light is received as A and 6B. In this case, in the light receiving sensor 6, the difference A-B between the output from the area 6A and the output B from the area 6B is O. In terms of the optical path, the light emitted from the light projecting element 3 passes through the optical path, hits the subject, is diffusely reflected, and further passes through the entire optical path to form an image on the light receiving sensor 6. So, at this time, assuming that lens group 1 is at the in-focus position, subject 5! Assume that it has moved to a distance of . Then, surprisingly, the focus position of lens group 1 shifts to the rear, resulting in a rear bin state. On the other hand, if the light projecting element 3 and the light receiving sensor 6 remain in the same position, the light path a hits the subject and is diffusely reflected, and an image is formed on the light receiving sensor 6 through the light path a, /.
As shown in Figure 2 (bl), the imaging position is large in the near area 5.
It shifts to the B side, and the above A-B does not become 0.

Therefore, this amount of shift is calculated as the amount of movement of the subject 5, that is, A2-11
The lens group 1 is moved to the in-focus position in response to this. That is, the sign of A-B (including its size in some cases).

), the AF circuit '9 rotates the motor 8 forward or backward, and moves the light emitting element 3, light receiving sensor 6, and lens group 1 in conjunction with a cam etc., so that A-B=0, that is, the light emitting spot. When the image comes to the intermediate position between areas 6A and 6B on the light receiving sensor 6, the image of the object at a distance of 11 is formed sharply on the image forming plane 2.

As a result, the light projecting element 3 moves to the position 3', the light receiving sensor 6 moves the boundary line between the far area 5A and the near area 5B to the position 6', and the lens group 1 moves to the position f.

In this case, the projection optical path is a□.

The reflected optical path is indicated by bl. On the other hand, if the subject moves to position l, lens group 1 etc. will move in the opposite direction to the above,
A focusing operation is performed so that A-B=O. In this case, the projection optical path is indicated by C1, and the reflected optical path is indicated by C1.

3 to 6 show other embodiments of an automatic focus/detection device that performs distance measurement based on the same principle as the device shown in FIG.
The light emitting and receiving forms are different from the device shown in FIG. below,
The same members as those in the apparatus shown in FIG. 1 are given the same numbers and will be briefly described.

FIG. 3 shows a type of so-called half-TTL distance measurement in which a light spot image is projected from a light projecting element through a photographing lens, and the light is received by a light receiving sensor provided outside the camera. Reference numeral 10 denotes a half mirror having a reflective surface 10a configured as a cold mirror, and is arranged between the imaging lens group 1 and the imaging plane 2, which move for focus adjustment, in particular, of the photographing lens. 4' is a floodlight lens.

3 is a light projecting element, and it is preferable that the light projecting cable 3 is placed at a position optically conjugate with the imaging plane 2. The movement of the photographic lens 1 is performed in mechanical conjunction with the light receiving element 6.

FIG. 4 shows a so-called TTL distance measuring type automatic focus detection device in which both light is projected from a light projecting element and light is received by a light receiving element through a photographing lens. 10' is a half mirror placed at the same position as 10 in FIG. The light beam spot image of the element is designed to pass near the outer circumference of the pupil of the photographing lens 1. 7' is a light-receiving lens; 6 is a light-receiving element disposed at a position optically conjugate with the imaging plane 2 of the photographic lens 1;
1. The luminous flux is near the outer periphery of the lens 1, and
It is designed to pass through a position that is different from the projected light beam. Note that the light emitting element 3 and the light receiving sensor 6 are fixedly installed.
, there is no mechanical linkage with the photographic lens.

Figure 5 is a modification of Figure 4, in which the emitted light flux is aligned with the photographing optical axis. Figure 6 uses the same light emitting system as in Figure 3, and serves as a light receiving sensor. This figure shows an automatic focus detection device in which an image sensor 13 provided on the imaging plane is used for focus adjustment and imaging. The image signal received by the image sensor 13 is divided by the distribution circuit 11 to the υAF circuit 7 and the image sensor 12.

FIG. 7 shows the photosensitive surface of the image sensor 13 of the device shown in FIG.
The signals from the two zones B are sent to AF via the distribution circuit 11.
Send to circuit 7. Further, in the case of the one shown in FIG. 6, it is necessary to devise a method to allow infrared light to pass through the image pickup element 13 during distance measurement, and to remove the infrared light during image pickup.

By the way, in the above embodiment of the type shown in FIG. 1, since the light emitting lens 4 and the light receiving lens 7 are located outside the photographing lens 1, it is possible to increase the size of the projecting and light receiving lenses 4 and 7. Me9, it has an advantage in terms of reach distance, but on the other hand, it has the disadvantage that the overall structure is not neatly organized.On the other hand, the type shown in Figure 3 is different from the type shown in Figure 1. It has the opposite advantages and disadvantages.In addition, it does not require mechanical interlocking that requires precision between the photographing lens 1 and the projection/reception system.
It also has the advantage of a simpler structure. The type shown in FIG. 3 has properties intermediate between those of FIGS. 1 and 4.

The type shown in Figure 5 has a shorter baseline length of the light emitting/receiving system than the one shown in Figure 4, which 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-mentioned types, the light spot image formed on the subject 5 by the light projecting element 3 is formed on the optical axis of the photographing lens when in focus. In other words, the distance measurement zone for any of the above ITs is
Located in the center of the viewfinder, it is an automatic focus detection device with no variation.

Furthermore, in the case of the one shown in FIG. 6, the light receiving aperture of the light receiving sensor 13 is almost 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 reach distance can be improved. It is advantageous. or,
In the device shown in FIG. 5, the signal from the image sensor 13 is sent to the AF circuit 9.
and to the imaging circuit 12, but since it is practical to distribute this in a time-division manner, this type of system is suitable for systems such as methyl video cameras that complete distance measurement prior to photographing.

FIG. 8 shows the configuration of the electric circuit in the above device. As described above, the optical information received by each region 6A, 6B of the light receiving sensor 6 and photoelectrically converted is sent to the amplifier circuit 101a,
101b. At this time, the amplifiers 101a and 101b have sufficient amplification for the modulation frequency of the projected infrared light that becomes the projected light spot image, and have sufficient amplification for the frequency of modulated light from unnecessary sunlight and commercial power. It is desirable to use an amplifier circuit with frequency characteristics that suppress the frequency as much as possible. The output of this amplifier is applied to synchronous detection circuits 102a and 102b for synchronous detection. 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 an integrator circuit 103a.

103b, and increases moment by moment at an increasing rate proportional to the signal strength of the target signal. The integrated voltages Vm and VB obtained independently from the integrating circuits 103a and 103b through the above signal processing are processed and judged by the arithmetic circuit described below and converted into several bits of digital information.

That is, from the integrated voltage V, the subtracter 104 produces a difference signal -VB on the one hand, and the adder 105 produces a sum signal V+Vi+ on the other hand.

The difference signal ■mu-VB is added to the absolute value circuit 106 and
Get V Mu V B l. This value 1vmu-Vsl is compared with a comparison value VD in a comparator 107, and the magnitude relationship is output. On the other hand, the sum signal V+Vi+ is output by the comparator 10
8 and 109, they are compared with comparison values VLI and VH, respectively, and the respective magnitude relationships are output. Furthermore, the comparator 110 compares the magnitude relationship between Vm and Vm. The four digital information obtained from the above, namely, the comparator 107,
The outputs of 108°, 109, and 110 are applied to a sequence control circuit 111 to determine the operation of the entire system.

Reference numeral 112 denotes a light emission drive circuit, which supplies current to the light projecting element 3 in synchronization with a synchronization signal from the control circuit 111, and controls the light emission of the light projecting element 20.

A motor drive circuit 113 controls the rotational direction and rotational speed of the photographing optical system drive motor 7 according to signals from the control circuit 111.

FIG. 9 shows a further embodiment of the circuit configuration shown in FIG. 8.

FIG. 9 shows the part (4) of the circuit in FIG.
01a and 201b, the feedback circuit 202a
, 202b have a bypass characteristic. Among the energy of the infrared light actually projected from the light projecting element 3, the external light component can have a very large value compared to the energy returned to the light receiving sensor 6. The visible light cut filter 76' and this circuit have a relatively effective effect of suppressing external light components, and depending on the settings, can be used practically for most subject conditions. Furthermore, capacitors 203a and 203b
Direct current components such as sunlight are almost completely cut out.

204a and 204b are AC amplifiers, and the modulation layer
After sufficiently amplifying the components near the number, the signal is supplied to the next stage of the same detection circuit.

The synchronous detection circuits 102a and 102b shown in FIG. 8 include inverters 205a and 205b and analog switches 206a and 2
06b, and 207a, 207b.

and analog switches 206a, 206b.

This is achieved by switching 207a and 207b using a synchronizing signal 5YNO and alternately selecting a non-inverted signal and an inverted signal.

In addition, as another example, there is a method of using a four-phenomenon analog multiplier to obtain the product of the input signal and the AC component of the synchronous signal 8YNO (not shown).
pulsating flow) component and the next stage integration circuit 103a, 103
b. These integrating circuits 103a and 103b are
Operational amplifiers 208a, 208b, resistor 209a.

It consists of 209b, -M/differential f210a, 210bK. Then, a current proportional to the synchronous detection output voltage flows from the synchronous detection circuits 102a and 102b through resistors 209a and 209b, respectively, to a capacitor 210a.
, 210b and is stored as an integrated voltage to operational amplifier 208a.

It is output from 208b. This voltage is VA.

It is VB. In addition, 211a and 211b are capacitors 21
This analog switch is used to initialize the charges accumulated in the capacitors 210a and 210b, and the charges accumulated in the capacitors 210a and 210b are cleared by the CLR signal from the control circuit 111 in preparation for the next accumulation.

Figure 10 shows the i-minute voltage VA, Vn to l VA-
This shows the (J3) part of the circuit of FIG. 8 which generates Vn 1 and compares it with the comparison voltage VD. Integrating circuit 10
3a.

The integrated voltage Vm, Vn outputted from 103b is subtracted by a subtraction circuit 104, which includes an operational amplifier 212 and resistors 213 to 216, to obtain -Vm+VB.

This value is added to the absolute value circuit 106 at the next stage. The absolute value circuit 106 includes an operational amplifier 217. Diode 218,2
19. It is composed of resistors 220 to 223. Operational amplifier 217. Diode 238, 219° Resistor 22
With the configuration of 0.0,221, the cathode of the diode 219 has a high impedance when a negative input is applied, and a potential that is 11 times the input voltage when a positive input is applied. As a result, the negative input of comparator 224 receives a voltage of -0.5 IV -V B l.

By applying a voltage of -0.5VD to this positive input, l VA -VB l and VD are compared. Let this comparison value be DD. 0. Also, note that FIG.
VA and Va are added together by resistors 225 and 226Kj, and 0.5 (VA + VB) is co/. Shif
i 22 is added to the positive input of L228. 0.5 vL, 0.5 VH on the negative input of each comparator
is added >p, (VA +VB): VL,
(VA+VB): Comparison of Vii is performed and comparison values LL and HH are output.

Furthermore, FIG. 12 shows part (6) of the circuit of FIG. 8, where VA and VB are directly compared by a comparator 229, and a comparison value AB is output.

FIG. 13 shows another embodiment for obtaining the comparison value DD from VA and VB. VA, Vn are comparator 230,
It is added to the positive input of 231.

It is also applied to the negative input via resistors 232 and 233. In addition, constant current sources 234 and 235 are also connected to the negative input, and as a result, the negative input has Vn + iR,
A voltage of VA + iR is applied.

However, i is the current value of 234,235, and R is 232°23
The resistance value is 3. The outputs of comparators 230 and 231 are applied to an OR circuit 236 to obtain an output DD.

Output DD is VA Vn>iR= VD or Va −
vA > iR= VD (becomes true logic at 0 o'clock, IV
Mo - represents the logic of VB l > VD.

