JPS62148912A - Auto-focusing device - Google Patents

Abstract

PURPOSE:To focus a photographic lens on even an object whose contrast and luminance are reduced, by extracting modulated components of an image pickup signal by plural frequency bands and synthesizing extracted signals and controlling the lens to the in-focus position based on the synthesized output. CONSTITUTION:An object image is focused on the photoelectric conversion face of an image pickup element 10 provided in an image pickup means 100. A luminance signal Y separated from the image pickup signal is supplied to a signal processing circuit 300 and passes BPFs 25, 26, and 27 to extract modulated components by bands having 2-fold, 1/2-fold, and 1/32-fold subcarrier signal frequency (fSC). Extracted signals are subjected to envelope detection and are synthesized and are supplied to a multiplexer 32, and a horizontal-direction contrast information signal OUT.H for the center part of one scanning line in the center of the picked-up image is outputted by the scanning signal of a logic circuit 33. The signal is supplied to a signal processing circuit 400 also, and a vertical-direction contrast signal OUT.V is generated similarly. The lens is focused on even the object, whose contrast and luminance are reduced, based on signals OUT.H and OUT.V.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic focus adjustment device, and more specifically, the present invention relates to an automatic focusing device, and more specifically, an automatic focusing device that performs focusing based on a modulation component of an imaging signal when the optical path length of an imaging optical system is modulated. The present invention relates to an automatic focusing device that detects a focused state and brings the optical path length into a focused state.

[Prior Art] This type of automatic focus adjustment device is disclosed in Japanese Patent Application Laid-open No. 11600/1986.
As already disclosed in Japanese Patent No. 7 and Japanese Patent Application Laid-Open No. 57-93307, part or all of the photographic lens is vibrated, and the high-frequency components of the imaging output obtained at this time are modulated by the vibration. Therefore, the in-focus state is detected by detecting this modulation component, and the photographing lens is driven to the in-focus position based on this detected value.

[Problems to be Solved by the Invention] In such conventional automatic focusing devices, focus detection is performed using imaging signals, so an extremely simplified configuration can be obtained; however, detection of modulation components is difficult. Since the modulation component is detected in one preset frequency band, if the contrast component of the object is weak, the sensitivity will be extremely poor. Further, even when the subject brightness is extremely low, the detection sensitivity becomes extremely poor as described above.

The present invention was made in view of these circumstances, and its purpose is to provide an automatic focus adjustment device that can adjust the photographic lens to an accurate focusing position even when the subject is in poor contrast or brightness. It is about providing.

[Means for solving the problem] The automatic focusing device according to the present invention detects the focusing state based on the modulated component of the imaging signal when the optical path length of the imaging optical system is modulated, and adjusts the focusing state to -. Auto focus U to keep the optical path length in focus. 'J section device extracts modulation components of an image signal corresponding to a first range set horizontally in a band shape in a captured image in a plurality of frequency bands, and synthesizes each extracted signal. and a second signal processing circuit that extracts modulation components of the imaging signal corresponding to a second range set vertically in a band shape in the captured image in a plurality of frequency bands, and synthesizes the respective extracted signals. and a control means for controlling the two-leg optical path length to a focused state based on the respective outputs of the first and second signal processing means. That is.

[Operation] The automatic focus adjustment device according to the present invention extracts modulation components of an imaging signal in a plurality of frequency bands, and adjusts a photographing lens to a focusing position based on an output obtained by combining the extracted signals. This is what I did.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described.

A subject image is formed on the photoconductive surface of the imaging element 10 provided in the imaging means 100 shown in FIG. 1(A) by optical means as shown in FIGS. 2 and 3. It has become. That is, as shown in FIG. 2, the image of subject 1 is
By using a photographic lens formed by the ff lens 2 and the rear J1τ lens 3, an image is formed on the photoelectric conversion surface of the imaging probe 10. Each of the front group lens 2 and the rear 7FF lens 3 is actually formed of ten or more lenses, and the front group lens 2 is a so-called taking lens, and is attached to the camera body. A lens that forms a fixed or different focal pressure f'flll is provided removably, or a lens that forms a zoom lens. Then, by moving the rear group lens 3 in the optical axis direction, the subject pressure ffilE,'),',I section is performed.

The rear m1 nons 3 is supported by a lens holder 4, and a coil 5 is wound around the peripheral surface of the lens holder 4. A ring-shaped magnet 6 is disposed around the coil 5, forming a so-called voice coil type magnetic circuit.

Further, the lens holder 4 is movable with respect to the guide rod 7, and focusing information is obtained by vibrating the rear group lens 3 in the direction of its optical axis.Based on this focusing information, Appropriate subject distance adjustment is now possible.

The image sensor 10 configured as described above has a horizontal synchronizing signal H, a vertical synchronizing signal V, and a vertical synchronizing signal V generated by the synchronizing signal generator 200.
Subcarrier signal SC, signal 2 SC having twice the frequency of the subcarrier signal.

For example, NTS based on other various synchronization signals SYNC.
A signal suitable for obtaining a signal of the C method is generated. This signal is amplified by a predetermined gain by a preamplifier 11 and supplied to a color separation circuit 12 and a luminance signal separation circuit 13. The color separation circuit 12 separates and extracts the signal into a red signal (hereinafter abbreviated as "signal R") and a blue signal (hereinafter abbreviated as "signal B"). On the other hand, in the luminance signal separation circuit 13, the luminance signal (hereinafter, "signal Y
) are separated and extracted. The signal R and signal Y separated and extracted in this way are used to obtain a red color difference signal (hereinafter abbreviated as "signal R-Y") by the difference detection circuit 14, and the signal B and signal Y are processed by the difference detection circuit 14. 15, a blue color difference signal (hereinafter abbreviated as "signal B-YJ") is obtained. This signal R-Y and signal B-Y are supplied to an orthogonal modulation circuit 16, and the subcarrier signal is generated in each frequency band. The chroma signal C is orthogonally modulated by the SC, and the chroma signal C obtained in this way is superimposed on the negative signal Y by the mixing circuit 17, and the NTSC video output signal OUT is The output of the circuit 100 is sent to a recording device 150 such as a VTR, and includes a superimposed signal IN such as a superinvoice signal and a video output signal O.
The UT is mixed by a mixing circuit 18 and supplied to an electronic viewfinder (hereinafter abbreviated as rEVFJ) 19.

