JP2000214372A - Lens drive device and lens position or speed detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lens drive device and a lens position or speed detecting device controlling a lens based on a digital signal by converting an analog control signal outputted from a lens controller and an analog position signal outputted from a lens position detector into a digital signal, and capable of easily and accurately correcting an error caused by the deviation of the respective elements of a circuit for converting an analog signal into a digital signal by correcting the error by a specified arithmetic operation to the acquired digital signal. SOLUTION: An analog control signal outputted from the lens controller 10 is inputted in a CPU 16 through a level conversion circuit 12 and an A/D converter 14. The CPU 16 corrects the error caused by the deviation of the circuit elements in the case of converting the analog control signal into the digital signal by the specified arithmetic operation to the digital signal acquired from the A/D converter 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device and a lens position or speed detecting device, and more particularly to an analog control signal output from a lens controller or the like, an analog position signal output from a position detector, and the like. The present invention relates to a lens driving device and a lens position or speed detecting device that convert a digital signal and recognize the control signal, the position signal, and the like based on the digital signal.

[0002]

2. Description of the Related Art A television lens device mounted on a television camera generally includes a lens driving device for driving a focus lens or a zoom lens based on a control signal applied from a lens controller such as a focus demand or a zoom demand. It is installed. Some lens driving devices include a microcomputer (CPU). If the lens controller outputs an analog control signal (voltage signal) to such a lens driving device, Then, the analog control signal is converted into a digital signal by a level conversion circuit and an A / D converter and input to the microcomputer, whereby the instruction of the lens controller is recognized by the microcomputer. Based on this, the microcomputer controls the position of the focus lens and the zoom lens and the like.

In detecting the position and moving speed of a lens, if the detector (potentiometer or the like) outputs an analog signal (voltage signal), the analog signal is converted into a digital signal. The lens position and the moving speed are recognized by the microcomputer.

[0004]

However, when an analog signal is converted into a digital signal and a control signal, a lens position, and the like are recognized as a digital signal as described above, an error generated in a circuit that converts the analog signal into a digital signal. Is a problem. That is, before the analog signal is converted to a digital signal and input to the microcomputer, the voltage level of the analog signal is changed to A / D in addition to the A / D converter.
A level conversion circuit or the like for converting the input range of the D converter is provided. Usually, an operational amplifier is used for this level conversion circuit, and various resistors are connected to the operational amplifier. For this reason, the voltage of the analog signal converted by the level conversion circuit varies due to the offset of the operational amplifier and the resistance value deviation of the resistor. When the voltage range of the analog signal is 5 V and the A / D converter is 12 bits, the conversion accuracy of the level conversion circuit needs to be 1.2 mV or less.

When an error occurs in the conversion circuit for converting an analog signal into a digital signal, for example, when the lens does not move to a position designated by a lens controller or at a speed, and the position is controlled like a focus lens, If the focus lens does not reach the moving end even though the control signal from the lens controller instructs movement to the moving end, or if the speed is controlled like a zoom lens, the lens controller However, there is a problem that the zoom lens moves slightly without stopping even though the control signal from the camera instructs to stop.

Conventionally, in order to solve such a problem, an offset adjuster (trimmer) and a gain adjuster (trimmer) are provided in a level conversion circuit, and the offset and gain of the level conversion circuit are adjusted by these adjusters. In order to be able to adjust, or to use high precision operational amplifiers and resistors. However, the adjustment of the level conversion circuit is a part that requires high precision, and in the former case, it is difficult to perform high-precision adjustment, and in the latter case, the required precision is high even if high-precision parts are used. Could not get.

The present invention has been made in view of such circumstances, and when an analog control signal or a position signal is converted into a digital signal for recognition, an error included in the digital signal is easily and accurately corrected. It is an object of the present invention to provide a lens driving device and a lens position or speed detecting device which can perform the operation.

