JPS58223108A - Lens drive controlling device of automatic focusing camera - Google Patents

Abstract

PURPOSE:To perform a focusing in a short time, by interrupting to electrify to a motor when a lens approaches the focusing point and making a reduction of a motor by shortening the electrifying time as the lens approaches nearer. CONSTITUTION:A defocus amount DELTAL outputted from a range finding part 9 and a signal in the direction of lens extension are inputted to a controller 11, and here a lens extension amount DELTAd is counted and converted into a digital value to be outputted to an up down counter 12. A signal of driving a motor is outputted to a driving circuit 13 from the controller 11. The up down counter 12 inputs pulses outputted at each unit distance of lens movement from a generator 10 and subtracts the lens extension amount DELTAd which is reset at each input of pulse, and when its value becomes zero, the lens is focused and a signal to stop a motor 2 is outputted to the driving circuit 13 from the controller 11 and the motor 2 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a lens drive control device for an autofocus camera.

Conventional technology Generally, in automatic focus cameras, the amount of lens extension for focusing is calculated based on the amount of defocus, that is, the amount of deviation between the focal point of the image and the film surface, and the lens is moved by the amount of lens extension obtained. is driven by a motor to perform focusing.

In a conventional autofocus camera, the power supply voltage to the motor remains the same until the lens reaches a focal point, and the power supply is stopped when the lens reaches a single focal point. However, even if the power supply is stopped, the lens does not stop immediately at the in-focus point due to inertia, but overshoots, and this overshooting and return is repeated until the lens stops at the in-focus point, so it takes time to reach the in-focus point. It had

The present invention has been made in view of the above-mentioned problems in the conventional art, and its purpose is to cut off the power supply to the motor when the lens approaches the focal point, thereby reducing the distance between the current position of the lens and the focal point. By controlling the intermittent energization period to be sequentially shortened as the motor becomes shorter, the motor is decelerated.
An object of the present invention is to provide a lens drive control device for an autofocus camera that enables focusing in a short time.

Abstract: In a lens drive control device for an autofocus camera, which uses a motor to extend the lens by the distance between the current position of the lens and the focal point to achieve focusing, a lens drive controller that outputs pulses corresponding to the amount of lens extension is used. A means for detecting the amount of extension, a signal generating means for outputting a signal indicating where the current position of the lens is relative to the focal point number, and a signal generating means for outputting a signal indicating where the current position of the lens is relative to the focal point number; a counting means for subtracting or adding the output pulse of the detecting means according to the output of the signal generating means; a motor drive signal generating means that generates a motor drive signal that is intermittent with a width corresponding to the distance between the position and the focal point, and the motor is decelerated as the lens is extended and approaches the focal point, and the motor is decelerated as the lens approaches the focal point; It is characterized in that when the count value of the means reaches 0, it is detected that the lens has reached a focused point and the power supply to the motor is stopped.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIG. 1, an autofocus camera equipped with a lens drive control circuit according to the present invention includes a motor 2 provided inside a camera body 1, and a slide mechanism 3 driven by this motor 2.
Then, the feed screw 5 coupled to the drive transmission portion 4 is driven, and the lens portion 7, to which the nut 6 that engages with the feed screw 5 is fixed, is guided by the guide bar 8 and moves in the left-right direction in FIG. Focusing is performed. 9 is a distance measuring section, and 10 is a pulse generator that generates a number of pulses corresponding to the amount of movement of the lens section 7.

The lens drive control circuit of the present invention, as shown in FIG.
A signal representing the defocus amount ΔL output from the distance measuring section 9 and the direction in which the lens is extended is input to the controller 111, and the defocus amount ΔL is input to the controller 111.
A lens extension amount Δd for 7 orcasing is calculated based on L, and this lens extension amount Δd is converted into digital data and output to the up/down counter 12.

The controller 11 outputs signals for roughly driving the motor 2 to the drive circuit 13 . The up-down counter 12 also receives the output of the pulse generator 10 which generates this pulse every unit distance of movement of the lens driven by the motor 2; Each time is input, the preset lens extension amount Δd in 8h is subtracted.When the up/down counter 12 becomes zero by the above-mentioned subtraction, that is, when the lens stops at the in-focus point, the controller 11 sends the motor A signal for stopping the motor 2 is output to the drive circuit 13, and the motor 2 is stopped.

