JPH0713703B2 - Automatic focus adjustment device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention is capable of selecting a specific distance range included in the entire shooting distance range by the selection means, and matching a subject within the selected distance range. The present invention relates to an automatic focusing device that drives a taking lens so as to focus.

(Background of the Invention) Conventionally, as a device of this type, Japanese Patent Application No.
56-183002, there is proposed an automatic focusing device that drives a photographing lens so that only a subject within a selected distance range within the entire photographing distance range is focused by the selecting means.

However, in the proposed device, the focus position direction is not displayed when the focus position is identifiable at the end of the selected shooting distance range, but the focus position direction is not displayed. It has a drawback that the distance range cannot be switched quickly by the means.

(Object of the Invention) The present invention solves these drawbacks and provides an automatic focusing apparatus that can quickly switch a selected distance range when a main subject exists outside the selected shooting distance range. With the goal.

(Example) Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows a camera 1 equipped with an automatic focus adjusting device according to the present invention at the right end, where B ₁ is the closest position and B ₅ is the ∞ position when viewed from the camera 1.
And from the closest position B ₁ to the infinity position B _{5 the} boundary points B ₂ , B ₃ ,
The focusable range of the field of the camera 1 is divided with B ₄ as a boundary.

That is, B _{1 to} B ₅ are the total distance range in which the focus of the camera 1 can be matched, and in the present embodiment, B _{1 to} B ₃ , B _{2 to} B ₄ , and B _{3 to} B ₅ are the selected distance ranges. is there.

FIG. 2 is a schematic view of an embodiment of the present invention. Behind the taking lens 3, a field lens 4 formed on a focusing plate and a pair of re-imaging lenses 5 symmetrical with respect to the optical axis of the taking lens 3, 6 is arranged, whereby a part of the transmitted light flux of the photographing lens 3 is guided to the light receiving surfaces of the pair of photoelectric elements 7 and 8 via the re-imaging lenses 5 and 6, respectively. A pair of photoelectric elements 7,
Reference numeral 8 serves as a photoelectric exchanger for detecting the image position, and is specifically composed of a photoelectric element array. Processing circuit 9
When the focus position can be identified by inputting the output signals from the pair of photoelectric element arrays and comparing them, the front pin, the rear pin, and the focus state are determined, and the terminal T ₆ The display unit 32 connected by ~ T ₁₁ displays the front pin, the rear pin, and the focus state in the finder, and based on the result, the motor drive circuit 10 connected by the terminals T ₂ and T ₃ The motor 33 connected by the circuit 10 and the terminals T ₄ and T ₅ is driven, and the photographing head 3 is moved to the in-focus position by the rotation of the gear head 34. In the state in which the focus position cannot be identified, that is, in the state in which the front focus, the rear focus, and the focus cannot be accurately identified, the processing circuit 9 scans the photographing lens 3 via the drive circuit 10 to identify the focus position. It is provided to find the position. Specifically, when the taking lens 3 is first within the range corresponding to the selected distance range, the taking lens 3 is scanned within the range corresponding to the selected distance range to search for a state in which the focus position can be identified, First, when the taking lens 3 is not within the range corresponding to the selected distance range, the taking lens 3 is guided from outside the range to within the range, and then scanned within the selected distance range as described above. . Furthermore, when the distance range is not selected and the total shooting distance range is set, this distance range (B _{1 to} B ₅ )
The photographing lens 3 is scanned within a range corresponding to the condition (1) to search for a state in which the focus position can be identified.

The conductive member 11 is a member that moves in conjunction with the objective lens 3, the taking lens 3 is driven position which is the focal point aligned with those in the B ₁ the conductive member 11 when in the (below, B _1, as referred to the corresponding position) the position of the electrical contacts 13, the position of the electrical contacts 14 when in the position corresponding to the B _2, the position of the electrical contacts 15 when in the position corresponding to the B _2, electricity when in the position corresponding to B ₄ The conductive member 11 comes to come to the position of the electrical contact 17 when the position of the contact 16 corresponds to B ₅ .
When the conductive member 11 contacts any one of the electric contacts 13, 14, 15, 16, 17, the electric contact 12 becomes the conductive member 11.
And becomes equipotential with the electrical contact in contact therewith. Electrical contact
13 is always at Vcc and electrical contact 17 is always at ground. The other electrical contacts 14, 15 and 16 are brought into any one of Vcc, ground and open states by the operating member 19 for selecting the photographing distance range. The state of the electrical contacts 13 to 17 is transmitted to the electrical contact 12 via the conductive member 11, and this information is transmitted through the conductor 18 to the input terminal T ₁
Is transmitted to the processing circuit 9. When the output signal of the lead wire 18 is Vcc, the processing circuit 9 sends a signal via the motor drive circuit 10 to rotate the motor 33 so that the objective lens 3 may move once from the closest side to the infinity side (to the right in the drawing). Output and conductor 18
When the output signal of (3) is ground, the objective lens 3 outputs the signal so as to move from the ∞ side to the close side (to the left in the drawing).