[0008]

According to a first aspect of the present invention, an analog control signal indicating a position or a speed of a movable lens is converted into a digital signal, and the digital signal is converted into a digital signal. In a lens driving device that moves the lens by a motor based on the value of, a conversion circuit that converts the analog control signal into a digital signal,
A reference data acquisition unit for inputting a predetermined reference voltage to the conversion circuit and acquiring a value of a digital signal output from the conversion circuit with respect to the reference voltage, and a digital signal acquired by the reference data acquisition unit. Output from the conversion circuit in response to an analog control signal input to the conversion circuit, based on a value and a predetermined value as a value of a digital signal to be output from the conversion circuit with respect to the reference voltage. Correction means for correcting the value of the digital signal obtained as a value of the digital signal to be output from the conversion circuit to a predetermined value, and the motor based on the value of the digital signal corrected by the correction means. Lens driving means for driving and moving the lens at a position or at a speed designated by the analog control signal. To have.

According to the present invention, an error generated when an analog control signal indicating a position or a moving speed of a lens is converted into a digital signal is not removed by adjusting a resistance value of a circuit as in the related art. Since the correction is performed by a predetermined operation on the digital signal acquired from the conversion circuit, the error can be corrected automatically and accurately without any trouble.

According to a second aspect of the present invention, in a lens position or speed detecting device for detecting the position or speed of a movable lens, the position or speed of the lens is detected, and the detection result is converted into an analog signal. And a conversion circuit for converting an analog signal output from the detection means into a digital signal. A predetermined reference voltage is input to the conversion circuit, and the conversion circuit outputs a reference voltage to the reference voltage. Reference data acquisition means for acquiring a value of a digital signal to be obtained, a value of the digital signal acquired by the reference data acquisition means, and a value of a digital signal to be output from the conversion circuit with respect to the reference voltage. And converting the value of the digital signal output from the conversion circuit with respect to the analog signal input to the conversion circuit, And correcting means for correcting the predetermined value as the value of the digital signal to be outputted from the road,
And a lens position or speed detecting means for detecting the position or speed of the lens based on the value of the digital signal corrected by the correcting means.

According to the present invention, an error generated when an analog signal indicating the position or speed of a lens is converted into a digital signal is not removed by adjusting the resistance value of the circuit as in the conventional case, but is converted by a conversion circuit. Because it was corrected by a predetermined operation on the digital signal obtained from
The error can be corrected automatically and accurately without any trouble.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a lens driving device and a lens position or speed detecting device according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a circuit configuration of a lens driving device applied to a television lens. The lens driving device shown in FIG. 1 drives a lens 22 of a television lens by a motor 20 based on an operation of a lens controller 10, and the lens controller 10 performs, for example, a focus demand for indicating a position of a focus lens, or a movement of a zoom lens. This corresponds to a zoom demand or the like that indicates a speed. From the lens controller 10, 2.5 V to 7.
A voltage signal of 5 V is output. Hereinafter, this voltage signal is referred to as an analog control signal.

The analog control signal output from the lens controller 10 is first input to a level conversion circuit 12, where it is converted to a voltage signal of 0 to 5V. Subsequently, the analog control signal is input to the A / D converter 14 and is converted into an 8-bit digital signal. That is,
The voltage signal of 0 to 5 V is converted into a digital signal of 00H to FFH. Then, this digital signal is input from the A / D converter 14 to the CPU 16.

The CPU 16 detects the position of the lens 22 or the moving speed of the lens 22 specified by the lens controller 10 from the value of the digital signal obtained as described above. That is, when the CPU 16 of the lens driving device is to perform position control corresponding to the lens controller 10 for instructing the position of the lens such as a focus demand, the lens controller 10 instructs the lens controller 10 from the value of the acquired digital signal. CPU 16 recognizes the position of the lens
Is to perform speed control corresponding to the lens controller 10 that instructs the movement speed of the lens such as zoom demand, the movement speed of the lens indicated by the lens controller 10 is determined from the value of the obtained digital signal. recognize. Then, an instruction signal for moving the lens 22 to the instructed position or at the moving speed is sent to the driving circuit 18.
Output to The drive circuit 18 drives the motor 20 based on an instruction from the CPU 16 to move the lens 22 to a specified position or at a moving speed.

