JP2644736B2 - Auto focus device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus apparatus based on a video signal used in, for example, a video camera, and more particularly, to a photographic lens system provided with a means for changing an optical path length. Auto-focusing device that determines the in-focus state and the in-focus direction of the video from the phase of the video signal obtained through the camera and the phase of the changing means, and moves the focusing lens of the photographing lens system to the in-focus position It is about.

2. Description of the Related Art It is well known that a high frequency component of a video signal obtained by a video camera or the like increases as an image comes closer to a focused state and becomes maximum during the focused state.

In addition, when the lens that can change the optical path length of the photographing lens system is finely moved in the front-back direction of the optical axis with reference to a predetermined position, if the high-frequency component increases, there is a focus position in the moving direction at that time,
Conversely, it is also known that if the distance decreases, the focus position is located in the direction opposite to the moving direction at that time, and the so-called focus direction can be detected. It goes without saying that even if the lens is slightly moved in any direction with respect to the optical axis, if the high-frequency component is reduced, it can be detected that the lens is already at the in-focus position.

Therefore, a means for changing the optical path length of the photographing lens system is provided, the high-frequency component of the video signal obtained via the optical path length changing means is peak-held for each screen, and the peak-held signal is referred to as the changing means. A control signal is formed through a band-pass filter having the same frequency, the focusing direction is determined based on the phase of the control signal, and when the amplitude of the control signal is lost, it is determined that the camera is in a focused state. Can be moved to the in-focus position.

For example, Japanese Patent Application Laid-Open No. 56-116007 discloses that a focusing lens is vibrated by a DC reversible motor and an oscillation circuit to change an optical path length, and a video signal obtained through the vibrating focusing lens. An automatic focus control device that determines a focus state by moving the focus lens to a focus position is disclosed.

JP-A-59-201237 discloses an optical lens fine-movement device in which a lens capable of changing the optical path length is provided in a taking lens system and the lens is finely moved by using a piezoelectric element. It shows that it can be used for an autofocus device, as well.

Problems to be Solved by the Invention As described above, various auto-focusing devices that vary the optical path length of a photographic lens system and determine the focus state based on the state of a video signal at that time have been proposed, including means for varying the optical path length. However, in practical use, the following points must be considered.

First, in a video camera or the like, an image cannot be disturbed during imaging, and when the optical path length is varied for a focusing operation, the amplitude does not affect the image and is used to determine a focused state. The amplitude must be such that the required signal is obtained, and therefore its maximum amplitude is limited by the permissible circle of confusion of the taking lens system. On the other hand, the permissible circle of confusion varies depending on the aperture and focal length of the photographing lens system. As a result, it is necessary to consider that the variable amplitude of the optical path length of the photographing lens system must be controlled in a very large range and finely. There is.

In addition, lightweight and small size are strongly demanded as important performances of current video cameras and the like, and it is necessary to consider such a point. In other words, if an autofocus device using a variable optical path length is configured to be heavy and large in size, practical application becomes difficult even if the autofocus performance is improved.

Taking the above points into consideration, the conventional device described above shows that the device disclosed in Japanese Patent Application Laid-Open No. 56-116007 uses a DC reversible motor as a motor, so that the torque transmission characteristics and Considering the rotational inertia or the magnitude of the load on the lens system, there is a problem that it is extremely difficult to finely control the variable amplitude of the optical path length, that is, the movement amount of the lens system over a wide range.

Further, with respect to the optical system lens fine-moving device disclosed in Japanese Patent Application Laid-Open No. Sho 59-201237, the variable amplitude of the optical path length of the taking lens system can be finely controlled by using it. It is supposed to be added to the system, and there is still a problem in practical use in terms of weight, dimensions, and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an autofocus device using a variable optical path length of a photographic lens system that can solve the above problems.

Means for Solving the Problems An autofocus apparatus according to the present invention includes a pulse motor which is connected to a focusing lens of a taking lens system and serves as a driving source for driving the focusing lens in the optical axis direction; A high-frequency component is extracted from a video signal obtained through the system, and a high-frequency component detection unit that peak-holds and outputs as a high-frequency component amount and receives an output of the detection unit and operates to detect fluctuations and fluctuation states of the high-frequency component. A focus state determination means comprising a control signal output unit for independently outputting a vibration control signal, a stop control signal, or a vibration movement control signal, and outputting a focus direction signal; By rotating the pulse motor forward and backward with the same number of steps based on aperture value information indicating the current aperture value of the lens system, the focusing lens A vibration signal for vibrating at a vibration amplitude that causes a blur state is output, and a vibration movement signal for rotating the pulse motor forward and backward with a different number of steps in consideration of the focusing direction signal in response to the vibration movement control signal is output. And a drive control circuit for the pulse motor for stopping the output of the vibration signal and the vibration movement signal in response to the stop control signal, and driving the pulse motor based on the vibration signal or the vibration movement signal to perform the focusing. And a pulse motor drive control means comprising a drive circuit for the pulse motor for vibrating or moving the lens in the focusing direction.

Since the autofocus device according to the present invention is based on the above-described configuration, the focusing lens of the photographing lens system is controlled by the drive control circuit based on the diaphragm value information indicating the current diaphragm value of the photographing lens system. Amplitude determined by the above-mentioned vibration signal by forward / reverse rotation of the pulse motor by a vibration signal which is a forward / reverse rotation pulse signal of the same number of steps output to vibrate the focusing lens with a vibration amplitude that causes a predetermined blur state , Vibrates in the direction of the optical axis at intervals, and the optical path length is varied to determine the focus state. In addition, the pulse motor and the forward / reverse rotation by a vibration movement signal composed of different numbers of forward / reverse rotation pulses output by the drive control circuit Moves while oscillating in the optical axis direction based on the difference in the number of forward and reverse rotation pulses of the vibration movement signal, and moves to the in-focus position while varying the optical path length for determining the in-focus state Will be performed.

Embodiment FIG. 1 is a schematic configuration diagram including a partial schematic cross-sectional view showing an embodiment of an autofocus device according to the present invention, and its operation will be described below.

Now, the image obtained via the photographing lens system 1 changes, for example, when the subject moves while focusing is obtained.
In other words, if blurred, such a change can be detected as a change in the high-frequency component of the video signal in the imaging unit 8, so that the focus state determination unit 9 outputs a vibration control signal and supplies it to the pulse motor drive control unit 10.

The means 10 receives the vibration control signal and operates to rotate the pulse motor 5 forward and reverse with the same number of forward and reverse rotation pulses. The forward and reverse rotation driving force of the pulse motor 5 is controlled by a belt provided on its output shaft 5a. The focusing lens 2 supports the focusing lens 2 via the pulley 6, the belt 7, and the belt receiving portion 3b, and has a screw portion 3a screwed with the screw portion 4a of the fixed lens frame 4, and is movable in the optical axis direction. This is transmitted to the lens frame 3. Therefore, the focusing lens 2 moves back and forth in the optical axis direction, that is, vibrates.

When the focusing lens 2 vibrates, the video signal output from the imaging unit 8 also fluctuates, and the means 9 detects the increase or decrease in the high-frequency component of the video signal, thereby detecting the focusing direction with respect to the previous change in coupling. This means that the means 9 outputs a vibration movement control signal in consideration of the focusing direction and supplies it to the means 10.

The means 10 receives the vibration movement control signal and operates to rotate the pulse motor 5 forward and backward with different numbers of forward and reverse rotation pulses. As a result, the focusing lens 2 is determined by the larger number of pulses. It moves while oscillating in the direction shown. It is needless to say that the moving direction is the focusing direction with respect to the previous change in the image formation.

When the focusing lens 2 moves and reaches a focus position corresponding to the previous change in the image formation, the means 9 detects the above state from the state of the high frequency component based on the vibration of the focusing lens 2 and performs stop control. A signal is output and supplied to the next stage means 10.