Next, the detailed circuit configuration of the above-mentioned lens drive circuit will be explained.

As shown in Figure @3, the distance measuring section 9. Pulse generator 1
0. The circuit excluding the up/down counter 12 and the drive circuit 13 forms the controller 11 shown in FIG. Reference numeral 14 denotes a calculation unit, into which a signal representing the defocus amount ΔL is inputted from the distance measuring unit 9, and in this calculation unit 14, the lens extension amount Δd is calculated by the well-known formula Δd=C・
It is calculated based on ΔL. The coefficient C is a constant determined by the focal length of the lens. Arithmetic unit 14-4
The bit data output terminal is connected to the 4-bit preset data terminal of the up/down counter 12, and the arithmetic unit 1
The absolute value of the lens extension amount Δd calculated in step 4 is converted into a binary signal and sent to an up/down counter 12.
& This will be preset.

The 4-bit data output terminal of the up-down counter 12 described above is connected to the 4-bit first data input terminal of the comparator 15, and the most significant bit of the 4-bit data output terminal of the comparator 15 is grounded. , the following three bits are connected to the three-bit data output terminal of the counter 16. Furthermore, the count input NOR terminal of the counter 16 (to which the output terminal of the pulse oscillator 17 is connected). This circuit consisting of the comparator 15, counter 16, and pulse oscillator 17 stops power supply to the motor when the lens approaches the in-focus point. At the same time, it outputs a message for decelerating the motor by sequentially shortening the intermittent energization period.

The oscillator 17 outputs pulses with a constant frequency, and the counter 16 counts these pulses.

Since the counter 16 has 3 bits, its content Y can repeat from 00o'' to 5111' as shown in FIG. When the output of the up-down counter 12 is greater than the output of the counter 16, the terminal 15a is set to "0". 6X decreases as the lens approaches the focal point l, but since the distance from the focal point is large, when the L-most bit of the 4-bit output of the up/down counter 12 is 11', The terminal 15a of the comparator 15 is a secret number.
Thus, the motor 2 is continuously driven.

The lens approaches the in-focus point by one point and the up/down counter reaches 12.
The output data of counter 16 decreases, and this output data is sent to counter 16.
During the period when the periodic count value of
5's terminal 15a+; The state in which the output of the counter 12 is greater than the output of the counter 16 is intermittent and the period becomes shorter in sequence. Therefore, the state in which the terminal 15a of the comparator 15 is ``0'' is intermittently and the period becomes shorter in sequence. As shown in FIG. Slowed down.

Reference numeral 18 indicates a flip 70 knob on J-, and this flip 70 knob 18 on J- is operated through an AND circuit 19 when the terminal 14a which outputs a signal representing the direction in which the lens of the computing unit 14 is extended is 0". The pulse during the period in which the synchronizing pulse is output from the terminal 14b of the calculation section 14 is taken in via the preset terminal, and the terminal 14a of the calculation section 14 is
1', this signal is inverted by the inverter circuit 20, and further, the pulse during the period in which the synchronizing pulse of the arithmetic unit 14 is outputted is taken in via the clear terminal via the AND circuit 21. The flip-flop 18 is initialized in the driving direction of the lens by the input to the preset terminal and the clear terminal. The output terminal of the AND circuit 22 is connected to the CK input terminal of the 7-lip flop 18, and the 4-bit inverting input terminal of the AND circuit 22 is connected to the CK input terminal of the 7-lip flop 18. The 4-bit data output terminals of the up/down counter 12 are connected to each other.Therefore, when the contents of the up/down counter 12 reach 0, the flip 70 block 18 changes the state of the Q and Q outputs by the pulse input to the GK input terminal. Invert.