As described above, the CPU 16 controls the voltage of the analog control signal output from the lens controller 10 from 0 to 0.
5V is recognized by a corresponding value from 00H to FFH of the digital signal, and the lens 22 is moved to a position or a speed determined in advance with respect to the value of the digital signal. By the way, the digital signal input to the CPU 16 usually includes
The digital signal includes an error caused by a deviation (tolerance) of circuit elements constituting the level conversion circuit 12 and the A / D converter 14, and this digital signal is converted into an A / D converter with respect to the voltage of the analog control signal. 14 differs from a value determined in advance as a value of the digital signal to be output from the digital signal processor 14. That is, the value of the digital signal actually output from the A / D converter 14 with respect to the voltage of the analog control signal input to the level conversion circuit 12 depends on the deviation of the circuit element, and Different from signal value. For this reason, there occurs a problem that the position or speed at which the lens 22 actually moves does not match the position or speed of the lens 22 specified by the lens controller 10. In the present invention, in order to prevent such a problem, the value of the digital signal obtained from the A / D converter 14 becomes the value of the digital signal that should originally correspond to the voltage of the analog control signal output from the lens controller 10. As described above, the CPU 16 corrects the error. In the following description, a value of a digital signal that is predetermined as a value of a digital signal that should correspond to the analog control signal is simply referred to as an “original digital signal value”.

FIG. 2 is a circuit diagram showing the level conversion circuit 12, the A / D converter 14, and its peripheral circuits of the lens driving device according to the present invention. As shown in the figure, a switch 24 is connected between the lens controller 10 and the level conversion circuit 12, and the lens controller 10 is connected to a terminal 0 of the switch 24 to which an input terminal of the level conversion circuit 12 is connected. Terminal 1 of the switch 24
When the switch 24 to the reference voltage C _L of 2.5V is applied
And terminal 2 of the terminal 3 of the switch 24 to the reference voltage C _M of 5V is applied, so that the terminal 4 of the switch 24 to the reference voltage C _H of 7.5V is applied are switchably connected Has become. The reference voltages C _L , C _M , and C _H are generated by the power supply of the lens driving device, and their operations will be described later.

The analog control signal of 2.5 V to 7.5 V output from the lens controller 10 is input to the level conversion circuit 12 via the switch 24. The level conversion circuit 12 converts the voltage level of the analog control signal as described above, and the level conversion circuit 12 uses an operational amplifier OP. The terminal 0 of the switch 24 is connected to the non-inverting input terminal of the operational amplifier OP via a resistor R1 of 100 kΩ, and a voltage (VREF / 2) of 2.53 V is connected via a resistor R2 of 100 kΩ. . On the other hand, a resistor R4 of 100 kΩ is connected between the inverting input terminal and the output terminal, and a voltage of 5 V is connected via a resistor R1 of 100 kΩ. The switch 2 is provided by the level conversion circuit 12 configured as described above.
Of the analog control signal input from the terminal 0
Is:

[0018]

## EQU1 ## The output voltage is converted into an output voltage Vo by Vo = Vi-2.47. Therefore, an analog control signal of 2.5 to 7.5 V output from the lens controller 10 is output by the level conversion circuit 12.
It is converted to a voltage of 0.03 to 5.03V. In FIG. 1, it has been described that the voltage is converted to a voltage of 0 to 5 V.
By setting the lower limit to 0.03 V instead of 0 V, it is possible to prevent the output voltage of the level conversion circuit 12 from becoming smaller than the lower limit 0 V of the input range of the A / D converter 14 due to the deviation of circuit elements.

The A / D converter 14 is formed of an IC chip, and converts the voltage signal of 0.03 to 5.03 V output from the level conversion circuit 12 into an 8-bit digital signal as described above. Since a voltage of 5.06 V (VREF) is applied to a VREF terminal that determines the input range of the A / D converter 14, the input range of the A / D converter 14 is 0 to 5.06V. It is. Therefore, the A / D converter 14 converts the voltage signal in this range into a digital signal of 00H to FFH. Note that the upper limit of the input range is 5.0
By setting the voltage to 6 V, the upper limit of the analog control signal of 0.03 to 5.03 V output from the level conversion circuit 12 does not exceed the range of the input range due to an error in the circuit element.