FIG. 14 shows a hardware implementation of the order control circuit 111. The clock C determines the minimum cycle of the sequential control circuit 111, and becomes the source of the light emission modulation of the light projecting element 4 and the synchronization signal 5YNC of the synchronous detection circuits 102a and 102b. 236 is an n counter, and the period of this output Cn determines the distance measurement period and the maximum integration time. Flip-flops 237 and 238 receive signals DD and HH, respectively.
and is reset every distance measurement cycle by the signal C1. The respective outputs DDQ and HHQ of the flip-flops 237 and 238 are integral abort signals, and the OR
It is input to the flip-flop 240 via the circuit 239 and held at the period of the signal Cu. flip flop 240
The inverted output Q becomes the infinite signal FAR. Signal F A R
and DDQ are connected to flip-flop 2 via OR circuit 241.
42 to output the motor rotation signal MO. This flip-flop 242 is also reset by the focus signal HHQ signal, prohibits output of the motor rotation signal MO during focusing, and stops the motor 6. The signal AB is updated in the flip-flop 243 by a signal DDQ representing out-of-focus to become ABQ. Here, the front pin is the 0 signal AB, which is true logic when VA > VB.
Q and the signal FARfJ are passed through the OR circuit 244 to become a signal FN representing the rotational direction of the motor. The final motor drive signals FF (towards infinity) and NN (toward close range) are the output of an AND circuit 245 which receives signals FN and MO as inputs, or the output obtained by passing signal FN through NOT circuit 246 and signal MO. The selection is made by the output of the AND circuit 247 which receives as inputs.

The synchronizing signal 8YNC is output from the OR circuit 239°NOT circuit 24 when the signal DDQ and the signal HHQ are both in pseudo logic.
8 to the AND circuit 249,
It is input to an AND circuit 249. Output CL of clock C
It is output in synchronization with K. The integration initialization signal CLR output from the OR circuit 250 becomes true logic from when the end of integration is determined based on the output of the OR circuit 239 input to the OR circuit 250 and the signal Cn until the start of the next integration.

FIG. 15 shows waveforms observed as each signal in FIG. 14 when the state changes from front focus to back focus to focus to infinity.

At the front pin, DD rises first, and AB is at H11 at this time. In the rear bottle, pDD stands up first, but AB'
L''. When in focus, HH rises. At infinity, the maximum integration time is reached before any of them rise.

FIG. 16 shows a sequential control circuit realized by software using a microcomputer.

This figure also shows an example of a light emission drive circuit 112 and a motor drive circuit 113 of the light projecting element 3. 251 is a microcomputer (for example, it has an internal structure as shown in FIG. 17), and the above-mentioned signals D are connected to the long sword terminal.
D, AB, LL, HH are input, and from the output terminal, these are also the aforementioned signals 5YNC, C1, l(.

FF and NN are output. Further, it is easy to add a signal LOW for controlling the rotational speed of the motor.

The current flowing through the light emitting element 2 is the transistor 252.25.
3 via signal 5YNC.

The current flowing through the motor 7 is switched by the signals FF and NN via the transistors 254 to 257, and flows in the forward or reverse direction. transistor 258,
259, diode 260 has a voltage control circuit, and the LOW
The voltage applied to the motor is switched in two stages according to the signal. Reference numerals 261 and 262 are a close range switch and an infinity switch, respectively, which close when the photographing optical system hits the close end or infinity end to prevent driving beyond the limit.

FIG. 18 shows electrical signal waveforms at various parts of the circuit shown in FIG.

The synchronous signal 8YNC is the synchronous detection circuit 102a.

102b, it is also used for current driving the light projecting element 3, and the light emission output IRED is obtained. Light receiving sensor 4a
, 4b is obtained as a superimposition of 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 signal 8PC. The signal Amp is obtained by applying this signal to amplifiers 101a and 101b having high-pass characteristics. When the CLR signal is released almost simultaneously with the start of light emission, the synchronous detection circuit 102
a.

The output of 102b is integrated, and the integration circuits 103a and 103
An integral waveform like the signal Int appears at the output of b.

This integral waveform increase is proportional to the amount of emitted light component of the emitted infrared light. Extreme [sufficient number of times (time) even for weak inputs
A large signal-to-noise ratio can be obtained by integrating .

Next, the operation of the above apparatus will be explained based on FIG. 8 and according to the flowcharts shown in FIGS. 19 to 22.

Here, the control circuit 111 is a microcomputer (
A microcomputer (hereinafter referred to as a microcomputer) 251 is used.

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

(2) First, it is determined whether the input terminal 5ENS terminal of the control circuit 111 is at a high level.

When the 5ENS terminal is at a high level, the adjustment mode is entered and distance measurement is not performed. The adjustment mode will be described later with reference to FIG. 21, and here, the normal distance measurement will first be described based on FIG. 19.

■ When entering normal distance measurement mode, first reset the ■ flag. The purpose of this ω flag will be described later in the flowchart of FIG. Microcomputer 251 for ω flag
It is assumed that memory M(1) in the RAM area is used.

■ The distance measurement operation continues, but first the light emission drive circuit 112 and the synchronous detection circuits 102a and 102b
is driven in synchronization with the synchronizing signal 5YNC, and the clear state of the integrating circuits 103a and 103b is released. As a result, infrared light is projected from the light projecting element 3 toward the subject in synchronization with the synchronization signal 5YNC, and the reflected light is transmitted to the light receiving element 6.
is detected. In the light receiving element 6, the two 6A and 6B output electric signals according to the amount of received light, which are sent to the amplifiers 101a and 6B.
101b and the synchronous detection circuits 102a and 10
2b performs synchronous detection. The optical information thus obtained is sequentially integrated by integrating circuits 103a and 103b, and the outputs thereof become integrated voltages VA and VB. And these integrated voltages VA and VB are shown below.
The four digital information of 0 is processed and input to the control circuit lll. The difference signal vA-VB is generated by the subtracter 104 and is added to the absolute value circuit 106, and the absolute value IVAVBI is compared with the value and the magnitude relationship with D is determined. The output of the comparator 107 that compares
DD ■ To VB ■ Output of the comparator 108, which compares the magnitude relationship between the sum signal I by the adder 105 and the comparison value UL, L Output of the comparator 110, AB On the other hand, in the control circuit 111, the integrating circuit 103 a ,
The integration time of the signal at 103b is measured, and let this be t, the predetermined maximum integration time T.

The size relationship between the two is compared.

Make a judgment. When any one of these three conditions is met, the control circuit 111 determines that distance measurement is complete,
DD, AB, LL, H) 1 of the control circuit 111 at that time
(i.e. comparator 107, 108, 109, 110
(output) is stored in memory M(0) in the RAM area of the microcomputer. Thereafter, by stopping the synchronization signal 5YNC, the light emitting drive circuit 112 is stopped, and accordingly, the infrared light emitting diode 3 stops emitting light. At the same time, the synchronous detection circuit 10
2a and 102b are also stopped. Then, by setting the output of the control circuit lll to a high level, the integration circuit 103a.

103b is brought into a clear state and prepared for the next distance measurement.

(2) After performing the above series of controls, the 4-bit data stored in M(0) performs distance measurement and movement to another distance measurement mode to be described later, so it is determined that the object is in focus.

(2) When the focus is determined, a stop signal (FF=NN=0) is supplied from the control circuit 111 to the motor drive circuit 113 to stop the AF momo-7.

■ Maximum integration time T for distance measurement. The lift that was finished within
Maximum integration time T to keep the time for one distance measurement cycle constant. The time until reaching To is counted, and the next distance measurement cycle is started after To is completed.

Therefore, according to the present device, the automatic focus detection operation is performed as soon as the level at which focus determination is possible is reached, while distance measurement is performed at regular intervals to reduce power consumption.

■ Once the focus/no-focus signal is output, from the next distance measurement cycle, the focus mode will continue and distance measurement will continue. The reason for normal distance measurement in focus mode is to change the voltage level vH for determining focus to vL, widen the dead zone, and ensure stability of autofocus when focusing. It is something to do. For example, by setting L=%vH, it is possible to obtain the same effect as doubling the effective dead zone VD, and it is possible to reduce malfunctions caused by noise superimposed on the integral signals VA and VBK. . In addition, by lowering the determination voltage, the integration time, that is, the time during which the infrared light emitting diode 3 is emitting light, can be shortened, and in a system like this system, where one distance measurement cycle is a fixed time, the power consumption can be reduced. Needless to say, it is advantageous in terms of consumption.

Now, as mentioned earlier, the other operations are exactly the same as in ■.

■Here, in ■, based on the data stored in M(0)ttc, it is determined whether or not I VA =Vs↓≧vD.If DD=1, it is out of focus. As mentioned above, the camera returns to the normal distance measurement mode and then enters the next distance measurement cycle.

[Phase] When DD=O, it is determined whether the object is in focus or the object is far away. When LL=0, the mode shifts to low level ranging mode. When LL=1, it is determined that the camera is in focus.

■ Next, count up to To in the same way as described in ■.

■ Next, it is determined how many times the focusing routine has been repeated. Repeat count n (If no, return to focus mode again and measure distance in focus mode until n=no is reached or press ■ or [phase] to switch to another mode. Switch focus mode n0 times. When n=n, the mode returns to the normal mode, and the next distance measurement is performed in the normal mode and in the normal dead zone.

As stated above, the purpose of returning the dead zone to its normal state every o times is to prevent a decrease in accuracy. The purpose of the focusing mode is to prevent this and at the same time achieve stability during focusing, which will result in a decrease in accuracy as a reaction), and no and VL are appropriate for the above purpose. It is necessary to set it to a certain value.

Above, we have described the operation when the in-focus state is detected in the normal ranging mode and the focus mode is entered based on the flowchart shown in Fig. 19. Let me explain.

As previously explained in the operation of (■) in Fig. 19, the control circuit I
This is a diagram showing all infrared light when the 9CLEAR release signal clears the integrator and the 5YNC signal is output.

Alternatively, distance measurement is completed when t=T0. Figure 22 shows the waveform when the focus is on, so 7f = sugotoku a.
When the light emission is stopped, the synchronous detection is also stopped.
Therefore, the distance measurement information for the four lines at this point is HH=1. LL
= 1. DD=0 (AB=1) is output, and is input to the control circuit 111 (microcomputer 251) to determine focus. (2) is a diagram showing the positional relationship between the light receiving element 6 and the image of the reflected light from the object of the infrared light emitting diode when in focus.

FIG. 23 shows waveforms in the focusing mode as described above. The normal distance measurement mode shown in FIG. 23 has been changed. It is clear that this is equivalent to doubling the value VD of the out-of-focus judgment.

Determine whether there is one here. When Tsubai≧■D does not exist, that is, when DD=0, the measurement is carried out in the low level mode after moving to the low level mode. The determination is made based on t- and To. At this time, the value becomes 0, and at this time, the mode is changed to the low level mode, and the determination condition for completing distance measurement is changed and distance measurement is performed again. The low level mode will be described later.

In other words, when AB=l, the rear focus is on, and the photographing lens 1
It is determined that it is necessary to drive the motor 7 to move the object to the nearest side.

(2) Next, the speed at which the motor should be driven is determined.

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 is prevented from overrunning. It is designed to stop smoothly. Determine whether it is close to being in focus or is significantly out of focus>
As mentioned above, the motor 7 is controlled by the control circuit 111 to rotate at low speed η#4 (Vs,
29, as mentioned above, the speed control of the motor described above and the image of the infrared light emitting diode 3 P (hereinafter referred to as Subotsu) P
Fig. 27 (■) shows the positional relationship of the sensors 6 (referred to as ) on the sensor 6.

■It is. Spot P is from Pl position (rear pin) to P2
It shows the magnitude of the light amount of sensor 6a and sensor 6b 113D when moving to position P (front bin) via (joint bin). The middle part of the figure indicates the range within the low speed range. The koO value is determined by the speed of the motor and the vL′ of the system.
However, other values may be set.

A signal is output from the control circuit 111 to drive the tough,
The photographing lens is controlled to the close side, and t=T as in the case of ■.
After the time has elapsed to reach 0, when < VL, the motor should be rotated at high speed as mentioned above, but here, the signal to drive the motor at even higher speed to the nearest side is continuously transmitted. It is determined whether it has been output n2 times. If it is less than n2 times, it moves to @ and is driven to the closest side at low speed.