- 10,000, the output terminals of the two photocouplers 10a and 10b forming the pulse generator 10 are connected to the waveform shaping circuit 23.
24 input terminals, and the output terminal of the waveform shaping circuit 23 is connected to the first input terminal of the AND circuit 25.
The output terminal of the waveform shaping circuit 24 is an exclusive OR circuit 26.27
．． 28 first input terminals, respectively. The output terminal of the waveform shaping circuit 24 is also connected to a second input terminal of an exclusive OR circuit 26 via a delay circuit 29, and the output terminal of this exclusive OR circuit 26 is connected to a second input terminal of an AND circuit 25. Ru. The Q output terminal of the flip-flop 18 described above is connected to the second input terminal of the exclusive OR circuit 27, and the Q output terminal of the flip-flop 18 is connected to the second input terminal of the exclusive OR circuit 28. be done. The output terminals of the exclusive OR circuits 27 and 28 are respectively connected to the first input terminals of the NAND circuits 30 and 31.
The output terminals of the AND circuit 25 described above are connected to the second input terminals of the AND circuits 1 and 2, respectively. The output terminal of this NAND circuit 30 is connected to the up input terminal 12b of the up/down counter 12, and the output terminal of the NAND circuit 31 is connected to the down input terminal 12H of the up/down counter 12.

The operation of the above-mentioned circuit will be explained with reference to the time chart of FIG. 6. The outputs of the waveform shaping circuits 23 and 24 that shape the outputs of the two 7-inch automatic couplers 10a and 10b of the pulse generator 10 have a phase of 90 degrees with respect to each other. When the moving direction of the lens is reversed, this phase difference is reversed (FIGS. 6A and 6B). The output of the exclusive OR circuit 26 has a width equal to the delay time of the delay circuit 29, that is, the period during which the output of the waveform shaping circuit 24 and the output of the waveform shaping circuit 24 differ from each other in the states of the signals delayed by the delay circuit 29. pulse (
In FIG. 6C), this pulse is generated at the rising and falling edges of the output signal of the waveform shaping circuit 24. moreover,
The output of the AND circuit 25 becomes 11' only when the output of the waveform shaping circuit 23 and the output of the exclusive OR circuit 26 are both h1#, and when the lens is driven in the positive direction, that is, in the direction away from the camera body, the output of the waveform shaping circuit 25 becomes 11'. Only the pulse at the rising edge of the output of the waveform shaping circuit 24 is output, and when the lens is driven in the opposite direction, that is, in the direction approaching the camera body, only the pulse at the falling edge of the output of the waveform shaping circuit 24 is output (Fig. 6D). ).

The exclusive OR circuit 27 has a Q output of the flip 70 knob 18.
When the Q output of the flip-flop 18 is 1#, the output of the waveform shaping circuit 24 is inverted and output, and when the Q output of the flip-flop 18 is 0#, the output of the waveform shaping circuit 24 is output as is (Fig. 6E).
). Furthermore, when the q output of the flip-flop 18 is 1#, the exclusive OR circuit 28 inverts the output of the waveform shaping circuit 24 and outputs it, and the Q output of the 7 flip-flop 18 is 0#.
In this case, the output of the waveform shaping circuit 24 is output as is. That is, the Q output and Q output of the flip-flop 18 are always l.
Since these states are opposite, if one of the outputs of the exclusive OR circuits 27 and 28 is the same as the output of the waveform shaping circuit 24, the other is an inverted version of the output of the waveform shaping circuit 24. For example, when the Q output of the flip-flop 18 is '1', the output of the exclusive OR circuit 27 is the inverted output of the waveform shaping circuit 24, and the output of the exclusive OR circuit 28 is the same as the output of the waveform shaping circuit 24. become.