Explaining in detail the configuration of the switch portion for selecting the photographing distance range, the selection switch portion can be selected from four stages of F, M, N and FULL by the operation member 19. Conductive members 20 and 21 are fixed to the insulating operating member 19 at regular intervals, and the selection switch portion includes, in addition, an electric contact 22 to which Vcc is applied, an electric contact 23 to which ground is applied, and an electric contact. It includes contacts 24 to 31 (contacts 24, 25, 28, 31 shown in broken lines may be omitted). FIG. 2 shows a state in which the operating member 19 is set to M. In this state, the conductive members 20 and 21 fixed to the operating member 19 at a constant interval are in contact with the electric contacts 26 and 30, respectively, and thus Vcc is applied to the electric contact 14 and the contact 16 is applied. Ground is applied to each. Therefore, in this state, the conductive member 11 is connected to the electrical contact 14.
Therefore, the photographing lens 3 moves between the positions corresponding to B ₂ and B ₄ . Even when the initial position of the taking lens 3 is not between the positions corresponding to B ₂ and B ₄ , once the position corresponding to B ₂ or B ₄ is passed, the desired range (B ₂ It moves only in the range corresponding to ~ B ₄ ). This will be described later in detail. Similarly, when the operating member 19 is set to F, the electric contacts 13 and 15 are Vc.
At c, the contact 17 becomes the ground, the conductive member 11 moves between the electric contacts 15 and 17, and when the operating member 19 is set to N, the electric contact 13 becomes Vcc and the contact 15 becomes the ground, and the conductive member becomes conductive. 1
One will move between electrical contacts 13 and 15. When the operating member 19 is set to FULL, the electric contact 13 is connected to Vcc and the contact 17 is always connected to the ground, and the contacts 14 to 16 are in the open state, so that the conductive member 11 connects between the electric contacts 13 and 17. It will move. Therefore, in this device, the operation member 19 is set to F,
When either M or N is set, as long as the subject is within the set distance range, even if the subject is removed and scanning of the lens 3 is started, it is set to FULL The in-focus state can be obtained more quickly than in the previous case. Further, when any one of F, M, and N is set, even when the subject is outside the set distance range, the subject is near the end of the distance range and the focus position can be identified at the end of the range. It may be in a state. In this case, the present apparatus stops the taking lens 3 at its end and causes the display unit 32 to display the focus position direction (front focus, rear focus).

Next, details of specific examples of each element and circuit having the above functions in FIG. 2 will be described. In FIG. 2, the photoelectric element arrays 7 and 8 are provided at positions conjugate with the fixed focal plane of the lens 3 as described above.
8 is eight photoelectrons P _{1 to} P ₈ , as shown in detail in FIG.
It is composed of P ₁ ′ to P ₈ ′. When the photographing lens 3 is focused on a subject to be focused, the photoelectric lens arrays 7 and 8 are respectively formed by the photographing lens 3 and the re-imaging lenses 5 and 6.
The positional relationship between the reimaging lenses 5 and 6 and the arrays 7 and 8 is determined so that the optical image of the subject formed above and the arrays 7 and 8 are the same. Therefore, in the focused state, the incident light intensities of the photoelectric elements P ₁ and P ₁ ′, ..., P ₈ and P ₈ ′ corresponding to the positions of the pair of arrays 7 and ₈ become equal to each other. Further, when the image of the subject by the lens 3 is formed in front of the field lens 4 by the movement of the photographing lens 3 (at the time of front focus), the image on the array 7 is downward and the image on the array 8 is upward. Move to. On the contrary, when the image formed by the taking lens 3 is formed behind the field lens 4 (in the rear focus), the images on the arrays 7 and 8 move in the opposite directions to those in the front focus. Each photoelectric element P _{1 of the} array 7
The photoelectric output of P ₈ is linearly amplified or logarithmically amplified, and is output from the output terminals 7a to 7h of the array 7 as electric outputs v _{1 to} v ₈ related to the photoelectric output. The photoelectric outputs of the photoelectric elements P ₁ ′ to P ₈ ′ of the array 8 are also the same, and the related electric outputs v ₁ ′ to v ₈ ′ are output from the output terminals _{8 a to 8} h.