The CPU 16 corrects the error of the digital signal input from the A / D converter 14 as described above in the following procedure. First, when power is turned on, C
PU16 a reference voltage C _L terminal 0 of the switch 24
(2.5 V), C _M (5.0 V), and C _H (7.5 V) are sequentially connected to terminals 2 to 4, and the reference voltage C _{L to} C _{H is} supplied to the level conversion circuit 12 instead of the analog control signal. And enter
At this time, the value of the digital signal output from the A / D converter 14 is obtained. The digital signal values obtained for the respective reference voltages C _L , C _M , and C _H are denoted by C _LD ,
C _MD and C _HD .

The CPU 16 supplies a reference voltage C _L (2.
_{5V), C M (5.0V)} , the original value C _LR of the digital signals corresponding to _{C H (7.5V), C MR} , is recorded in advance internal memory C _HR. The CPU 16 calculates a gain correction value A and an offset correction value B used for the correction based on the data. The gain correction value A is given by the following equation:

[0022]

A = (C _HR −C _LR ) / (C _HD −C _LD ) (1) On the other hand, the offset correction value B is given by the following equation:

[0023]

2B = (C _HD + C _LD ) − (C _HR + C _LR ) (2) If the correction values A and B can be registered in the non-volatile memory, the process of obtaining these correction values A and B can be omitted from the next power-on. The switch 2 for determining the correction values A and B
The switching of the connection 4 may be manually performed by the user. In this case, the CPU 16 can detect which terminal the terminal 0 of the switch 24 is currently connected to.

Next, the CPU 16 connects the terminal 0 of the switch 24 to the terminal 1 and inputs an analog control signal of the lens controller 10 to the level conversion circuit 12. Thereby, the control of the lens 22 is started, and the lens controller 1
The analog control signal output from 0 is converted to a level conversion circuit 1
2 and a digital signal via the A / D converter 14. The value of the digital signal obtained at this time is represented by SIG.
DATA. Here, the CPU 16 determines whether the SIG. DA
TA is corrected to the value of the original digital signal.
6 is a lens controller 1 for indicating the position of the lens 22
The correction is different between the case where the position control is performed corresponding to 0 and the case where the speed control is performed corresponding to the lens controller 10 that instructs the moving speed of the lens 22.

First, when performing position control, the lower limit and the upper limit of the value of the digital signal obtained from the A / D converter 14 are set to the lower limit (2.5 V) and the upper limit (7.5 V) of the analog control signal.
Are matched with the original digital signal values C _LR and C _HR corresponding to, so that the lens 22 can be appropriately moved to the end point of the movement range. Accordingly, CPU 16 has the following formula values C _LD of the digital signal obtained for 2.5V reference voltage C _L as a reference,

[0026]

D = SIG. The value of D is calculated from DATA-C _LD (3). Then, using the gain correction value A obtained by the above equation (1), a value E obtained by adjusting the gain of the value D is expressed by the following equation:

[0027]

E = A × D (4) Subsequently, using the offset correction value B obtained by the above equation (2), a value F obtained by performing an offset adjustment on the value of E is expressed by the following equation:

[0028]

F = E−B (5) From the value F obtained by the equation (5),
The CPU 16 can acquire the value of the original digital signal corresponding to the analog control signal output from the lens controller 10. By moving the lens 22 to a position corresponding to the value of F, the lens 22
Moves accurately to the position specified by the lens controller 10.

On the other hand, when the CPU 16 performs speed control,
Normally, the output range from the lens controller 10 is 2.5 V to
In order to control the lens 22 to stop when the median value of 7.5 V, that is, the voltage of 5 V is output, the value of the digital signal obtained when the analog control signal of 5 V is output is When the lens controller 10 instructs the stop, the lens 22 is stopped appropriately so as to match the original digital signal value C _MR corresponding to the analog control signal of 5 V. Accordingly, CPU 16 has the formula based on the value C _MD of the digital signal obtained for the reference voltage C _M of 5V,

[0030]

G = SIG. The value of G is calculated by DATA-C _MD (6). Then, using the gain correction value A obtained by the above equation (1), a value H obtained by adjusting the gain of this G value is expressed by the following equation:

[0031]

H = A × G (7) The CPU 16 can obtain the original digital signal value C _MR corresponding to the analog control signal of 5 V when the voltage of 5 V is output from the lens controller 10 based on the value H obtained by the equation (7). When the lens controller 10 instructs the stop,
The lens 22 can be stopped appropriately.

