JPH0147764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens control method suitable for automatic focus adjustment and the like.

In applications that require the lens to be driven, such as automatic focus adjustment or zooming, the range of movement of the lens is limited, so when the lens reaches the limit of its range of movement, , we need to know this somehow.

Regarding this, in the past, a limit switch was provided at the limit point of the lens's movable range, and the limit was detected by this switch.
The method using such a mechanical switch has disadvantages in terms of construction, as well as the need for lenses and
There is also the hassle of adjusting the limit position, etc.
Precise limit detection has always been difficult.

In view of these circumstances, the present invention solves the above-mentioned inconveniences associated with the provision of conventional mechanical switches, and is extremely advantageous in terms of lens drive control and control circuits. It is an object of the present invention to provide a novel lens control method that can easily detect limits suitable for each lens, and with this purpose in mind, the present invention provides a method for detecting a signal related to the movement of the lens when the lens moves. The limit judgment is performed by detecting that the signal does not change within a predetermined time while driving the lens, and the predetermined time for this judgment is set depending on the type of lens. It is characterized by being able to be changed.

Other objects and features of the present invention will become apparent from the description that follows with reference to the accompanying drawings.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

In Fig. 1, 1 is a photographing lens, and the lens 1 is moved back and forth along the optical axis 0 as shown by arrow 3 so that the image of the object is correctly formed on the intended image formation plane 2. However, in order to detect the focus, images at a position equivalent to the planned imaging plane 2 and positions before and after it, that is, positions indicated by 4, 5, and 6, for example, are converted into electrical signals using a sensor, and comparison processing is performed. By doing so, the differential focus for the planned imaging plane 2 is calculated, and the lens 1 is moved and stopped.

Next, in FIG. 2, the images at the positions 4, 5, and 6 mentioned above are converted into electrical signals by the sensor unit 11, and this is applied to the focus detection unit 12, thereby detecting the amount of defocus and adjusting the focus. The system is configured such that a drive instruction unit 13 calculates a drive amount for correct and quick focusing, and a drive control unit 14 controls a drive system 15.

Next, an example of the focus detection unit 12 will be explained with reference to FIG.
Sensors 3 are arranged to see equivalently the same area corresponding to the positions 4, 5, and 6, respectively, and in order to stabilize the signal due to brightness, sensors are arranged to see approximately the same area and further sensor A sensor 24 is provided, and a constant current circuit 25 applies a constant current to the sensor 24 to generate a potential on a line 26 that becomes low depending on the brightness of the distance measurement area. This brightness signal is resistor 2
Line 3 is amplified differentially with the reference potential by 7 and 28.
0, a signal that goes high depending on the brightness is generated. This signal controls the constant current circuits 31, 32, and 33 so that the brighter the current, the more current is applied to the points 34, 35, and 36 to generate signals that are independent of the brightness and correspond only to the visibility of each position.

In this way, the predetermined focal plane and the front and rear visibility signals are amplified by the amplifiers 37, 38, and 39 to line 4.
At 0, 41, and 42, it is possible to obtain sharpness signals in front of the intended focal plane, in the intended focal plane, and behind the intended focal plane, respectively.

Of these three signals, two signals on lines 40 and 42 are applied to a differential amplifier 43 to determine the difference in sharpness between the images before and after the intended image forming plane, and at the same time, an summing amplifier 44 is applied to Calculate the sum of the sharpness of the image of the subject, give both of them to the divider 45, and divide the difference by the sum to normalize the sharpness of the subject's own image, and calculate the sharpness of the subject's own image from the front and rear positions of the planned image plane. A signal proportional to the imaging position, that is, the amount of defocus is output to the terminal 46.

At the same time, the comparator 47 outputs the polarity, that is, high when the front side is more clear, and low when the opposite side is in focus (ie, when the rear side is more clear) as the def focus direction. However, the above-mentioned defocus amount of the terminal 46 can only be determined correctly when the imaging point is at the internal division point of the front and rear sensors 21 and 23, and the entire image is greatly blurred at positions 4, 5, and 6. In this case, the defocus cannot be determined correctly. For this purpose, the diodes 49, 50 and the resistor 51 are used to obtain a large value of front and rear sharpness on the line 52, and this is converted into the signal on the line 41, that is,
The comparator 53 compares the sharpness signals to the planned focal plane, and when the sharpness at the planned focal plane is greater than the sharpness at the front and rear planes, that is, when the front and rear sensors 2
When the imaging plane is located at the internal division point of 1 and 23, in other words, when the defocus amount of the terminal 46 is a definite value, a high signal is output to the 54 terminal.