Next will be described the processing circuit 9 performs processing of the associated electrical output _{v 1 ~v 8, v 1 '} ~v 8' with reference to FIG. 4 to 7 FIG.
In FIG. 4, the spatial frequency component extraction circuit 91 has an input terminal
7a to 7h are connected to the output terminals 7a to 7h of the array 7 having the same symbols. This extraction circuit 91 is provided with a first electrical signal v ₁ representing a specific first spatial frequency component of an optical image on the array 7 and its
A second electric signal v ₂ representing a 1/2 spatial frequency component is extracted from the related electric outputs v _{1 to} v ₈ . The second spatial frequency component is not limited to the above example as long as it has a spatial period different from that of the first spatial frequency component. This first electric signal v ₁ is the phase information that changes in a fixed relationship according to the displacement when the optical image on the array 7 is displaced in the array direction of the elements.
₁ and magnitude information r ₁ indicating the magnitude of the extracted spatial frequency component. The same applies to the second electric signal V ₂ , and the phase information
₂ and size information r ₂ . The other spatial frequency component extraction circuit 92 is the same as the circuit 91, and from the associated electrical outputs v ₁ ′ to v ₈ ′ of the array ₈ , the first and second optical images on that array are extracted.
First to extract spatial frequency components and represent them respectively,
Generate a second electrical signal V ₁ ′, V ₂ ′. The first and second electric signals V ₁ ′ and V ₂ ′ include phase information ₁ ′ and ₂ ′ and magnitude information r ₁ ′ and r ₂ ′, respectively. The spatial frequency component extraction circuit
The principle of 91 and 92 and a concrete configuration example are disclosed in detail in JP-A-55-98710. Spatial frequency component extraction circuit 91,
The first electric signal V ₁ of the 92 'phase difference of ₁ - _1' V ₁ is becomes zero when the photographing lens, as shown in FIG. 5 (a) is in the focus position becomes a for example positive in the previous pin location, It becomes negative at the rear focus position, and the magnitude of the difference increases in accordance with the amount of deviation from the in-focus position. Phase difference between the second electric signals V ₂ and V ₂ ′
₂ - About ₂ 'is the same as shown in FIG. 5 (b). But FIG. 5 (a), as is clear from (b), the phase difference even when deviated from the focusing position to the large front focus or rear focus position ₁ - _{1 ',} 2 _{- 2'} is zero and Do connexion Therefore, if the focus detection is performed only from this phase difference, there is a risk of making a mistake. In order to prevent this, the correlation detection unit 93 that detects that the taking lens is near the in-focus position
Is provided. This correlation detection unit 93 To calculate. The numerator of this correlation function I _COH becomes smaller when the luminance distribution of the object is almost uniform, and the denominator also becomes smaller accordingly, so this correlation function depends on the focal position of the taking lens, regardless of the luminance distribution. It has become standardized like this. To be more specific, vi = v at the in-focus position
Since it is i ', the numerator becomes zero, I _COH = 0, and it is irrelevant to the brightness distribution of the object in the case of the rear focus or the front focus that is shifted by one photoelectric element relative to the image on the array 7. , V ₂ ′ ＝ v ₁ , v ₃ ′ ＝ v ₂ , ……, v ₈ ′ ＝ v ₇ , or v ₂ ＝
Since v ₁ ′, v ₃ = v ₂ ′, ..., V ₈ = v ₇ ′ are established, respectively, I _COH = 1. Thus, as shown in FIG. 5 (c), this correlation function I _COH is 3 as the in-focus position α, the front focus position β in which the relative position of the image is shifted by one photoelectric element, and the similar rear focus position γ.
It is standardized in terms. Of course, such a standardized correlation function is not limited to this, and various types can be considered.

For example, But it is okay.