The means 10 receives the stop control signal and operates to stop the generation of the forward / reverse rotation pulse for driving the pulse motor 5. As a result, the focusing lens 2 stops moving, and the focusing position Will be located.

The embodiment of the auto-focusing device according to the present invention has been briefly described above. Next, FIG.
Specific examples of both means shown in 10 will be described.

FIG. 2 is a block diagram showing a specific example of the two means 9 and 10, in which the same reference numerals as those in FIG. 1 denote the same components, and FIG. 3 is a signal waveform diagram of FIG.

The operation will be described below, but before that, the setting contents of the amplitude and cycle in the vibration amplitude setting means and the vibration cycle setting means indicated by reference numerals 23 and 24 in FIG. 2 will be described.

First, the vibration amplitude is set in the means 23. This vibration operation is performed in order to change the optical path length of the photographing lens system and to detect the in-focus state. However, during such operation, the blur of the image cannot be confirmed with the naked eye. It is desired.

Therefore, the amplitude of the vibration operation must be set within the depth of focus of the taking lens system. That is, when the vibration operation is performed with an amplitude equal to or greater than the depth of focus, a change in the image formation state can be confirmed with the naked eye, which is nothing but a screen disturbance.

On the other hand, the depth of focus A of the photographing lens system is expressed as A = 2 · F · d where F is the aperture value of the lens system and d is the permissible circle of confusion.

That is, the depth of focus A is proportional to the aperture value F, so that the amount of movement of the focusing lens from the in-focus position where a certain blur state occurs varies according to the aperture value F.

Therefore, in order to perform the variable optical path length of the photographing lens system and to stably determine the in-focus state at a constant blur state at all times,
That is, it is necessary to change the amount of movement of the focusing lens, that is, the vibration amplitude in accordance with the aperture value F.

In other words, the vibration amplitude W for an arbitrary aperture value F is
R = kF (k: constant). For example, now,
Assuming that the open aperture value F ₀ is 1.2 and that any vibration amplitude W _1.2 within the depth of field at this time is a reference, k in the above equation is k = W / F = W _1.2 / F ₀ = The vibration amplitude W is 1 / 1.2, so that the same blur state can be obtained when the aperture value F is 5.6.
_5.6 is W _5.6 = K · F = 1.2 × 5.6 = 4.5. Similarly, when the aperture value F is 22, the amplitude W ₂₂ is W ₂₂ = kF = 1 / 1.2 × 22 = 18.

That is, the vibration amplitude W of the focusing lens for an arbitrary aperture value F can be set by the calculation of W = F / F ₀ if the data at the open aperture value F ₀ is stored as a reference. Means 23 in the example also performs the above calculations.

In this embodiment, the vibration amplitude W corresponds to the number of driving steps since the focusing lens is driven by the pulse motor, and therefore the integer must be set. It is configured to output the result of the calculation as a vibration amplitude signal by truncating the decimal part.

 Next, the setting of the oscillation period in the means 24 will be described.

Now, the oscillation period of the focusing lens is t ₀ , the frame synchronization of the video signal is t ₁ , and the shortest period of the driving pulse for driving the pulse motor required to operate the focusing lens stably without misstep is If it is assumed that t ₂ and one vibration operation is performed on two screens, that is, assuming that t ₀ = 2 · t ₁ , the vibration amplitude W is limited to W ≦ t ₁ / t _2. become.

For example, in the case of the NTSC system of the period, one frame period t ₁ of a video signal is t ₁ = 1/30 (second), and if t ₂ is 3 milliseconds, t ₁ / t ₂ ≒ 11, and two screens are obtained. Only a maximum of 22 drive pulses can be supplied in some cases, so the vibration amplitude W in this case is
Is limited to a maximum of 11 when considered in terms of drive pulses, that is, W ≦ 11.

As a result, when the aperture value F which can be set from the limitation of the vibration amplitude W in the photographing lens system in which the above-mentioned open aperture value F ₀ is 1.2 is calculated backward, from the equation of W = F / F ₀ , F = W × F ₀
= 11 × 1.2 ≒ 13, and if the vibration operation is limited to once for two screens as described above, it will not be possible to cope with an aperture value F larger than F = 13.

Therefore, in the embodiment shown in FIG.
24 performs the following calculation to lengthen the oscillation period t ₀ of the previous constitute the above t ₀ to variably set.

That is, the means 24 first selects a positive integer a that satisfies the conditional expression (a-1) t ₁ <Wt ₂ ≦ a · t ₁ , and then sets the vibration period t ₀ to t ₀ = 2 · a · It operates to set as t _1.

Therefore, considering an example of the above-described photographing lens system,
The vibration period t ₀ is set as shown in the following table based on the relationship between the vibration amplitude W and the integer a.

As described above, in the embodiment shown in FIG. 2 are set vibration amplitude W and the oscillation period t _0.

Now, while the operation of the embodiment shown in FIG. 2 is being performed, if the subject changes during focusing, the high-frequency component extraction circuit 11 that extracts the high-frequency component from the video signal, the high-frequency component in a desired range in the screen, The gate circuit 12 which allows only the output of the vertical gate signal generation circuit 13 and the horizontal gate signal generation circuit 14 to pass through, and supplies the supplied high frequency component to one screen, for example.
The output of the circuit 15 in the high frequency component detection unit 16 composed of a peak hold circuit 15 for peak hold changes,
First, the subject change detection means 20 of the control signal output unit 22 operates.

The control signal output unit 22 includes a difference circuit 17 that detects a difference between the outputs of the circuit 15, an optical path length variable frequency component detection circuit 18 that detects only the output of the circuit 17 corresponding to the previous oscillation cycle,
A focus state is determined based on an output of the circuit 15 and an output of the circuit 17 via the circuit 18, and a change in a focus state signal indicating whether or not focus is achieved and a change in a high-frequency component are increased. Focus determination means 19 for detecting the direction of movement of the focusing lens and outputting it as a focus direction signal, and a circuit 15 for determining that focus has been achieved.
The subject change detecting means 20, which compares the stored value with the current output of the circuit 15 and outputs a signal indicating the necessity of the focusing operation at the time of inconsistency, the signal output by the means 19, 20 The operation state control means 21 receives the signal and outputs a control signal such as the above-described vibration control signal based on the signal.

Accordingly, the operation state control means 21 outputs a vibration control signal in order to perform the determination of the in-focus state with respect to the change in the object by changing the optical path length of the photographing lens system by the operation of the object change detection means 20, and the pulse motor It is supplied to the drive control means 10.

The means 10 is a means 24 in addition to the means 23 and 24 described above.
The vibration starting means 25 which receives the output from the control circuit 31 and outputs a start signal for starting driving in the next vibration direction in response to an end signal indicating the end of driving in the previous vibration direction from the comparison circuit 31 described later, A pulse generating circuit 26 that receives a start signal and generates a drive pulse signal for driving a pulse motor of a predetermined cycle until the end signal is received, a rotation direction signal of a pulse motor that is inverted every time the start signal is received, that is, a focusing lens The vibration direction setting means 27 which outputs the driving direction signal of the above is provided.

Further, the pulse motor drive control means 10 is
A comparison circuit 28 that compares the direction signal from 27 with the direction signal indicating the focusing direction output by the operation state control unit 21 receiving the output from the focus determination unit 19, and the vibration amplitude setting unit 23 Pulse number setting means 29 for setting a specific pulse number n for driving the urus motor in consideration of the output of the comparator 28 and the comparison result of the comparison circuit 28, and counting the number of drive pulse signals output from the previous pulse generation circuit 26. The number of pulses 30 to be set, the number of pulses n set by the means 29
The comparison circuit 31 compares the count value of 0 with the count value of 0, outputs a termination signal for stopping the driving of the current pulse motor, and supplies the end signal to the vibration starting means 25 and the pulse generation circuit 26 as described above. Pulse signal from and means 27
And a driving circuit 32 that receives the direction signal from the controller and drives the pulse motor 5 based on the two signals.