When a signal to drive the vehicle to the closest side is outputted at high speed for n2 or more consecutive times, the speed increases from then on, and speed control is performed according to the principle described above.

However, if the same signal is not output n2 times in a row and, for example, a signal such as a focus signal is output halfway, n6
The high speed will not be achieved until the signal to be driven to the closest side is outputted at high speed twice in succession.

As stated above, the reason for controlling the speed of the motor is to ensure that the motor 7 always moves at a low speed when starting, thereby reducing the tendency to perform operations such as 71 pinching.

[Phase] ~ [Phase] Ω For operation, O ~ [Phase] and motor 7
The operation is exactly the same except that the driving direction is reversed. Next, the operation in the low level mode will be described based on FIG. 20.

■ The reason why the exact same operation judgment conditions as explained in Figure 19■ are omitted is that in low-level mode, the distance of the object is far away, or the relationship between the reflection size of the object is reversed, and the close direction and infinity direction are If the direction signals are repeated and output, the direction signals will be output alternately, which may cause the operation to become unstable.

The control circuit 111 outputs a control signal to drive the motor 7 in the infinite direction. Also, it becomes even. In the case described above, this results in outputting a direction signal completely opposite to that of the path. Due to the concerns mentioned above, the decision is made without using 1+G1≧VD as the ranging optical r signal. 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 stability of the low level mode.

[Phase] This means that the flowchart signal in the low level mode shown in FIG. 20 is sufficiently large again, and it is determined that it is no longer necessary to perform distance measurement in the low level mode, and the process returns to the normal distance measurement mode. When the low level a is reached in FIG. 108, the distance measurement is completed and the normal distance measurement mode is returned to, meaning that the distance measurement is performed under the condition of To. Continuing to judge the level of ■A+VB, it was determined that it should be judged as infinite,
Perform subsequent distance measurements in infinite time mode. In Fig. 30, it is determined that the infinite time mode is entered, and as a general rule, the motor is focused at a low speed and a motor stop signal is output from the control circuit 111 with low level focusing. When the flag is -1, the stop signal is not output, and the signal is the same as the previous time.In other words, as will be explained later in Fig. 21, the particular flag is set to 1 when entering the infinite mode, so the direction of the infinite signal is set. Signal to drive Hemo-Tough (FF=1.
NN=0) will be output.

The reason for this exception is that when focusing on a subject whose distance and reflectance are so false that a low-level focusing signal is output, if you start distance measurement from a state far out of focus, the focusing process will be delayed. It has been experimentally confirmed that a false low-level focus signal is output. If the motor 7 is stopped with such a false low-level focusing signal, it will stop in a state where the focus is greatly out of focus. In order to solve these drawbacks, the ω flag is used to identify false focus signals. As described above, in the case of flag -1, the control circuit 111 continues distance measurement in the low level mode while outputting the infinite direction signal.

[Phase] (1) When the flag is -0, in principle, a motor stop signal (FF-0, NN20) is output from the control circuit 111 and the motor 7 is stopped.

[Phase] Next, enter the next distance measurement cycle and perform distance measurement at VL.
or t=TI(O which is what is done at T1(To)
T, to T. By making it shorter, it is possible to obtain the same effect as when the dead zone VD is widened as in the focusing mode explained with reference to FIG. Also, since the 8/N ratio of the A and VB signals is worse during low-level focusing than during focusing, it is desirable to have a much larger dead zone. Such measures can increase the stability when focusing on the bell. Furthermore, the 19th
As mentioned when focusing on the image, in order to prevent the accuracy from deteriorating, return to the low level mode every third time, t = T0.
Return the distance measurement time to 1 and perform distance measurement. By changing the distance measurement mode as described above, it is possible to simultaneously ensure stability during low-level focusing, power saving, and maintenance of accuracy.

The Vn l signal has become sufficiently large by AB times that it can be used for distance measurement.
When ≧VD, it is determined to return to normal ranging mode as in ■,
After counting until t=ToK is reached, it is determined whether the low-level focusing mode has been repeated n3 times, and if YES, the low-level focusing mode is activated, and if NO, the low-level focusing mode is repeated.

Figure 31 shows the VAsVB signal in low-level focusing mode.
Indicates the status of VA + VB signal, l VA - VB l signal.

[Phase] Returning to flowchart Figure 2000 again, l VA -
Vn! When ≧VD, it is determined that low-level out-of-focus has occurred.

Direction cannot be determined after low-level out-of-focus is determined VA>
Make a judgment on VB.

[Phase] When MA>VB, it is in the rear bin state, and the control circuit 111 outputs FF=O1NN=1.

As a general rule, when the level is low, the motor should rotate at a low speed. The reason is that when the level is low, the S/N is low and a sufficiently reliable direction signal cannot be obtained, so in principle it always rotates at a low speed to ensure the stability of autofocus operation. - [Phase] Next, it is determined whether the bin state has occurred continuously after n4 low-level out-of-focus times. When a constant direction signal is obtained n1 times in a row, it is determined that the S/N of the VA%Vn signal has become sufficiently high, and the mode returns to the normal distance measurement mode. In this way, power saving (I
VA VB I≧VD completes distance measurement and rests until T) and low-level out-of-focus stability (judgment after integrating up to To,
In other words, it is possible to achieve both

[Phase] Return to [Phase] again. When VA>VB is not established, when the focus is on the front, it is determined whether the ω flag is -1 as in the case of low-level focusing, and when it is 0 ω flag -1. The speed of the motor 7 is set to high speed @ When the ω flag is 0, the speed of the motor 7 is driven at a low speed according to the principle described above.

The reason for the high speed in [Phase] is that, as with low-level focusing, there is a false low-level focusing signal, and in the process of driving the motor to the closest focus point, there is a false low-level focusing signal in the vicinity of the false-level focusing signal. This is to prevent the speed from once becoming low.

@Next, for the same reason as [phase], if the direction signal is outputted n5 times or more in a row, it returns to normal distance measurement, otherwise it performs distance measurement again in the low level mode.

Figure 32 shows the VA at the low level out of focus mentioned above.

VB double signal l MA + Vn l, I VA -V
It is a diagram showing the n I signal o-state st. After integrating until t=To, vL≦I VA+VI31 <Vu TeIy
F), I MA VB I > VD.

Next, the 0 o'clock mode will be explained. As shown in FIG. 30, the maximum distance measurement time T. Even after , VA +VB <
At Vt0, the reflected light from the infrared light emitting diode 3 from the object is very small, so it is determined that distance measurement is impossible. This situation occurs when the object is far away, or even if the object is nearby, the reflectance is so low that sufficient reflected light does not return to the sensor 6.

In an active distance measuring device like this distance measuring system, it is very difficult to distinguish whether an object is far away or has a low reflectance. Control circuit 1 to drive Tough
A signal of 11 (FF=1, NN=0) is output.

Naturally, if a signal that allows distance measurement is obtained before the photographing lens 1 reaches the ω end, a stop or reverse signal is applied to the motor 7 at that point.

First, the characteristics of the ω mode distance measurement system will be briefly described.

First, in the 0 o'clock mode, the maximum distance measurement time is 'L (,
Ty<To). The reason is V
A+VB=Vt, t-boundary VA +VB > Vt
, then VA.

The direction is determined based on the magnitude relationship of Vn, and VA+VB<
In order to determine that the direction is infinite regardless of the size relationship of VA and VB for VL, VA+VB and VA1 for VL.
This is because, due to the influence of noise superimposed on the VB signal, there is a possibility that a completely opposite direction determination will be made and hunting will occur. Therefore, in order to stabilize distance measurement, it is necessary to provide a level VtK hysteresis for determining infinity and to prevent hunting due to the influence of noise and the like. In this mode, the integration time T should be changed by changing Vt.
.

A similar effect can be obtained by changing T2 to T2.

In this way, the maximum integration time T0 is set to T2 (T2<To)
By doing so, stable operation is obtained even near the distance measurement limit.

Another feature is that, like the low-level focusing mode mentioned above, the maximum integration time is set to T3 (T, < T2), which widens the dead zone and achieves both stability and power saving. It's about being there.

The purpose of returning the integration time to T2 every predetermined number of times (n7) is to prevent a decrease in accuracy, as in the case of the low-level focusing mode described above.

Another feature is that the maximum integration time is T for a predetermined period of time (a predetermined number of times n9) after starting distance measurement in ω mode.
2 (T2 < TO), but Ts (Ts
<T2<To) should not be changed.

The reason for this is that an infinite signal is generated because, as mentioned above, the object is actually far away, or the signal is small because the reflectance is low, so it can be determined that it is infinite, or it is unavoidable. The other is that the object is at a distance that can be measured, but because the size of the object is finite, the distance of the object and the current position of the autofocus system are significantly different, so the infrared light emitting diode 3's When the image or sensor 6 is removed from the object, it is initially driven in an infinite direction by an infinite signal, and when the image of the reflected light from the object of the infrared light emitting diode 3 starts to be correctly formed on the sensor 6, it is measured. Distance becomes possible, V
This is a case where the lens is driven to the in-focus position based on the magnitude relationship of the A% VB multiplied signal.

In such a case, the maximum integration time Tll (T3<T2<T
If the period o) is provided, there will be a period in which the dead zone is widened, and the response will be delayed.As a result, in order to remove the maw, it is difficult to determine whether it is a true ω signal or whether it is a short period during the focusing process. n6 to distinguish whether it is the ω signal or not.
During the times, the maximum integration time is not changed to T3, but T2 (T
2 < To ), distance measurement is performed.

The ω mode described above will be explained again based on FIG. 21.

(2) Now, as explained in the flowcharts of FIGS. 19 and 20, when it is determined that the distance measurement result is correct, the ω-time mode is entered. Since it has already been determined that it is the ω signal, the motor 7 is first driven at high speed in the infinite direction.

@ Next, the ω flag is set to 1 to indicate that an infinite signal has been generated. As explained above with reference to the flowcharts of FIGS. 19 and 20, the ω flag is used to distinguish false focus signals, and is reset to 0 in the normal distance measurement mode.

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

0 As shown in Fig. 33, the maximum integration time T2 (T2 < T
Measure the distance at step o). The conditions for completing distance measurement are VA+VB
≧VH or t=T2.

(When I VA + VB≧VHO, it is determined that distance measurement is possible in the normal distance measurement mode as described above, the system returns to the normal distance measurement mode, and enters the next distance measurement cycle.

■ Since the maximum integration time is set to T, (T, -T2)
Count the time.

(I VA+VI3≧VL (7) OV for hitting judgment
When A+VB≧VLO, distance measurement should be performed in the low level mode as described in FIG. 20, so the mode returns to the low level mode and the next distance measurement cycle begins.

@Continuous n since the mode here started.

Determine whether the number of times has elapsed. If the nc-1st time has not been reached, the process returns to [phase] again and distance measurement is performed in the maximum integration time T2. Note that, as long as distance measurement is performed in the ω mode, the control circuit 111 always outputs FF=1, NN=O, and the motor 7 is driven in the infinite direction. However, when the lens 1 reaches the infinite end, the infinity switch 262 is turned on and the motor 7 is stopped.

[Phase] Maximum integration time Ts (Ts
<T2). Judgment of completion of distance measurement is V
A Perform at 10VB≧Vt or t=T3.

■ If VA +VB≧VL, maximum integration time Ts <
VA1 has reached Vt even though it is T2.
It is determined that the VB signal is large enough to enable distance measurement even in the normal distance measurement mode, and the mode returns to the normal distance measurement mode.

◎ VA +VB < Vt When 0, it is determined that the distance measurement result is ω, and the ('ro-'rs) time is counted.

(2) Next, it is determined whether distance measurement has been performed n1 times during the maximum integration time T, and if n7 times have not been reached, the process returns to [phase] again and enters the next distance measurement cycle.

When the o ny distance measurement is completed, next distance measurement is performed once with the maximum integration time set to T2. At @, M (6
) = no, but here it is only once, so M(
6)=1.