The signal Y described above is supplied to the first signal processing circuit 300. The first signal processing circuit 300 extracts modulation components of the imaging signal corresponding to a first range set horizontally in a band shape within the captured image in one frequency band, and extracts each extracted signal. This is for the horizontal contrast of the combined images. The above-mentioned signal Y is supplied to each of the bypass filter (hereinafter abbreviated as rHPFJ) 20 and mixing circuit 21 that constitute the first signal processing circuit 300. The high-pass frequency characteristics of this HPF20 are:
The frequency is set to approximately 2 MHz, and the mixing ratio of the output of the HPF 20 and the signal Y in the mixing circuit 21 is set to 1:1.

Therefore, the signal Y1 output from the mixing circuit 21 has the high frequency components of the signal Y emphasized, which is useful for improving the detection accuracy of focus information. Therefore, the frequency spectrum of the signal Y1 output from the mixing circuit 21 has high frequencies emphasized as shown in FIG.

This signal Y1 is transmitted through three types of sampling and hold circuits (hereinafter abbreviated as "rSH circuit") 22, 23.

24. This SH circuit 22 performs sampling and holding of the signal Y1 based on a sampling pulse HSPI as shown in FIG. 5, which is generated by a sampling pulse generator (hereinafter referred to as rsPGJ) 37. The frequency of HSPI has a tail frequency of 27fSC (about 7.2 MHz), which is twice the frequency of signal 2.SC (about 3.58 MHz).

Similarly, the SH circuits 23 and 24 perform sampling and holding of the signal Y1 based on the →nobling pulses HSP2 and HSP3, and the sampling pulse HSP
The frequency of 2 is (1/2) fSC, which is obtained by dividing the signal of frequency 2·fSC by 1/4 by the 1/4 frequency divider 35. Furthermore, the frequency of the sampling pulse HSP3 is determined by dividing the output of the 1/4 frequency divider 35 into a 1/16 frequency divider 36.
The frequency is divided by 1/16 (1/32) fSC.

Then, the sampling hold signals HSHI, HSH2, HSH in each of the SH circuits 22, 23, and 24 are
Each of 3 is a bandpass filter (rBP
(abbreviated as FJ)25. 28.

27 respectively. The center frequency characteristic of this BPF25 has 2·fSC as shown in FIG.
PF26 is (1/2) fSC, BPF27 is (1/3)
2) It is set to fSC.

In this way, the role of PF25, 26.27 is to
This is to detect the magnitude of the contrast.

For convenience of drawing, FIG. 5 shows the relationship between sampling pulse HSPI and sampling hold signal HSHI,
This is to explain the magnitude relationship of the sampling frequencies of each of the three types: the relationship between the sampling pulse HSP2 and the sampling hold signal HSH2, and the relationship between the sampling pulse HSP3 and the sampling hold signal HSH3, so it does not correspond to the actual frequency. The same applies to FIG. 8, which will be described later.

Now, FIG. 7 shows a change in the contrast of the signal Y1 output from the mixing circuit 21 when a certain subject is imaged. Comparing the contrast when out of focus and the contrast when in focus, the contrast is higher when in focus.

The waveforms of the in-focus signal Y1 and the out-of-focus signal Y1 shown in FIG. 7 correspond to the boundary between black and white of an object whose right half is white and whose left half is black. The time for the signal Y1 to completely change from black to white is represented by time Ta during out-of-focus and time Tb during focus. This is because when the object is out of focus, the time Ta is long and the boundary between black and white appears blurred on the screen, whereas when the object is in focus, the time Ta is short as the time Tb and appears sharp on the screen. That is, the state in which the object appears sharpest is the in-focus state. Further, the out-of-focus signal Y1 is sampled and bolded by the SH circuit 22 with a sampling pulse H8PI having a frequency of 2·fSC from the 5PG 37, and becomes a sampling hold signal H3HI. This signal H3HI
The level based on the frequency component of 2・fSC is the signal Y1
If the levels of are the same, the shorter the times Ta and Tb, the greater the occurrence. At that time, the level per sampling step is greater for the signal Y1 corresponding to the time Ta, as shown by ΔEa and ΔEb. This means that the steeper the slope of the signal Y1, in other words, the closer to the in-focus state, the larger ΔEa and ΔEb become, and reach their maximum value in the in-focus state.

Such a sampling hold signal HS H1 is B
Only the frequency component of 2·fSC is extracted by the PF 25, and a signal HBP1 is generated at the output of the BPF 25. The level of this signal HBPI occurs in proportion to the magnitudes of ΔEa and ΔEb, and is a small voltage when out of focus and becomes a large voltage when in focus (voltages ea, eb).

The signal HBPI output from the BPF 25 is supplied to the envelope detection circuit 28, subjected to envelope detection, and input to the mixing circuit 31.

On the other hand, the signal Y1 is transmitted to the SH circuit 23. BPF26° envelope detection circuit 29 circuit system, SH circuit 24, BPF
27. The same processing as described above is performed in each of the circuit systems of the envelope detection circuit 30, and the respective sampling frequencies at that time are (1/2) fSC and (1/3)
2) becomes fSC. The reason why three types of sampling frequencies are used and the respective outputs are mixed in the mixing circuit 31 is that the contrast of the subject is not necessarily sharp, but may be, for example, extremely gentle contrast (changes in brightness and darkness). In some cases, the levels of voltages Ea and Eb shown in FIG. 7 may become so low that they cannot be detected. Therefore, if the contrast is gentle (changes in brightness and darkness), fSC (1/2) or (1/2) lower than the frequency 2fSC
/32) Sampling pulse I-IS with fSC
Sampling and holding is performed using P2 or sampling pulse H3P3 to obtain a large sampling step and a large step voltage.

On the other hand, for an object with extremely sharp contrast, even the sampling pulse HSPI with the lowest frequency of 2fSC has a coarse sampling step, making it impossible to detect the contrast. Therefore, in this case, the sampling pulse H with higher frequency (1/2) fSC or frequency (1/'32) fSC
If detection is performed using SP2 or sampling pulse HSP3, a large detection output can be obtained.

Figure 8 shows the signal Y1, sampling hold signals HSHI, HSH2, HSH3, and signal HBPI corresponding to a subject for which only a mild contrast can be obtained even when in focus.
, HBP2, and HBP3. As is clear from the figure, the lower the sampling frequency, the larger the voltage e1. signal HBPI with e2, e3,
HBP2 and HBF4 are obtained.

Such a method detects that the signal gradient corresponding to the contrast of the signal Y1 becomes steep as the focus is achieved, using the SH circuit 22, BPF 25 or the SH circuit 23, BP
F26 or SH circuit 24.

Voltage el corresponding to the signal slope by BPF27.

This means that e2 and e3 are detected.

