JP4809415B2 - Iris control device and iris control method - Google Patents

Description

  The present invention relates to an iris control device and an iris control method that are used in an optical apparatus and control an opening / closing operation of an iris.

  2. Description of the Related Art Conventionally, an imaging device such as a digital camera has an iris (IRIS: stop) on an incident optical path so that an image with appropriate luminance can be obtained, and an object image condensed through the iris is captured by an imaging element ( For example, there is one configured to form an image on a light receiving surface of a CCD).

  For example, as illustrated in FIG. 6A, the imaging device 100 collects light from the subject with the imaging lens 21, adjusts the light amount to an appropriate amount with the iris 22, and forms an image on the imaging element 23. Next, after being converted into a video signal by the image sensor 23 and amplified by the amplifier 24, the exposure level detection circuit 27 detects the luminance level of the video signal. Next, the aperture value determination circuit 28 determines how to change the aperture value based on the detected luminance level, and sends the command signal (reference value of the iris opening amount) to the iris control device 101. Send to. Next, upon receiving the command signal, the iris control device 101 drives the actuator 31 so that the opening area of the iris 22 is in a position corresponding to the command value, and controls the video signal level to be in an appropriate range. To do.

  The iris 22 is composed of a plurality of blade members, and these blade members open in a direction perpendicular to the optical axis of the incident light, and are configured to guide the amount of light corresponding to the opening size to the image sensor 23. . At that time, an actuator 31 such as a drive motor (hereinafter also referred to as drive motor 31) is used as a drive source for the operation of the iris 22, and the opening / closing operation of the iris 22 is controlled through the drive control of the drive motor 31. .

Specifically, as shown in FIG. 6B, the luminance Sy imaged on the image sensor 23 is taken into the iris control device 101 and processed inside the iris control device 101. The iris control device 101 takes the luminance Sy into the comparison operation unit 29a, performs A / D conversion, compares it with an appropriate reference value Sb, and outputs a difference from the reference value Sb to the addition operation unit 29b. On the other hand, when the position information Sr of the rotor 31b which is output from the rotor rotation angle measurement circuit 32 is captured by the A / D conversion in the differentiating unit 29c are both differential operation, rotor speed signal adder is the result 21 is output.

  The addition calculation unit 21b generates control data based on the difference from the input specified value and the rotor speed signal, and supplies the generated control data to the integration calculation unit 29d for integration, and the integration is performed. The generated data is PWMed to generate a drive signal Sd, which is output to the IRIS motor driver 30.

  The IRIS motor driver 30 is provided as means for generating a magnetic field for rotating the rotor 20b according to the drive signal Sd output from the iris control device 29, and amplifies the control signal Sd to a predetermined level via the amplifier 31c. Then, a drive signal of the drive motor 31 is generated and supplied to the drive coil 31a. A current corresponding to the magnitude of the drive signal output from the amplifier 31c flows through the drive coil 31a, and a magnetic field corresponding to the current is generated.

  At that time, a switching element (not shown) provided in the driving circuit is switched at high speed by a pulse width demodulated signal (hereinafter also referred to as a PWM (pulse width modulation) signal), thereby achieving a duty ratio of the on time of the PWM signal. Corresponding electric power is supplied to the drive motor, and the rotation operation of the drive motor is controlled.

  On the other hand, the electromotive force generated by the movement of the rotor 31b is taken into the rotor rotation angle measurement unit 32 via the Hall element 33, is generated as a rotation position signal of the rotor 31b, and is fed back to the actuator control circuit 29.

  That is, the magnetic flux density changed by the rotation of the rotor 31b is detected by the Hall element 33, and a voltage corresponding to the rotation angle of the rotor 31b is output from the Hall element 33. The voltage output from the Hall element 33 is amplified and the rotor is amplified. The rotation angle measurement circuit 32 takes in the information about the opening / closing operation amount of the iris 32.

The iris control device 101 controls the opening / closing operation of the iris 22 by feedback-controlling the rotation operation of the drive motor 31 based on information on the opening / closing operation amount of the iris detected via the hall element 33. (For example, refer to Patent Document 1).
JP 7-239492 A

  By the way, when the iris opening diameter is small in the iris opening / closing operation range, the rate of change of the incident light amount with respect to the constant opening / closing operation amount of the iris (a constant opening amount operation amount) is large, and the iris opening diameter is large. Accordingly, the change rate of the amount of incident light with respect to a fixed operation amount of the iris opening / closing operation appears small.

  However, according to the conventional iris control technology, since the resolution for controlling the iris opening / closing operation is constant over almost the entire opening diameter of the iris opening / closing operation, the minimum controllable amount of incident light changes according to the change in the opening diameter. However, there is a problem that it cannot be obtained uniformly over the entire opening / closing operation. That is, the amount of incident light is proportional to the aperture area and proportional to the square of the aperture diameter. Therefore, if the control amount of the iris opening operation is made uniform over substantially the entire aperture diameter in the iris opening / closing operation, the aperture diameter becomes small. As the amount of incident light is controlled, the control amount becomes coarse.

  Further, when the amount of incident light is controlled through the iris, the change in the amount of incident light increases as the aperture diameter decreases with respect to a constant opening / closing operation amount of the iris, which may impair operability.

  Therefore, the present invention provides an iris control device and an iris control method capable of controlling with high accuracy and at an appropriate speed without causing the control amount of the incident light amount to be non-uniform throughout the iris opening / closing operation. With the goal.