Note that the pulse number n in the pulse number setting means 29 described above.
For example, when the focusing lens is simply vibrated based on the above-described vibration control signal, the number of drive pulses X of the pulse motor required to realize the amplitude set by the vibration amplitude setting means 23 is set to the above-mentioned means 23. When the focusing lens is moved in the focusing direction based on the vibration signal and the setting and output based on the amplitude signal from the controller, the comparison circuit of the comparison circuit 28 is taken into consideration. If the set direction of 27 is the in-focus direction, a number obtained by adding the predetermined number m to the above-described number X is set and output as n, and if the direction is out of focus, the predetermined number m is subtracted from the above-described number X. It operates to set and output the number as n.

Thus, the unit 10 by the vibration control signal from the operating state controlling means 21 starts operating from any point T _1, severally vibration amplitude at means 23, 24, 29 described above, to realize the oscillation period and amplitude Drive pulse number n is set.

If the vibration cycle is made to vibrate once every two screens, the periodic signal becomes as shown in FIG. 3C with respect to the vertical synchronization signal and the field signal shown in FIGS. 3A and 3B.

On the other hand, simultaneously with the above setting, the vibration starting means 25 outputs one starting signal in two fields as shown in FIG. 3 (d) in response to the field signal in consideration of the above cycle.
In FIG. 3 (d), the starting signal phase is made coincident with the field signal phase. However, if the starting signal is output at a cycle in consideration of the above-mentioned set cycle, the above-mentioned phase matching is not necessary. .

Thus, the pulse generating circuit 26, the vibration direction setting means 27 starts its operation from time T _1, respectively, Figure 3 (e), and outputs a drive pulse signal and the arbitrary direction signal shown in (f) It is supplied to the drive circuit 32.

The circuit 32 drives the pulse motor 5 based on the vibrations shown in FIGS. 3 (e) and 3 (f).
It moves in the direction determined by the direction signal output from the means 27 as shown in FIG.

Here, assuming that the number of pulses X capable of realizing the set amplitude by the means 23 is five, the circuit 29 sets and outputs n = 5 in the case where the vibration control signal is supplied, The circuit 31 for comparing the pulse number n with the count value of the counter 30 outputs a third signal when the count value reaches 5.
The end signal shown in FIG.

The end signal is supplied to the vibration starting means 25 and the pulse generating circuit 26 to stop the respective operations. Therefore, as shown in FIG. No output is made, and the movement of the focusing lens stops at this point, and at the same time, the means 25 is set to a state where it has detected that the movement of the focusing lens this time has ended.

When the focusing lens moves as described above, the imaging state changes as a matter of course.
FIG. 3 (i) formed once for example on one screen by means of 12
The high-frequency component is detected by peak-holding as shown in FIG. 3 (j) in the peak hold circuit 15 based on such a gate signal.

In this state Figure 3 (d) to indicate activation signal is time T ₂
When the signal is again output from the means 25, the pulse generation circuit
26 outputs a pulse signal, and the vibration direction setting means 27 outputs a direction signal in a direction opposite to the previous case, as shown in FIGS. 3 (e) and 3 (f).

At this time the start signal is the comparison result of the comparison circuit 31 to perform a reset of the counter 30 becomes mismatched, thus end signal from the circuit 31 will be output in the time T ₂ is stopped.

Accordingly, the pulse motor 5 is driven at time T ₂ after the opposite direction, Figure 3 also lens focusing in the previous as shown in the time T ₂ after the opposite directions from the circuit 26 five of the (g) The driving pulse signal is output and the circuit 31 moves until the next end signal is output from the circuit 31, and the peak hold of the high-frequency component by the circuit 15 during the reverse movement is also performed as shown in FIG. 3 (j). .

When the focusing lens is moved in a different direction, that is, vibrated, as described above, the focus determination unit 19 determines the focus state based on the output of the differential rotation 17 or the like. Needless to say, the number of vibrations of the focusing lens can be appropriately set in consideration of the focus determination accuracy and the like. In consideration of the above operation, the pulse generation circuit 26 supplied to the drive circuit 32
And the direction signal from the vibration direction setting circuit 27 can be regarded as a vibration signal for vibrating the focusing lens.

As a result of the determination by the focus determination means 19, when the focus lens needs to be moved, the means 19 outputs a signal indicating the required movement direction of the focus lens and supplies the signal to the next-stage means 21.

The operation state control means 21 receives the signal from the focus determination means 19, and outputs a vibration movement control signal this time to output the vibration amplitude setting means 23.
And outputs the required moving direction to the comparison circuit 28 as the focusing direction.

Accordingly, it means 23,24,25,27 and circuit 26 starts from the time T ₃ the same operation as described above. That is, the signals shown in FIGS.
Is driven, and the focusing lens starts moving as shown in FIG. 3 (g).

On the other hand, the number-of-pulses setting means 29 is a means for setting the number of pulses n, which is the operation of the comparison circuit 28, since the operation state control means 21 outputs the vibration movement control signal this time.
Control is performed based on a comparison result between the focusing direction signal from 21 and 27 and the driving direction signal.

That is, based on the coincidence and non-coincidence of the two signals, the pulse number X corresponding to the set vibration amplitude is adjusted by a predetermined number m to set the above n. The addition and subtraction are subtracted when the two signals are coincident and the driving direction of the focusing lens is in the focusing direction when the two signals coincide.

Now, the direction to start movement at t ₃ coincides with the focus direction, similarly in the previous case, when the number X and the predetermined number m corresponding to the set amplitude and respectively 5,1, setting pulse number setting means 29 The number of pulses n to be performed becomes n = X + m = 5 + 1 = 6, and the comparison circuit 31 outputs an end signal when the six driving pulses are output by the pulse generation circuit 26 as shown in FIG. Then, the movement of the focusing lens is stopped.

Then, when a signal for reversing the direction of vibration activating unit 25 from the vibration period setting section 24 at the time T ₄ is output, the means 25 outputs the activation signal, each means described above from the point in time T _4, The circuit resumes operation, and the focusing lens starts to move in the opposite direction to the above case, as shown in FIG. 3 (g).

However, in this case, the comparison result by the comparison circuit 28 does not match, and the pulse n set by the pulse number setting means 29
Is n = X−m = 5-1 = 4, and the pulse generation circuit 26
When four drive pulses are generated, the circuit 31 outputs an end signal, at which point the movement of the focusing lens stops.

On the other hand, even during the above-described operation, the detection unit 16 operates, and the high-frequency component is peak-held as shown in FIG.
Means 19 also operates continuously.

As a result, the means 21 outputs the vibration movement signal until the focus determination means 19 determines that the focus is achieved, and the above operation is continued.

At this time, the focusing lens moves in the focusing direction by the difference of the number of pulse signals in the focusing direction within the previously set vibration cycle. In other words, the difference is the focusing lens in the present embodiment. It corresponds to the moving speed of. Further, in the above case, a different number of drive pulse signals from the pulse generation circuit 26 supplied to the drive circuit 32 and the vibration direction setting means 27
Can be regarded as a vibration moving signal for vibrating the focusing lens.

In the above example, m that forms the difference is set to 1 as a predetermined number. However, for example, focusing of the focusing lens is performed based on the change characteristic of the high-frequency component peak-held by the focusing determination unit 19 and the like. It is also determined whether or not the movement in the focus direction is significantly required, and a signal corresponding to the determination result is output from the operation state control means 21 as indicated by a broken line in FIG. It is needless to say that the speed of movement of the focusing lens in the focusing direction may be appropriately controlled so as to be variously changed by supplying it to the focusing lens 29.