In the above, we will mainly explain the five ranging modes: 19 Normal ranging mode 2, Focusing mode 3, Low level mode 4, Low level focusing mode 5, and CO mode. By switching between modes 5 and 5 as appropriate for distance measurement, it has become possible to obtain highly reliable and stable operation, and also to save power.

For reference, a flowchart of the ranging subroutine and adjustment mode is included in FIG. The adjustment mode is different from when measuring distance! 17. Integrate the 0N-OFF of the infrared light emitting diode 3 and the A, B signals regardless of the magnitude of the A, B signals. Although distance measurement is not performed to avoid time digits, Figure 8 (
4) Offset adjustment of analog IC section or 101a,
102a.

To adjust the total gain of the two series of amplifiers 103a, 101b, 102b, and 103b, or to adjust the positional relationship of the infrared light emitting diode 3 or the light emitting lens 4', the sensor 6, the light receiving lens 7, etc. using an adjustment mechanism (not shown). It is for occasional use.

Further, in the above embodiment, in-focus or out-of-focus is determined based on the absolute value l of the difference between the signals VA and VB indicating the light receiving position of the projected spot image.
Although it is determined from the magnitude relationship of VA - VB l , it goes without saying that this may also be determined from a ratio such as VA/vB. That is, the present invention can be applied to any type of device as long as the magnitude relationship between the signals VA and Vn can be known. Furthermore, instead of determining the signal level from VA + VB as in the above embodiment, the signal level may be determined from either VA or VB. That is, the signals VA, Vn
The present invention can be applied to any device whose level state 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 the present invention, the integral value of the output of the light receiving element that 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 is An automatic focus detection device for an imaging optical system that forms an image on a predetermined focal plane, the device comprising: a time detection means for detecting that a light projection time of the light projection spot image has reached a predetermined time; and a light receiving element. level detection means for detecting that the integrated value of the output 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 apparatus is provided with a determining means for determining the focus adjustment state of the imaging optical system based on the integral value of the output/power of the light receiving element, the integral value of the output of the light receiving element can be used to detect the focal position. It is possible to provide an automatic focus detection device that detects the focus position immediately when the focus level is reached, has no waste in power consumption or focus detection time, has a high power saving effect, and has a fast detection speed. It is. Therefore, the present invention is particularly effective for automatic focus detection devices such as cameras, where miniaturization does not allow for the incorporation of a large-capacity power supply, and where the quality of focus detection speed may lead to missing a momentary photo opportunity. It is.