In order to achieve the above object, the invention according to claim 1 is an iris control device that applies a pulse signal to an actuator and controls an opening / closing operation of the iris in accordance with a duty ratio of the pulse signal. The actuator includes an inductor having S and N poles magnetized on the outer surface, a drive coil disposed so as to face the outer surface of the inductor, and a drive for applying a driving voltage to the drive coil. And a control means for controlling the opening / closing operation of the iris with different resolutions, and the control means associates the resolution of the control of the opening / closing action with the opening diameter of the iris. Resolution switching means for finely switching as the diameter decreases is provided, and the resolution switching means is provided on the supply path of the drive voltage to the drive coil. A first switching unit that is connected to one end of the drive coil, switches the presence / absence of connection of a predetermined resistance to the drive coil, and switches the drive voltage applied to the drive coil; And a second switching means that is connected to an end and switches between application and interruption of the pulse signal applied to the drive coil, and the first switching means has an opening diameter of the iris of a predetermined opening diameter. The predetermined resistance is connected to the drive coil when the diameter is smaller than the predetermined resistance, and when the opening diameter of the iris is larger than the predetermined opening diameter, the predetermined resistance is connected to the drive coil. blocked, said second switching means, in response to said opening diameter and switching of connection of the resistance of the first switching means of said iris The duty ratio of the pulse signal at the predetermined opening diameter is larger than when the resistor is disconnected when the resistor is connected; and In a range where the opening diameter is small via the predetermined opening diameter, the change in the duty ratio of the pulse signal with respect to the change of the opening diameter of the iris is made larger than the large range via the predetermined opening diameter. It is characterized by being.

According to the iris control device of the first aspect, the resolution switching means is provided which switches the resolution of the control of the opening / closing operation of the iris more precisely as the opening diameter becomes smaller in correspondence with the opening diameter of the iris. Is connected to one end of the drive coil on the supply path of the drive voltage to the drive coil, and switches the drive voltage applied to the drive coil by switching the presence or absence of a predetermined resistance to the drive coil. Switching means, and a second switching means connected to the other end of the drive coil and switching between applying and interrupting a pulse signal applied to the drive coil. The first switching means has an aperture diameter of the iris. Is connected to the drive coil when the diameter becomes smaller than the predetermined opening diameter, while the iris opening diameter is the predetermined opening Shutdown connection predetermined resistance to the drive coil when it becomes more, the second switching means, the duty ratio of the pulse signal in accordance with the opening diameter and switching of connection of the resistance of the first switching means of the iris The duty ratio of the pulse signal at a predetermined opening diameter is made larger than when the resistance is cut off when the resistor is connected, and the opening diameter is set via the predetermined opening diameter. In a small range, the change in the duty ratio of the pulse signal with respect to the change in the aperture diameter of the iris is configured to be larger than the large range via the predetermined aperture diameter . The resolution for controlling the amount of incident light does not become non-uniform and can be controlled with high accuracy and at an appropriate speed.

That is, in the opening / closing operation range of the iris, as the iris opening diameter becomes smaller, the change rate of the incident light quantity with respect to the constant operation amount of the iris opening / closing (which is the constant operation amount of the opening diameter) is greatly expressed . By connecting a resistor via the first switching means when the opening diameter becomes smaller, the current flowing in the drive coil with respect to the change in the control amount is reduced, and the opening / closing operation amount per pulse is also reduced. The resolution for controlling the opening / closing operation of the aperture can be precisely switched, and the amount of incident light can be accurately controlled regardless of the change in aperture. Further, by increasing the resolution of the control of the opening / closing operation as the opening diameter increases, the control speed can be improved and the load required for the control can be reduced.

In the iris control device according to claim 1, since the opening / closing amount of the iris depends on the current flowing through the drive coil, the second switching means is configured to connect the opening diameter of the iris and the resistance of the first switching means. It is configured to switch the duty ratio of the pulse signal according to the switching, and the duty ratio of the pulse signal at a predetermined opening diameter is larger than when the resistance is cut off when the resistance is connected, and In the range where the aperture diameter is small through the predetermined aperture diameter, the change in the duty ratio of the pulse signal to the change in the aperture diameter of the iris is configured to be larger than the large range through the predetermined aperture diameter. Is preferred.

Next, the iris control apparatus according to claim 1, as in the invention according to claim 2, a sensor for outputting an electric signal corresponding to the opening and closing operation of the iris, the electric signal output from the sensor Amplifying means for detecting the opening / closing operation amount of the iris based on the electrical signal amplified by the amplifying means, and the amplifying means for the predetermined resistance in the resolution switching means In association with the presence or absence of connection, when the iris opening diameter is smaller than the predetermined opening diameter, the amplification degree of the electrical signal is switched so as to increase the amplification degree when larger than the predetermined opening diameter, The amount of change in the electrical signal output from the amplifying means with respect to the predetermined operation amount of the iris is, for example, in a range where the opening diameter is large and small via the predetermined opening diameter. Characterized in that it is configured to Kusuru so.