When the focusing lens moves and reaches the in-focus position by the operation described above, the pulse number setting means 19 detects the above state by the output of the peak hold circuit 15 and the like, and stops at the operation state control means 21. It operates to output a control signal.

The vibration amplitude setting means 23 receives the stop control signal and operates to set the number of pulses n in the pulse number setting means 29 to n = 0, so that the comparison circuit 28 receives the start signal and resets the counter 30 at the same time. Output an end signal
The operation of the pulse number generation circuit 26 is stopped, and as a result, the focusing lens is moved to the in-focus position without moving.

In the case where the moving speed of the focusing lens is varied as shown by the broken line in FIG.
If a signal indicating m = 0 is output at the same time when the stop control signal is output at 21, the focusing lens can be similarly stopped at the in-focus position.

As described above, a series of focusing operations in one embodiment of the autofocus apparatus according to the present invention is completed. In such an embodiment, the optical path length is changed by the vibration of the focusing lens, and the focusing is performed by the vibration. The movement in the direction is performed, and the vibration operation and the movement operation in the focusing direction are performed using a single pulse motor as a drive source.

FIG. 4 is a block diagram showing another embodiment of the autofocusing device according to the present invention, and particularly showing another embodiment of the focus state judging means 9 and the pulse motor drive control means 10 in the previous embodiment.

In this embodiment, the vibration amplitude W set based on the above-described calculation of F / F ₀ changes the frame cycle of the video signal to t ₁ ,
Assuming that the shortest cycle of the drive pulse capable of accurately driving the pulse motor is t ₂ , when W> t ₁ / t ₂ , the previous embodiment increases the oscillation cycle t ₀ , that is, always vibrates. While the operation is performed to move the focusing lens to the in-focus position, the vibration and the vibration moving operation are stopped, and the well-known mountain climbing autofocus operation is performed.

 Hereinafter, the embodiment of FIG. 4 will be described.

In the figure, the same reference numerals as those in FIG. 2 denote the same functional components, and reference numeral 21 'denotes a function equivalent to the operation state control means 21 described in FIG. oscillation amplitude W of indicates the operating state controlling means for controlling operation of outputting a movement control signal receives a signal indicating when the W> t ₁ / t _2.

23 'in addition to functions equivalent to those of the vibration amplitude setting means 23 described in Figure 2, the vibration amplitude W computed set, W> when t ₁ / t _2, the order to stop the vibration of the focusing lens A vibration amplitude setting means for outputting a signal of W = 0 indicating the state and supplying the signal to the means 21 ', the pulse number setting means 29 in the subsequent stage, and the changeover switch 34 described later.

24 'when the cycle of the oscillation operation unlike W> distinguishes the case of t ₁ / t _2, i.e., the previous example as described above in this embodiment not being limited to once every two screens Therefore, the vibration cycle setting means only serves as a timing means for outputting a start signal to the vibration start means 25 once per screen in response to a field signal. Note that the output time point of the start-up signal by the vibration start-up means 25 does not need to be synchronized with the time point at which the field signal is output, that is, it can be set appropriately in response to the field signal.

Numeral 34 denotes a changeover switch for transmitting the driving direction signal from the vibration direction setting means 27 or the focusing direction signal from the means 21 'to the comparison circuit 28, and W = 0 from the means 23'.
The comparison circuit compares the focusing direction signal when a signal indicating
Switched to transmit to 28. That is, when W = 0,
The comparison circuit 28 compares the focusing direction signals with each other,
A signal indicating a match is always output. The optical path length variable frequency component detection circuit 18 stops its operation upon receiving the signal indicating W> t ₁ / t ₂ , that is, supplies the output of the difference circuit 17 to the focus determination means 19 as it is. Controlled.

 Hereinafter, the operation of the example shown in FIG. 4 will be described.

The subject changes during focusing and the operation state control means 21 '
Outputs the vibration control signal, and the next stage vibration amplitude setting means 23 'performs the operation of setting the vibration amplitude W in the same manner as in the example of FIG.

Now, when the vibration amplitude W set by the vibration amplitude setting means 23 'satisfies W ≦ t ₁ / t ₂ , the changeover switch 34
Is switched to transmit the driving direction signal output from the vibration direction setting means 27 to the comparison circuit 28 and the driving circuit 32 of the pulse motor.

Therefore, the configuration shown in FIG. 4 is substantially the same as the configuration shown in FIG. 2 except that the vibration cycle setting means 24 'is different. However, the means 24 'from the work to be output once activation signal on one screen as described earlier, the embodiment shown in FIG. 4 in the case of such a W ≦ t ₁ / t ₂ The operation of the device is the same as the example shown in FIG.
That is, the operation is to vibrate the focusing lens and further to vibrate to the in-focus position.

On the other hand, the vibration amplitude setting means 23 'has been set vibration amplitude W by the, W> when a t ₁ / t _2, the means 23' W
= 0, so that the operating state control means 21 '
Operates so as to output a movement control signal in place of the previous vibration control signal, and the changeover switch 34 transmits the focusing direction signal output by the means 21 'to the comparison circuit 28 and the pulse motor drive circuit 32. Is switched to At the same time, the number-of-pulses setting means 29 sets the number n of driving pulses determined based on X as n = m since W = 0 and X = 0 as described above.

Therefore, when the vibration cycle setting means 24 'operates in response to the field signal and a start signal is output from the vibration start means 25, the pulse generation circuit 26 generates a drive pulse signal and the drive circuit 32 of the pulse motor 5 Receives the drive pulse and the focusing direction signal from the operating state control means 21 ', the pulse motor 5 is driven, and the focusing lens outputs the focusing direction signal output from the means 21'. Start moving to.

At the same time, the counter 30 counts the number of driving pulses, and
As in the example shown in the figure, the comparison circuit 31 compares the count value of the counter 30 with the number n of pulses set by the pulse number setting means 29, and outputs an end signal when they match, and at this time the pulse number generation circuit
The operation of 26 is stopped, and the movement of the focusing lens is also stopped.

Thereafter, if the focusing direction signal from the operation state control unit 21 'is accurate, the above-described operation is repeated every time a start signal is output from the vibration start unit 25 by the operation of the vibration cycle setting unit 24'. That is, the focusing lens moves only in the direction based on the focusing direction signal.

Here, when considering the focusing direction signal from the means 21 ', when the movement is started, it is a state in which only a change in the subject has been detected since the focusing, and it is not accurate.
Naturally, a situation arises that must be reversed.

As for this reverse rotation, as described in the previous example, if the focusing lens moves, the output of the peak hold circuit 15 changes, and the focusing state is determined by the means 19 based on the change and the like. If the above-described movement operation of the focusing lens is performed any number of times, an accurate focusing direction signal can be obtained,
That is, if the high-frequency component increases in the above-described movement operation, the direction remains unchanged, and if the high-frequency component decreases, the signal indicating the reverse direction becomes the focusing direction signal. Since the output can be performed by the operation, the output is automatically performed. In other words, the focus direction signal output from the operation state control means 21 'is supplied to the drive circuit 32 of the pulse motor via the changeover switch 34, and if the focus direction signal changes in the opposite direction, it is natural that The focusing lens also moves in the opposite direction. Note that the output state of the comparison circuit 28 does not change even if the moving direction is reversed, and the number n of pulses set by the pulse number setting means 29 does not change at all.

As described above, the focusing lens moves in the accurate focusing direction, and when the focusing lens is reached, the focusing determination unit 19 detects the state by the output of the peak hold circuit 15 and the like,
The operation state control means 21 'outputs a stop control signal.