The signals HBPI, HBP2, and HBP3 output from the BPF 25, BPF 26, and BPF 27 are sent to envelope detection circuits 28, respectively.

29 and 30, and taking the sampling hold signal HSHI as an example, an envelope detected signal HEI is obtained as shown in FIG. Similarly, envelope detection signals HE2 and HE3 are obtained in envelope detection circuits 29 and 30 as well.

Envelope detection signals HEI, HE2 . HF2 is mixing circuit 3
1 and frequency 2fSC.

Sampling pulses H3PI, H3P2 .with (1/2) fSC, (1/32) fSC. Contrast information detected by H3P3 is combined.

The composite signal M1 of the mixing circuit 31 is supplied to a multiplexer 32 provided with a voltage hold function. As shown in detail in FIG. 10, this multiplexer 32 converts the synthetic signal M1 into eight channels of bold signals ao, al, a2, . . . based on control from the logic circuit 33.
...obtains a7. That is, the composite signal M1 is
It is supplied to each of the hold capacitors 32aO to 32a7 through each of the eight field effect transistors (rFETJ) 32bO to 32b7, and the hold signals aO to 8 channels are supplied from each of the hold capacitors 32aO to 32a7. a7 is now generated. Scanning signals Hφ0 to Hφ7 from the ring counter 32c, which are scanned by the scanning signal Hφ from the logic circuit 33, are supplied to the respective gates of the FETs 32bO to 32b7.
T32bθ to T32b7 are turned on in sequence. This scanning signal Hφ is generated by the logic circuit 33. The logic circuit 33 generates a scanning signal Hφ based on the horizontal synchronization signal H and the vertical synchronization signal V.
As shown in FIG. 11, the contrast information detection range is the central part of one scanning line in the center of the captured image, and the horizontal synchronizing signal H is transmitted to the one-shot multi-circuit 3 at its falling edge.
3a and a signal a33 is obtained. Furthermore, the 20 μsec pulse generator 33b is triggered at the rising edge of the signal a33 output from the one-shot multi-circuit 33a, and a signal b33 is obtained. The output pulse width of the one-shot multi-circuit 33a is set so that the H level section of the signal b33 is located at the center of one scanning line of the captured image. And signal b33 is Antogame I-33c
becomes one of the inputs.

On the other hand, the vertical synchronizing signal V triggers the one-shot multi-circuit 33d at its falling edge, and a signal c33 is obtained. Further, when the signal c33 output from the one-shot multi-circuit 33d rises, the IH pulse generator 33e is triggered and a signal d33 is obtained. This signal d33
The output pulse width of the one-shot multi-circuit 33d is set so that the H level section is located at the vertical center of the captured image. Then, the signal d33 becomes the other input of the ant gate 33c.

Therefore, the signal e33 output from the anime game h33c has a pulse width of 20 μsec, which corresponds to one scanning line at the center of the captured image, as shown in FIG. This signal e33 activates the oscillator 33f, and its output is
This results in a signal f33 having eight pulse widths. This signal f33 is supplied to the multiplexer 32 as the scanning signal Hφ output from the logic circuit 33.

Therefore, the signal f33 (scanning signal Hφ) is generated only in the H level section of the signal e33 as shown in FIG. 13, and based on this signal f33 (scanning signal Hφ), the scanning signal Hφ0 to Each of Hφ7 occurs. The repetition period of the scanning signals Hφ0 to Hφ7 is one period (IV) of the vertical synchronizing signal V, in other words, the signal Y1
This will occur for each field. as a result,
As shown in FIG. 12, one scanning line in the central part of the captured image and the H level section of the signal e33 are divided into eight equal parts.
For each field, the output level of the mixed signal M1 of the mixing circuit 31 is held by the capacitors 32aO to 3.
This means that it is incorporated into 2a7. Of course, the hold voltage at that time is updated every 1V.

Next, as shown above, the multiplexer 32 outputs the composite signal M1.
The reason for dividing into 8 parts will be explained. If the brightness distribution of the subject is partially extremely high, the brightness level may become saturated at the stage of the image sensor 10. Figure 14 shows
Indicates a case where part of the level of signal Y1 is in a saturated state,
For that clip value, there will be no accurate contrast. For example, if the composite signal M1 of the mixing circuit 31 is simply subjected to peak detection, accurate contrast information will not be obtained even if the focus of the contrast shadow lens is adjusted with respect to the clip value. Therefore, multiplexer 3
Scanning signals Hφ0 to Hφ7 from 2 are time-divided, and contrast information is obtained at timings Φ0 to Φ7 of each phase. In the case of the example shown in FIG. 14, the accurate contrast at timing (I) 3 will also be achieved at other timings.

Returning to FIG. 1(A), the signal aO~ which is taken in every field by the multiplexer 32 and whose voltage is maintained is
a7 is combined by the mixing circuit 34 to obtain horizontal contrast H. This horizontal direction contrast) information signal OUT-H is input to BPFGO and a mixing circuit 64, not shown in FIG. 1(B).

Next, regarding the second signal processing circuit 400, FIG.
Explain using. The second signal processing circuit 400 extracts modulation components of the image signal corresponding to a second range set vertically in a strip shape in the captured image in a plurality of frequency bands,
This is for synthesizing the respective extracted signals to obtain a vertical contrast information signal OUT-V. The above-mentioned signal Yl is supplied to each of the HPF 40 and the mixing circuit 41 that constitute the second signal processing circuit 400.

The mixing ratio of the output of the HPF 40 and the signal Y1 in the mixing circuit 41 is set to 1:1. Therefore, the signal Y2 output from the mixing circuit 41 has the high frequency components of the signal Y1 emphasized, which is useful for improving the detection accuracy of focus information. Therefore, the frequency spectrum of the signal Y2 output from the mixing circuit 41 has high frequencies emphasized.

This signal Y2 is sent to three types of SH circuits 42 and 43.

44. This SH circuit 42 performs sampling and holding of the signal Y2 based on a sampling pulse VSPI as shown in FIG. have.

Further, the SR circuits 43 and 44 similarly perform sampling and holding of the signal Y2 based on the sampling pulses VSP2 and VSP3. The frequency is divided by 2 (1/2) fH. Furthermore, the frequency of the sampling pulse VSP3 is (1/4) fH, which is obtained by further dividing the output of the 1/2 frequency divider 55 by 1/2 using the 1/2 frequency divider 56.

Then, the sampling hold signals VSHI, VSH2, VSH in each of the SH circuits 42, 43, and 44 are
3 are B P F 45, 46, respectively.