The iris control device according to claim 2 outputs an electrical signal corresponding to the opening / closing operation amount of the iris through the sensor, and then amplifies the electrical signal output from the sensor and based on the amplified electrical signal. The opening / closing operation amount of the iris is detected, and the amplifying means is associated with the presence / absence of connection of the predetermined resistance in the resolution switching means, and the predetermined opening diameter is smaller than the predetermined opening diameter. The degree of amplification of the electrical signal is switched so that the amplification degree is larger than when it is larger than the opening diameter, and the change amount of the electrical signal output from the amplifying means with respect to the predetermined operation amount of the iris is changed via the predetermined opening diameter. Te by opening diameter is configured to equalize in the range of the range and the small becomes large, over the entire opening and closing operation of the iris, detection of the opening and closing operation of the iris Not be able to properly detect that the loss of accuracy.

That is, according to the iris control device of the second aspect, when the resolution for controlling the iris opening / closing operation is finely switched by the resolution switching means, the amplification means for amplifying the operation amount is increased to increase the amplification means. The resolution of the electrical signal output through the amplifier is increased while the resolution of the electrical signal output through the amplifier is decreased. As a result, the resolution for detecting the iris opening / closing operation can be obtained with high accuracy and the operability when controlling the amount of incident light can be improved.

Further, the iris control apparatus according to claim 2, the range in which the variation of the electric signal outputted from the amplifying means to a predetermined operation amount of the iris, the aperture diameter through a predetermined aperture diameter becomes larger By making it equal in the small range, the amount of change in the electrical signal of the iris operation output via the amplifying means can be matched with the amount of change in the incident light amount, and the operability when controlling the incident light amount is improved. Can be improved.

According to a first aspect of the present invention, the iris control device according to the first aspect of the present invention includes a sensor that outputs an electric signal corresponding to the opening / closing operation amount of the iris, and an electric signal output from the sensor. amplifying means for amplifying, detecting means for detecting the opening and closing operation of the iris based on the amplified electric signal in the amplifying means, and sensitivity switching means for switching the sensitivity of the sensor for a given operation amount of the iris, the The sensitivity switching means includes a first sensitivity when the resistor is connected and a second sensitivity when the resistor is disconnected according to whether the predetermined resistance is connected or not in the resolution switching means. The amount of change in the electrical signal after the sensitivity is switched is equal between the first sensitivity and the second sensitivity with respect to the predetermined operation amount of the iris. By being configured, it can not accurately detect that impair the detection accuracy of the opening and closing operation of the iris.

That is, according to the iris control device of the third aspect, when the resolution of the control of the iris opening / closing operation is precisely switched by the resolution switching means, the sensitivity of the sensor is increased and the electric power output via the sensor is increased. While increasing the signal resolution, on the other hand, when it is roughly switched by the resolution switching means, by reducing the sensitivity of the sensor and decreasing the resolution of the electrical signal output through the sensor, over the entire iris opening and closing operation, The resolution for detecting the opening / closing operation of the iris can be obtained with high accuracy, and the operability when controlling the amount of incident light can be improved.

In the iris control device according to the third aspect, the change amount of the electric signal after the sensitivity is switched is equal between the first sensitivity and the second sensitivity with respect to the predetermined operation amount of the iris. With this configuration , when the resolution for controlling the iris opening / closing operation is switched by the resolution switching means, the change amount of the electrical signal of the iris operation output via the sensor is matched with the change amount of the incident light amount. Therefore, operability when controlling the amount of incident light can be improved.

Next, an invention according to claim 4 is an iris control method in which a pulse signal is applied to an actuator and an opening / closing operation of the iris is controlled in accordance with a duty ratio of the pulse signal. Using an inductor having a pole and an N pole magnetized on the outer surface, a drive coil arranged to face the outer surface of the inductor, and a drive circuit for applying a drive voltage to the drive coil, A control step for controlling the opening and closing operation of the iris with different resolutions;
A resolution switching step of switching the resolution of the iris opening / closing operation in association with the opening diameter of the iris and finely switching as the opening diameter decreases, and the resolution switching step includes: On the supply path to the drive coil, a first switching step for switching the drive voltage applied to the drive coil by switching presence / absence of connection of a predetermined resistance to the drive coil, and applying to the drive coil A second switching step for switching between application and interruption of the pulse signal, and in the first switching step, when the iris opening diameter becomes smaller than a predetermined opening diameter, A predetermined resistance is connected, while the opening diameter of the iris is larger than the predetermined opening diameter; The cut off the connection of the predetermined resistance to the drive coils upon Tsu, the second in the switching step, the pulse signal in response to the opening diameter and the first switching connection resistance of the switching steps of the iris The duty ratio of the pulse signal at the predetermined opening diameter is made larger than when the resistor is cut off when the resistor is connected, and the predetermined ratio is set. The change in the duty ratio of the pulse signal with respect to the change in the opening diameter of the iris is made larger than the large range through the predetermined opening diameter in a range where the opening diameter is small through the opening diameter. To do.

The iris control method according to claim 4 uses a resolution switching step in which the resolution of controlling the opening / closing operation of the iris is correlated with the aperture diameter of the iris, and is switched more precisely as the aperture diameter becomes smaller. A first switching step for switching a driving voltage to be applied to the driving coil by switching whether or not a predetermined resistance is connected to the driving coil on a supply path of the driving voltage to the driving coil, and a pulse to be applied to the driving coil A second switching step for switching between application and interruption of a signal, and in the first switching step, a predetermined resistance is connected to the drive coil when the aperture diameter of the iris becomes smaller than the predetermined aperture diameter. On the other hand, when the opening diameter of the iris becomes larger than the predetermined opening diameter, the predetermined resistance with respect to the drive coil is reduced. In connection blocks the second switching step, is configured to switch the duty ratio of the pulse signal in accordance with the opening diameter and a first switching connection resistance of the switching steps of the iris, at a given aperture size A pulse for a change in the aperture diameter of the iris within a range in which the duty ratio of the pulse signal is larger than when the resistance is cut off when the resistance is connected and the opening diameter is small through a predetermined opening diameter By making the change in the duty ratio of the signal larger than a large range through a predetermined aperture diameter, the resolution of the control of the incident light amount can be achieved over the entire area of the iris opening / closing operation, as in the first aspect of the invention. It does not become non-uniform and can be controlled with high accuracy and at an appropriate speed.