Therefore, the vibration amplitude setting means 23 'controls the operation of the pulse number setting means 29 as in the previous example, that is, the means 29 sets the X =
The predetermined number m added to 0 is also set as m = 0, and as a result,
The set pulse number n becomes n = X + m = 0 + 0 = 0, the comparison circuit 31 immediately outputs an end signal, the pulse motor 5 is not driven, and the focusing lens is stopped at the focusing position. Become.

The example shown in FIG. 4 operates as described above, ie,
When the setting of the vibration amplitude W in the means 23 ′ is W ≦ t ₁ / t ₂ , the same operation as in the example of FIG. 2 is performed, and when W> t ₁ / t ₂ , the well-known mountain climbing autofocus operation is performed. It does.

In order to set the pulse number n in the pulse number setting means 29, the vibration amplitude W set by the means 23 'is W ≦ t ₁ / t ₂
In the case of, the number of pulses X for realizing the above W is added or subtracted, and W>
When t ₁ / t _2, the number becomes the set number of pulses n itself m
Is set to a predetermined number m in the above-described example, so that the moving speed of the focusing lens is controlled to be constant.
At 19, it is also determined whether or not the focusing lens needs to be largely moved in the focusing direction together with whether or not it is in focus, and a signal according to the determination result is indicated by a broken line. It is needless to say that the number can be variably set to various numbers by outputting from the operating state control means 21 'and supplying it to the pulse number setting means 29, that is, the moving speed of the focusing lens can be appropriately controlled.
In this case, it goes without saying that the operation control means 21 'simultaneously outputs a signal indicating m = 0 to the pulse number setting means 29 when outputting the stop control signal.

Further, in the example of FIG. 4, when W> t ₁ / t ₂ , the climbing autofocus operation is performed, but the vibration amplitude set by the vibration amplitude setting means 23 ′ is shown by a broken line in FIG. As in the embodiment shown in FIG. 2, the vibration period setting means 24 'is supplied to this means so that this means 24' can perform the same function as the example shown in FIG. 2, and the control means 35 operates. The condition for causing the state control means 21 to output the movement control signal is W> 2t ₁ / t ₂
Alternatively, by setting W> 3t ₁ / t ₂ , it is needless to say that the vibration amplitude condition for performing the well-known mountain climbing autofocus operation can be appropriately set.

Lastly, the transmission means which comprises the belt pulley 6, the belt 7 and the like and transmits the driving force of the pulse motor 5 to the focusing lens 1 in the above-described embodiment will be described in detail.

In the present invention, the relationship between the focusing lens 1 and the pulse motor 5 is such that if the pulse motor 5 is driven by one step, the focusing lens 1 always needs to be moved and moved by one step. The driving force of the motor 5 needs to be accurately supplied to the focusing lens 1.

On the other hand, the autofocus device according to the present invention aims at miniaturizing the shape of the device, and the pulse motor 5 is a driving source that is used for both the vibration operation of the focusing lens 1 in the optical axis direction and the movement operation to the focusing position. It is desirable to employ a small-sized one.

Furthermore, in order to improve the accuracy of the determination of the in-focus state, for example, in order to realize the vibration operation of the in-focus lens once per two screens, the pulse motor 5 is driven at a high speed. That is, the cycle of the drive pulse supplied for one-step drive in a small pulse motor is usually several tens of meters.
sec is a rating, and as described above, driving at a drive pulse cycle of, for example, 3 msec is a very high-speed driving.

In general, the driving force obtained from the pulse motor becomes smaller as the shape is reduced and the driving pulse period is shortened. In the driving force transmission configuration using a well-known gear configuration, the driving pulse is supplied depending on the load. Even so, there is a possibility that a so-called misstep in which the pulse motor is not accurately driven may occur.

This will be described with reference to FIGS. 5 and 6.

FIG. 5 is a schematic diagram of a pulse motor known per se, and it goes without saying that the rotation of the rotor R is controlled by controlling the power supply to the coils L ₁ and L ₂ .

FIGS. 6 (a) to 6 (e) show a fifth embodiment through a well-known gear configuration.
FIG. 7 is an operation state diagram when the driving force of the pulse motor as shown in the figure is transmitted to the focusing lens, and FIG. 7A is a waveform diagram of the driving pulse corresponding to FIG. FIGS. 4B and 4C show the coils L ₁ and L 2 in response to the drive pulse.
₂ shows a waveform diagram of a drive voltage supplied to _2. FIG.

FIG. 6D is a characteristic diagram of the driving force supplied from the rotor R of the pulse motor to the focusing lens, and FIG. 6E is a moving characteristic diagram of the focusing lens moving based on the driving force. It is.

Sixth, as shown in Figure (a), the coil L ₁ when the drive pulse is generated at time S _1, the relative L ₂ FIG. (B),
The drive voltage shown in (c) is supplied, and the rotor R generates a drive force with rising characteristics determined by the impedance of the coils L ₁ and L ₂ from the time point S ₁ . This driving force is directly transmitted to the focusing lens without delay because of the use of a well-known gear configuration, and becomes the driving force as shown in FIG. 6 (d).

However, as described above, this driving force decreases when the apparatus shape is reduced, so that the focusing lens does not start moving upon receiving the driving force, that is, the rotor R is driven. Although it generates a force, it does not start rotating, and when viewed microscopically immediately after the driving force is transmitted to the focusing lens, the focusing lens becomes slower in a very slow speed range. began finely with or faster, to start a substantial movement at a time point S ₂ became more than a certain value the speed becomes gradually faster rate, in other words the focusing lens is very small in itself Due to the fluctuation of the frictional load caused by the movement, the load state becomes an intermediate state between the static friction and the kinetic friction, and the operation is performed so as to completely shift to the kinetic friction through this state, and the shift is shown in FIG. 6 (e). With inertial load and so on It will be performed to move in either smooth function determined by the friction load. Incidentally, it is needless to say that the rotation of the rotor R rises at the point S _2.

When the rotor R when S ₃ reaches the normal stop position of one step driving force of the rotor R caused by magnetic force polarity is reversed, the reversal driving force would brake the lens focus.

On the other hand, the focusing lens receives continues to show the driving force supplied by the time S ₃ also inertia later what the braking is applied to FIG. 6 (d) point S ₃ and later, the driving force by the inertia gone would be controlled by the reverse driving force of the rotor R at time S ₄ has its moving direction at the point S ₄ is first inverted as shown in FIG. 6 (e), the time
It will stop the stop position where the movement amount N of one step of the normal at S _5.

Figure 6 driving voltage drive pulses to be one step rotation of the pulse motor again when S ₆ is supplied when generated in the coil L _1, L ₂ is (b), the polarity is inverted as shown in (c) that is, the direction of the driving force generated with the rotor R becomes equal to the desired direction, thus the focusing lens is the same operation until S ₅ from the previous time point S _1, as shown in Figure No. 6 (e) The movement is performed by the movement amount N for one step, and thereafter, the same operation is repeated every time a drive pulse is output.

The problem here is a period from time S ₁ to S _2, the pulse motor is a lens for focusing to have occurred the driving force does not perform substantial movement as described above, i.e. That is, there is a time when the rotor R is almost stationary on the upper body. As described above, this time is a time influenced by the frictional force, and it is needless to say that the variation greatly increases due to an accidental factor.

Thus, for example, the rising time of substantial movement of the focusing lens is to be caused by S _7, the driving force pulse motor is transmitted to the focusing lens occur are indicated by broken lines in FIG. 6 (d) (E)
As shown by a broken line in FIG. ₇ , the delay indicated by L in the drawing occurs at the next drive pulse generation time S6 as compared with the case described above.