47 respectively. The center frequency characteristic of this BPF 45 has fH, and the BPF 46 has (1/2) fH
In this case, the BPF 47 is set to (1/4) fH. Like this, PF45, 46.

The role of 47 is to detect the magnitude of the contrast of the above-mentioned signal Y2.

The outputs of each of the BPFs 45, 46, and 47 are sent to envelope detection circuits 48, respectively.

49 and 50, and envelope detection is performed.

The outputs of the envelope detection circuits 48, 49, and 50 are combined by a mixing circuit 51.

The composite signal M2, which is the output of the mixing circuit 51, is supplied to a multiplexer 52 which is provided with a voltage hold function. As shown in detail in FIG. 17, this multiplexer 52 inputs the composite signal M2 to hold signals bO, b of 8 channels based on control from the logic circuit 53.
l, b2...b7 are obtained. That is, the composite signal M2 is generated by eight field effect transistors (hereinafter referred to as
rFETJ) 52bO to 52b7, respectively, to the hold capacitors 52aO to 52a7, and the hold capacitors 52aO to 52
8 channels of hold signals bO to b from each of a7
7 is now generated.

The gates of the IK FETs 52bO to 52b7 receive scanning signals Vφ0 to Vφ from the ring counter 52c, which are scanned by the scanning signal φ from the logic circuit 53.
φ7 is supplied to each of the above FETs 52bO to 52
b7 are turned on sequentially. This scanning signal ■φ is generated by the logic circuit 53.

This logic circuit 53 sends a scanning signal +! based on the horizontal dome signal I and the vertical synchronization signal V. The first
As shown in Fig. 6, the second range, that is, the vertical band in the center of the captured image is the contrast I/information detection range, and the horizontal synchronization signal The one-shot multi-circuit 53a is triggered at the falling edge, and a signal a53 is obtained. Further, the 5Lisec pulse generator 53b is triggered by the rising edge of the signal a53 output from the one-shot multi-circuit 53a, and a signal b53 is obtained. The output pulse width of the L one-shot multi-circuit 53a is set so that the H level section of this signal b53 is placed at the horizontal center of the captured image. It becomes one input.

On the other hand, the vertical synchronizing signal (2) triggers the one-shot multi-circuit 53d at its falling edge, and a signal c53 is obtained. Furthermore, the one-shot multi-circuit 53
e is triggered and a signal d53 is obtained. This signal d
The output pulse width of the one-shot multi-circuit 53d is set so that the H level section 53 is located at the vertical center of the captured image. Then, the signal d53 becomes the other input of the anime game 1□53c.

This signal e53 activates an oscillator 53f, the output of which becomes a signal f53 having eight pulse periods, as shown in FIG. This signal f53 is the logic circuit 53
is supplied to the multiplexer 52 as a scanning signal φ of the output.

Therefore, the signal f53 (scanning signal Vφ) is generated only in the H level section of the signal e53 as shown in FIG. 18, and based on this signal f53 (scanning signal Vφ), the scanning signal ■ Each of φ0 to Vφ7 occurs. The repetition period of the scanning signals .phi.O to V.phi.7 is generated every one period (1) of the vertical synchronizing signal V, or in other words, every field of the signal Y1. As a result, as shown in FIG. 16, the H level section of the signal e53 corresponding to the second range in the vertical direction of the captured image is divided into eight equal parts, and the mixed signal of the mixing circuit 51 is divided into eight equal parts for each field. Capacitor 52aO to hold the output level of M2
~52a7. Of course, the hold voltage at that time is updated every IV. The reason why the composite signal M1 is divided into eight by the multiplexer 52 is the same as that explained in connection with the first signal processing circuit 300 of two series.

The signals bO to b7, which are taken in by the multiplexer 52 every 1 and whose voltage is maintained, are sent to the mixing circuit 54 as follows.
The signals are combined to obtain a vertical contrast information signal OUT-V. This 1Tr direct contrast information signal OU
TV is a BPF 61 and a mixing circuit 6 shown in FIG. 1(B).
4 is input.

Next, details of the control means 500 will be explained.

The control means 500 controls the photographing lens based on the horizontal contrast information signal OUT·H and the vertical contrast information signal OUT-V, which are the respective outputs of the first and second signal processing circuits 300 and 400 described above. The optical path length of the lens is controlled to be in focus. That is, the vertical contrast information signal OUT-V has a center frequency of 15
Hz is input to the BPF 61, and the output of the BPF 61 is forcibly modulated at 15 Hz as described above, and as a result, the contrast fluctuation of the component synchronized with the modulation (
Variant 2I) Only information is separated and extracted. And the same BPF
The output of BPF 61 is supplied to a mixing circuit 62 together with horizontal contrast information, which is the output of BPF 60, and the two are mixed. The output of this mixing circuit 62 is input to a synchronous detection circuit 63, and only the contrast modulation component synchronized with the modulation frequency of 15 Hz is separated and extracted by the synchronous detection circuit 63.

The vertical synchronization signal (2) is frequency-divided by 1/4 by a 1/4 frequency divider 70 to become a 15 Hz signal. This 15Hz signal is sent to the Domei Kenpa pulse generator 71.72 as the signal a70.
A synchronous detection pulse generator 71.7
2, a signal a71. Rectangular waves of 30 Hz and 15 Hz are generated as a72, respectively.

Next, details of the synchronous detection circuit 63 will be explained using FIGS. 19 and 20. The signal a62 shown in FIG. 19 is an example when the output of the mixing circuit 62 is in an out-of-focus state, and a modulation component of 1 (<15 Hz) is generated in the optical path length modulation. , the synchronous detection circuit 63 includes 5PG
63a, 63b are provided, and these 5PG63a, 63b
A 15 Hz rectangular wave signal a72 output from the synchronous detection pulse generator 72 is supplied to each input of the synchronous detection pulse generator 72. The signal b63 output from the 5PG63a is
The phase is such that an H level pulse having a width of 5H (5 pulses of the horizontal synchronizing signal H) falls at the rising edge of the signal a72 from the synchronous detection pulse generator 72. In other words, the phase is such that an H level pulse having a width of 5H (5 pulses of the horizontal synchronizing signal H) falls at a time point corresponding to the minimum level position of the signal a62 output from the mixing circuit 62.

Further, the signal C63 output from the 5PG63b is the signal a? from the synchronous detection pulse generator 72? 5H(
The phase is such that an H level pulse having a width of 5 pulses of the horizontal synchronizing signal H falls.