The iris control method according to claim 4 is configured to switch the duty ratio of the pulse signal in the second switching step in accordance with the switching of the opening diameter of the iris and the connection of the resistor in the first switching step. In the range where the duty ratio of the pulse signal at the predetermined opening diameter is larger than that when the resistance is cut off when the resistance is connected and the opening diameter is small via the predetermined opening diameter, It is preferable to make the change in the duty ratio of the pulse signal with respect to the change in the opening diameter larger than the large range through the predetermined opening diameter .

In the iris control method according to claim 4 , the resolution switching step switches the driving voltage to be applied to the driving coil by switching the presence or absence of a predetermined resistance on the supply path of the driving voltage to the driving coil. Thus, similarly to the first aspect of the invention, when a resistance is added, the amount of change in the current flowing through the drive coil with respect to the change in the control amount is reduced, and the resolution for iris control can be improved.

Next, according to a fourth aspect of the present invention, in the iris control method according to the fifth aspect, the iris operation amount detecting step for outputting an electric signal corresponding to the opening / closing operation amount of the iris, and the iris operation amount are provided. An amplification step for amplifying the electrical signal detected through the detection step, and a feedback control step for feedback-controlling the opening / closing operation amount of the iris based on the electrical signal amplified in the amplification step, Corresponding to the presence / absence of connection of the predetermined resistor in the resolution switching step , when the amplification step is smaller than the predetermined opening diameter, the amplification degree is larger than that when the iris is larger than the predetermined opening diameter. The amplification degree of the electric signal is switched so as to increase, and the electric power after the amplification is performed with respect to a predetermined operation amount of the iris. The variation of the signal, the opening diameter through said predetermined opening diameter is equal at the range of the range and the small becomes large, by, similarly to the invention according to claim 2, the opening and closing operation of the iris Can be detected properly without degrading the detection accuracy.

According to a fifth aspect of the present invention, in the iris control method according to the fifth aspect, the electric signal after being amplified with respect to the predetermined operation amount of the iris is divided into a range in which the opening diameter is increased and a range in which the opening diameter is increased through the predetermined opening diameter. As in the second aspect of the present invention, when the resolution of the control of the iris opening / closing operation is switched by the resolution switching step, the change in the electric signal of the iris operation output through the amplification step is performed. The amount can be adjusted to the amount of change in the incident light quantity, and the operability when controlling the incident light quantity can be improved.

According to a fourth aspect of the present invention, in the iris control method according to the sixth aspect, the iris operation amount detection step for outputting an electrical signal corresponding to the opening / closing operation amount of the iris, and the iris operation amount detection An amplification step for amplifying the electrical signal detected through the step, a feedback control step for feedback controlling the opening / closing operation amount of the iris based on the electrical signal amplified in the amplification step, and the iris operation amount detection A sensitivity switching step for switching the detection sensitivity of the step, wherein the sensitivity switching step is associated with the presence or absence of the connection of the predetermined resistor in the resolution switching step, Switch to the second sensitivity when the connection of the resistor is interrupted, Since the amount of change in the electrical signal after the sensitivity is switched is equal between the first sensitivity and the second sensitivity , the opening / closing operation amount of the iris is similar to the invention according to claim 3 . Appropriate detection is possible without impairing the detection accuracy.

Further, in the iris control method according to the sixth aspect, the change amount of the electric signal after the sensitivity is switched is equal between the first sensitivity and the second sensitivity with respect to the predetermined operation amount of the iris. Thus, similarly to the third aspect of the invention, when the resolution of the control of the iris opening / closing operation is switched by the resolution switching step, the change amount of the electric signal of the iris operation output through the sensor is calculated as the incident light amount. The amount of change can be matched, and the operability when controlling the amount of incident light can be improved.

  The iris control device and the iris control method according to the present invention relate to the opening diameter of the iris, and switch the resolution of the opening / closing operation of the iris more precisely as the opening diameter becomes smaller. The resolution of the control of the incident light quantity does not become non-uniform so that it can be controlled with high accuracy and the operability can be improved.

  In other words, as the iris aperture diameter decreases, the change rate of the incident light quantity with respect to a constant operation amount of the iris opening and closing (which is a constant operation amount of the aperture diameter) becomes larger, so that the opening / closing operation of the aperture diameter decreases as the aperture diameter decreases. By precisely switching the control resolution, the amount of incident light can be accurately controlled regardless of the change in aperture diameter. Further, by increasing the resolution of the control of the opening / closing operation as the opening diameter increases, the control speed can be improved and the load required for the control can be reduced.

  An iris control device and an iris control method according to the present invention are an iris control device and an iris control method for applying an pulse signal to an actuator and controlling an open / close operation of the iris in accordance with a duty ratio of the pulse signal. By switching so that the opening / closing operation of the iris with respect to the change of the duty ratio of the pulse signal becomes finer as the aperture becomes smaller, the resolution of the control of the opening / closing operation of the iris can be changed more precisely as the aperture diameter becomes smaller. .