If delay L is about half the step portion of the above point S _6, although the driving force rotor R occurs during inversion of the driving voltage to the coil L _1, L ₂ in the above S ₆ is the direction is the same is about half of the normal, the driving force transmitted to the lens for focusing also become a course approximately half as indicated by the broken line in time S ₆ subsequent FIG. 6 (d), the time S ₆ after the delay L further increases.

As a result, further delay L of the next drive pulse generation time S _8, for example, reaches about one step, the driving force which the rotor R is transmitted to focusing lens generated by inversion of the driving voltage sixth Figure will be that direction is inverted as shown by the broken line in time S ₈ or later (d), the focusing lens is no longer able to move in the desired direction, so-called misstep will occur.

To eliminate missteps as described above, it is conceivable to increase the generation driving force of the pulse motor. For this purpose, shape and size, also longer between point S ₁ to S _2,
That is, it is necessary to lengthen the driving pulse period, and the object of the present invention may not be sufficiently achieved.

In addition, it is possible to increase the relative driving force by reducing the inertial load and the frictional load, but it is technically difficult at present.

Therefore, in the present invention, as a transmission structure, a means including the belt pulley 6, the belt 7 and the like as shown in FIG. 1, that is, a transmission means capable of accumulating and delaying the driving force of the pulse motor and transmitting it to the focusing lens is used. Have applied. Incidentally, the belt 7 in the above embodiment has, for example, a circular shape and is made of a synthetic resin or the like having an elastic force with its elongation in the circumferential direction suppressed, and as shown in a schematic diagram in FIG. A belt whose circumference is longer than the circumference of the belt pulley 6 and the belt receiving portion 3b indicated by a broken line in the drawing can be adopted. Therefore, a restoring force is exerted on the belt 7 so as to always return to the circular shape, and the restoring force can transmit the driving force of the pulse motor to the focusing lens without causing backlash. still,
The belt 7 can be formed of, for example, hard rubber.

Hereinafter, an operation state when the driving force of the pulse motor is transmitted to the focusing lens via the transmission means shown in FIG. 7 will be described with reference to FIGS. 8 (a) to 8 (f). .

In FIGS. 8 (a) to (f), the objects of the waveforms (a) to (e) correspond to the objects of FIGS. 6 (a) to (e), and FIG. The position of the rotor R is shown.

Figure 8 (a) ~ (c) to the drive pulse at time S ₁ is supplied as indicated coil L ₁ of the pulse motor, L ₂ that each drive voltage is supplied to the the previous example The same is true, and the rotor R naturally generates the same driving force.

However, the load of the pulse motor at the time S ₁ is only restoring force to the circular by the elastic force of the rotor R itself and the belt 7, the rise of the rotation of the rotor R Figure 8 (f)
As shown in the above, the point in time through the previous gear configuration
S ₂ becomes earlier performed at S ₉ unlike.

During some time up to the time indicated by S ₁₀ in FIG. 8, for example, from the point S ₉ (f), while working as the rotor R further increases the deflection of the other without deflection one of the belt 7 of, and rate of Is performed, that is, it moves.

The driving force supplied to the focusing lens in between the time S ₉ to S ₁₀ is the center restoring force of the belt 7 described above is, as shown in Figure No. 8 (d) smaller, drawing ( As shown in e), the focusing lens does not substantially move.

When one of the deflection is eliminated almost focusing lens of the belt 7 at the time point S ₁₀ begins to act on the rotor R as a load of the pulse motor, the rotor R consuming braking, the rotor R is 8 ( The speed is reduced as shown in f).

At this time, a large driving force corresponding to the product of the deceleration and the rotating mass of the rotor R is applied to the focusing lens, and the driving force is illustrated in FIG. 8D. Thus, a sharp rising characteristic is formed.

As a result, the focusing lens shifts from the static friction state to the kinetic friction state in the course of the increase in the supplied driving force.
Move to start as shown in the time S ₁₁ and subsequent FIG. (E).

When focusing lens starts moving, when the speed of the rotor R is increased as FIG. 8 (f) point S ₁₁ and later, thus driving force is drawing to be supplied to the lens focus (d) decrease until the driving force regular generated in the rotor R by the magnetic force as S ₁₁ and later.

When the rotor R at S ₁₂ reaches the normal stop position of one step, the driving force generated by a later force reversed, thus the rotor R takes braked by the restoring force of the inverted driving force and the belt 7, the rotor R is reversed at the point S _13, as shown in Figure No. 8 (f), it stops when S ₁₄ in the normal stop position.

On the other hand, the driving force supplied to the lens focus at the point S ₁₂ and later, reduces the influence of inversion driving force of the rotor R as described above, the time S ₁₄ after the rotor R is stopped, the restoring force of the belt 7 As shown in FIG. 8D, the driving force is obtained only by the driving force.

Therefore, the focusing lens moves at a reduced speed,
The deflected state of the belt 7 is Yuki returns to equal a state as shown in FIG. 7, the focusing lens at S ₁₅ will be stopped by moving the moving amount N of one step.

Thereafter, the above operation is repeated by controlling the polarity of the drive voltage supplied to the coils L ₁ and L ₂ every time a drive pulse is generated, and the focusing lens is shown in FIG. 8 (e). It will move like so.

Here, when focusing lens from the drive pulse generation time S ₁ in the above-mentioned operation is started substantial movement S
Time to ₁₁ has a steep rise characteristic point shown in S ₁ after the Figure 8 to be supplied to the lens focus (d), and a large driving force than in the case of transmitting in the previous gear arrangement Therefore, even if the load state of the focusing lens with respect to the pulse motor fluctuates slightly, the above-mentioned time variation becomes small, and therefore, it is extremely advantageous in setting the drive pulse period. Becomes

That is, unlike the transmitting means of the gear arrangement by using a belt pulley 6 or the like, will be able to supply after a delay time a large driving force was more stable than the drive pulse generation time S ₁ steep rise characteristic lens focus As a result, in the case of the above gear configuration, there is a possibility that a misstep may occur due to a variation in the movement start time of the focusing lens, and it is necessary to pay great attention to the setting of the drive pulse period. In the case of the transmission means such as the belt pulley 6, the drive pulse cycle can be set without consideration, and of course the cycle can be shorter than when the transmission means having the gear configuration is used.

From a different point of view, from the viewpoint of supplying the same driving force, the pulse motor can be further reduced in size as compared with the case where the transmission means having a gear configuration is used.

FIGS. 9 (a) and 9 (b) are schematic structural views showing another embodiment of the transmission means for transmitting the driving force of the pulse motor 5 to the focusing lens 2, and have the same reference numerals as the positions in the figure. Indicates the same functional component.

FIG. 9 (a) shows an example in which the inertia load of the focusing lens 2 and the like, which is a load, is reduced so that the pulse motor 5 can be driven at a higher speed.

The focusing lens frame 3 supporting the focusing lens 2
Moving shafts 35 and 36 provided on the main body 1a of the taking lens system 1
End 3c, 3d, 3e into which is inserted, and an end 3f that can rotate at the illustrated position with the moving shaft 36 as a central axis, and is screwed with a drive screw 37 integrally provided with a belt pulley 38,
It slides with respect to the main body 1 '.

The moving shaft 36 is also provided with a locking member 39 for controlling the sliding of the focusing lens frame 3.

The belt pulley 38 includes a pulse motor 5 and its output shaft 5a.
The driving force is transmitted via the belt 7 to rotate when the pulse motor 5 is driven, and of course the drive screw 37 is rotated. .

As a result, the rotational force of the drive screw 37 is supplied to the focusing lens frame 3 via the end 3f screwed with the screw 37, and the focusing lens frame 3, that is, the focusing lens 2 is attached to the main body 1a. On the other hand, it slides in the optical axis direction.