As described above, in the above embodiment, the lens 2 is controlled based on the analog control signal from the lens controller 10.
The lens driving device for controlling the position and the moving speed of the lens driving device 2 has been described. However, the present invention is not limited to this. The present invention can be applied even to a control signal or the like from an external device.

Further, the present invention can be applied to a lens position detecting device and a lens speed detecting device for detecting a position and a moving speed of a lens in the same manner as the circuit configuration shown in FIG. That is, if a detector (a potentiometer or the like) for detecting the position or the moving speed of the lens 22 is connected instead of the lens controller 10 in FIG. 2, an analog position signal or speed signal output from the detector Can be accurately detected by the above-described correction calculation. Further, such a configuration of the detecting device can be applied as a feedback circuit that feeds back the position or the moving speed of the lens 22 to the CPU 16 in the lens driving device of FIG. In this case, the CPU 16 can accurately detect the analog control signal from the lens controller 10 based on the value of the digital signal obtained by the above-described correction operation, and also determines the position or the moving speed of the lens 22 by the feedback circuit. Since the detection can be accurately performed by the correction calculation, the lens 22 can be controlled with high accuracy by the feedback control.

The numerical values such as the voltage value and the resistance value specifically shown in the above-described embodiment are merely examples, and are not particularly limited to the numerical values.

[0035]

As described above, according to the lens driving device and the lens position and speed detecting device according to the present invention, an analog control signal indicating a lens position and the like and an analog position signal indicating a lens position and the like are output. When recognizing with a digital signal, an error generated in a circuit that converts an analog signal into a digital signal is not removed by adjusting the resistance value or the like of the conversion circuit as in the related art. By performing the correction by a predetermined calculation, the error can be corrected automatically and accurately without any trouble.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a lens driving device applied to a television lens.

FIG. 2 is a circuit diagram showing a main configuration of a lens driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Lens controller 12 ... Level conversion circuit 14 ... A / D converter 16 ... CPU 18 ... Drive circuit 20 ... Motor 22 ... Lens

Claims (2)

[Claims] 1. A lens driving device for converting an analog control signal indicating a position or a speed of a movable lens into a digital signal and moving the lens by a motor based on a value of the digital signal, wherein the analog control signal A conversion circuit that converts a digital signal into a digital signal; a reference data acquisition unit that inputs a predetermined reference voltage to the conversion circuit and acquires a value of a digital signal output from the conversion circuit with respect to the reference voltage; Based on the value of the digital signal obtained by the data obtaining means and the value of the digital signal to be output from the conversion circuit with respect to the reference voltage, the analog signal input to the conversion circuit is used. The value of the digital signal output from the conversion circuit with respect to the control signal, the digital signal to be output from the conversion circuit Correction means for correcting to a predetermined value, and driving the motor based on the value of the digital signal corrected by the correction means, and moving the lens to a position or at a speed specified by the analog control signal A lens driving device for driving the lens. 2. A lens position or speed detecting device for detecting the position or speed of a movable lens, comprising: detecting means for detecting the position or speed of the lens and outputting the detected result as an analog signal; A conversion circuit for converting an analog signal output from the means into a digital signal; and a reference for inputting a predetermined reference voltage to the conversion circuit and obtaining a value of the digital signal output from the conversion circuit with respect to the reference voltage. Data acquisition means, based on a value of the digital signal acquired by the reference data acquisition means, and a value predetermined as a value of the digital signal to be output from the conversion circuit with respect to the reference voltage, The value of the digital signal output from the conversion circuit with respect to the analog signal input to the conversion circuit is converted to a digital value to be output from the conversion circuit. Correction means for correcting the value of the digital signal to a predetermined value, and lens position or speed detection means for detecting the position or speed of the lens based on the value of the digital signal corrected by the correction means. A lens position or speed detecting device.