Further, the iris control device and the iris control method of the present invention add a resistor by switching the voltage applied to the drive coil by switching the presence or absence of connection of a predetermined resistor on the supply path of the drive voltage to the drive coil. In this case, the current flowing through the drive coil with respect to the change in the control amount is also reduced, and the iris control resolution can be precisely switched.

  Further, the iris control device and the iris control method of the present invention, when the resolution of the control of the iris opening / closing operation is precisely switched, increases the amplification degree of the electric signal representing the amount of operation of the iris detected through the sensor. To increase the resolution of the electrical signal. On the other hand, when the control resolution of the iris opening / closing operation is roughly switched, the electrical signal resolution is reduced by lowering the degree of amplification of the electrical signal representing the operation amount detected through the sensor. By reducing the value, the accuracy of detection of the iris opening / closing operation in the entire area of the iris opening / closing operation can be made appropriate. Also, at this time, the amount of electric signal after amplification is substantially equal between the plurality of resolutions with respect to the predetermined operation amount of the iris, so that the sensor is switched when the resolution of the control of the iris opening / closing operation is switched. The amount of change in the electrical signal of the iris operation detected via this can be matched to the amount of change in the incident light amount, and the operability when controlling the incident light amount can be improved.

  In addition, the iris control device and the iris control method of the present invention increase the sensitivity of the sensor and increase the resolution of the electric signal output through the sensor when the resolution of the iris opening / closing operation control is finely switched. On the other hand, when the control resolution of the iris opening / closing operation is roughly switched, the iris sensitivity is lowered to lower the resolution of the electric signal output through the sensor, thereby reducing the iris opening / closing operation over the entire area. The accuracy of the detection of the opening / closing operation can be optimized. At this time, since the change amount of the electrical signal of the iris operation after the sensitivity of the sensor is switched with respect to the predetermined operation amount of the iris is substantially equal at a plurality of different resolutions, the iris opening / closing operation is performed. When the control resolution is switched, the change amount of the electrical signal of the iris operation output via the sensor can be matched with the change amount of the incident light amount, and the operability when controlling the incident light amount can be improved. .

  Next, an embodiment of an iris control device and an iris control method of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an iris control device 1 of the present embodiment, FIG. 2 is a diagram showing an iris drive circuit in the iris control device 1 of the same embodiment, and FIG. 3 is an iris control device of the same embodiment. 4 is a diagram showing the iris opening / closing operation and its driving current in FIG. 1, and FIG. 4 is a diagram showing the sensitivity of the Hall element according to the change in the aperture diameter of the iris in the iris control device 1 of the same embodiment. The iris is arranged in the lens module 2 of the imaging optical system as in the conventional example of FIG.

  As shown in FIG. 1, the iris control device 1 of the present embodiment is configured so that the opening diameter of the iris 6 becomes a predetermined value based on, for example, an IRIS control command input from a device such as a digital camera body. The drive motor 3 is driven to control the opening / closing operation of the iris 6.

  The IRIS control device 1 includes a drive motor (so-called actuator in the present invention) 3 as a drive source for driving the IRIS 6 and a hall element (so-called sensor in the present invention) as means for detecting the rotation amount of the drive motor 3. 7), and controls the drive motor 3 based on the IRIS control command, detects the drive amount of the drive motor 3 via the Hall element 7, and feedback-controls the opening / closing operation amount of the iris 3 Is configured to do.

  As shown in FIG. 1, the iris control device 1 generates a drive signal for the drive motor 3 based on the control signal output from the IRIS digital control unit 8 for digitally calculating the IRIS control signal and the IRIS digital control unit 8. IRIS motor driver 16 that performs, Hall driver 17 that generates a drive signal for the Hall element 7 based on the control signal output from the IRIS digital control unit 8, and drive that rotates according to the drive signal input from the IRIS motor driver 16 A hall element 7 that detects the rotational motion of the motor 3 and the drive motor 3 and outputs an electrical signal corresponding to the amount of rotation, and an amplifier that amplifies the electrical signal output from the hall element 7 and outputs the amplified signal to the IRIS digital control unit 8 (Op-amp) 9 and so on.

  Further, the drive coil 4 and the hall element 7 of the drive motor 3 have temperature characteristics in which output characteristics change depending on the temperature. Therefore, the iris control device 1 according to the present embodiment includes a thermistor that measures the temperature rise of the drive coil 4 and the Hall element 7, and a current that flows through the drive coil 4 so as to cancel the temperature difference according to the detection result of the thermistor. And the input / output voltage of the Hall element 7 are corrected.

  The drive motor 3 includes a rotor 5 having S and N poles magnetized on the outer surface, a drive coil 4 disposed so as to face the outer surface of the rotor 5, and the like, and is driven via an IRIS motor driver 16. Is done. The drive motor 3 is a servo motor whose rotation angle is controlled by a PWM (pulse width modulation) control method, and is configured such that the rotation angle is controlled in accordance with a change in the duty ratio of the pulse signal. ing.

In the iris control device 1, the iris opening / closing operation is proportional to the rotation angle of the rotor 5, and a detection signal is output from the Hall element 7 according to the amount of rotation of the rotor 5, and the detection signal of the Hall element 7 is observed. Thus, the opening / closing operation of the iris 6 is controlled.