With the above configuration, the inertia load is limited to the rotor of the pulse motor 5, the belt pulleys 6, 38, the belt 7, and the moving shaft 36 on which the drive screw 37 is formed. Since the moving speed of the lens frame 3 is low, it hardly affects the inertial force. Therefore, the rising characteristic of the focusing lens becomes steep correspondingly, so that the pulse motor 5 can be rotated at a higher speed. Become.

FIG. 9 (b) is a partial configuration diagram showing still another embodiment of the transmission means, in which the same reference numerals as those in FIG. 1 and FIG. 9 (a) indicate the same functional components.

In this embodiment, as is clear from the drawings, the focusing lens frame 3 has the end portions 3e and 3g into which the moving shaft 36 provided on the main body 1 'is inserted similarly to the above-described embodiment. The end 3g is further screwed with a drive screw 40 connected to the output shaft 5a of the pulse motor 5 via an elastic joint 41 made of a synthetic rubber pipe or a coil spring or the like.

Therefore, when the pulse motor 5 is driven, its driving force is first transmitted to the joint 41, and the joint 41 is twisted. At this time, the restoring force against torsion of the joint 41 is equal to the drive screw 37.
And transmitted to the pulse motor 5, but the drive screw 37
Does not rotate immediately due to the load of the focusing lens 2 and the like, and the pulse motor 5 also keeps rotating until the rotational force due to the magnetic force disappears.

As a result, the restoring force of the joint 41 increases remarkably, and when the load exceeds the load in the middle, the drive screw 37 starts rotating, and the focusing lens frame 3 and the like start moving. Become.

The other embodiment of the transmission means has been described above. The operation mode of the transmission means is similar to that of the embodiment described with reference to FIGS. It goes without saying that this is an operation mode of transmitting.

Effect of the Invention As described above, the autofocus device according to the present invention uses the single pulse motor to oscillate the focusing lens by performing the optical path length variable operation and the moving operation to the focusing position in the focusing lens. In addition, since it is performed by vibrating and moving, it is not necessary to use two driving sources as in the conventional apparatus, and it is possible to reduce the size of the apparatus and to finely control the two kinds of moving operations of the focusing lens. Has the following effects.

Further, the auto-focusing device according to the present invention may include, as a transmission means for transmitting the driving force of the pulse motor to the focusing lens, a belt, a belt pulley, or the like which can accumulate and delay the driving force and transmit the driving force to the focusing lens. By adopting such a transmission means, there is an effect that the vibration or the vibration moving operation of the focusing lens described above can be realized with a smaller pulse motor and a shorter driving pulse period without misstepping. doing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram including a partial schematic cross-sectional view showing an embodiment of an autofocus apparatus according to the present invention, FIG. 2 is a block diagram showing an example of means 9 and 10 in FIG. 1, and FIG. Second
FIG. 3 is a signal waveform diagram showing a signal of an arbitrary part in the figure.
FIG. 4 is a block diagram showing another embodiment of the autofocus apparatus according to the present invention, which corresponds to the means 9 and 10 in the previous embodiment. FIG. 5 is a schematic diagram of a pulse motor, FIG. 6 is a diagram for explaining an operation state when a driving force of the pulse motor is transmitted to a focusing lens through a well-known gear structure, and FIG. FIG. 8 is a schematic view of a transmitting means in the apparatus shown in FIG. 8, and FIG. 8 is a view for explaining an operation state when the driving force of the pulse motor is transmitted to the focusing lens via the transmitting means shown in FIG. is there. FIG. 9 is a schematic diagram showing another embodiment of the transmission means used in the autofocus device according to the present invention. Reference numeral 1 denotes a photographing lens system, 2 denotes a focusing lens, 3 denotes a focusing lens frame, 4 denotes a lens frame, 5 denotes a pulse motor,
38: belt pulley, 7: belt, 8: imaging unit, 9
... Focusing state determination means, 10 pulse motor drive control means, 11 high frequency component extraction circuit, 12 gate circuit, 13
... vertical gate signal generation circuit, 14 ... water gate signal generation circuit, 15 ... peak hold circuit, 16 ... high frequency component detection unit, 17 ... difference circuit, 18 ... optical path length variable frequency component detection circuit, 19 ... Focusing determination means, 20 subject change detection means, 21 and 21 ′. Operation state control means, 23 and 23 ′. ... vibration starting means, 26 ... pulse generation circuit, 27 ... vibration direction setting means, 28, 31 ... comparison circuit, 29 ... pulse number setting means, 30 ... pulse number counter, 32 ... driving circuit, 33 ......
Drive control circuit, 34 switch, 35, 36 moving shaft, 37, 40 drive screw, 39 locking member, 41
Fittings.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-299926 (JP, A) JP-A-59-66274 (JP, A) JP-A-58-123508 (JP, A) JP-A-56-123 116007 (JP, A) JP-A-55-76309 (JP, A) JP-A-60-122696 (JP, A) JP-A-52-27315 (JP, A)

Claims (12)