[Brief Description of the Drawings] Figures 1 to 7 are schematic diagrams showing the optical system of the automatic focus detection device according to the present invention, and Figures 8 to 18 are electric circuits of the automatic focus detection device according to the present invention. 19 to 21 are operation flowcharts of the automatic focus detection device according to the present invention. FIGS. 22 to 33 are supplementary explanatory diagrams of the operation flowcharts shown in FIGS. 19 to 21. FIG. 34 is a schematic diagram showing a conventional example. 1... Photographing lens, 2... Planned focal plane, 3... Light projecting element, 4... Light projecting lens, 5... Subject, 6...
- Light receiving element, 7... Light receiving lens, 8...
...Motor, 9...AF circuit. Figure 8'7 IRECM& Relationship with the case of a person who does
Shimomaruko, Ota-ku, Tokyo? )-! 10-25, the entire text of the specification to be amended and drawing 6, the content of the amendment (1) As shown in the attached sheet, the specification descendant #: Disaster v1 diagram ke zu mitsu amend douro. Description 1, Title of the invention Automatic focus detection device 2, Claims (1) Projecting a projected light spot image onto an object and outputting at least two types of signals depending on the receiving position of 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 based on the magnitude relationship between the integral values of the output of the light receiving element, Comparing means for detecting that the magnitude relationship has exceeded a predetermined level; and time detecting means for detecting that the projection time of the projected spot image has reached a predetermined time are provided, and the comparing means or the time detecting means is provided. It is characterized by comprising determining means for determining the focus adjustment state of the imaging optical system based on the integral value of the output of the light receiving element when at least one of the above detects the predetermined level or the predetermined time. Automatic focus detection device. (2. In the device described in claim (1),
The automatic focus detection device is characterized in that the comparison means is a comparison means for detecting whether a difference between one integral value of each output of the light receiving means exceeds a predetermined level. (3) The apparatus according to claim (1) or (2), further comprising a driving means for moving the imaging optical system to a focusing position based on the output of the determining means. Automatic focus detection device. (4) In the device according to claim (6),
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 integral value is high, the driving means is operated at high speed. (5) In the device according to claim (3),
An automatic focus detection device, wherein the determining means operates the driving means at a low speed for a certain period of time from the start, and then at a high speed. (6) In the device according to claim (5),
An automatic focus detection device characterized in that the determination means is a microcomputer. 6. 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 shown in FIG. 1, an automatic focus detection device for an imaging optical system projects a light spot image from a light projecting element LT toward an object OB, and the reflected light is divided into two into a photosensitive area PA;
Some devices are designed to receive light by a light receiving element FD having a PB and detect the distance from the light receiving position to the object OBj, or to detect the focus adjustment state of the imaging optical system. That is, in FIG. 1, when the object OB is at position Ra1, the projected light spot image projected from the light projecting element LT toward the object *OJh hits the object OB and is reflected. Assume that a light spot image is formed at a position exactly midway between the photosensitive areas P and FB of the light receiving element PD. Then, for the object OB located at a position 82 far away from position s1, the reflected light of the projected spot image is at position 81 and position 8.
2, the photosensitive area FA of the photodetector FD is large.
It is formed closer to the side (in the upper □ direction of arrow A in FIG. 1). On the other hand, for the object OBs K located at a position 8s which is much closer to the position S1, the reflected light of the projected spot image has a large distance from the position '8th' tR8s to the photodetector element PDδ photosensitive area P. ] 114C (in the downward direction of the arrow in FIG. 1). Therefore, the above photodetector "7"
By detecting the position of the reflected light projection spot image formed on FD'J:, it is possible to tell what distance the object is currently at.
Comparing the outputs of the photosensitive area P and FB, the photosensitive area F
Since A and FB are outputted in a size corresponding to the amount of received light, the position where the reflected light spot image is formed can be known. Furthermore, as shown in FIG. 1, in the case of an image forming optical system that forms an image of the object on the predetermined focal plane 7M, the distance state of the object is different from the distance state of the object as described above. Since the focus of the imaging optical system can be adjusted according to When the light-receiving element ゛P is in the middle position between the beam and the PB, the focus is adjusted so that the imaging optical system is in focus.
If the imaging optical system is moved in the direction of the arrow Lt-t, that is, in the direction of the optical axis X, in conjunction with the movement of Do, the focal point fA'KJ of the imaging optical system can be achieved. In other words, if the difference between the outputs of the photosensitive areas P and FB of the photosensitive element FD is zero, the focus is reached, and the output of the photosensitive area FB is also larger than the output of the photosensitive area FA. Front focus (state where the focus position of the imaging optical system is in front of the planned focal plane), photosensitive area F
If the output of A is thicker than the output of photosensitive area FB, this indicates that the focus position of the imaging optical system is placed on the rear side (from the expected focal plane), and the front focus is i if
s*Optical system is planned to move in the focal plane FM direction (to the right of arrow B)
In the case of rear focus, if the imaging optical system is moved manually or automatically in the direction opposite to the planned focal plane FM (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 the front bin, focus, and rear bin based on the output state of the light receiving element, the accuracy of the focus detection generally deteriorates unless the integrated value of the output of the optical element reaches a certain level. It is generally known that it does not behave well. 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 reflected. I don't know if it's formed. By integrating the output of the light receiving element FD, the signal level increases and the ratio B/N of the signal level S to the noise level H increases, so that the output levels of the photosensitive sections FA and FB can be compared. This makes it possible to accurately detect the focus position. That is, the focus detection 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 receiving signal is integrated. For this reason, the conventional automatic focus detection device (d) generally continues to project the above-mentioned light spot image for a certain predetermined period of time, integrates the amount of received light, and then compares its output 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 in order to downsize, only a small-capacity ft source can be incorporated. Therefore, this has been a very serious problem in devices such as cameras that require an improvement in 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 image of the object is determined by the integral value of the output of the light receiving element which receives the reflected light of the projected light spot image projected onto the object and outputs a signal according to the receiving position. An automatic focus detection device for an imaging optical system that forms an image on a predetermined focal plane, the device comprising: a time detection means for detecting that the projection time of the projected light spot image has reached a predetermined time; and an output of the light receiving element. level detection means for detecting when the integral value 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, Integral 1 of the output of the above photodetector
The automatic focus detection device is equipped with a determination means for determining the focus adjustment state of the imaging optical system based on the directivity, so that when the integrated value of the output of the light receiving element reaches a level that allows focus detection, This is intended to save power consumption and improve focus detection speed by performing focus determination. 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 AF 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. , an image forming surface of a solid-state image sensor, or a film surface. Reference numeral 3 denotes a light projection element for projecting a beam of light onto a field of view (generally a range to be measured), and is composed of a laser diode, an infrared light emitting diode, or the like. Reference numeral 4 denotes a light projecting lens, and a light projecting element 30 forms a projected spot image on a subject 5 (generally an object to be measured). 6Fi, a light receiving element, 2
The light can be divided into two photosensitive areas 6A and 6B to determine the light output, and the area 6A is arranged to be on the light projecting element 6@U, and the area 6B is on the opposite side. The light receiving element 6 is composed of, for example, a two-area P/N photodiode or a charge-coupled resistor. F'L is a visible light cut filter), which allows as much light from the infrared light emitting diode 3 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 an AP 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. s m 2, the subject 5
When is at a distance of 12 from the imaging plane, the reflected light from the projected spot image P is received by the optical sensor in two areas 6A and 6B with an equal amount of light as shown in FIG. 3(a). Suppose that In this case, in the light receiving element 6, the integral value VA of the output from the area 6A and the integral value vB of the output from the area 6B
The difference between Vmu and vB becomes 0. In terms of the optical path, the light emitted from the light projecting element 3 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. At this time, assuming that lens group 1 is in focus tti, object 5 is at l! Assume that it has moved to a distance of 1. 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, if the light projecting element 3 and the light receiving element 6 remain in the same position, the light path will be diffusely reflected from the bl and hit the subject, pass through the optical path 31, and form an image on the light receiving element 6, as shown in FIG. 3(b). The imaging position is largely shifted toward the region 6B, and the above-mentioned VA-VB does not become zero. Therefore, this shift tray is determined by the amount of movement of the subject 5, that is, 12-A
The lens group 1 is moved to the in-focus position in accordance with I. That is, according to the sign of V^-VB (including its magnitude in some cases), the motor 1 circuit 9 rotates the motor 8 in the forward or reverse direction, thereby causing the light emitting element 3 to the light receiving element 6 and the lens group to rotate. 1 by a cam, etc.), and when VA-vB=o, that is, the projected spot image reaches the intermediate position between areas 6A and 6B on the light-receiving element 6, the image of the object at a distance of b Jl is focused. To form a sharp image on an image plane 2. As a result, the light emitting element 3 moves to the 3' position, the light receiving element 6 moves to the 6' position, and the boundary line between the areas 5 and 5B moves to the 6' position, and the lens group 1
It will move to the position #'i1'. In this case, the projection optical path bi and the reflected optical path (daz') are shown. On the other hand, if the subject 5 moves to the position Is, the lens group 1 etc. move in the opposite direction to the above, so that s VA - yB = Q. In this case, the projection optical path is shown as C1, and the reflected optical path is shown as C2. Figures 4 to 7 show an automatic focus detection device that performs distance measurement based on the same principle as the device shown in Figure t52. This shows another example,
The configuration of the projecting and receiving systems is different from that of the device shown in FIG. Hereinafter, the same numbers are given to the same parts as those in the device shown in Figure 2.
Explain briefly. Figure 4 shows a type of so-called half-TTL distance measurement in which a light spot image is projected from a light projecting element through a photographing lens, and the light is received by a light receiving element provided outside the camera. . Reference numeral 10 denotes a half mirror 69 having a reflective surface 10ai configured as a cold mirror, and a lens group 1 that moves for the focusing lens of the photographic lens, and an image forming lens t.
It is placed between fr2. 4' is a light projecting lens, and 5 is a light projecting element. S) Preferably, the light projecting element 3 is disposed 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 the so-called 'l'T, in which both the light emitted from the light emitting element and the light received by the light receiving element are passed through the photographing lens.
Necessary for L distance measuring type automatic focus detection device. IO'Fi
Half mirror 1 placed at the same position as 10 in Figure 5
4' is a light projecting lens; 3 is a light projecting element arranged at a position optically conjugate with the focal plane 2 of the photographic 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 imaging plane 2 of the photographic lens 1. It is designed to pass through a position where the light beam is flat. 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. Figure 7 shows an automatic focus detection device that uses the same light projection system as in Figure 4 and uses the image sensor 13 provided on the focal plane as a light receiving element for focus adjustment and imaging. It is. The image signal received by the image pickup device 13 is divided by the distribution circuit 11 into the 'Bhy circuit 7 and the image pickup circuit 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 5B are sent to A through the distribution circuit 11.
Send to P circuit 7. Further, in the case of the one shown in FIG. 7, it is necessary to devise a method to allow infrared light to pass through the image pickup element 13 during distance measurement, and to remove the infrared light during image capture. By the way, in the above embodiment, in the type shown in FIG. 2, the light emitting lens 4 and the light receiving lens 7 are located outside the photographing lens 1, so it is necessary to increase the size of the light emitting and receiving lenses 4 and 7. This is advantageous in terms of reach distance, but on the other hand, it has the disadvantage that it cannot be assembled compactly. 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 FIG. 4 has properties intermediate between those shown in FIGS. 2 and 5. The type shown in Figure 5 has a shorter base line length of the light emitting/receiving system than the one shown in Figure 4), distance measurement accuracy, and flI. It also has the advantage that the projected light beam is centered in the viewfinder. Incidentally, in all of the above types, the light spot image formed on the subject 5 by the light projecting element 6 is formed on the optical axis of the photographing lens when in focus. That is, in any of the above devices, the distance measurement zone is located at the center of the finder, and is an automatic focus detection device without parallax. In addition, in the case of the one shown in FIG. 7, the light receiving aperture of the light receiving element 13 is almost equal to the F nano (-) of the photographing lens, so compared to other types of devices, the area of the light receiving aperture can generally be larger, and the reaching distance can be reduced. It is advantageous in terms of.Also,
In the apparatus shown in FIG. 6, the signal tAF circuit 9 from the imaging probe 15 is
However, since it is practical to distribute the distance in a time-division manner, this type is suitable for systems such as still video cameras 2 that complete distance measurement prior to shooting. . Next, the configuration of the electric circuit in the above device will be explained based on FIG. 9. As described above, each area 6A, 6B of the light receiving element 6
The reflected light projection spot image received at 101 a e 101 b, A is supplied to an amplifier circuit as photoelectrically converted optical information and is sufficiently amplified. At this time, the intensifiers 101a and 101b have sufficient amplification for the modulation frequency of the infrared light that becomes the projected spot image, and amplify the frequency of the modulated light from unnecessary sunlight and commercial power. It is desirable to use an amplifier circuit with nine frequency characteristics that suppresses the frequency as much as possible. The output of this amplifier is the synchronous detection circuit 1
02a and 102b, and synchronous detection is performed. This desynchronization signal has the same frequency as the light emitting drive signal for the light projecting element 30), and maintains a constant phase relationship. The output of this synchronous detection circuit is integrated by integration circuits 105a and 105b, and increases moment by moment at an increasing rate proportional to the signal intensity of the reflected light spot image. By filling in the above signals, the integration circuit 105