Next, the control unit 94 will be described in detail with reference to FIGS. 6 and 7. In FIG. 6, the AC signals representing the phase information _{1 1} and ₁ ′ are input to the waveform shaping circuits 113 and 114 via the switching FETs 111 and 112, respectively. Similarly, phase information ₂ ,
_The alternating signal representing 2'is the switching FET 115,
It is input to the above-mentioned waveform shaping circuits 113 and 114 via 116. The pair of FETs 111 and 112 and the pair of FETs 115 and 116 are alternatively turned on and off. The front-pin and rear-pin signal generating D-flip flops 117 (hereinafter, the flip-flops are abbreviated as FF) have their Q output terminals at the H level or in accordance with the sign of the phase difference between the rectangular wave outputs of the shaping circuits 113 and 114. Generates an L level output. That is, D-FF117 is FET111,112 is on, Q output phase ₁ - _{1 '>} 0, that becomes the H level when the front focus when the phase difference ₁ - _1' <time when i.e. the rear pin 0 the L level, also FET115,116 if oN, Q outputs ₂ - 'when the words front focus when> 0, H _level, 2 _- 2' ₂ becomes <0 L level when the time ie the rear pin . The exclusive OR circuit 118 is an absolute value of the phase difference between the outputs of the waveform shaping circuits 113 and 114, that is, | ₁ −
₁ '| or _{| 2} - _2' outputs a. A smoothing circuit consisting of resistor R ₁ and capacitor C ₁ smoothes the output of circuit 118. Focus signal generator comparator 119 the absolute value of the smoothed phase difference | ₁ - _{1 '|} or | ₂ - _2' | and the reference voltage
Compared with Vf ₁ , when the former is smaller than the latter, an H level signal is output as a focus signal. Here, the magnitude of the reference voltage Vf ₁ is selected in consideration of the depth of focus of the taking lens so that the comparator 119 generates a focusing signal when the taking lens is in focus. Thus elements 7, 8, 91, 9
Reference numerals 2, 111 to 119 constitute a front focus position, a rear focus position, and a focus position detecting device for generating a focus signal. The selection circuit composed of the comparator 120, its input resistors R _{2 to} R ₆ and the inverter INV 1 determines whether to generate the focus detection signal based on the first spatial frequency component or the second spatial frequency component. is there. The input resistors R _{2 to} R ₅ all have the same resistance value and resistor R ₆
Has twice the value of. The comparator 120 compares 1/2 of the sum of the size information r ₁ and r ₁ ′ regarding the first spatial frequency component with the sum of the size information r ₂ and r ₂ ′ of the second spatial frequency component, and the former is large, the H level output, phase ₁ - ₁ turns on the FET111,112 about _'when other latter is large,
It becomes L level output, and phase ₂ via inverter INV1
_The FETs 115 and 116 for 2'are turned on. The reason why the sum of the magnitude information r ₁ and r ₁ ′ is halved is that the phase information regarding the second spatial frequency component is more accurate than the first spatial frequency component. Thus, the D-FF 117 and the comparator 119
Is based on the former phase information ₁ , ₁ ′ when the first spatial frequency component in the optical image on the arrays 7, 8 is sufficiently larger than the second spatial frequency component, and vice versa. Based on the information ₂ and ₂ ′, a front focus signal or a rear focus signal and a focus signal are output, respectively. The contrast of the object image is low, first, the size is small of the second spatial frequency components, the phase difference ₁ - _{1 'or 2} - _2' front focus to the influence of noise increases, the rear focus and focus The accuracy of the focus signal decreases. Therefore, a contrast detection circuit for detecting whether the contrast of the subject image on the array is high or low is provided. The contrast detection circuit includes a comparator 122-125, the reference voltage source Vf _2, Vf _3, OR gate OR1, OR
2, AND3, AND gate AND1, AND2. The comparators 122 and 123 respectively measure the magnitude of the first spatial frequency component.
r ₁ , r ₁ ′ and the reference voltage Vf ₂ are compared, and their magnitudes r ₁ ,
When r ₁ ′ is large enough to guarantee the accuracy of the focus detection signal, it becomes L level. Similarly, the comparators 124 and 125 are respectively at the L level when the magnitudes r ₂ and r ₂ ′ of the second spatial frequency components are large enough to guarantee the above accuracy. Since the first spatial frequency component is large, when the comparator 120 of the selection circuit outputs H level, the inverter INV1 outputs L level. Therefore, the AND gate AND2 is forcibly set to the L level and the size r
Only when both ₁ and r ₁ ′ are large as described above, the OR gate O
R3 becomes L level output. On the contrary, when the second spatial frequency component is large, the AND gate AND1 is forced to output the L level, so that the OR gate OR3 outputs the L level when both the sizes r ₂ and r ₂ ′ are large as described above. Becomes Comparator 126
Compares the correlation signal I _COH with the reference voltage Vf _4, and outputs H level when the former is smaller than the latter and outputs L level when the former is smaller. The H-level output and the L-level output serve as a focusing near predetermined range signal and an out-of-range signal indicating that the photographing lens is within and outside the predetermined range near the in-focus position.
From this focus within the neighborhood predetermined range as shown in FIG. 5, the phase difference signal ₁ - _{1 ',} 2 _{- 2'} when the previous pin positive, determined so as to ensure that the negative when the rear pins ing. In the present embodiment, when the signal within the predetermined range near the focus is output, it is the above-mentioned correlation state and the focus position, that is, the front focus, the rear focus, and the focus can be correctly identified (focal position identifiable state). . When the out-of-range signal is output, there is a non-correlation state, and the focus position cannot be correctly identified (the focus position cannot be identified). Adder circuit 127
Is the total electrical output v ₁ -v ₈ , v ₁ ′ of the first and second arrays 7, ₈ .
Add ~ v ₈ ′. Therefore, the output of this circuit 127 represents the brightness of the subject image on both arrays. The comparator 128 compares the output of the adder circuit 127 with the reference voltage Vf _5, and when the subject brightness is so low that the focus detection cannot be performed, the comparator 128 outputs the H level. The voltage dividing resistors R ₇ and R ₈ divide the voltage Vcc of the driving power source of this automatic focusing device. Power supply voltage detection comparator 1
Reference numeral 29 compares the divided voltage with the reference voltage Vf _6, and outputs an H level signal when the power supply voltage Vcc is a value that can guarantee normal operation of the automatic focusing device and outputs an L level signal when the power supply voltage Vcc is less than that value. .

To summarize the above, an H level signal is output to the front and rear pin signal terminals T ₆ when the front pin is used, an L level signal is output when the rear pin is used, and a focus signal terminal T ₇ is used when the focus is used. An H level signal is output and an L level signal is output when out of focus,
An L level signal is output to the contrast signal terminal T ₈ when the subject image has a high contrast, and an H level signal is output when the subject image has a low contrast, and the taking lens is connected to the focusing near predetermined range signal terminal T _9. An H level signal is output when it is within a predetermined range near the focus position, and an L level signal is output when it is outside, and the brightness signal terminal T ₁₀ outputs L level when the subject brightness is high enough for focus detection. The level signal is
When it is low, the H level signal is output. Further, an H level signal is output to the power supply voltage detection signal terminal T ₁₁ when the power supply voltage is sufficient for the normal operation of the automatic focusing device, and an L level signal is output when the power supply voltage is insufficient.