  As shown in FIG. 2, the IRIS motor driver 16 includes a first FET (Field Effect Transistor) 1 and a resistor R on the voltage supply path to the drive coil L, and the first FET is provided at one end of the drive coil L. A voltage V is applied via the second coil 2, and a drive signal PWM is applied to the other end of the drive coil L via the second FET 2.

The IRIS motor driver 16 switches the presence / absence of connection of the resistor R through the first FET 1 and switches ON / OFF of the PWM signal through the second FET 2.
The function of the first switching means in the present invention is expressed by the first FET 1, and the function of the second switching means in the present invention is expressed by the second FET 2.

  Further, as shown in FIG. 3C, the IRIS control unit 12 increases or decreases the average current passed through the drive coil L according to the opening diameter D of the iris 6, and the drive coil L increases as the opening diameter of the iris 6 increases. To increase the rotational torque of the rotor 5. That is, since the load required for the opening operation of the iris 6 increases as the opening diameter increases, the drive current of the drive motor 3 is increased to increase the drive torque.

  The first FET 1 is a P-channel MOS transistor and the second FET 2 is an N-channel MOS FET. When a predetermined potential is applied between the source S and the gate G, the drain D and the source S are energized. On the other hand, when the voltage applied to the gate G is substantially the same potential as the source S or zero, the drain D and the source S are insulated from each other, and a function as switching means is provided.

  When the drain D and the source S in the first FET 1 are energized, the voltage V is applied to the drive coil L including the coil resistance Rc. On the other hand, when the drain D and the source S in the first FET 1 are insulated, a voltage drop corresponding to R appears in the supply path of the drive coil L, and the internal resistance included in the drive coil L is Rc. When the drive voltage applied to the coil L is V1, the voltage V1 applied to the drive coil L is V1 = V * Rc / (Rc + R).

  Further, ON / OFF of the voltage applied to the drive coil L is switched according to the switching of the second FET 2, thereby supplying a current corresponding to a predetermined duty ratio of PWM to the drive coil L for driving. The rotation angle of the motor is controlled.

  Next, S and N pole permanent magnets are magnetized on the rotor 5, and when the rotor 5 rotates, the magnetic flux density with respect to the Hall element 7 changes. And the magnetic flux density which passes the Hall element 7 changes with the position of a permanent magnet.

  The Hall element 7 is disposed at a position facing the magnetized surface (that is, the outer peripheral surface) of the permanent magnet in order to detect the instantaneous rotation position (rotation phase) of the permanent magnet, and a voltage corresponding to a change in magnetic flux density. Is output as a signal representing the amount of rotational operation of the rotor 5. Next, this output signal is amplified by the amplifier 9 and is taken into the IRIS digital control unit 8 as a value indicating the opening / closing operation amount of the iris 6.

  As shown in FIG. 5, when the control signal (PWM) output from the IRIS digital control unit 8 is input to the hall driver 17, the hall driver 17 generates a drive current for the hall element 7. 7 is input to one end. The other end of the Hall element 7 is grounded via a current detection resistor Ri, and the current detection value output from the other end is input to the Hall driver 17 so that the drive current of the Hall element 7 is It is controlled so as to have a predetermined value. The hall driver 17 controls the current value applied to the hall element 5 in accordance with a command signal from the hall gain control unit 14.

  The Hall element 7 has a Hall effect in which when a current is applied to a semiconductor, when a magnetic field is applied in a direction perpendicular to the current, a voltage approximately proportional to the current and the strength of the magnetic field is generated in the direction perpendicular to the current and the magnetic field. Utilizing it, the electromotive force due to the Hall effect is measured to detect changes in the strength of the magnetic field.

  Next, the output voltage output from the Hall element 7 is input to an amplifier (operational amplifier) 9. In the amplifier 9, high-frequency components are removed from the output signal of the Hall element 7 to match the level of the A / D converter 10. Are amplified and input to the A / D converter 10.

Then, IRIS digital control unit 8 converts the analog electric signal supplied from the amplifier 9 into a digital signal in the A / D converter 10, based on the converted digital signal, Te IRIS controller 12 smell, as the opening diameter of the iris becomes the target value, and generates a PWM (Pulse Width Modulation) signal by performing feedback control computation, and supplies the generated PWM signal to the IRIS motor drive 10.

  The IRIS control unit 12 includes a PWM generator that outputs a PWM duty waveform corresponding to a duty setting value indicated by a digital value. The PWM duty waveform output from the PWM generator is output to the IRIS motor driver 16 and driven. The motor 3 is driven. By repeating this, the drive motor 3 is stopped when the opening diameter of the iris 6 reaches an allowable range (IRIS control command) with respect to the command value.

  Next, as shown in FIGS. 2 and 3, in the iris control device 1 of the present embodiment, the opening diameter of the iris 76 is set to a predetermined value (D1 in the present embodiment) via the IRIS control unit 12. Then, the opening / closing operation of the iris 6 with respect to the change of the duty ratio is switched so that the operation of the aperture diameter with respect to the change of the drive pulse signal (PWM signal) applied to the drive coil L becomes fine.

  Specifically, in the drive circuit shown in FIG. 2, when the opening diameter of the iris 6 reaches a predetermined value D1, the first FET 1 is operated, and on the supply path of the drive voltage to the drive coil L, The voltage applied to the drive coil L is switched by switching the connection of the resistor R.