Also, each sensor 21, 22,
Since the output of 23 may be uncertain, each sensor output is connected to diodes 55 to 57 to detect it.
The maximum sharpness is obtained by applying the signal to the circuit consisting of the resistor 58, and this signal is compared with the reference value by the resistors 59 and 60 using the comparator 61. If there is sufficient sharpness, the same output is set to high and the AND gate 6
2, the output is set high when only the direction is determined outside the calculation area, and the terminal 63 is set high when only the direction is determined.

In addition, in the case of a large blur where no accuracy can be obtained from the signal, the low output of the comparator 61 is inverted by the inverter 64 and a high level is outputted to the terminal 65 to distinguish that the signal mentioned above is uncertain. It is structured like this.

In addition, when it is dark, the overall response becomes slow, so in order to stabilize the response, the brightness signal of the line 30 mentioned above is applied to the voltage controlled oscillator 67 through the amplifier 66, so that when it is bright, the high frequency pulse is changed to the low frequency pulse when it is dark. is outputted to the terminal 68 as a timing signal of a stable distance measurement result to prevent this operation.

Also, while the lens is being driven, that is, while the motor is being driven, erroneous distance measurements often occur, so a signal that goes high is given to the terminal 69 from the drive control unit, which will be described later, while the voltage controlled oscillator 67 is cleared. Prevent the generation of erroneous strobe pulses. Furthermore, when storage type sensors such as CCDs are used as the sensors 21 to 23, erroneous storage can be prevented by entering a new storage sequence when the drive signal goes low.

These signals may be used as other examples, but in a distance measuring device using an accumulation type sensor such as a CCD,
The pulse at the terminal 68 corresponds to the timing at which the distance measurement result is determined.

Furthermore, even with completely different rangefinding devices, such as the image shift method, there is a limited area in which the calculation of the differential focus is certain, and if there is a large deviation, the accuracy of the calculation will decrease, and if the differential focus is large, such as a large blur of the image, etc. (for example, when shooting a flat subject)
The direction calculation accuracy is also lost and a similar signal is generated.

Next, an example of the drive instruction unit 13 will be explained with reference to FIG. An undetermined signal (output from terminal 62) is applied to terminal 102, a determined signal (output from terminal 63) is applied to terminal 103 when only the direction is determined, and a direction signal (output from terminal 48) is applied to terminal 104. In addition, in the case of a computable region, its confirmation signal (output at terminal 54) is obtained at terminal 105, and the amount of defocus at that time (output at terminal 46) is obtained at terminal 106.

Of these, the differential focus amount signal is output by the absolute value circuit 10.
7, the signal is converted into an absolute value, and further converted into a digital value by a converter 108. Here, when in focus, that is, within the AF (autofocus) convergence range, the absolute value is smaller than a certain value, so the comparator 111 compares it with the reference level by resistors 109 and 110, and the output is sent from the terminal 105. By applying this to the AND gate 112 together with the defocus value determination signal, a high signal is generated at the terminal 113 when in focus or within the AF convergence region. This AF convergence range may be widened depending on the aperture value of the lens, so in that case, by increasing the convergence level by these resistors 109 and 110, it will converge more quickly.
Needless to say, AF is completed and meaningless convergence is no longer required. In this embodiment, A/D conversion is not required if the focus is within this range, so the A/D converter 1
I am trying to clear 08.

When each calculation is confirmed, the above calculated values are
Therefore, when the voltage controlled oscillator 69 shown in FIG. 3 generates a signal confirmation pulse during non-drive, the signal is updated or the pulse is sent to line 1.
15 to clock D-latch 116 to capture new drive data. When the lens is outside the AF convergence range, that is, when the lens is to be driven, the signal on line 113 is inverted by the inverter 117, and the signal that goes high when a drive request is made is synchronized with the new clock on line 115. When the signal is determined, it is outputted to terminals 119 and 120 through D-flip-flop 118. The lens is driven by this high signal, and when the lens drive ends, a high signal from the drive end signal terminal 121 or a high signal from the lens limit signal terminal 122, which will be described later, is input to the OR gate 123. Or, when the drive reaches the limit, the flip-flop 118 is reset by a high signal to stop the drive and perform subsequent processing based on the next data.