Next, a photographing lens drive system for driving the photographing lens based on each output of FIG. 6 will be described with reference to FIG. In FIG. 7, the input terminals T _{6 to} T ₁₁ are connected to the output terminals T _{6 to} T ₁₁ in FIG. The input terminal T ₁ has a second
Taking lens as shown in figure (in FIG. 2 B ₄₎ infinity end when and selected distance range reaches the infinity position (in FIG. 2 B ₂ .about.B ₄₎ reaches At the same time, an L level signal is input, and when the shooting lens reaches the close-up position and when it reaches the close end (B _{2 in} FIG. ₂ ) of the selected distance range, H
When the level signal is other than that, an open signal is input. The resistors R _{11 to} R ₁₄ are set so that R ₁₁ > R ₁₂ > R ₁₃ > R ₁₄ so that when the terminal T ₁ is L, the comparator 16
The outputs of 0 and 161 both become H, and when the terminal T ₁ is H, the comparator
The outputs of 160 and 161 both become L, and when the terminal T ₁ is open, the comparator 160 becomes L and the comparator 161 becomes H. Input terminal T ₁₂
Is input with a release signal for releasing the blocking of the driving of the photographing lens described later. The terminal T ₆ is connected to the NOR gate NOR1 via the inverter INV2 and directly connected to the NOR gate NOR2. The other input terminal of each of the two NOR gates NOR1, NOR2 are both connected to the terminal T _9. The output terminal of NOR gate NOR1 and the set input terminal of FF162 and NAND gate NAND1
One input terminal, and the output terminal of NOR gate NOR2 is FF
162 reset input terminals and one input terminal of the NAND gate NAND2, respectively. NAND gate NAND1, NAN
The other input terminals of D2 are connected to the outputs of the comparators 160 and 161, respectively. FF162 is a terminal immediately before the change when the signal H within the predetermined range near the focus is changed to the signal L out of the range.
The front pin signal or rear pin signal input to T ₆ is stored during the generation of the out-of-range signal. The Q output of this FF162 is sequentially sent to the NOR gate NOR3 via the AND gate AND3, the OR gate OR4, and the NAND gate NAND3, and the output is the AND gate.
It is sent to NOR gate NOR4 via AND4, OR gate OR5, and NAND gate NAND4. Motor drive circuit 10 described in detail later
Is controlled by the outputs of NOR gates NOR3 and NOR4, and the shooting lens is driven by the front pin when NOR gate NOR3 is H level output,
That is, it drives toward the infinity position, while when the NOR gate NOR4 is at the H level output, it is driven to the rear pin, that is, toward the closest position, and when both are at the L level, the driving is stopped. The other two input terminals of the AND gates AND3 and AND4 are connected to the output terminal of the NAND gate NAND5 and the output terminal of the OR gate OR6, respectively. Both input terminals of this OR gate OR6 are T
₉ and the terminal T ₇ via the inverter INV3, respectively. NOR gate NOR5 has AND gates on both input terminals
The output terminal is AND gate AND to the output terminals of AND3 and AND4
5 and AND6 are connected respectively. This AND gate AND5, AND
The output terminals of 6 are connected to OR gates OR4 and OR5, respectively.
AND gate AND7 the two input terminals is terminal T _8, are respectively connected to the terminal T ₉ by way of an inverter INV4, and an output terminal connected to a NOR gate NOR3 and NOR4. Terminal T ₁₀ is to NOR gates NOR 3 and NOR 4, terminal T ₁₁ is NAND gates NAND 3 and NAND 4.
Respectively connected to. The outputs of the comparators 160 and 161 are respectively connected to the set input terminal and the reset input terminal of the FF163, and the Q output terminal of the FF163 is directly connected to the AND gate AND5 and the AND gate AND6 via the inverter INV5. . The outputs of comparators 160 and 161 are also connected to the set input terminal of FF164 via OR gate OR7. Q of this FF164
The input terminal of the output terminal is the NAND gate NAND5, clear terminal Cl is connected to the terminal T ₉ via the inverter INV6.
The terminals T ₁₂ and T ₉ are connected to the input terminals of the NAND gate NAND 6, respectively, and the output terminal of this NAND gate is connected to the clear terminal Cl of each of the FF 165 and FF 166. The set input terminal of the FF165 is connected to the output of the comparator 161, and the Q output terminal is connected to the D input terminal of the FF166. The clock input terminal CK of the FF166 is the output of the comparator 160, and the output terminals are NAND gates NAND3 and NA.
It is connected to the input terminal of ND4 and the subject information storage circuit 167, respectively. The subject information detection circuit 168 detects information such as brightness and contrast of the subject of focus detection. The memory circuit 167 stores the output of the detection circuit 168 when the output of the FF 166 becomes L level. The release circuit 169 is a storage circuit 167.
Is compared with the detection output of the detection circuit 168, and when the difference between the two is greater than a predetermined value, an L level output is sent to the terminal T ₁₂ . These object information detection circuit 167, storage circuit 1
68, the release circuit 169, when the subject has low brightness or low contrast, stops the driving of the photographing lens because accurate focus detection is impossible and stores the subject information at that time, and then the brightness and contrast of the subject change. Then, it is a circuit for releasing the stop and enabling driving again. Regarding the details, the applicant of the present invention filed Japanese Patent Application No. 56-
Since it was disclosed in 176758, detailed description is omitted here. In the above, NOR gate NOR1, NOR2,
A lens drive signal generator is composed of FF162 and the like, and a drive block signal generator is composed of NAND gates NAND3, NAND4, FF165 and 166. The circuits up to FIG. 7, more specifically the elements 7 and 8 in FIG. 2 and the circuit corresponding to the processing circuit 9 in FIG. 2, constitute focus detection means for producing a signal for guiding the photographing lens to the in-focus position. is doing.