Integral voltage VA obtained independently from a and 103b. VB is processed and determined by an arithmetic circuit described below, and converted into several bits of digital 1a information. That is, the integral inguinal pressures vA and vB are converted into a difference signal -vB by the subtracter 104 on the one hand, and a sum signal -+ by the adder 105 on the other hand. The difference signal VA-■ absolute (is added to the direct circuit 106 to obtain l vAvn 1. This value I VAvB l is compared with the comparison value vD in the comparator 107 as comparison means, and the magnitude relationship is output. On the other hand, the sum signal -+vB is compared with the comparison value -9vH in comparators 108 and 109 as level detection means, and the magnitude relationship of each is outputted.Furthermore, in the comparator 110, the integral voltage - and vB The 4 digital information obtained from the above are as follows:
That is, the outputs of the comparators 107, 108, 109, and 110 are applied to a sequence control circuit 111 as a determining means, and the operation of the entire system is determined. Reference numeral 112 denotes a low light oscillation circuit, which supplies current to the light projecting element 6 in synchronization with a synchronization signal from the control circuit 111, and controls 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 based on signals from the control circuit 111. FIG. 10 shows a further embodiment of the circuit configuration shown in FIG. 9. Figure 10 #'i shows part (A) of the circuit in Figure 9, in which a low-noise operational amplifier a201 a t 201 b is used in the first stage of the amplifier f; 5101 a, 101 b, and a feedback circuit 202 a, By setting 202b, bypass characteristics are provided. In the energy of the infrared light actually emitted from the light emitting element 3, the external light component is transmitted to the light receiving element 6.
Compared to the energy that is returned to the body, the amount of energy that is returned to the body is large. Visible light cut filter R This circuit has a relatively effective effect of suppressing external light components, and depending on the settings, it can be put to practical use for most subject conditions. Furthermore, a capacitor 203a. 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 modulation frequency and then supply the signals to the next-stage synchronous detection circuit. The synchronous detection circuits IQ2a and IQ2b shown in Figure 9 are inverted.
Q2Q5a, 2051) and analog switch 206
a, 206b and 207a, 207b, and analog switches 206a, 206b, 20
This is realized by switching the signals 7a and 207b using the synchronization signal BYNO and alternately selecting the non-inverted signal and the inverted signal. As another example, there is a method (not shown) in which a four-phenomenal analog multiplier is used to calculate the product of the input signal and the alternating current component of the synchronizing signal 8YNO. The synchronously detected signal becomes a direct current (pulsating current) component and is supplied to the next stage integration circuits 103a and 105'b. These integrating circuits 103a and 105b are connected to an operational amplifier 208.
1! It is composed of L1208b, resistors 209a and 209b, and capacitors 210a and 210b. Then, a current proportional to the synchronous detection output voltage flows through the synchronous detection circuit 1.
Resistors 209a and 209 from 02a and 102b respectively
b escapes, flows into the capacitors 210a and 210b, is stacked, becomes an integrated voltage, and is applied to the operational amplifiers 208a and 208a.
It is output from 208b. This voltage is -1V respectively.
It is B. In addition, 211a and 211b are capacitors 21Q
This is an analog switch for initializing the charges accumulated in capacitors 210a and 210b.
Clear by LR signal. Figure 11 shows the circuit of Figure 9 which generates 1vA-vBl from the integrated voltage -w
) indicates the part. Integrating circuits 104a, 103b
The integrated voltage -9VB outputted from is subtracted by the subtraction circuit 104 constituted by an operational amplifier 212 and resistors 213 to 216 of equal resistance value R, and -v, +vB(
i? obtain. This value is added to the absolute value circuit 106 at the next stage. The absolute value circuit 106 includes an operational amplifier 217, diodes 218 and 219, resistors 220 to 222 with a resistance value of 2R,
It is constituted by a resistor 223 having a resistance value R. Operational amplifier 217, diodes 218, 219, resistor 220
．． According to the configuration of 221, the cathode of the diode 219 is
It has a high impedance when a negative input is made, and a potential that is 11 times the input voltage when a positive input is made. As a result, a voltage of -G-51VA vB l is applied to the negative input of the comparator 224. By applying a voltage of 10.SVD to this positive input, + vA - vBt and - can be compared. Let this comparison value be DD. Figure 12 II'i This shows the (re) part of the circuit in Figure 9. VA and VB are added by a resistor 225.226 with a resistance value R, and 0.5 (vA + vB) is compared. 227.22B 0.5v1.0-5 vII is added to the negative input of each comparator, (vA+VB) : % b (vh
+ vB): Comparison of vm is performed and the comparison value ll1
1. Output HR. Furthermore, FIG. 13 shows the circuit CD> portion of FIG. 9, where - and - are directly compared by a comparator 229, and a comparison 1 direct AB is output. FIG. 13 shows another embodiment for obtaining the comparison value DD from -2VB. -9vB is applied to the positive input of comparator 230, ii. Also, a resistor 252 with a resistance value R.
255 to the negative input. A constant current source 264.degree. 255 is also connected to the negative input, and as a result, voltages of vB+iR and vA+iR are applied to the negative input. However, 1 is the current value of 254, 2550', and the outputs of the comparators 230 and 231 are added to the OR circuit 236 to obtain the output DD. Output DD is -VB>
iR"Vp or v8-vA> iR=v, becomes true logic when OJ) % l VA vnl>vD. Figure 8g15 is a part of the sequential control circuit 111 realized in hardware. Yes, clock C is sequential control circuit 1
11, and becomes the source of the synchronization signal 5YNO for the light emission modulation of the light projecting element 40 and the synchronous detection circuits 102a and 102b. The period of this output ON determines the distance measurement period and the maximum integration time. 7
Rig 70 knobs 257 and 258 are connected to signals DD and HH, respectively.
It is set by the signal On, and is reset every distance measurement cycle by the signal On. Each output DDQ of 7 rigs 70 tubes 257, 25B
. HRQ is an integral aborted multi-signal), which is input to the clip 70 tube 240 via the OR circuit 259 and held at the period of the signal Ou. The inverted output Q of the flip 79 tube 240 becomes the infinite signal PAR. Signals FAX and DDQ are OR circuit 2
41, the clip 70 knob 242 is set, and the motor rotation signal MO is output. This 7 lip 70 lip 2
42 is also reset by focus signals 1iHQ and 4'ra, prohibits output of motor rotation signal MO during focusing, and stops motor B. Signal B is Noritsubu flop 2
At 43, it is updated to ABQ by a signal DDQ representing out-of-focus. Here, the previous pi/, that is, VA〉V
When B, it becomes true logic. Signal BQ and Signal FAR
via the OR circuit 244 becomes a signal FM representing the rotational direction of the motor. The final motor drive signals FF (towards infinity) and IN (toward close range) are the output of the AND circuit 245 using human power from the signal FM and the signal MO, or 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. The synchronizing signal 5xNa is input to the shMD circuit 249 by inputting the signal to the AND @ path 249 via the OR circuit 239 and the NOT circuit 248 when both the signal DDQ and the signal JiHQ are pseudo-logic. It is output in synchronization with the output OLE of clock 0. The integration initialization signal (LR) output from the OR circuit 250 becomes true logic from when the end of integration is determined based on the output of the OR circuit 259 input to the OR circuit 250 and the signal On until the start of the first integration. Figure 16 shows the waveforms observed as each number 46 in Figure 15 when there is an infinite state change from front bin to pigeon bin to focus.In the front bin, DD is the first to rise. AB is at a high level.In the rear bin, SHDD rises first, but AB is at a low level.HE rises when in focus.At infinite time, the maximum integral is reached when none rises. FIG. 17 shows a part of the present device which is controlled by software using a microcomputer as the sequence control circuit 111. In this figure, the light emitting WAtjJ circuit 112 of the light projecting element 3 and motor drive circuit 11
Example 3 is also shown. 251 is a microcomputer) (For example, p'3' as shown in FIG.
f! 5), each of the above-mentioned signals D is connected to the input terminal.
D.AB. LL and HH are input, and the aforementioned signals 5XNO, OLR, F'F, and NN are also output from the output terminal. Further, it is easy to add a signal LOW 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.
3 by the signal BYklO. The current flowing to the motor 8 is transmitted via the transistors 254 to 257 to the signal 1i'? and the signal NN, and flows in the forward or reverse direction. The circuit configuration consisting of transistors 258, 259 and diode 260 is a voltage control circuit, and the four voltages applied to the shimo motor are switched in two stages by a LOW signal. 261
, 262 are a close range switch and an infinity switch, respectively, which are closed when the photographing optical system hits the close end or infinity end to prevent driving beyond the limit. FIG. 19 shows electrical signal waveforms at various parts of the circuit shown in FIG. The synchronous signal BYlIO is the synchronous detection circuit 102a. 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 from 6b is obtained in the form of a superimposition of 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 BPO. This signal is sent to an amplifier 101a with high-pass characteristics. 101'k) is obtained as the signal MP. When the CL signal is released almost simultaneously with the start of light emission, the outputs of the synchronous detection circuits 102a and 102b are integrated,
An integrated waveform like a signal generator nt appears at the output of the integrating circuits 105a and 105b. The -minute waveform and the rate of increase are proportional to the amount of emitted light component of the emitted infrared light. Even for very weak inputs, a large 13N ratio can be obtained by integrating for a sufficient number of hours each time. Next, the operation of this apparatus will be explained based on FIG. 9 and according to the flowchart numbers shown in FIGS. 20 to 24. Here, as the control circuit 111! It is assumed that Iku can use a computer (hereinafter referred to as a microcomputer) 251. ■ When the muy operation switch (not shown) is closed, the control circuit 1
11 starts operating. (2) First, it is determined whether the Sjl:N8 input terminal of the control circuit 111 is at a high level. When the 8gN5 input terminal is at the sieve level, the operation is in the adjustment mode shown in FIG. 25, and distance measurement is not performed. In the adjustment mode, the ON-OFF of the infrared light emitting diode 3 and the output of the light receiving element 6 are integrated for 10 hours, and the IC offset adjustment 5%a width circuit 101a is performed. 1oib, synchronous detection circuits 102a, 102b, integration circuit 1 (15a, 103b), i, infrared light emitting diode 3 or light emitting lens 4,
The positional relationship of the light receiving element 6, the light receiving lens 7, etc. is adjusted. Therefore, the normal control circuit 1110BANG input terminal is in a low level state, and when the above-mentioned MU operation switch is closed, the apparatus first operates in the following normal ranging mode. ■ When entering normal ranging mode, first reset the (to) flag. The contents of Sofujig will be described later. Furthermore, it is assumed that the memory M(1) in the RAM area of the microcomputer 251 is used as the memory for this oo7 lag. (2) After this, the control circuit 111 starts the distance measuring operation. That is, the control circuit 11F first controls the light emission drive circuit 112 and the synchronous detection circuits 102a and 102b using the synchronous signal BYNO.
The integration circuits 105a and 103 are driven in synchronization with the
Release the clear state of b. According to this number C, the light emitting element 6
A spot image of infrared light is projected toward the object field in synchronization with the synchronization signal BYNO, and the reflected light is detected by the light receiving element 6. In the light receiving element 6, an electric signal corresponding to the amount of light received is output from the two light sensitive areas 6M and 6B according to the light receiving position of the reflected light projection spot image, and this is outputted to the amplifier 10.
1a and 101b, and the synchronous detection circuit 102
A and 102b perform synchronous detection. The optical information obtained in this way is sequentially integrated by each of the five integrating circuits 103a and 105b, and the output of the IA is an integrated voltage -? It becomes VB. This integrated voltage -, VB'' is shown below as described above.■4
■04 digital information is processed by 5 control circuits 111
is input. That is, ■ the difference signal -vB is added to the absolute value circuit 106 by the subtracter 104, and the digital output from the comparator 107 compares the magnitude relationship between the absolute value lvh-vnl and the comparison value VD. , DD■ A digital output from the comparator 108 that compares the magnitude relationship between the sum signal -+vB from the adder 105 and the comparison value v1, LL ■ The sum signal -+vB from the adder 105 and the comparison value VH (W
Comparator 10 comparing the magnitude relationship with H>Vl, )?
The digital output, HH ■ The digital output from the comparator 110 that compares the magnitude relationship between the signals - and -, MU The integration time of the signal, that is, the projection time of the light projecting element is measured, and if this is t, the magnitude relationship with the maximum integration time T0 is compared. When these pieces of information are given separately, the control circuit 11
1, the ship signal is 1vA-vBl≧5 or -+ vB≧v
, or whether t≧To. When any one of these three conditions is met, the control circuit 111 determines that distance measurement is complete. Figure 25 shows
Reflected light projection spot image P and integral signal vAt VB when in focus
As shown in FIG. The photosensitive areas 6A and 6B both provide outputs of substantially equal large values. For this reason, the values ri of the integral signals vA and vB
As shown in FIG. 25 (2), both of them increase rapidly in almost the same state. For this reason, as shown in FIG. 25 (■), the signal vA+-
also increases rapidly with time t, while the signal l VA
As shown in Figure 25 (■), vBl hardly increases on the t-hill. Therefore, for the comparison value VHt VD and the maximum integration time T, it is determined that if vA+vB≧-I VA VBl < VD and t<T, the lens is in focus. On the other hand, FIG. 26 shows the state of the reflected light projected spot image and the integral signal Vh t VB when there is no attendance. When the lens group 1 is in the front focus or rear focus state, the reflected light projected spot image P
As shown in FIG. 26 (2), since the photosensitive area of the light receiving element 6 is biased towards either the photosensitive area 6 or 6B, the output signal from the photosensitive areas 6A and 6B of the photosensitive element 6 generally has a larger value. Therefore, as shown in FIG. 26 (2), one of the integral signals VA t Vn increases rapidly with time t, but the other integral value hardly increases. Therefore, the second
As shown in Figure 6 ■ and ■, the signal vh + vn is the comparison value V
By the time H increases, and by the time the integration time t reaches the maximum integration time T0, the signal I VA vB 1 becomes l vh.
vn l≧chi. Therefore, 1vA-vBl≧vD
is detected, and if VA + vB<- and t<T, it is determined that the front pin or rear pin state is present. 27th
The figure shows the reflected light spot image P and the integral signal -2V when the subject 5 is far away or the reflectance of the subject 5 is extremely low.
This shows the state of B, in which case the reflected light spot image P
is not formed on the receiving element 6, or even if it is formed, the amount of light received is extremely weak. Therefore, the output signals of the photosensitive areas 6A and 6B of the light receiving element 6 are both small values, and the integrated signal VA as shown in FIG.
+ VB does not increase at all. Therefore, the integration time t is the maximum integration time T. Even if the signal is -+vB. Both l VA VB l do not satisfy 1+-≧vHI VA VB l≧vD as shown in FIG. 27. Therefore, t'; jH% e vA+VB<% l V
If A VB l <Vp, it is determined that the subject 5 is far away or in a state where distance measurement is difficult. As above, −+−≧VH or l vA−vBl ≧V
By setting D or t≧T0 as the condition for determining the completion of distance measurement, when the value of VB reaches the level that allows distance measurement to be applied to the integral signal, automatic focus detection operation can be immediately started, and the charge is not wasted. consumption will be prevented. In particular, with this device, as will be described later, distance measurement takes a maximum integration time T. If it was completed within