Since the distance measurement data as described above is held in the latch 116 when each data is determined, it is necessary to drive the lens based on this data.

For example, if the amount of defocus is also confirmed, line 1
24 goes high, the output of OR gate 125 also goes high, opening AND gate 126 (at this time, since the uncertainty signal at terminal 102 is low, the signal at point 127 is also low, so D-flip-flop 128 is Since the clear line 129 is also low, the AND gate 130 is closed) Information on the determined direction (sign) of the terminal 104 is given to the terminal 132 through the OR gate 131, instructing the lens to be driven in this direction.

D flip-flop 133 is used to store the previous indicated direction and is clocked by the signal on line 115 mentioned above.

Now, if the instruction is in the same direction as last time, regardless of the direction, the exclusive OR gate 13
4 (exclusive OR), a low signal is output to line 135, so the divider circuit 136 that outputs 1/2 of the input passes the input as is, and the AND gate 1
37 is open due to the high signal on line 124 (at this time, the AND gate is connected to terminal 103).
Since "direction only determined" is low, it is closed to the low of line 139, and the AND gate 140 is closed by the low of line 129 mentioned above).The required defocus amount is indicated to the terminal 142 through the OR gate 141.

Note that the divider circuits 136 and 143, which output 1/2 of the input, are connected so as to be shifted by 1-bit depending on the high level of the control terminal.

The D-flip-flop 133 and the exclusive OR gate 134 reduce the current amount of defocus instruction (1/2 This circuit is very effective because it can prevent oscillation and quickly converge. In other words, if the distance measurement result is in the opposite direction to the previous one, regardless of the direction, the high output of the exclusive OR gate 134 causes the divider circuits 136 and 1 to
43 to reduce the current drive requirement by half to prevent oscillation near the in-focus point.

For example, if only the direction is determined and the amount of defocus instruction is not accurate, the terminal 105 becomes low, the terminal 103 becomes high, and the terminal 102 becomes low, so that line 124 becomes low, line 139 becomes high, and line 127 becomes low.
and 129 are low, so a drive request is made in the determined direction by a certain amount. Here, the direction is configured such that the output of the OR gate 125 goes high when the line 139 goes high, and the determined direction is outputted to the direction indicating terminal 132 through the AND gate 126 with the AND gate 130 closed and further through the OR gate 131. There is. In addition, the amount of drive required rarely exceeds the differential focusing range, and
In addition, a value that does not pass through the range determined only in the direction, for example, a code corresponding to 2 mm is given as a constant by the constant setter 144 (which may be changed depending on the lens, etc.) to prevent oscillation by the aforementioned divider circuit 143. If the direction is the same as last time, the value is half the value, and if the direction is different from the previous time, it is passed through the AND gate 138, and the AND gates 137 and 140 remain closed.
Furthermore, the terminal 142 is outputted as the required driving amount through the OR gate 141.

If the direction is also uncertain, the aforementioned terminal 105 becomes low, terminal 103 becomes low, and terminal 102 becomes high, so that line 124 becomes low, line 139 becomes low, and line 127 becomes high. If this direction is also uncertain, it may occur due to a momentary accident (for example, due to camera shake), but if it is essentially uncertain, searching over the entire area of the lens will allow you to adjust to a point that is far out of focus. I am trying to set it up.
For this reason, starting a search operation due to a momentary shake etc. tends to lead to a lack of stability in terms of usability, and it is also necessary to prevent the focus from being momentarily moved away from the focus point that has been adjusted due to the start of a search operation, and losing the focus point. The following stabilization circuit is used to stabilize the current. That is, in one indeterminate case, flip-flop 128 is released from reset by line 127 going high, but line 129 does not go high, AND gates 126 and 130 are closed, so terminal 132 goes low, and the AND gate goes high. 1
37, 138, and 140 are also closed, so a drive request amount of zero is output to the terminal 142 through the OR gate 141, and the lens is not driven. However, in the case of two or more consecutive uncertainties, the flip-flop 12
By setting 8, 129 becomes high, and by opening the AND gate 140, a search step for searching the entire area of the lens determined by the lens drive constant for search from the constant setter 145 searches the entire area as quickly as possible. In addition, an amount that does not miss the in-focus point, that is, does not pass through the direction discrimination range, is outputted as the required drive amount from the terminal 142 through the OR gate 140, and a drive request is made.