The NAND circuit 30 outputs a pulse of 10' when the output of the exclusive OR circuit 27 and the output of the AND circuit 25 are both 11#, and in other situations, the output of the NAND circuit 3° is '''1'.
(Figure 6 UP). In addition, the NAND circuit 31 outputs a pulse of 'θ' when the output of the exclusive OR circuit 28 and the output of the AND circuit 25 are both 11#, and the output of the NAND circuit 31 maintains '1#' except in this state ( to No. 6 Kaida). In other words, when the lens moves in the positive direction,
For example, when the Q output terminal of the flip 70 tube 18 is 50#, the output of the waveform shaping circuit 24 is directly outputted from the exclusive OR circuit 28, and the output of the NAND circuit 31 is '' at the rise of the output of the waveform shaping circuit 24. This pulse is input to the down input terminal 12H of the up/down counter 12. At this time, the output of the NAND circuit 3o holds 11', and this signal is input to the down input terminal 12H of the up/down counter 12. It is input to the up input terminal 12b.Furthermore, when the lens moves in the opposite direction, for example,
When the Q output terminal of the flip-flop 18 is 1o#, the output of the waveform shaping circuit 24 is output as is from the exclusive OR circuit 27, and the output of the NAND circuit 30 is a pulse that becomes 1o# when the output of the waveform shaping circuit 24 falls. This pulse is input to the up input terminal 1 of the up/down counter 12.
2b. Further, at this time, the output of the NAND circuit 31 holds 11', and this signal is input to the down input terminal 12a of the up/down counter 12. That is, the state of the flip 70 knob 18 and the direction of movement of the lens
up/down counter 12 depending on either of the two states.
Q of flip 70 knob 18 when the counting operation is switched from up to down or from down to up and the direction of movement of the lens is in the positive direction until the lens reaches the in-focus point.
When the output is ゞ1#, it counts down, the lens passes through the focused point, and the Q output is v? o”, it will count up, and if the lens is moving in the opposite direction, the Q of 7 lips, 70 lips, 18 until the lens reaches the in-focus point.
When the output is '0#', the count is down, and when the Q output is 11# after the lens passes through the in-focus point, the count is up.

The Q output terminal of the above-mentioned 7-rip 70-tube 18 is also connected to the first input terminal of the inverting input AND circuit 32, and the Q output terminal of the flip-flop 18 is also connected to the first input terminal of the inverting input AND circuit 33. be done. Furthermore, the terminals 15a of the comparators 15 which output a signal 0# when the count data of the counter 16 mentioned above is smaller than the data of the up/down counter 12 are connected to the second input terminals of the AND circuits 32 and 33, respectively. Connected. The output terminal of the AND circuit 32 is connected to the base of the transistor 13H for supplying power to the motor 2 of the drive circuit 13 in the direction of reverse rotation, and the output terminal of the AND circuit 33 supplies power to the motor 2 of the drive circuit 13 in the direction of forward rotation. The base of the transistor 13b is connected to the base 1 of the transistor 13b.

These AND circuits 32 and 33 are circuits for switching the direction of power supply to the motor 2 depending on the contents of the flip-flop 18, and when the terminal 15a of the comparator 15 is 10'', the Q output or the Either the AND circuit 32 or 33 to which the terminal 10# is connected is 1.
1', the transistor 13b or 13a becomes conductive, and power is supplied to the motor 2 in the direction of forward or reverse rotation.

For example, when the Q output of the flip-flop 18 is ``1#'' and the terminal 15a of the comparator 15 is 10#, the output of the AND circuit 33 is 11#, and the transistor 13b
The direction in which the motor 2 is rotated in the forward direction by making it conductive (power is supplied in this direction).

Next, the operation of the above circuit will be explained.

The defocus amount △L output from the ranging section 9 is calculated by the calculation section 1.
4, the arithmetic unit 14 calculates the lens extension amount d for focusing, and digital data l representing the lens extension amount Δd is input to the up/down counter 12. In addition, the calculation unit 14 inverts the Q output of the flip 70 knob 18 to 51" if the lens position for focusing is the position of the lens at that time, and the current position of the lens moves the lens in the opposite direction. Even at the position where the in-focus point is reached, the Q output of the i'i' flip-flop 18 is inverted by one degree.

The transistor 13a or 13b of the drive circuit 13 is made conductive by the Q output or Q output number of the 7-lip flop 18, and power is supplied in a predetermined direction so that the motor 2 rotates forward or backward.

When the motor 2 is driven and the lens is extended, the photocoupler 10a of the pulse generator 10.

10b with a phase difference of 90° from each other/Curs force;
The pulse is output from the NAND circuit 30 according to the Q output and Q output number of the flip 70 amplifier 18 corresponding to the current position of the lens after the above-mentioned operation. input to the terminal,
Alternatively, the pulses output from the NAND circuit 31 are input to the down count terminal of the up/down counter 12.