Such a signal b63. Based on the H level section of c63, FETs 63c and 63d are turned on alternately, the maximum level of the signal a62 is held as a voltage in the hold capacitor 63e, and the minimum level of the signal a62 is held as a voltage in the hold capacitor 63f. Such voltage holding is updated every 1/4 of the period of the vertical synchronization signal V. The output difference between the respective outputs of the hold capacitors 63e and 63f is converted into a DC voltage by an operational amplifier 63g, and focusing information is obtained as a signal a63.

On the other hand, the signal a70 output from the 1/4 frequency divider 70 is input to a gain control type amplifier circuit (hereinafter abbreviated as rGCAJ) 73, and its amplitude level is controlled by the output of a mixing circuit 74, which will be described later. Current amplification circuit 75 and mixer 7
6, the coil 5 is energized. As a result, the rear lens group 3 (see FIGS. 2 and 3) is vibrated, and the optical path length of the photographing optical system is changed to 1/2 period of the vertical synchronization signal V (15I-I z
).

FIG. 21 shows the properties of the contrast modulation component of the signal a62 obtained at the output of the mixing circuit 62 when the optical path length of the imaging optical system is modulated.

That is, when the subject is at the in-focus position, the signal a6
2 has a substantially sinusoidal rectified waveform, and at the time of front pin and rear pin, each has a substantially sinusoidal waveform. Here, comparing the signals of the front pin and the rear pin,
Each of them changes into an advanced phase and a delayed phase with respect to the signal a62 at the time of focusing.

Further, the frequency of the signal A62 when in focus is 30 Hz, which is twice the frequency that vibrates the rear group lens 3, and when out of focus, it is 15 Hz.

Therefore, as shown in FIG. 20, in the synchronous detection circuit 63, the peak values in the positive and negative directions of the output are
Signal b of each sampling pulse of 3a and 63b
63. Hold capacitor 63e, 63 by c63
Sampling and holding for each of f, operational amplifier 6
3g is used to convert the voltage difference. As a result, the output of the synchronous detection circuit 63 is a signal a63 whose output changes in the positive and negative directions depending on the direction of the front focus and the rear focus, with the voltage in the focused state as the boundary. The signal a63 becomes AF information.

Furthermore, the 30Hz component that occurs in signal a63 during focusing is:
Since the center frequency of each BPF 60.61 is 15 Hz, -30= is not input to the synchronous detection circuit 63.

The A P information tlj (signal a63) which is the output of the synchronous detection circuit 63 is sent to the mixer 76 by turning the time constant switching circuit 68 red and white.
It is supplied to one of the human power sources, and the direct current or voltage is applied to the 15Hz variable signal to control the position of the rear Ji mini-lens, forming a negative feedback loop in the entire control system.

As a result, the rear 11 lens 3 is controlled to be in focus.

On the other hand, the horizontal contrast H and the vertical contrast are synthesized by the vertical contrast mixing circuit 64, and the center frequency is 30Hz.
As shown in FIG. 22, the output signal a65 of the BPF 65 is input to the 30 I-I z contrast synchronous detection circuit 66 only when in focus, and the signal a65 is The positive and negative peak values of the generated 30 Hz component are extracted. This synchronous detection circuit 66 is a synchronous detection pulse generator 71.
Since the signal a71 of I-1 z is input manually, this synchronous detection circuit 66 detects the synchronous detection circuit 6 described in -.
Similar to 3, synchronous detection is performed. At the output of the synchronous detection circuit 66, a DC voltage signal a66 whose magnitude is proportional to the peak value of the signal a65 output from the BPF 65 is generated.

This signal a66 is input to a level sensor 67 formed by a voltage comparison circuit (not shown) or the like.

Then, this level sensor 67 detects a signal a66.
is within a predetermined voltage range, the same bell sensor 67
The output is now generated.

This output is a focus signal a67, which is set at H level when in focus and at L level when out of focus. This focus signal a67 is supplied to the mixing circuit 18 as a superimposition signal IN for the EVF 19 (see FIG. 1(A)) used in the TV camera system, and is displayed in a superimposed manner on the EVF 19. This focusing signal a67 is further input to a time constant switching circuit 68, and the time constant of the control loop of the imaging optical system is switched. This time constant switching circuit 68
As shown in detail in FIG. 3, the input terminal of the simultaneous constant switching circuit 68 is supplied with the signal a83 from the synchronous detection circuit 63, and the signal I1. The signal a68 is sent to the input end of the mixer 76 from the 111 output ◇;1 of the constant switching circuit 68. At the same output end, there is a resistor b'l: 6 8
The connection point between the resistor 68b and the capacitor 08c is grounded through a series circuit of the source and drain of the capacitor 68d and the FETC 8e. Yes, this F
The focus signal a67 from the J5 level sensor 67 is supplied to the gate of the ET68e.This is done in order to help suppress noise components included in the detected AF information. It is.

When the focus is achieved, the focus signal a67 output from the level sensor 67 becomes H level, and along with this, the FET6
8e turns on. Then, since the capacitor 68d is grounded, it can be switched to the 11.7 constant or longer direction. In addition, the focus signal a. [In the out-of-focus state where i7 is at L level, FET68e is off, so n:
;The constant is switched in the opposite direction by 1υ.

Another example of such a time constant switching circuit 68 is a second
There is something like the one shown in Figure 4. That is, the time constant switching circuit 6
The input terminal of 8' receives a signal a63 from the synchronous detection circuit 63.
is supplied, and the doujinshi end has a resistance of 68
A signal a6 is output from the output terminal of the simultaneous constant switching circuit 68 via f.
8 is delivered to the input of the mixer 76. The output terminal is grounded via a time constant circuit consisting of a series circuit of a resistor 68g and a capacitor 68h, and the connection point between the resistor 68g and capacitor 68h is connected to the above output terminal via the source and drain of an FET 68e. It is connected.

A focus signal a67 from a level sensor 67 is supplied to the gate of this FET 68i.

When the focus is reached, the focus signal a67 output from the level sensor 67 becomes H level, and along with this, the FET6
8i turns on. Then, the resistor 68g is short-circuited, so that the time constant is switched to a longer direction, and at the same time, the amount of attenuation in the noise band is increased. In addition, the focus signal a
When in an out-of-focus state at 67 or L level, FET6
Since 8i is off, the time constant is switched to a shorter time constant.

The reason why such a time constant switching circuit 68 or 68' is provided is that once the control loop of the imaging optical system is stabilized in the focused state, there is no need to increase its response speed. High-frequency components of the control loop system (e.g., 5H2 and above)
), there is no need to control it, and it is better to attenuate it in order to reduce various adverse effects caused by noise.