The direction of the T-flip-flop 1 is reversed by an end signal applied to a terminal 122, which will be described later, which occurs when the lens is driven to the limit for searching the entire area.
46, and its indicated direction is applied to the drive direction terminal 132 through an AND gate 130 and an OR gate 131. By means of this flip-flop, when searching, the lens is searched by a constant drive amount until it reaches the limit, and at the limit it is reversed and the search is repeated.

Next, an example of the drive control unit 14 described above will be explained with reference to FIG. This control unit drives the lens in the drive direction indicated by the drive direction signal (output at terminal 132) only while the drive signal (output at terminal 119) applied to terminal 203 is high. The lens side has a motor as described below, which drives the lens to extend and retract.It also has a means for generating a pulse-like signal in relation to the lens movement to monitor the movement of the lens, Since the phase of the signal at the focus plane may change due to design or zooming, a signal of (focus movement amount) (one pulse interval) is held as a code for this by a resistor or a variable resistor. A signal of (focus movement amount)/(1 pulse interval) from the lens, which will be described later, is given to a terminal 204 and read out as a voltage related to the movement amount through a constant current circuit 205. This voltage is converted to a line 207 (multi-bit) through an A/D converter 206 as a code (for example, proportionally) that increases as the amount of movement increases. Note that the conversion characteristic of the A/D converter 206 does not need to be linear, and can be arbitrarily determined in relation to the lens side signal, but in the embodiment, the opening of this lens side signal can be set to a maximum movement. This amount is used to prohibit movement, which will be described later.

Now, in the unit 14 shown in FIG. 5, I will first explain the lens drive monitor circuit section.A pulse-like signal corresponding to lens drive, which is applied to the monitor terminal 208, is converted into a voltage signal by a resistor 209. In order to pick up one side of the signal, a capacitor 210 and a resistor 211 create a signal that is always high at point 212 and becomes low for a period of time (during the CR time constant) when the pulse signal changes (falling to the GND level). is obtained and processed as a changing pulse by the amplifier 213. Diode 214 is provided to prevent point 212 from becoming an abnormally high voltage due to a reverse change. Further, the time constant provided by the resistor 211 and the capacitor 210 is used to prevent the pulse generation source from chattering.

Next, I will explain the arithmetic circuit section. This circuit section is a circuit that determines whether or not the lens has been moved by the required defocus amount at the terminal 201. Since the amount of movement per pulse interval is obtained on the line 207, the current D-flip-flop 2
15, and an adder 216 adds this value and the amount of movement per pulse interval, and outputs the amount of movement when the next pulse arrives on line 217 to obtain the required amount of movement (signal at point 201). is compared with the magnitude comparator 218, and when the amount of movement when the next pulse arrives is greater than the required amount of movement, a high signal is output to line 219.
Driven by AND gate 220, i.e. terminal 203
When is high, a high signal is output to the terminal 221 to send a signal indicating that the movement has been completed by the requested movement amount to the drive request circuit described above to stop the drive and perform the next distance measurement. The above addition is performed using D-flip-flop 2.
15 is low when the drive signal of the terminal 203 is low, that is,
It is reset when not driven, and the flip-flop 215 is reset by the output of the amplifier 213 for each pulse.
The content of is updated and the addition result of the movement amount up to the same pulse is reloaded and added.

By adding each pulse in this way, compared to first calculating the required number of pulses by multiplication and division, the configuration can be realized only by addition and subtraction, and since the time interval of the pulses is based on mechanical movement, there is enough time between the pulses. Since it can be calculated, it becomes possible to control movement more easily and easily than by first taking a long time to perform sophisticated calculations using multiplication and division.

Next, to explain the lens limit detection circuit section, first, when the lens is not driven, the terminal 203 is low, so the output line 223 of the inverting input OR gate 222 becomes high, and the frequency divider 224 and the RS flip-flop 225 are reset. . Therefore, the Q output of flip-flop 225, ie, the end signal terminal 226 becomes low. On the other hand, when driving, terminal 2
03 becomes high, the aforementioned amplifier 21
Change of output from 3 to low (i.e., fall of pulse signal related to lens movement to GND level)
Unless there is, the output of the inverting input OR gate 222 will be low, the frequency divider 224 will be cleared, and the oscillator 2
Start counting pulses from 27. This count causes line 228 to go high and provide a carry output when it has counted the number indicated by the signal at point 207. That is, even if a pulse is generated in connection with driving the lens, if the lens does not move more than the specified amount even after a certain predetermined time has elapsed, that is, when the pulse does not come, a carry output is output, the flip-flop 225 is set, and the terminal is connected. A high signal is output to 226 to indicate that the lens is liquid. Of course, if a pulse comes within this fixed time, the output of the amplifier 213 changes to low, and the inverting input OR gate 222
The output of will go high and divider 224 will be cleared and carry, so a high at terminal 226 will not occur.