  That is, in the range where the opening diameter of the iris 6 is equal to or smaller than D1, the drain D and the source S in the first FET 1 are insulated, R is added to the supply path of the drive coil L, and R is added to the supply path of the drive coil L. A corresponding voltage drop is developed to reduce the voltage V applied to the drive coil L to V1.

  On the other hand, in the range (D1 to D2) in which the aperture diameter of the iris exceeds D1, the voltage V is applied to the drive coil L by energizing between the gate G and the source S in the first FET1.

  In this embodiment, R = Rc is set, and as a result, by adding R to the supply path of the drive coil L by switching of the first FET 1, the voltage applied to the drive coil L is reduced to ½. To do.

  At this time, as the drive voltage V decreases, the current applied to the drive coil L decreases, and as shown in FIG. 3D, the current of the PWM signal is inversely proportional to the decrease in the current. Switch the input. That is, the gradient of the control characteristic B shown in FIG. 3D is configured to be 1/2 with respect to the gradient A of the control characteristic.

That is, in the range where the opening diameter of the iris 6 is equal to or less than D1 , the gate G and the source S in the first FET 1 are cut off, R is added to the supply path of the drive coil L, and R is added to the supply path of the drive coil L. A corresponding voltage drop is developed to reduce the voltage V applied to the drive coil L to ½, and the PWM duty associated with the change in the aperture diameter is switched to the characteristic A shown in FIG.

  On the other hand, in a large range where the iris opening diameter exceeds D1, the current applied between the drain D and the source S in the first FET 1 is set to V and the voltage applied to the drive coil L is set to V, and the opening diameter changes. The accompanying PWM duty is switched to the characteristic B shown in FIG. Note that the function of the resolution switching means in the present invention is expressed by the FET 1 and the resistor R, the IRIS control unit 12, the IRIS motor driver 16, and the like.

  Next, as shown in FIG. 4A, the iris control device according to the present embodiment increases the sensitivity of the Hall element 7 when the aperture diameter of the iris 6 is reduced via the Hall gain control unit 14. When the current input to the Hall element 7 is increased and the aperture diameter of the iris 6 is increased, the current input to the Hall element 7 is decreased so that the sensitivity of the Hall element 7 is decreased.

At this time, in accordance with switching of the control resolution of the iris 6, the aperture diameter is configured to be the sensitivity characteristic A in FIG. 4A in the range of D1 or less, and in the range where the aperture diameter is larger than D1, The sensitivity characteristic B in FIG. 4A is configured.
The sensitivity characteristic A corresponds to the first sensitivity in the present invention, and the sensitivity characteristic B corresponds to the second sensitivity in the present invention.

  In addition, the iris control device 1 of the present embodiment has a plurality of different amounts of change in electrical signals output from the Hall element 7 after the sensitivity of the Hall element 7 is switched with respect to a predetermined operation amount of the iris 6. The resolutions are substantially equal to each other. Note that the function of the sensitivity switching means in the present invention is expressed by the Hall gain control unit 14.

Further, when the sensitivity switching of the Hall element 7, instead of switching the input current to the Hall element 7 through the holes gain controller 14 as described above, the amplification degree in association with Oite opening diameter to the amplifier 9 It may be switched.

  That is, the output from the amplifier 9 is configured so as to become the sensitivity characteristic A in FIG. 4A in the range of the aperture diameter D1 or less in accordance with the switching of the resolution of the control of the iris 6, and is configured to be larger than the aperture diameter D1. In a large range, the sensitivity characteristic B in FIG. At this time, the change amount of the electric signal output from the amplifier 9 is set to be substantially equal at a plurality of different resolutions with respect to the predetermined operation amount of the iris 6. At this time, the function of the sensitivity switching means in the present invention is expressed by the amplifier 9.

  As described above, the iris control device 1 and the iris control method of the present embodiment apply the pulse signal (PWM) to the drive motor 3 and control the opening / closing operation of the iris 6 according to the duty ratio of the pulse signal. In addition, as the opening diameter D of the iris 6 is decreased, the opening / closing operation of the iris 6 is switched so as to be fine with respect to the change in the duty ratio of the pulse signal. Can be switched precisely.

  Further, in the iris control device and the iris control method and the iris control method of the present embodiment, the drive motor 3 is disposed so as to face the rotor 5 with the S pole and the N pole magnetized on the outer surface and the outer peripheral surface of the rotor 5. The drive coil L and the IRIS motor driver 16 that applies a drive voltage to the drive coil L are configured to switch the presence or absence of connection of a predetermined resistor R on the supply path of the drive voltage to the drive coil L. By switching the current flowing through the drive coil L, the resolution of the control of the opening / closing operation of the iris 6 can be precisely switched.

  In addition, the iris control device 1 and the iris control method of the present embodiment are configured to pass through the hall element 7 via the hall gain control unit 14 or the amplifier 9 when the resolution of the iris opening / closing operation control is finely switched. The resolution of the electric signal is increased by increasing the amplification degree of the electric signal representing the operation amount of the iris 6 detected in this way. On the other hand, when the resolution of the control of the iris opening / closing operation is roughly switched, the Hall element 7 is used. By reducing the amplification degree of the electric signal representing the detected operation amount and reducing the resolution of the electric signal, the accuracy of detection of the iris opening / closing operation in the entire area of the opening / closing operation of the iris 6 can be optimized. At this time, when the resolution of the control of the iris opening / closing operation is switched because the electric signal amount after amplification is substantially equal to the plurality of resolutions with respect to the predetermined operation amount of the iris 6, The change amount of the electrical signal of the iris operation detected through the element 7 can be matched with the change amount of the incident light amount, and the operability when controlling the incident light amount can be improved.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken. For example, in the iris control device 1 of the present embodiment, the iris control resolution is switched to two steps via the opening diameter D1, but may be configured to be switched at a larger number of steps. The drive source of the iris 6 is not limited to the drive motor 3, and an inductor having S and N poles magnetized on the outer surface and a drive coil disposed so as to face the outer surface of the inductor And a driving circuit that applies a driving voltage to the driving coil, the present invention can be summarized.