On the other hand, the signal a66 output from the synchronous detection circuit 66 is supplied to the control J11 input terminal of the GCA 73 via the mixing circuit 74. This GCA73 is set so that its gain decreases as it approaches focus, and as a result, when in focus, the amount of vibration of the rear 7 lenses 3 is reduced compared to when out of focus. . This is caused by the flicker that occurs in the reproduced image obtained when actually observing the imaging signal, which is caused by forcibly modulating the optical path length of the imaging optical system.
This is done to minimize the amount of damage caused by visual damage.

As a result, when out of focus, the coil 5 is energized so that the amount of vibration of the rear group lens 3 increases, and when in focus, the coil 5 is energized so that the amount of vibration of the rear group lens 3 is increased. By doing this, AF control with good response speed can be achieved. Furthermore, the aperture information Av of the photographic lens is inputted into the mixing circuit 74 manually, and the GCA 73 is also controlled by the aperture information Av. That is, as is well known, when the brightness of the subject is extremely high and the aperture is set to a large value, the depth of field becomes deep. As a result, even if the rear lens group 3 is vibrated the same, the amount of contrast modulation decreases, and the detection accuracy of AF information deteriorates. Therefore, when the aperture becomes a large value, the gain of the GCA 73 is increased, and when the aperture becomes a small value, the gain of the GCA 73 is increased to increase the amount of vibration of the rear lens group 3. Controls energization.

The input of the mixer 76 described above is supplied with the voltage of a reference voltage source 81 via a switch 80 that switches the AF operation between automatic mode and manual mode.

Further, the switch 80 is linked to the switch 82, and when both switches 80 and 82 are turned on, the input terminal of the current amplification circuit 75 is grounded and the voltage of the quasi-voltage source 81 is connected to the mixer 76. is supplied to the coil 5 via A.
The F control system is disconnected, and the coil 5 is energized via the mixer 76 so that the rear IF lens 3 is located at a desired position depending on the position of the variable resistor forming the 12+' voltage source 81.

The lens position detector 79 detects the position of the rear J1″f lens 3, and may be of a photoelectric type, electromagnetic type, etc. In this example, a magnet is fixed to the rear group lens 3, and this magnet A Hall element is provided in close proximity to the Hall element, and a circuit is provided to amplify the output of this Hall element.Therefore, as the output of this lens position detector 79, a voltage signal corresponding to the amount of lens movement is generated, and this output or is supplied to a mixer 76.

The reason why such a lens position detector 79 is provided is to sequentially compare the output level of the current amplification circuit 75, which is the manual power of the mixer 76, in order to keep the amount of vibration of the rear group lens 3 at a constant level. The amount of movement is made to accurately follow the output of the current amplification circuit 75. Also, switch 80.82
Similarly, in the manual mode in which the voltage is turned on, the output voltage of the reference voltage source 81 is accurately followed. Furthermore, it also has a function of preventing the rear group lens 3 from moving due to external force applied to the camera body.

Now, the focus signal a67 which is the output of the level sensor 67
is supplied to one input terminal of the comparison circuit 69, and the signal a63 output from the synchronous detection circuit 63 is supplied to the other input terminal. Then, both are compared by a comparison circuit 69,
The output of the comparison circuit 69 controls on/off of the switch 83. If the subject has no contrast at all, this automatic focus adjustment device will not detect any AF information. In this case, the position of the rear group lens 3 is in an extremely unstable state. To solve this problem, AF
If the information cannot be detected, the position of the rear T lens 3 is forcibly set to a predetermined position.

In this example, the limb photographing distance 11 of the photographic lens formed by the rear li mini-lens is set to an intermediate position between the far position and the close distance. Details of the comparator circuit 69 having such a function are shown in FIG. In the figure, the comparison circuit 69 has one input terminal supplied with a signal a63 from the synchronous detection circuit 63, and the other input terminal supplied with a signal a67 from the level sensor 67. Then, the signal a63 is supplied to one input terminal of each of the comparators 69a and 69b, and the signal a63 is
, 69b are connected to the reference voltage source 6 at the other input end of each of them.
9c and 69d are supplied respectively. The voltages of the base q voltage sources 69c and 69d are respectively set to a voltage value when the signal a63 from the 1171 detection circuit 63 has an AF information component and a voltage value when there is no AF information component. In addition, the comparators 69a and 69b each have a single power input, which is supplied to each of the two manual power inputs of the three-manpower type game 1-69f, and the other input terminal receives the focus signal a67 from the level sensor 67. It is supplied via an inverter 69e. This anime game-1” 6
The output of 9f is supplied to the control end of the switch 83 as a signal a69 of the output of the comparator circuit 69.

Therefore, if the subject has no contrast at all, the focus signal a67 from the level sensor 67 will not be at the focus determination level, and the AP information will also be at the focus level.

If the subject has contrast, if the AF information is at the focus level, the focus signal a67 of the level sensor 67 should be at the focus level. Comparator 69a.

The output level of 69b becomes H when the AF information enters the in-focus area.
become the level. Like the two series, the signal a67 of the level sensor 67 becomes H level when in focus.

Therefore, if the object has no contrast, the focus signal a67 of the level sensor 67 is at the L level, and this L level is inverted by the inverter 69e.
-69f is manually operated. As a result, and gate 69f
The H1 power becomes H level only when the AP information is in the focus area and no focus determination signal is generated. This H level signal a69 becomes a detection signal for detecting the presence or absence of contrast of the object.

This signal a69 is supplied to the switch 83 as the output of the comparator circuit 69, and when the switch 83 is turned on, the voltage of the reference voltage 1l-IE source 84 is forcibly applied to the current amplification circuit 75. The output voltage of the current amplifier circuit 75 is locked. This voltage is suitable for the coil 5 when the rear lens group 3 is located between the rotating speed position and the close-up position.
The current is set so that the current is applied to the This signal a
69 is E shown in FIG. 1(A) as the superimposed signal IN'.
An appropriate display can be made on the V F 19 as focus information using an LED or the like.

Further, the output of the GCA 73 is grounded via a series circuit of a resistor 77 and a switch 78. This is because when the mode of imaging is close-up, close-up photography is performed with the front lens group 2 moved along the optical axis.
At this time, the amount of movement of the rear group lens 3 is smaller than in normal shooting, so if the amount of vibration of the rear group lens 3 is made the same as in normal shooting, the contrast modulation component will become too large, resulting in stable AF control. Preventing from being unable to do 11
This is for the purpose of two things.