In this way, by detecting the lens limit based on the presence or absence of a change in the lens-related pulse signal, one signal line for drive monitoring is sufficient.
Furthermore, even if the interval between the generated pulses at the lens focus position changes depending on the type of lens, the above-mentioned terminal 20
Since the frequency division ratio of the frequency divider 224 is changed by the resistor code No. 4, the lens limit detection ability can always be changed according to the defocus in terms of the focal plane. Therefore, the pulse interval can be changed depending on the lens. However, appropriate judgments can be made accordingly.

This limit signal causes new sampling to be performed through the OR gate 123 in FIG.
Further, inversion in the search mode is performed by the T-flip-flop 146 to search the entire area.

Next, I will explain about the control circuit for the lens driving force.The circuit section is designed to control the motor's driving force, speed, etc., which differ depending on the lens, and the interval between the lens-related pulses mentioned above. The output of the reference oscillator 230 is sent to the terminal 232 by the variable frequency divider 231 using the signal on the line 207, that is, the signal of (defocus amount)/(1 pulse interval). A pulse corresponding to the expected pulse and period per constant defocus amount is generated and the actual lens, which is the output of the amplifier 213, is sent to the phase comparator with phase lock loop (having a low bus filter at the output) 233. The power of the motor is increased or decreased by an amplifier 235 through a resistor 234, along with the associated pulses, producing a high output if the actual lens-related pulse is slower than the expected pulse, and a low output if vice versa. This prevents the response speed from changing depending on the lens and the aforementioned limit detection circuit from malfunctioning, thereby preventing the sensor from becoming difficult to use. The oscillator 236 is a limiting oscillator that prevents lens-related pulses from becoming too fast and indistinguishable from chattering or becoming difficult to control. A comparator 237 (having a low-pass filter on the output) compares the lens-related pulse with the output pulse of this oscillator 236, and if the lens pulse is abnormally fast, its output is set high and the resistor 2
By turning on the npn-transistor 239 through the lens 38, the speed control (constant control of the amount of movement of the focus plane) by the phase comparator 233 mentioned above is restricted, thereby preventing the lens pulse from becoming abnormally fast and causing malfunction. . That is, turning on transistor 239 lowers the input to amplifier 235, limiting motor power and slowing down, so that different lenses correspond to the drive system.

Next, the motor drive circuit section will be explained. When the motor drive circuit section is not driven, the output of the gate 241 is set low by the low terminal 203, and the inverter 24
Make the output of 2 high and connect it to pnp- through resistor 243.
Turn off transistor 244. OR gate 2
45 has its inverting input low, causing its output to go high, and is connected to the npn-transistor 2 through the resistor 246.
Turn on 47. Similarly, since the output of the AND gate 248 is low, the output of the inverter 249 becomes high and is connected to the pnp-transistor 2 through the resistor 250.
Turn off 51. The inverting input OR gate 252 has an output high due to its inverting input going low, turning on the npn-transistor 254 through the resistor 253. As a result, transistors 247 and 2
Diodes 255 to 25 to prevent damage to the transistors due to turn-on of 54 and back electromotive force of the motor.
8, the motor terminals 259 and 260 are shot and a brake (electromagnetic brake) is applied. If the lens has not reached the above-mentioned limit, the Q output of flip-flop 225 is low.
The outputs of the NAND gates 260 and 261 are high.

For example, if the drive direction terminal 202 is high and the terminal 203 is set high to drive, the output of the AND gate 248 becomes high, the output of the OR gate 252 becomes high, and the transistor 254 turns on.
The low output of inverter 249 turns transistor 251 on. Also, since the output of APD gate 241 is low, the output of OR gate 245 is low, so transistor 247 is off, and since the output of inverter 242 is high, transistor 244 is also off. Therefore, the output (positive) of the amplifier 235 is given to the terminal 259,
Terminal 260 is also grounded by transistor 254 to drive the motor in the desired direction. And if the limit is reached, NAND gate 26
Since the output of 2 becomes low, the drive is stopped.