Next, the structure of the display unit 32 will be described with reference to FIG. Input terminal
T ₆ through T ₁₁ is connected to the output terminal T ₆ through T ₁₁ in Figure 6 respectively. To both the input terminal of the OR gate OR8 is and each terminal T ₆ T _7,
Input terminal of the OR gate OR9 directly also to the terminal T ₆ via the inverter INV7, is connected to the terminal T _7. OR gate OR10
The input terminal of is connected to terminals T ₈ , T ₉ and T _10, and the input terminal of NAND gate NAND 7 is connected to terminal T ₁₀ and the clock pulse generator.
Connected to 39. The input terminal of the AND gate AND8 is the OR gate OR8 and the OR gate OR10 via the inverter INV8.
, And the terminal T ₁₁ respectively, and the output terminal is a resistor R
It is connected to the light emitting diode LED1 via 9. The input terminals of AND gate AND9 are OR gate OR9 and inverter INV.
8 and a terminal T ₁₁ , respectively, and the output terminal is connected to the light emitting diode LED2 via the resistor R10. AND GATE AN
The input terminals of D10 are OR gate OR10 and NAND gate NAND7
When, are respectively connected to the terminal T _11, the output terminal is connected to the light emitting diode LED3 through a resistor R11.

Finally, the operation in each state will be described with reference to FIGS. 7 and 8. In the description, the subject itself has a high contrast, a sufficiently high brightness, and a sufficiently high power supply voltage. The case of low contrast and low brightness and low voltage is described in detail in Japanese Patent Application No. 56-176758.
Further, since it can be inferred from the description in this specification, the description thereof will be omitted here. Now, when the contrast is high, the brightness is high, and the power supply voltage is sufficiently high, the terminal T ₈ receives an L level signal representing high contrast, the terminal T ₁₀ receives an L level signal representing high brightness, and the terminal T ₁₁ receives. Is inputted with an H level signal representing a high power supply voltage.

(I) When the photographic lens is in the focus position identifiable state (correlation state in FIG. 5) At this time, the L level signal which is a signal within a predetermined range near the focus is input to the terminal T ₉ . This signal causes the NAND gate NA
Both ND5 and NAND6 become H level output. The latter H level output clears the FFs 165 and 166.

(I · 1) Front Focus First, the case where the subject is within the selected distance range will be described.

When it is the pin, an H level signal is input to the terminal T ₆ .
By this H level signal and the L level signal of T ₉ , NOR gate NOR1 becomes H level output, NOR gate NOR2 becomes L level output, Q output of FF162 becomes H level, and output becomes L level. Since the terminal T ₇ is out of focus, an L level signal is input, and as described above, the NAND gate NAND 5 is an H level output, so the AND gate AND 3 has its gate open. FF
The Q output of 162 is input to the NAND gate NAND3 via the AND gate AND3 and the OR gate OR4. Now, assuming that the taking lens is located within the selected distance range (distance range, other than the end), the open signal is input to the terminal T ₁ , so the NAND gate NAND 1 is at the H level output. and the output of the FF166 is H level output, terminal T ₁₁
Is an H level signal, the NAND gate NAND3 becomes an L level output by the H level output of the OR gate OR4.
AND gate AND7 by L-level signal at the terminal T ₈ also becomes L level output, and because the terminal T ₁₀ is also at L level signal, NOR gate NOR3 has an H level output by the L level output of the aforementioned NAND gates NAND3. This H level output causes the motor drive circuit 10 to rotate the motor in the normal direction and drive the photographing lens toward the infinity position to bring it closer to the in-focus position.

The display state at this time will be described below.

In FIG. 8, OR gates OR8, OR9 and OR10 are H level output, L level output and L level output, respectively, and the NAND gate NAND7 is H level output. As a result, the AND gate AND8 becomes the H level output and the light emitting diode LED1 is turned on. Since the other AND gates AND9 and AND10 both output L level, the other light emitting diodes LED2 and LED3 are turned off. In this way, the front pin state is displayed by turning on only the light emitting diode LED1.

Next, the case where the focus position can be identified and the subject is outside the selected shooting distance range will be described.

This is a story when, for example, when the photographing lens is driven toward the infinite position in accordance with the front pin signal, the photographing distance range is limited by the operation member 19 and the photographing lens cannot reach the focal position. is there.