That is, the switch 78 is turned on in conjunction with the movement of the front group lens 2 toward the close-up side, and when the switch 78 is turned on, the resistor 77 is forcibly connected in parallel to the output impedance of the GCA 73. The current amplification circuit 7
The input level to 5 is attenuated. As a result, the amount of vibration of the rear group lens 3, in other words, the current applied to the coil 5 is reduced.

Now, the signal b33 in FIG.
The output of the 20 μsec pulse generation circuit 33b of the logic circuit 33 in FIG. 1 and the series of signals d53 in FIG. It is supplied to each input terminal of the OR gate 85 shown in B), and the output of the OR gate 85 is used as the display signal IN'.
When superimposedly displayed on the EVF 19 based on this display signal IN', a cross-shaped distance measurement mark can be displayed in the center of the captured image as shown in FIG.

It goes without saying that the present invention is not limited to the automatic focus adjustment device of the embodiment described above, and can be implemented in various modifications.

For example, in this embodiment, the front Jff lens 2 is fixedly provided and the rear 1iT lens 3 is vibrated, but the rear 11T lens 3 is fixedly provided and the front group lens 2 is vibrated. You may also do so. Also, the front group lens 2 and the rear! A photographic lens formed by the ff lens 3 may be provided in a fixed manner, and the imaging cable 10 may be vibrated.

The point is that any mode may be used as long as the optical path length of the imaging optical system is substantially modulated.

Also, multiplexer 32 or multiplexer
52, instead of mixing signals sampled and held at different sampling frequencies in the mixing circuit 34 or mixing circuit 54, the output of the mixing circuit 31 or mixing circuit 51 is simply envelope-detected and then integrated as appropriate. Output horizontal contrast information signal 0U
T-H or vertical contrast information signal OUT/
It may be set to V.

Further, the 5 μsec pulse generator 53b of the logic circuit 53 in the second signal processing circuit 400 is replaced with the 20 μsec pulse generator 53b of the logic circuit 33 in the first signal processing circuit 300.
It may be the same as the pulse generator 33b, and in this case, the ranging range will not be cross-shaped but band-shaped.

Further, the automatic mode and manual mode switching means formed by the switch 80 and the reference voltage source 81 is provided with a focus ring on the photographing lens, and when in the manual mode, the Api;+I control is stopped and adjustment using the focus ring is performed manually. You may also do so.

Furthermore, in the case of close-up photography, a resistor 77 and a switch 78 are used to reduce the amount of vibration of the rear group lens 3, but instead of this, the amount of vibration of the rear group lens 3 is kept constant, and the synchronous detection circuit 63
By providing a resistor selectively connected in parallel to the output of the synchronous detection circuit 63, the control loop gain of the imaging optical system may be reduced by forcibly lowering the output impedance of the synchronous detection circuit 63.

FIG. 27 shows a modification of the first signal processing circuit 300 or the second signal processing circuit 400 described above.

In this example, the signal processing circuit 310 corresponds to the first signal processing circuit 300. In the figure, the signal Y from the imaging circuit 100 (see FIG. 1(A)) is transmitted through the HPF
Each of IOI, 102, and 103 is manually operated. The cutoff frequencies of this HPFIOI, 102° and 103, are different from each other, 100KHz, IM
Hz, 2MHz. This is because the frequency component of the contrast component of the subject covers a wide range, so AF information is detected for the entire range.

The respective outputs of this I(PFIOI, 102, 103) are input to envelope detection circuits 104, 105° 106, respectively, and envelope-detected.
The respective outputs of the envelope detection circuits 104, 105, and 106 are mixed in a mixer 107 and converted into eight channels of signals aO to a7 by a multiplexer 108. This multiplexer 108 is the multiplexer 32 or the multiplexer 52 (see FIG.
It is formed in the same way as A).

Therefore, if the signal Y is as shown in FIG. 28, the signal Y has a frequency of 100 KHz, IM Hz,
HPFIO with a cutoff frequency of 2 MHz
I, 102. Differentiated by 103, signal a 101°a1
02. It becomes a103. This signal a101゜a102.
Since a103 is differentiated with different cutoff frequencies, their falling characteristics are different. Then, this signal a101. a102. a10
3, its peak values in the positive and negative directions are detected by envelope detection circuits 104, 105, and 106. The peak values e101 to e103 obtained in this way.
e lot' to el (each of 13' is the 29th
As shown in the figure, envelope detection circuits 104, 105.
The differential voltage is determined by a comparator forming a part of each of the envelope detection circuits 104 and 106 .
．． Signal a104 to each 111 power of 105.106
．． a105. a106 or II).

On the other hand, the respective outputs of HPF1, 01, 102, and 103 are combined by a mixer 110, and the output is voltage amplified by an amplifier 111 and input to a peak value detection circuit 112. This peak value detection circuit 112 bolds the maximum value of high frequency components in one horizontal section of the scanning line during one horizontal section of the scanning line, and is reset every horizontal section of the scanning line. The output of this peak value detection circuit 112 is passed through a switch 113 to a signal a11.
3 to the mixer 109.

FIG. 30 is a diagram for explaining the operation of the peak value detection circuit 112. For example, the peak value of the signal Y as shown in the figure is converted to the signal a112 of the output of the peak value detection circuit 112 as the voltage e1]2. Become. This signal a112 is one of the scanning lines.
It is held during the horizontal interval and reset at the falling edge of the horizontal synchronization signal H.

If the subject brightness is extremely low, the S/N ratio will naturally deteriorate, but if the distance measurement range is divided as in this example,
Some problems arise. That is, FIG. 31 is an example of a luminance signal when the subject luminance is extremely low, but there is contrast information between timings Φ3 and Φ4, and there is contrast information between timings Φ1 and Φ2. If there is no contrast information at timings Φ5 to Φ7, timings Φ1 to Φ2. Only noise components can be obtained from Φ5 to Φ7. Therefore,
Since the noise component is mixed with the control I/last information, the detection accuracy of the AF information is degraded. but,
In this example, the peak value is detected by the peak value detection circuit 112, and this peak value is manually input to the mixer 109 as the signal a113, so the above-mentioned problem is solved. Since such an operation needs to be performed only when the subject brightness is extremely low, the switch 113 described in (-) is turned on by the output of a subject brightness detection circuit (not shown) only when the subject brightness is extremely low. .

This object brightness detection circuit converts the aperture value into a voltage value on the assumption that the aperture will be wide open when the object brightness is extremely low, and if this voltage exceeds a predetermined voltage. The control deviation should be such that the switch 113 is turned on.

FIG. 32 shows a modification of the first signal processing circuit 300 or the second signal processing circuit 400 described above.