In order to keep the time for one ranging cycle constant, the maximum integration time T is set within the microcontroller. Count the time until it reaches T. After the time has elapsed, I start the next cycle to measure the distance again, so I wait until T from the completion of the distance measurement. There is no wasted charge dissipation over time, and the power saving effect is extremely high. The 24th section specifically shows the contents of ■ as a subroutine. I will explain the details below. (2) The light emitter 6 and other distance measuring circuits start operating as described above. @ Release the clear state of the integrating circuits 105a and 103b. The O light emitting cable 3 emits light. (2) Thereafter, by stopping the synchronization signal 8YNO, the light emitting drive circuit 112 is stopped, and therefore the light emitting element 50 stops emitting light. At the same time, the driving of the synchronous detection circuits 102a and 102b is also stopped. ■ Determine whether distance measurement has been completed according to the distance measurement completion determination conditions described above. θ When the above-mentioned distance measurement completion conditions are not met, the light projecting element 3 emits light again to repeat the a1 distance. [F] When the distance measurement completion conditions are met, the signal DD,
B, LL, ME (i.e. comparators 107, 108, 10
9°110 output) is stored in memory M (0) in the RAM area of the microcomputer. Thereafter, by stopping the synchronization signal S'fNO, the light emitting drive circuit 112 is stopped, and therefore the light emitting element 50 stops emitting light. At the same time, a synchronous detection circuit 102a. The drive of 102b is also stopped. (2) Then, by setting the 0IJAR output of the control circuit 111 to a high level, the integration circuit 103a. 1051) in a clear state to prepare for the next distance measurement operation. After performing the above series of controls, the 4-bit data stored in the memory M(0) is used to perform an automatic focus detection operation and a shift to another distance measurement mode to be described later. Furthermore, the second
The subroutine shown in FIG. 4 is also used in other distance measurement modes, which will be described later, by changing the conditions for determining the completion of distance measurement in step (2). (2) Returning to FIG. 20 again, when -+-≧- is detected, it is determined that the image is in focus, as described above. ■ When the focus is determined, the control circuit 111 sends a stop signal (IPF==N N=0) to the motor drive circuit 1.
15 is supplied and the motor 8 is stopped. ■ And the integration time t is the maximum integration time T. After reaching
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, when -+-≧vH, it means that the object is out of focus or the value of the #i integral signal -9vB is small, and it is determined here whether this is the case. If l vA--1≧-, the distance measurement will be completed at t≧T, and as mentioned above, in this case, the level of the % integral signal -9VB is low, so the low-level integral signal Perform distance measurement suitable for v and vB. Transition to low level distance measurement mode, which will be described later. ■ When I VA VB l≧-, the lens group'
1 is determined to be in an out-of-focus state, and then it is determined whether the front focus or the rear focus is present. When vA>-, it is determined that it is necessary to drive the motor 8 in order to move the lens and group 1 to the nearest side with the rear focus l). @ Next, the speed at which the motor 8 should be driven is determined. In this embodiment, the motor speed is controlled at 2R, and by switching the speed to a low speed when the object approaches the in-focus state from the out-of-focus state, lens #1 is brought into focus. This prevents overrunning the position and ensures a smooth stop. This motor speed can be changed to any number of speeds as needed. Here, in order to judge whether the focus is close to the in-focus state or if it is far off, set the level of the comparison value. Used as a criterion. When out of focus, when distance measurement is completed, 91 When the signal -+vB is vA+vB≧v1 at the time when vAvB l =VD is reached, the speed is low, -+vB<
71. As a general rule, the speed is high when This situation is shown in Figure 6 and Figure 28.
The figure is at 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 signal -'
The closer the level with FB is to the iX device, the lv, -vBl≧v
The time t required to reach D is not long, and the ratio of vA+VB increases accordingly. Therefore vA+ vBt:
l) The degree of out-of-focus can be determined by the size. The speed control of the motor 8 mentioned above and the reflecting light projection socket) (+
! The 29th figure shows the relationship between the positions of P on the light receiving element 6.
Figure ■■. As a result, the reflected light projection image P is at the position Pl ii
The magnitude of the amount of light received in the photosensitive areas 6m and 6B when moving from (rear focus) through P2 (combination bin) to position P5 (front focus) can be seen. The middle part in FIG. 29 (■) is within the low speed range and is represented by a square. The value of ko is directly set according to conditions such as the speed of the motor and the inertia of the system. This will help. Here, in this device, the completion of distance measurement is determined at the time of out-of-focus using l vA - vB l = vD = constant voltage, but other values 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 -+vB≧v
I, is determined. When o vA+VB≧VL, a signal is output from the control circuit 111 to move the motor 8 at low speed as described above, and the lens ILlj is controlled to the close side. After the time has elapsed until @t=To is reached, the process returns to (2) and distance measurement is performed again in the normal distance measurement mode. ■ On the other hand, when 1+vB<vl in the phase shown in Fig. 20, the motor 8 should be rotated at high speed in principle as described above, but here it is further driven to the nearby side at this high speed. It is determined whether or not the determination to be made has been made n2 times consecutively while the side distance mode is being returned n2 times. When the number of times is n2 or less, the process moves to 9, and the motor 8 is driven at low speed toward the closest side. (2) If it is determined that the motor 8 should move toward the closest position 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 to drive toward the closest position at high speed is not made n2 times in a row, and for example, a judgment such as focusing is made in the middle, the judgment to drive to the close side at high speed is again made n2 times in a row. The motor 8 will not reach high speed until then. As mentioned above, the reason for controlling the speed of the motor 8 is to make sure that the motor 8 moves at a low speed when starting, which improves the feel at the time of starting and also reduces noise in the integral signals VA and VB. In particular, this is to reduce the possibility of lens #1 performing hunting or other operations. 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. When it is determined that the camera is in focus at point O, and the integration time t reaches the maximum integration time T0, distance measurement is performed again in the normal focus ff1il distance mode, which is suitable for distance measurement from the focus state. It will be done. This is because, even after focusing, the distance of the subject may change moment by moment, so distance measurement is re-measured at fixed intervals (maximum in this case, integration time T0) to ensure that lens group 1 is in focus. This is because it is necessary to check whether the In the normal focus distance measurement mode, the conditions for determining the focus state are 1 + vB ≧ v 8 to VA 10 vn in the normal distance measurement mode as a judgment condition to complete the distance measurement.
≧vI, (vXJ<vH). The reason why the condition for determining completion of distance measurement is changed from 1+vB≧vH to vA+VB≧vL is to widen the range in which it is determined that the focus state is reached. A range that cannot be determined to be out of focus,
The black band of the thumb cine is widened, and the lens group 1 is moved 1C from the position previously determined to contain heat. For example, if vL is set to 2%-, as shown in the M2O diagram, it is possible to obtain substantially the same effect as when the comparison value VD is 2.
Since it is difficult to determine that VAvn l≧−, it is difficult to get out of focus. Therefore, it is possible to reduce malfunctions caused by noise superimposed on the integral signal -2vB. Also, by lowering the comparison value, it is possible to shorten the integration time and the time during which the light emitter 30 is emitting light, as in this device.
Needless to say, it is advantageous in terms of power consumption when one distance measurement cycle takes a certain period of time. 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 lit distance mode. Start distance measurement, l VAVn l≧vD or vA
When one of the three conditions +vB≧V or t≧T is satisfied, the control circuit 111 completes distance measurement, and the comparison signals DD, AB, LL, HE at that time are stored in the memory M(0
) is memorized again. [Ai] Note here on ■! Based on the data stored in JM (0), it is determined whether lvA-vBl≧- and whether the lens is out of focus. l vA-v
If it is determined that Bl≧vD, there is no focus, and distance measurement is performed again in the normal distance measurement mode. ■ When 1mmA-vBI≧VD is not the case, when sufficient signal cannot be obtained because the object is in focus or the object is far away or the reflectance of the object is low) % VA + VB≧vL? The level state of the integral signals vA and VB is determined by , and it is determined whether or not focus is achieved based on the state. - When vB≧VL does not exist, the distance measurement is completed at t≧T. Since the integrated signals VA and VB are extremely low, it is assumed that the object is far away or the reflectance of the object is low. After making a judgment, the system switches to low level distance measurement mode and performs distance measurement again. (2) On the other hand, when -+vB≧v1, 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 (2). 0 Next, it is determined how many times the normal focus distance measurement mode has been turned over. If the number of repetitions n is no, return to the normal focus and distance measurement mode, and when n = no is reached or #
Distance measurement is performed in the normal focus distance measurement mode until switching to another distance measurement mode with i [phase] or ■. energized focusing distance measurement mode. After repeating the rotation, when n=no, the mode returns to the normal distance measurement mode 9, and the next distance measurement is performed in the normal distance measurement mode and in the normal dead zone. As described above, a decrease in distance measurement accuracy can be prevented by returning the control to the normal state every -th time. As mentioned in section O above, widening the dead zone increases stability, but this also causes a reduction in oil distance accuracy as a reaction. Therefore, by returning to the normal distance measurement mode every time (nI), in-focus/out-of-focus determination is performed with a regular blind event, thereby compensating for the i% decrease in distance measurement accuracy. Therefore, by doing this, it is possible to achieve both stabilization at the time of eclipse focusing and distance measurement accuracy. Furthermore, -
and vL need to be set to appropriate values for the above purpose. Next, the operation in the low level ranging mode will be described based on FIG. [Phase] As mentioned above, it is determined that both the integral signals vA and VB are at a low level in the normal ranging mode or the normal focusing ranging mode, or the integral signal is determined to be at a low level in the time ranging mode described below When it is determined that the levels of vA and VB have become high to a certain extent and distance measurement is possible, the integral signal VA s VB
Distance measurement is performed in a low level ranging mode that is suitable for ranging when the level of the signal is low. In the low level ranging mode, the integral signal 'IFA' is
When tVB is obtained, completion of distance measurement is determined based on 1+vB≧vH or multi≧T0. Incidentally, here, as a condition for determining whether the distance measurement is completed, --vB≧vH is excluded, which is different from the case in the normal distance measurement 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 t VB B /
M is not very good, for example, the level relationship of the integral signals vA and vB may be opposite to the original values, and this is to prevent erroneous distance measurement from occurring. In other words, when the signals in the near direction and in the infinite direction are output repeatedly,
If these are detected as they are, out-of-focus signals in different directions will be output alternately, which may result in unstable operation. Figure 51 shows an example of such a bad 8/N integral signal. As shown in (1), l vA−vBl≧5. vB>VA
If this occurs, it is determined that the front bin state is reached, and the control circuit 111 outputs a control signal to drive the motor 8 in the infinite direction. Also, by chance (stochastically) (I), vB
>-, but as shown in (I)' (l vA-vBl
<If it is vD, distance measurement is not determined at point (1), and at point (II) -> vBI l VA
A determination will be made as to whether VB l > %. This results in outputting an out-of-focus signal to the motor 8 in a direction completely opposite to that in the above case. In order to reduce the instability described above as much as possible, in the ranging mode at low level, VA
+ 'When VB≧vFL is not determined, t: To
After continuing the integration up to the point where l vAvBl≧VD is determined. By switching between multiple modes in this way, the advantages of the normal ranging mode (power saving, etc.)
It becomes possible to achieve both stability and stability in distance measurement mode at low level. O Returning again to the flowchart of the distance measurement mode at low level in Figure 21, when the distance measurement is completed in ■, the next time the distance measurement is completed is 1 + vB ≥ -
Determine whether or not it was performed. VA10-2
When it is 7M, it means that the signal VQ- is sufficiently large, and it is determined that there is no need to perform the ζ1j distance in the low-level distance measurement mode, and the mode returns to the normal distance measurement mode. Figure 32 shows the signal VA s when returning from low level mode to normal ranging mode.
The states of signal VB, signal -+ vB, and signal lva vBl are shown. As shown in (2), even if 1vA-vBI>vD, distance measurement is not completed and lii distance measurement is continued. As shown in ■, when the conditions of 1<To, vA+VB≧- are met, distance measurement will be terminated and the mode will return to the energized distance measurement mode. @v, if 10vB≧vH is not met, distance measurement will be performed. Completion is t=
It means that it was carried out under the conditions of To. Continuing −＋−
The level of the distance is determined, and it is determined whether it should be determined as infinite or whether it is a measurable area within a finite distance. -+v
When B≧vL (VL < VH), the integral signal vA,
Since the level of vB is extremely 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 VA t VB s signal vA + MA 3 when entering the infinite distance measurement mode.
FIG. The result of distance measurement up to i;=T is -+v, < vL means that the integral signal is -1
Since the values of VB are both extremely low, it may be determined that the object is in an infinite state, and in this case, even if the value of 1 vAvBl is Fil VA−VB1≧−,
Even if Bl <-, this is ignored. Note that even when the object is not far away and the reflectance of the object is low, the light-receiving element 6 cannot receive sufficient reflected light, so this situation also occurs in this case. In systems that measure distance, it is very difficult to distinguish whether an object is far away or has low reflectance. Therefore, assuming that the former is the case, the control circuit 111 that drives the motor 8 in an infinite direction has multiple control signals (7F=1, NH=0).
) output to the t-motor drive circuit 113. Naturally, if another distance measurement signal is obtained before the photographing lens 1 reaches the φ end, a stop or reversal signal is applied to the motor drive circuit 113 at that point. @v, +vB≧71. When , the 1+vB signal after time integration of T0 is 11. If ≦vA+VB<-, then it is determined whether IVA-vBl≧-, and IV□
When −vn l <−, in principle, it is determined that the focus is at a low level. As shown in FIG. 34, when <IYA-vBl≧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 a low speed in the focusing direction. [Phase] Now, as mentioned above, when lvA+vBl≦VD, the control circuit @ 111 will output the simulator stop signal as low level focusing, but there are exceptions such as oo 7-
When yg=1, output this stop signal. The oo7 lag is set to 1- at the time of transition to the distance measurement mode at the time ①, and is reset to 0 in the normal distance measurement mode as described above. When oo7 lag is set to 1, the control circuit 111 sends the same control signal as before to the motor drive circuit 1.
13. oo in ranging mode at low level