For example, it is assumed that the operation member 19 is set to M and shooting is performed. In this case, the taking lens is from B _{2 in} Fig. 1.
Driven in the range corresponding to B ₄ . However, shooting in the subject as you move in the direction of infinity than B ₄ be out this distance range (B ₂ ~B _4), when the above such that arise. In such a case, when the taking lens reaches the position corresponding to the farthest position B ₄ of the area M, the L level signal is input to the terminal T ₁ , and therefore the outputs of the comparators 160 and 161 are both. H, this H
The NAND gate NAND1 becomes an L level output by the level signal and the H level signal of the NOR gate NOR1. By this L level output, the NAND gate NAND3 forcibly outputs the H level output, the motor is stopped, and the driving of the photographing lens is stopped.

Then, even though the photographing lens is stopped, the light emitting diode LED1 in FIG. 8 is still lit to display the front focus state, so that the photographer may switch the operation member 19 to another distance range F. You can know things.

(I.2) In the case of the rear pin The description of the rear pin is omitted because it is the same as the case of the front pin. In the rear pin state, the LED1
LED2 lights up in the same manner as.

(I.3) In focus In Fig. 7, when the in-focus position of the shooting lens is reached, the terminal
H-level signal is input to the T _7, this inverter INV3,
Both gates AND3 and AND4 are closed through OR gate OR6. This allows NOR gates NOR3 and NOR4
Becomes an L level output, and the motor drive circuit 10 stops the driving of the taking lens and stops it at the in-focus position.

The display mode at the time of focusing will be described. In FIG. 8, terminal T ₇
H level signal is OR gate OR8, OR9 AND gate AND
Both the light emitting diodes LED1 and LED2 are lit via 8 and AND9. The light emitting diode LED3 is off. Focusing is displayed by lighting both the light emitting diodes LED1 and LED2.

(II) When the taking lens is in a state where the focal position cannot be discriminated (state not in the correlation state of FIG. 5) At this time, the H level signal which is the out-of-focus near predetermined range signal is input to the terminal T _9. It The H-level signal, irrespective OR gate OR6 to focus the signal terminal T ₇ with the H level, the terminal and the AND gate AND7 via the inverter INV4 T ₈
L level output regardless of the contrast signal. In this way, both the focus signal and the contrast signal do not contribute to the driving of the photographic lens outside the predetermined range near the focus. When the H level signal is input to the terminal T ₉ as described above, this signal further causes both the NOR gates NOR1 and NOR2 to output the L level. As a result, the output of the FF 162 is maintained in a state immediately before it goes out of the predetermined range near the focus. Therefore, when it goes out of this predetermined range, the terminal immediately before going out of the predetermined range is completely irrelevant to the front pin signal or rear pin signal to the terminal T ₆ thereafter.
The taking lens is forcibly driven in the direction determined by the input signal to T ₆ . The forced driving, taking lens to the terminal T ₉ to fall within the vicinity of a predetermined range focus type L level signal, the operation of the aforementioned (I.1) ~ (I.3) is performed.

This will be described with a specific example. Now the subjects are B ₃ and B ₄
, And the operating member 19 is set to M (corresponding to the area of B _{2 to} B ₄ ). As a first case, it is assumed that the initial position of the taking lens 3 is outside the range corresponding to the B _{2 to} B ₄ areas, for example, at the position corresponding to the B _{1 to} B ₂ areas.
When thinking from this position when the focal position is unrecognizable,
The direction in which the taking lens 3 starts to move depends on the previous state as described above, and moves directly to the direction corresponding to B ₂ and moves to B ₂
.About.B ₄ enters the range corresponding to the region, sometimes leading to focus identifies the focus position and once moved in a direction corresponding to B _1, B from inverted at a position corresponding to the B _{1 2} There may be a case where focus is reached by entering the range corresponding to the B ₄ area. As a second case, consider a case where the initial position of the taking lens 3 is within the range corresponding to the B _{2 to} B ₄ region.

In this case as well, the direction in which the photographing lens 3 starts to move depends on the previous state, and it may move from the beginning in the direction corresponding to the subject position to identify the focus position and reach focus. Moves in the opposite direction, B ₂ or B ₄
There may be a case where focus is reached after reversing at the end of the selection distance range corresponding to.

The following operation is performed when the photographing lens reaches the end of the selected distance range or the infinity position or the close-up position without entering the predetermined range in the vicinity of the focus by the above-described forced drive. First, let us explain from the case where the operating member 19 is set to FULL (corresponding to the entire shooting distance range B _{1 to} B ₅ ).