In this example, the signal processing circuit 320 corresponds to the first signal processing circuit 300. In the same figure, the signal Y from the imaging circuit 100 (see FIG. 1(A)) is
It is input to F120. The cutoff frequency of this )-1PFI 20 is set to, for example, 2 MHz.

Therefore, the high frequency component of signal Y extracted is the same HPF.
The output will be 120.

This output is envelope-detected by an envelope detection circuit 121 and is directly input to the system and the amplifier 12.
The input signal is divided into three systems, one being input via each of 2 and 123, and manually inputted to the mixer 124. This amplifier 1
22 benefits? The gains of the amplifiers 123 and 123 are set differently. Then, the output of mixer 124 is input to multiplexer=125. This multiplexer 125 converts the signals into eight channels of signals aO to a7. This multiplexer 125 is constructed similarly to the double multiplexer 32 or the multiplexer 52 (see FIG. 1A).

The magnitude of the high frequency component included in the luminance signal varies depending on the degree of focus, and also varies greatly depending on the luminance of the subject. That is, the output of the envelope detection circuit 121 fluctuates within a range of several mV to several V. The gain of the amplifier 122 mentioned above is set to 2 times, and the gain of the amplifier 123 is set to 10 times, so even if the high frequency component contained in the luminance signal is weak, it is amplified by the amplifiers 122 and 123 and sent to the mixer. Multiplexer 1 via 124
25.

On the other hand, in the case of a subject whose luminance is sufficiently high and whose contrast is sufficiently high, both amplifiers 122 and 123 become saturated;
The setting may be made so that the output of 21 does not become saturated. When the amplifiers 122 and 123 are saturated,
The output of the envelope detection circuit 121 is directly sent to the mixer 12.
4, so AF control can be performed reliably.

In addition, although the ranging range is set in a cross shape on each side mentioned above, it can also be set in any shape such as a T shape, an inverted T shape, an L shape, an inverted shape, a simple band shape, a circle, a diamond shape, etc. In this case, it is of course necessary to change the extraction timing of the imaging signal as appropriate depending on the shape.

Further, the 1llll distance ranges having various shapes as described above do not need to be provided at the center of the captured image, and their positions may be made variable. For example, when panning is performed as a subject such as a person moves from the left side of the captured image to the right side, it is desirable to fix the moving subject on the right side of the captured image. Therefore, it is desirable to be able to change the distance measurement range so that it is set to the right side of the captured image.

[Effects of the Invention] = 51- As described above, according to the present invention, AF information is obtained by extracting the modulation components of the imaging signal in a plurality of frequency bands and synthesizing the respective extracted signals. It has the advantage of being able to handle a wide range of subject situations.

Further, even when the contrast of the subject is weak or the subject brightness is very low, a reliable in-focus state can be obtained.

[Brief explanation of drawings]

FIG. 1(A) is a circuit diagram of an automatic focus adjustment device showing one embodiment of the present invention, and FIG. 1(B) is a circuit diagram of a control means connected to the circuit shown in FIG. 1(A) above. 2 is a side view of the main part of the imaging optical system for the image sensor shown in FIG. 1(A) above, and FIG. 3 is a perspective view of the imaging optical system shown in FIG. 2 above. 4 is a diagram showing the characteristics of the HPF shown in FIG. 1 (A) above, and FIG. 5 is a diagram showing the sampling and holding operation of the SH circuit shown in FIG. 1 (A) above. Figure 6 is a diagram showing the characteristics of the BPF shown in Figure 1 (A) above, Figure 7 is the sampling hold output and BPF output shown in Figure 1 (A) above. 8 is a time chart showing the relationship between the sampling hold output and the BPF output, and FIG. 9 is the time chart 1 showing the relationship between the sampling hold output and BPF output.
FIG. 10 is a diagram showing the envelope detection waveform of the envelope detection circuit shown in FIG. 1(A), a detailed circuit diagram of the multiplexer and logic circuit shown in FIG. 1(A), FIG. Fig. 12 is a diagram showing the relationship between the fllll+ distance range and various signals, and Fig. 13 is a diagram showing the relationship between the fllll+ distance range and various signals.
Figure 14 is a waveform diagram showing the state where the luminance signal is clipped, and Figure 15 shows the sampling and holding operation of the SH circuit shown in Figure 1 (A) above. Time chart, Figure 16 is a diagram showing the relationship between the ranging range and various signals, Figure 17 is a detailed circuit diagram of the multiplexer and logic circuit shown in Figure 1 (A) above, Figure 18 17 is a time chart showing the operation of each part of the multiplexer shown in FIG. 17, FIG. 19 is a time chart showing various signals when out of focus, and FIG. 20 is a time chart shown in FIG. A circuit diagram showing the details of the synchronous detection circuit shown in FIG. 21, a waveform diagram showing the relationship between the photographing lens movement and the output signal, and FIG. 22 a time chart showing the relationship between in-focus and out-of-focus states. FIG. 23 is a circuit diagram showing an example of the time constant switching circuit shown in FIG. 1(B), FIG. 24 is a circuit diagram showing another example of the time constant switching circuit, and FIG. , -1-2 A circuit diagram showing an example of a comparison circuit that is reduced in FIG. -2 A circuit diagram showing a modification of the first or second signal processing circuit that is smaller than that shown in FIG. The figure is a circuit diagram showing a part of the envelope detection circuit shown in FIG. 27 above, FIG. 30 is a waveform diagram showing the operation of the peak value detection circuit shown in FIG. 27 above, and FIG. FIG. 32 is a circuit diagram showing another modification of the first or second signal processing circuit shown in FIG. 1(A). 100...Imaging circuit 200...Synchronizing signal generator 300...First signal processing circuit-55=400...Second signal processing circuit 500...Control means ¥]2El Force 3 and 8' Le 5■ HSP3"'LL Misakiji""""" 7th Garden 11 Danmetsu 1F ["Hao 12 ■ T3 10 Flash ← Φ1 Φ2 Φ3Φ4Φ5 Φ6Φ70 - ~
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Claims (1)

[Scope of Claims] An automatic focusing device that detects a focus state based on a modulation component of an imaging signal when modulating an optical path length of an imaging optical system and brings the optical path length into a focused state, comprising: a first signal processing circuit that extracts modulation components of an imaging signal corresponding to a first range set horizontally in a strip shape in a plurality of frequency bands and synthesizes the extracted signals; a second signal processing circuit that extracts modulation components of the imaging signal corresponding to a second range set vertically in the image in a band shape in a plurality of frequency bands and synthesizes the respective extracted signals; An automatic focusing device comprising: control means for controlling the optical path length to a focused state based on the outputs of the first and second signal processing circuits.