If it is 79 guni 1, it is only when you have transitioned from ■standby mode to low level distance measurement mode, and when you have transitioned from ψ standby mode to low level distance measurement mode, which will be described later. A signal to drive the motor in an infinite direction is output. Therefore, when oo7lag=1, the motor 8 continues to move the lens group 1 in the infinite direction even if it is determined that the focus is achieved at a low level. The reason why we created this exception for oo7 lag = 1 is that when focusing on a subject that is far away or has a reflectance that causes a low-level focus signal to be output, the focus may deviate greatly from the focused state to the close side. It has been experimentally confirmed that when distance measurement is started from a position, a focus signal is output due to the influence of leakage current of the light receiving element 6 while the object is still in the out-of-focus process. For this reason, 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, (3) flags are used to identify false focusing signals, and as described above (oo 7 lag = 1, the control circuit 111
is designed to continue distance measurement in the control distance mode when the level is low while outputting the infinite direction signal. @IX) When 7lag = 0, a motor stop signal is basically output from the control circuit 111, and the motor 8 is stopped. [Phase] On the other hand, when 1vA-vBl≧VD at O, it is determined that the lens is out of focus at a low level. After it is determined that the focus is out of focus at this low level, the direction of focus deviation is determined, and it is determined whether 9v,>vB. o When vA>-, there is no rear pin state, and the control circuit 111
motor 8 to push lens group 1 to the nearest side by
It is determined that there is a polished product that drives the. In the low level ranging mode, the motor rotates at a low speed in principle. The reason is that when the distance measurement mode is low level, the integral signal VA I
This is to prevent the lens group 1 from causing unstable operation such as hunting because the S/N is low and a sufficiently reliable direction signal cannot be obtained since the values of VB are both small. ■ The temporary bin state of out-of-focus at extremely low level continues n times.
It is determined whether or not the 41m determination has been made. When a constant direction signal is obtained n4 times in a row, the signal VA v
It is determined that the s/n of VB is sufficiently +'ji <, and the mode returns to normal distance measurement mode. In this way, the eyebrows i'j by CA distance measurement mode, force (distance measurement is completed with 1vA-vB1≧vD and rest until T.) and the feminine nature of 61+1 distance mode at low level (To') are clearly divided. This makes it possible to achieve both the following: 0 Return to (2) again. If vA>-, that is, if it is the previous bottle, it is determined whether the ω flag=1 as in the case of low-level heat content described above. @ ■When flag = 1, the motor 8 is rotated at high speed to move the lens group 1 to the close side. As with focusing at a low level, Kitayama's method for increasing the speed here is to prevent the motor 8 from temporarily slowing down near the false focus signal even though it is out of focus due to a false focus signal. This is to prevent this. (2) On the other hand, when oo,; ■ For reasons such as @ and 1m for a long time, the direction is output more than 5 times in a row. All distance measurements are carried out. ■ On the other hand, when it is determined that in-focus at a low level in [phase], a signal is output to stop the rotation of the motor 8.
At the low level, the focus distance measurement mode is repeated L times and then one distance control is performed again. Goldfish 6 at low level! ! ) In the distance mode, the condition for determining completion of distance measurement is vA+vB≧v1. (vL<vH) or t≧T, Judgment condition 1'F vA+ vB≧-
Or different from t≧To. This is done by making T shorter than To, as in the normal focusing distance measurement mode explained in Fig. 20, widening the dead zone as shown in Fig. 35, and determining that lens group 1 is in the focused state. This is to ensure that the machine stops stably at the specified position. Especially when the focus is low and Velor is m
@”IAp vB level is low <S/ 14 is bad ^
Therefore, stabilizing the in-focus state by widening the dead zone is extremely effective. The reason for setting -vA+vB≧vIl (vL<vH) is to enable focus determination even in the normal ζii distance mode in accordance with the maximum integration time T. [Phase] When distance measurement is completed, first, it is determined whether vA+vB≧vTJ. When vA+VB≧vL, the integral signal is above the predetermined level even though the integration time has become shorter, so it is determined that the signal has become large enough to enable distance measurement in normal distance measurement mode, and normal distance measurement is performed. Return to mode and perform distance measurement. o When vA+VB≧vL, it is determined whether 1vA−vB1≧VD or not. l vh-vn When l≧VD, it is determined that the signal has become sufficiently large, and the mode returns to the normal ranging mode, as in ■. @ v, + vB < vL and l VA vB
When l < VD, it is determined that the object is in focus, and the count is continued until t=:To is reached. ■ Focusing at low level 411 Determine whether distance measurement in distance mode has been repeated n3 times, and if n5 times, return to low level distance measurement mode') b If less than ns times, low level Focus 3jl distance mode is completely reversed. As in the case of the normal focus distance measurement mode, return to the distance measurement mode at low level every n, - eyes, and judge whether the distance measurement is completed by vA + vB ≧ v
When H or °C≧T0, the insensitivity and failure are returned to the original state and a decrease in the distance measuring distance t〆 is prevented. As mentioned above, focusing at low level (from distance measurement mode to low level d1 (1 distance mode to t:I distance mode), stability of focusing at low level, saving TE power, This makes it possible to simultaneously ensure the maintenance of the thighs.The Qo time mode will be explained with reference to Fig. 22.■When shifting to the time distance measurement mode, as mentioned above, the second
In od@, vA + vB (vL and) U addition! Cut tjj
This is the case. That is, as explained in the flowcharts of Figs. 20 and 21, it is determined that the result of the JI distance is a signal that both the AX signal - + VB are extremely low, and the subject 5 is in an infinite state. 6!11 distance in some cases: +3 flash 6. °
Enter 1-range mode. In the jlj distance mode at the time of ooo, since the ld in the 1st limit has already been determined, the motor 8 is first moved in the infinite direction at high speed. ■Subsequently, ■7lag is set to 1 to indicate that an infinite signal has been generated. As explained above in the flowcharts of FIGS. 20 and 21, the ω flag is used to distinguish between false focusing signals and is reset to 0 in the large mode. Set n6 to use M(6) from the RAM area in the microcomputer for the kakunta to count a predetermined number of times n6 times.
'2 determines 6.1 [distance completion. Here, the normal condition is 1-1vA- for distance measurement completion in j distance mode.
The reason why vI31≧VD is absent is that the integral signals vA, v are present in the flash ranging mode as well as in the low level ranging mode.
This is because the value of 1 vA-vBl is unreliable because both B are extremely low values. Furthermore, in the ω time distance measurement mode, the thickest distance measurement time direction T2 (T
2<T. ), the maximum integration time is higher than the dtil distance mode when the bell is low, as will be explained later, vA + VB = v
VA + % > 71. Then vA,
Judging the direction based on the magnitude relationship of VB, vA+VB<v
If L, -t is an infinite direction regardless of the magnitude of IA of VB. ・11 (To judge, when vL is in vA+vB, the signal -t is the shadow of noise etc. superimposed on VB.
This is to prevent hunting from occurring due to completely opposite direction determination. Then #''j: As shown in Fig. 36, the integral time T is changed to T2 by changing the value of vL.
A similar effect was obtained by changing to . @When vA+VB≧vH, 6i; 1 in normal distance measurement mode
It is determined that distance measurement is possible, and distance measurement is performed in normal distance measurement mode. @ vA-F When VB≧- is not true! ! Since the 1j distance is completed by t=:T2, the time T, -T2 is counted. It is determined whether OV, +VB≧v1. vA+v
When ≧vLO, as mentioned in Figure 21, the time distance is low! Since distance measurement should be performed in the 1-range mode, the mode is returned to the low-level distance measurement mode, and the next distance measurement mode is entered. ◎ At this point, after the distance measurement mode and - mode have started, continue α and n.
It is determined whether six times have elapsed. If it has not reached the n6th time, it returns to @ again and distance measurement is performed at the maximum integration time T2. In other words, this means that the maximum integration time is T2 (T2
< To ), but as described below, < Ts (T
s<T2<To) should not be changed. The reason for this is that, 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. One is that the reflectance is unavoidable due to low reflectance.One is that the object is at a distance that can be measured, but the size of the object is finite, so
Since the distance to the object and the current position of the distance measuring system are greatly different, the spot image P or the light receiving element 6 is deviated from the subject 5, and at first it is driven in the infinity direction due to infinity judgment, and the reflected projection is When the light spot image P starts to be formed correctly on the light-receiving probe 6, the distance becomes possible.')b%t'This is a case where the beam is brought to the in-focus position depending on the magnitude relationship of the FB signal. In such a case, the maximum integration time is Ts (Ts < T2
<T, ), the dead zone will widen, the response will be delayed, and as a result, the correct control of the motor 8 will be delayed, resulting in an overrun of 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. Instead of changing Ts to Ts, distance measurement is performed with T2 (T2<To) unchanged. Note that when distance measurement is being performed in distance measurement mode at ω, the control circuit 111 always outputs a signal to move the motor 8 in the infinity direction. When it reaches the end, the infinite switch 262 turns on.
I, motor 8 is stopped. After the 6th On, the maximum integration time Ts (Ts<T2
) to perform distance measurement. Judgment of distance measurement completion is vA+vB≧V
I, or t≧T3. This is similar to the low-level focus 611j distance mode described above, where the maximum integration time is Ts.
By setting (Ts<T2), the dead zone is widened,
It aims to achieve both stability and power saving. In the case of OVA+VB≧vL, the maximum integration time Ts (Ts
<T2) reaches the comparison value V even though the distance is shortened, so 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. @ When vA+ VB < VL, distance measurement result #'i integral signal c. Since the VB level is still extremely low, it is determined that subject 5 is in an infinite state again, and TO-73 time is counted. [Stock] Next, it is determined whether distance measurement has been performed n7 times during the maximum integration time T3, and if n7 times have not been reached, the process returns to [phase] again. When the seventh distance measurement is completed, Fi repeats the distance measurement once again with the maximum integration time set to T2. Here, the reason why the integration time is changed from T2 every predetermined number of times (n7) is to prevent a decrease in distance measurement accuracy, as in the above-mentioned low level focus-1ll distance mode. In addition, in ■, M (6) = n6 was set in order to carry out one distance n6 times in a row with the maximum integration time T2, but here, M (6) == Set to 1. Above are the 5 Bl distance modes: 10 Normal distance measurement mode 2, fullj distance mode 3 during continuous focusing, distance measurement mode 4 during low level, focusing distance measurement mode 5 when low level, and distance measurement mode when oo Mainly Figure 20~〆J22
A detailed explanation has been provided based on the flowchart in the figure. As is clear from this explanation, the automatic focus detection device according to the present invention performs distance measurement by switching the distance measurement modes 1 to 5 to the appropriate range, and is highly reliable and stable. Obtain the behavior that
Furthermore, it has become possible to achieve both power savings. In the above embodiment, the determination of focus and non-heat-containing is determined from the magnitude relationship of the absolute value 1vA-vBl of the difference between VA +v9, which indicates the light-receiving position of the projected spot image P. Needless to say, this can be determined from a ratio such as vA/vB.In other words, the present invention can be applied to any magnitude relationship between the signals vA and VB as long as it is within our control. It is not necessary to judge the entire signal level from VA + vn as in the embodiment. The signal level may be judged from either vA or VB. In other words, any device can be used as long as the level state of the signals vA and VB can be determined. It goes without saying that the present invention can be applied even if the light-receiving element has six or more photosensitive areas. The output of the light-receiving element receives the reflected light of the projected light spot image and outputs a signal according to the light-receiving position; The automatic focus detection device for the image optical system includes a time stopper means for detecting that the projection time of the projected light spot image has reached a predetermined time, and an integral 1a of the output of the light receiving element reaches a predetermined level. and a level detection means for detecting that the
Either the estimating means or the level detecting means estimating the focal point c of the image optical system based on the integral value of the output of the light receiving element, in addition to estimating the predetermined time or the predetermined level. ]
It is equipped with a determination means for determining a steady state, and the output of the light receiving element is =+>! When the 1-minute focus reaches a level where the focus position can be detected quickly, the focus position is detected immediately. (It is possible to provide a self-help focus detection device that is free of snowflakes, has high efficiency, and has a fast detection speed. Therefore, it is not possible to incorporate Inuyobo's iαO into the present invention #'i general for miniaturization. It is also very effective for automatic focus detection devices such as cameras, where the quality of focus detection speed can lead to missing a chance to shoot. 4. Brief explanation of drawings Figure 131 is a conventional method. Schematic diagrams illustrating examples, 4121-48 show the optical system of the self-help focus detection device 1 according to the present invention; Figures 201--24 illustrate the operation flow of the self-help focus detection device according to the present invention. Figures 25 +74 to 56 illustrate the operation flowcharts shown in Figures 20 to 24. Supplementary explanatory diagram. 1... Photographing lens 2... Planned focal plane 3... Light projecting element 4... Light projecting lens 5... Temporary photographic object 6... Light receiving element 7... Light receiving lens 8... Sota 9... API! 21st road 30th stomach ■ rt 7. Hand
Continuing amendment (Patent application filed by Kazuo Wakasugi, Commissioner of the Japan Patent Office, April 28, 1981) (34) No suffix 2, Title of invention Automatic focus detection device 3, Relationship with the person making the amendment 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 148 (telephone: 758-2111) 5, Specification subject to amendment 6, Contents of amendment (1) In the 5th line of page 29 of the specification, ``Hairuto first, flash flash'' is corrected to ``Hairu to first, flash hula as a prohibited means.'' (2) In the text on page 31 of the specification cylinder, change “minutes and hours To” to “
Correct it to ``with the minute time To (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) Page 54, line 15' of the specification r (Tl<T.)
r (Tl< To, e.g. 71 = 1.78
Corrected to m5ecJ. (6) In the second line of page 55 of the specification, ``It is intended to make it look like this.'' is corrected to ``It makes it look like this and reduces power consumption.'' (7) In the third line of page 58 of the specification, replace '(T2<To)J with '
T2<102 e.g. T2 = 19.3m5ec)
Correct to J. (8) Page 61, line 3 of the specification” (T3 < T2)
J to r (T3 < T2 + e.g. T3 = 1.
78m5ec) Corrected to J.

Claims (3)

[Claims] (1) The image of the object O is placed on the planned focal plane by the integral value of the output of the light receiving element which receives the reflected light of the projected spot image projected onto the object and outputs a signal according to the receiving position. An automatic focus detection device for an imaging optical system that forms an image on a
a time detection means for detecting that the light projection time of the light projection spot image has reached a predetermined time; and a level detection means for detecting that the integral value of the output of the light receiving element has reached a predetermined level; In case, when either the time detection means or the level detection means detects the predetermined time or the predetermined level, the focusing state of the imaging optical system is determined based on the integral value of the output of the light receiving element. An automatic focus detection device characterized in that it is provided with a determining means for determining. (2) The automatic focus detection device according to claim (1), wherein the signal obtained from the light receiving element is a difference between at least two outputs corresponding to the light receiving position. (3) The automatic focus detection device according to claim (1), wherein the signal obtained from the light receiving element is a ratio of at least two outputs corresponding to the light receiving position.