It is assumed that the output of the FF 162 is at the H level when the focus position cannot be identified. At this time, the photographing lens is driven by the rear pin and is forcedly driven toward the closest position. If the focus position cannot be identified and the camera reaches the closest position, the terminal
An H level signal is input to T ₁ , and this H level signal is FF16.
4. Set FF165 together and reset FF163. Due to the setting of FF165, the H level signal is input to the D input terminal of FF166. The fact that the taking lens has reached the closest position is stored in FF165 and FF166. Also, the above FF
By setting 164, the NAND gate NAND5 becomes the L level output, and AND gates AND3 and AND4 both become the L level output,
Stop the pin drive after the taking lens. Both gates AND3,
The NOR gate NOR5 becomes the H level output by the L level output of AND4. On the other hand, due to the reset of the FF163, the inverter INV5 becomes an H level output, and this H level output and the H level output of the NOR gate NOR5 cause an AND gate AND5.
Becomes an H level output. This H level output is an OR gate
The NOR gate NOR3 is set to the H level output via the OR4 and the NAND gate NAND3, the photographing lens drive is inverted, and the front pin is driven to forcibly drive the photographing lens toward the infinity position. By the forced drive to the infinity position, the state where the focus position can be identified is reached, and the operations (1.1) and (1.2) described above are immediately performed. However, even if the subject to be focused has a depth or the subject itself has a low contrast, the signal for identifying the focus position cannot be obtained even by this forced driving, and the photographing lens eventually reaches the infinity position. Then, the L level signal is input to the terminal T ₁ , which sets the FF 163 and causes the FF 166 to read the Q output of the FF 165. By this reading, the output of the FF 166 becomes L level, the output of the detection circuit 168 regarding the subject information at that time is stored in the storage circuit 167, and both NAND gates NAND3 and NAND4 are set to H level output to stop the driving of the photographing lens.

As described above, when the signal of which the focus position cannot be identified is generated, that is, when the correct focus detection signal is not guaranteed to be generated, the cause is that the photographing lens is largely separated from the in-focus position. In order to determine whether or not it is due to the low contrast of the subject image due to this, the photographing lens is forcibly driven regardless of the focus detection signal at that time. Even if this forced drive is performed over the entire range of movement between the close-up position and the infinity position, if the focus position identifiable signal is not obtained in the end, it is determined that the above cause is due to the nature of the subject itself. , The shooting lens drive is blocked at the infinity position, and the subject information at that time is stored. Next, consider a case where the operating member 19 is set to a value other than FULL, for example, M (corresponding to the B _{2 to} B ₄ area). In this case, the compulsory drive of the taking lens 3 is performed between the position corresponding to B ₂ and the position corresponding to B ₄ , but when the focus position recognition state cannot be obtained eventually, the infinity side of the selected distance range is reached. The driving of the taking lens 3 is stopped at the end portion of, ie, the position corresponding to B ₄ in this case, and the subject information at that time is stored.

After that, when the subject to be focused changes due to an operation such as pointing the camera to another subject, the cancel circuit 169 causes the detection circuit 168 representing the information of the subject after the change and the stored output of the storage circuit 167. The amount of change is obtained from and when it is equal to or more than a predetermined value, the L level output is sent to the terminal T ₁₂ . Receiving this L level output, NAND gate NAND6
Clears FF 165 and 166, and cancels the above-described stop of driving the taking lens. By this release, if the focus position is identified at this time, the operation (I) is performed, and if it is not identified, the operation (II) is performed.

In the present embodiment, the clearing of the FFs 165 and 166, that is, the cancellation of the stop of the driving of the photographing lens is performed by the output of the canceling circuit 169 and the signal indicating that the focus position can be identified. The reason for this is that when the non-discriminating state changes to the discriminating state, the output of the detection circuit 168 also generally changes, and the release circuit 169 also produces an L level output. Depending on the selection of contrast etc.,
This is because the canceling circuit 169 may not generate a canceling signal even in the focus position identifying state.

Further, regarding the display by LED1 and LED2, both are turned off when the focus position cannot be identified, and one or both of LED1 and LED2 are turned on as the focus position is identified.

As described above, according to the present invention, at the end of the selected shooting distance range, when the focus position can be identified even in the out-of-focus state, the lens is stopped at the end. In addition, since the direction of the focal position is displayed, it is possible to quickly switch the shooting distance range accordingly and quickly obtain the in-focus state.

[Brief description of drawings]

FIG. 1 is a diagram showing the spatial position of the object field, FIG. 2 is a diagram showing the outline of an embodiment according to the present invention, and FIG. 3 is a specific example of the photoelectric device shown in FIG. 4 to 7 are diagrams for explaining a concrete example of the processing circuit shown in FIG. 2, and FIG. 8 is a diagram showing a concrete example of the display section shown in FIG. (Explanation of symbols of main parts) 3 ... Shooting lens, 7.8 ... Photoelectric element array 9 ... Processing circuit, 10 ... Driving circuit 32 ... Display unit, 33 ... Motor 19 ... Operating member

Claims (1)

[Claims] 1. A selection means for selecting a specific distance range within the entire photographing distance range of the lens, a driving means for driving the lens only within the selected distance range, and a display means for displaying a focus state. In the automatic focus adjusting device having, in a focus position identifiable state, when the lens cannot be in focus within the selected distance range, the lens is provided at an end portion within the selected distance range. An automatic focus adjusting device comprising: a control unit that stops the driving unit so that the lens is positioned and displays a movement direction for bringing the lens into a focused state on the display unit.