(57) [Claims] A pulse motor connected to a focusing lens of a projection lens system and serving as a driving source for driving the focusing lens in the optical axis direction; and a high-frequency component from a video signal obtained through the photographing lens system. A high-frequency component detection unit that extracts, peak-holds, and outputs as a high-frequency component amount, and operates in response to the output of the detection unit to detect a fluctuation and a fluctuation state of the high-frequency component, and to perform a vibration control signal, a stop control signal or a vibration movement control signal. And a control signal output unit that outputs a focusing direction signal while independently outputting focus state determination means, and receives the vibration control signal to obtain aperture value information indicating a current aperture value of the photographing lens system. By outputting the vibration signal for causing the focusing lens to vibrate at a vibration amplitude that causes a predetermined blur state by rotating the pulse motor forward and backward with the same number of steps based on the pulse motor. Receiving the vibration movement control signal, outputting a vibration movement signal for rotating the pulse motor in a forward / reverse direction with a different number of steps in consideration of the focusing direction signal, and receiving the stop control signal, the vibration signal, the vibration movement A drive control circuit for the pulse motor that stops outputting a signal and the pulse motor that drives the pulse motor based on the vibration signal or the vibration movement signal and that vibrates or moves the focusing lens in a focusing direction. An autofocus device comprising: a pulse motor drive control unit including a drive circuit. 2. A control signal output unit comprising: focus determining means for determining a focus state based on a peak-held high-frequency component amount and an output of a difference circuit for detecting a difference between the high-frequency component amounts; The optical path length variable frequency component detection circuit for supplying only an output of the difference circuit according to the frequency to the focus determination means in order to consider a vibration frequency of a focusing lens by a motor according to claim 1. The autofocus device according to claim 1. 3. A drive control circuit for receiving a vibration control or vibration movement control signal and aperture value information indicating a current aperture value of a photographic lens system, and setting a vibration amplitude of the focusing lens in a predetermined blur state. Amplitude setting means, vibration cycle setting means for receiving the set vibration amplitude signal and field signal and setting a vibration cycle for each screen, and generating a start signal in response to the field signal in consideration of the set vibration cycle. Vibration start means, a pulse generation circuit for receiving the start signal and starting to output a drive pulse signal, vibration direction setting means for receiving the start signal and inverting the vibration direction, and determining the set vibration direction and focus A first comparison circuit for comparing the focusing direction output from the means, and a first pulse number and an arbitrary second pulse number for realizing the vibration amplitude in response to the set vibration amplitude signal The first pulse number when the amplitude setting means is receiving the vibration control signal, and the second pulse number based on the result of the first comparison circuit when the amplitude setting means is receiving the vibration movement control signal. Pulse number setting means for setting the number of pulses obtained by adding or subtracting the number of pulses as the number of driving pulses, a pulse number counter for counting the number of driving pulse signals output by the pulse generation circuit, a count value of the counter and the number of pulses 2. The pulse generating circuit according to claim 1, wherein the number of driving pulses set by the setting means is compared, and when the numbers coincide, an operation end signal is output, and the pulse generating circuit and a second comparing circuit for supplying to the vibration starting means. Autofocus device. 4. A focusing state judging means outputs a preferable moving speed signal of the focusing lens based on a degree of deviation of the focusing state, and a pulse number setting means appropriately determines a second pulse number based on the moving speed signal. The autofocus device according to claim 3, wherein the autofocus device is set. 5. A pulse motor which is connected to a focusing lens of a photographic lens system and serves as a drive source for driving said focusing lens in the optical axis direction, and a high frequency component from a video signal obtained via said photographic lens system. A high-frequency component detection unit that extracts, peak-holds, and outputs as a high-frequency component amount, and operates by receiving an output of the detection unit to detect a fluctuation and a fluctuation state of the high-frequency component. A control signal output unit for independently outputting a movement control signal, outputting a focusing direction signal, and independently outputting a movement control signal for simply driving the pulse motor in a predetermined direction. Means for receiving the vibration control signal and rotating the pulse motor forward and backward with the same number of steps based on aperture value information indicating a current aperture value of the photographing lens system. A vibration signal for causing the focusing lens to vibrate at a vibration amplitude that causes a predetermined blur state is output, and the pulse motor is received with the vibration movement control signal and a different number of steps in consideration of the focusing direction signal. When a vibration cycle based on the same number of steps is longer than a predetermined number of screen cycles, a control signal for outputting the movement control signal to the in-focus state determination unit is supplied. In response to the movement control signal, the pulse motor outputs a movement signal to drive the pulse motor to either forward rotation or reverse rotation based on the focusing direction signal, and stops the driving of the pulse motor in response to the stop control signal. A drive control circuit for the pulse motor, and the focus lens by driving the pulse motor upon receiving the vibration signal, the vibration movement signal or the movement signal Vibration or autofocus device that includes a pulse motor drive control means consisting of a focus direction and a driving circuit of the pulse motor for vibrating movement or movement. 6. The control signal output unit includes a focus determination unit that determines a focus state based on a peak-held high-frequency component amount and an output of a difference circuit that detects a difference between the high-frequency component amounts. When the motor is driven by the vibration or vibration movement signal, only the output corresponding to the vibration frequency of the focusing lens of the difference circuit is used. When the motor is driven by the movement signal, the output of the difference circuit is used as it is to determine the focus. 6. The auto-focusing device according to claim 5, wherein said auto-focusing device is supplied to said means. 7. A drive control circuit receives a vibration control or vibration movement control signal and aperture value information indicating a current aperture value of the photographing lens system, and sets a vibration amplitude of the focusing lens in a predetermined blur state, and sets the amplitude. A vibration for outputting a control signal for outputting a movement control signal to the focus state determination means when the set amplitude is equal to or greater than a predetermined number of screen cycles, and for outputting a signal for setting a movement speed of the pulse motor in response to the movement control signal; Amplitude setting means, vibration cycle setting means for receiving the set amplitude signal and the field signal and setting a vibration cycle for each screen, and vibration starting means for generating a start signal in response to the field signal in consideration of the set vibration cycle A pulse generation circuit that starts outputting a drive pulse signal in response to the start signal; vibration direction setting means that inverts and sets a vibration direction in response to the start signal; The outputs of the set oscillation direction by the first state and the vibration direction setting means for outputting a focusing direction to output the focused state setting means by which a signal is supplied 2
And a first switch for comparing a direction outputted from the changeover switch with the focusing direction.
A comparison circuit, receiving the output of the amplitude setting means, setting a first pulse number and an arbitrary second or third pulse number for realizing the set amplitude, and the amplitude setting means receiving the vibration control signal; When the first pulse number is received, when the vibration movement control signal is received, the control signal is output as a pulse number obtained by adding or subtracting the second pulse number to or from the first pulse number based on the result of the first comparison circuit. Pulse number setting means for setting the third pulse number as a drive pulse when receiving a movement control signal; a pulse number counter for counting the number of drive pulse signals output by the pulse generation circuit; The numerical value is compared with the number of drive pulses set by the number-of-pulses setting means, and when they match, an end signal indicating the end of operation is output and the pulse generation circuit and the second comparison circuit supplied to the vibration start means Autofocus device according to paragraph 5 claims that. 8. A focusing state judging means outputs a preferable moving speed signal of the focusing lens based on a degree of deviation of the in-focus state, and a pulse number setting means sets the second and third pulse numbers to the moving speed signal. The auto-focusing device according to claim 7, wherein the auto-focusing device is appropriately set based on the setting. 9. A pulse motor serving as a drive source for driving a focusing lens of a photographing lens system in an optical axis direction, and a driving force of all the pulse motors is accumulated and delayed through a member having a restoring force. Transmitting means for transmitting to the focusing lens; focusing state determining means for extracting a high-frequency component from a video signal obtained through the photographing lens system and determining a focusing state of the photographing lens system from a fluctuation state thereof; And a pulse motor drive control means for controlling the drive of the pulse motor based on the output from the focus state determination means. 10. A focusing state determining means for extracting and peak-holding a high-frequency component and outputting it as a high-frequency component amount; detecting a fluctuation and a fluctuation state of the high-frequency component amount; And a control signal output unit that independently outputs a vibration movement control signal and a focus direction signal, and the drive control unit receives the vibration control signal and sets a current aperture value of the photographing lens system. By outputting the vibration signal that causes the focusing lens to vibrate at a vibration amplitude that causes a predetermined blur state by rotating the pulse motor forward and backward at the same number of steps based on the indicated aperture value information, the vibration movement control signal Receiving the stop control signal in response to receiving the stop control signal while outputting the vibration movement signals for rotating the pulse motor forward and backward at different numbers of steps in consideration of the focusing direction signal. A driving control circuit for stopping the driving of the pulse motor, and driving the pulse motor for receiving the vibration signal or the vibration moving signal, driving the pulse motor, and vibrating or moving the focusing lens in the focusing direction. The autofocus device according to claim 9, comprising a circuit. 11. A focusing state determining means for extracting and peak-holding a high-frequency component and outputting it as a high-frequency component amount; detecting a fluctuation and a fluctuation state of the high-frequency component amount; A control signal output unit that independently outputs a signal and a vibration movement control signal and outputs a focusing direction signal, and independently outputs a movement control signal that simply drives a pulse motor in a predetermined direction,
The drive control means receives the vibration control signal, rotates the pulse motor in the same step number based on the aperture value information indicating the current aperture value of the photographing lens system, and rotates the focusing lens by a predetermined number. A vibration signal for vibrating at a vibration amplitude that causes a blur state is output, and a vibration movement signal for receiving the vibration movement control signal and rotating the pulse motor forward and reverse with a different number of steps in consideration of the focusing signal is output. And when the vibration movement cycle based on the same number of steps is equal to or longer than a predetermined number of screen cycles, supplies a control signal for outputting the movement control signal to the focus state determination means, and receives the movement control signal and outputs the pulse. Outputting a movement signal for driving the motor to either forward rotation or reverse rotation based on the focusing direction signal, and receiving the stop control signal, A driving control circuit of the pulse motor for stopping the driving of the motor, and receiving the vibration signal, the vibration movement signal or the movement signal, and driving the pulse motor to vibrate or move or move the focusing lens in the focusing direction. 10. The autofocus device according to claim 9, comprising a drive circuit for driving the pulse motor. 12. The transmission means includes a belt pulley provided on an output shaft of a pulse motor, and a ring-shaped belt combined with the belt pulley and having a restoring force capable of outputting a driving force to the pulse motor. Item 10. The autofocus device according to Item 9.