When driving in the opposite direction, if terminal 202 is low and terminal 203 is high, AND gate 2
The output of the inverter 241 becomes high, and the output of the OR gate 245 becomes high, which turns on the transistor 247. On the other hand, the output of the inverter 242 becomes low, which turns on the transistor 244, and
Due to the low output of AND gate 248, the output of OR gate 212 also becomes low, so transistor 25
4 is off, and since the output of the inverter 249 is high, the transistor 251 is turned off. Therefore, the output (positive) of the amplifier 235 is at terminal 2.
60 and terminal 259 is connected to transistor 2
47 is turned on, it is grounded and the motor is driven in the opposite direction to that described above. If the limit is reached, the output of the NAND gate 261 becomes low, thereby stopping driving. In both cases, when the drive is stopped due to the low drive terminal 203, the brake is applied as described above.

Finally, the drive system unit 15 will be explained with reference to FIG. The configuration shown in the figure corresponds to, for example, a conversion lens for a single-lens reflex camera. That is, in the example shown in the figure, the photographing lens 301 is
Through motor 304 terminals 305, 306
In this example, a similar focus mechanism can be realized not only by extending the entire lens, but also by moving the front lens and some lens groups. here,
Brush 30 linked to lens 301 and grounded
7 and a comb-teeth electrode pattern 308, the above-mentioned lens-related pulse can be outputted to a motor terminal 309 in accordance with the movement of the lens, and the resistor 31
0 allows a code of (defoccus amount)/(1 pulse interval) to be transmitted through the terminal 311. This code makes it possible to change this resistance value in accordance with, for example, zooming, and it is possible to compensate for focus movement by transmitting changes in the amount of lens movement and defocus amount due to zooming. 3
Reference numerals 12 and 313 refer to top members for extending and retracting the lens, and if the lens hits this member, the movement is blocked by the limit detection circuit in the drive control unit 14 shown in FIG. 5, which detects this and stops the drive. Therefore, limit control is possible without using any special switches or the like.

As described in detail above, the present invention eliminates the above-mentioned inconveniences associated with the provision of conventional mechanical switches, and is extremely advantageous in terms of lens drive control and control circuitry. ,
This makes it easy to detect limits suitable for each of various lenses, and is useful for devices that need to know the limits when moving a lens within a predetermined range, especially automatic focusing devices (especially for lens-related devices). It is extremely useful in the form of signal formation.

Incidentally, as an example of means for generating lens-related signals (pulses), in the embodiment (Fig. 6), a mechanical contact type using a brush 307 and a comb-teeth electrode 308 is shown, but of course other means are possible. In addition, non-contact types such as photo interrupters and electromagnetic pick-ups are also fully applicable.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an example of a focus detection method of an automatic focus adjustment device to which the method of the present invention can be applied, and FIG. 2 is a schematic diagram for explaining each of the above automatic focus adjustment devices to which the method of the present invention is applied. A system block diagram showing the general configuration of each functional system; FIG. 3 is a block circuit diagram showing an example of the focus detection unit in FIG. 2;
4 is a block circuit diagram showing an example of the drive instruction unit in FIG. 2, FIG. 5 is a block circuit diagram showing an example of the drive control unit in FIG. 2, and FIG. 6 is a block circuit diagram showing an example of the drive control unit in FIG. FIG. 2 is a schematic diagram showing an example of a system unit. 1,301... Lens, 11... Sensor unit, 12... Focus detection unit, 13... Drive instruction unit, 14... Drive control unit, 15
... Drive system unit, 304 ... Motor, 30
7, 308... Components of lens related signal generation means, 310... Code signal generation means representing the type of lens, 213... Amplifier, 222... Inverting input OR gate, 227... Oscillator, 224...
Frequency divider, 225...RS-flip-flop,
206...A/D converter.

Claims (1)

[Claims] 1. A lens driving circuit that controls the driving speed of the lens so that the amount of movement of the focal plane per unit time is constant according to the type of lens, and also that the lens A signal forming circuit forms a signal that changes repeatedly while moving.
A lens driving device equipped with a lens movement state detection circuit that monitors the movement state of the lens by detecting the signal change with a signal detection circuit, including a timer circuit that measures a predetermined time,
a determination circuit that generates a lens stop signal after time measurement by the timer circuit; and a prohibition means that prohibits the determination circuit from generating a lens stop signal by detecting a signal change in the signal detection circuit; A lens driving device characterized in that the time measured by a circuit can be changed in accordance with the characteristic of the amount of movement of a focusing surface with respect to the unit amount of movement of a lens.