The up/down counter 12 subtracts the lens extension amount Δd inputted from the calculation unit 14 every time a pulse is input to the down count terminal, and when the lens approaches the in-focus point, the contents of the up/down counter 12 become the contents of the counter 16. When a shorter period occurs, the power supply to the motor 2 is interrupted and the power supply period is sequentially shortened to decelerate the motor 2 by the above-described operation. When the lens reaches the in-focus point, the output of the up/down counter 12 becomes O, and the output of the AND circuit 22 becomes 11', and the output of the 7 lip-flop 1 becomes 0.
The clock is taken into 8 and the Q of flip-flop 18
Output and Q output are inverted. At this time, the lens passes past the focused point due to inertia and stops, so the pulse generator 1
A number of pulses corresponding to the amount of overshoot of the lens outputted from 0 are input to the up count terminal of the up/down counter 12 via the sundo circuit 30, and the contents of the up/down counter 12 are values corresponding to the amount of overshoot of the lens. 1 stroke. Here, the motor 2 is supplied with power in the direction in which it is reversed, and the motor 2 is fed in the direction opposite to that before the rental.

Also in this case, as the lens approaches the in-focus point, the intermittent power supply period to the motor 2 is sequentially shortened, and the motor 2
deceleration is performed. By repeating the above-mentioned operation (therefore, as shown in Figure 7), the lens is in the focus area P (
The camera then stops and focuses. The number shown in FIG. 7 is 3, which represents the content of the up-down counter 12. Also, since the signal measured while the lens is moving has a large error, the output of the AND circuit 22 is '1'', that is, the up-down counter 12. The synchronizing pulse may be input to the up/down counter 12 only when the output of When converted, the relationship between the lens extension amount and the duty is not only determined by the number of steps of the gradient, but also non-linear (it can also be rubbed).

Effects As explained above, in the present invention, the distance between the current position of the lens and the in-focus point is set, and the pulse is driven by the motor 1 in accordance with the amount of lens extension. , and when the counted value matches the set value, the supply to the motor is stopped, and the lens As the lens approaches the in-focus point, the power supply to the motor is interrupted depending on the result of this comparison, and the intermittent power supply period is gradually shortened to slow down the motor, so that the focusing operation can be controlled. It can be completed in a short time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a camera equipped with a lens drive control device of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention.
FIG. 3 is a circuit diagram showing an embodiment of the present invention, and FIG. 4 shows the output X of the up/down counter 12 and the output Y of the counter 16.
Figure 5 is a time chart showing the method of power supply to the motor, Figure 6 is a time chart of the main parts of the circuit in Figure 3, and Figure 7 is a graph showing the changes in the amount of power supplied to the motor due to changes in the lens. It is a graph showing a state when one focal point is stopped. 2...Motor, 7...Lens, 10...
Pulse generator, 12... Up/down counter, 14... Arithmetic unit, 15... Comparator, 16
...Counter, 17...Pulse oscillator, 1
8...Flip-flop to J-, 19.21.2
2.25.32゜33...AND circuit, 20...
Inverter circuit, 23.24... Waveform shaping circuit, 2
6.27, 28... Exclusive OR circuit, 29... Delay circuit, 30.31... NAND circuit. Patent applicant: Minolta Camera Co., Ltd. Patent attorney Aoyama, 2 people 4 Figure 4 Figure 5 Figure 6 Figure 7 ＼夛

Claims (1)

[Claims] (1) A lens drive control device for an autofocus camera that uses a motor to extend the lens by the distance between the current position of the lens and the focal point and perform focusing (here, a pulse is generated according to the amount of lens extension) a signal generating means for outputting a signal indicating which position the current position of the lens is relative to the focal point, and a signal generating means that outputs a signal indicating which position the current position of the lens is relative to the focal point; a counting means for subtracting or adding the output pulse of the detecting means according to the output of the signal generating means, and a current position of the lens and the in-focus point according to the count value of the counting means; and a motor drive signal generating means for generating a motor drive signal that is intermittent with a width corresponding to the distance between the lens and the in-focus point. A lens drive control device for an autofocus camera that detects when the in-focus point has been reached based on numerical values and stops power supply to the motor.