It is a figure showing the structure of the iris control apparatus of one Embodiment of this invention. It is a figure showing the iris drive circuit (IRIS motor driver) in the iris control device of the embodiment. It is explanatory drawing of control of the opening / closing operation | movement of an iris in the iris control apparatus of the embodiment, Comprising: (a) A figure and (b) figure are the figures showing the change of opening diameter, (c) A figure is iris opening diameter. The value of the current applied to the drive coil in response, and FIG. 6D shows the duty ratio of the PWM signal applied to the drive coil in accordance with the aperture diameter of the iris. In the iris control device of the same embodiment, it is a diagram showing output characteristics from the Hall element according to the change of the opening diameter, (a) is a sensitivity characteristic with respect to a predetermined operation amount of the rotor, (b) is a Hall element It is an amplification characteristic at the time of amplifying the output from. It is a drive circuit diagram of a hall element in the iris control device of the embodiment. It is a figure showing the structure of the iris control apparatus in a prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Iris control device, 2 ... Lens module, 3 ... Drive motor (actuator), 4 ... Drive coil, 5 ... Rotor (inductor), 6 ... Iris (diaphragm), 7 ... Hall element (sensor), 8 ... IRIS Digital controller (microcomputer), 9 ... Amplifier (op-amp), 10 ... A / D converter, 11 ... offset controller, 12 ... IRIS controller, 13 ... serial interface, 14 ... Hall gain controller, 15 ... A / D converter, 16 ... IRIS motor driver, 17 ... Hall driver, FET1 ... first FET, FET2 ... second FET, L ... drive coil, Rc ... coil resistance. DESCRIPTION OF SYMBOLS 21 ... Condensing lens, 22 ... Iris (aperture), 23 ... Image sensor, 24 ... Variable gain amplifier (AGC: Automatic Gain Control), 25 ... A / D converter, 27 ... Exposure amount detection circuit, 28 ... Aperture value Judgment circuit, 29 ... Actuator control circuit, 30 ... IRIS motor driver, A / D converter, 31 ... Iris, 31a ... Drive coil, 31b ... Rotor, 32 ... Rotor rotation angle measurement circuit, 33 ... Hall element, 100 ... Imaging Equipment, 101... Iris control device.

Claims (6)

An iris control device that applies a pulse signal to an actuator and controls the opening / closing operation of the iris according to a duty ratio of the pulse signal,
The actuator is
An inductor having S and N poles magnetized on its outer surface;
A drive coil arranged to face the outer surface of the inductor;
A drive circuit for applying a drive voltage to the drive coil;
Composed by
Control means that controls the opening and closing operation of the iris with different resolutions,
The control means includes a resolution switching means that switches the resolution of the opening / closing operation in correspondence with the opening diameter of the iris, and switches the opening / closing operation more precisely as the opening diameter becomes smaller.
The resolution switching means is
The drive voltage connected to one end of the drive coil on the supply path of the drive voltage to the drive coil, and applied to the drive coil by switching whether or not a predetermined resistance is connected to the drive coil. A first switching means for switching between, and a second switching means that is connected to the other end of the drive coil and switches between application and cutoff of the pulse signal applied to the drive coil,
The first switching means comprises:
When the opening diameter of the iris is smaller than a predetermined opening diameter, the predetermined resistance is connected to the drive coil, while when the opening diameter of the iris is larger than the predetermined opening diameter, Cutting off the connection of the predetermined resistor to the drive coil;
The second switching means comprises:
The duty ratio of the pulse signal is configured to be switched according to the switching of the opening diameter of the iris and the connection of the resistor of the first switching means.
The duty ratio of the pulse signal at the predetermined opening diameter is larger than when the resistor is disconnected when the resistor is connected,
And, in a range where the opening diameter is small via the predetermined opening diameter, the change of the duty ratio of the pulse signal with respect to the change of the opening diameter of the iris is made larger than the large range via the predetermined opening diameter.
It is comprised so that the iris control apparatus characterized by the above-mentioned.
A sensor that outputs an electrical signal corresponding to the opening / closing operation amount of the iris;
Amplifying means for amplifying the electrical signal output from the sensor;
Detecting means for detecting an opening / closing operation amount of the iris based on the electric signal amplified by the amplifying means;
With
The amplification means is
In association with the presence / absence of connection of the predetermined resistor in the resolution switching means, the amplification degree is increased when the iris opening diameter is smaller than the predetermined opening diameter than when the iris opening diameter is larger than the predetermined opening diameter. The amount of change in the electrical signal output from the amplification means with respect to a predetermined operation amount of the iris by switching the amplification degree of the electrical signal is defined as a range in which the opening diameter becomes large via the predetermined opening diameter. Configured to be equal in a small range,
The iris control device according to claim 1.
A sensor that outputs an electrical signal corresponding to the opening / closing operation amount of the iris;
Amplifying means for amplifying the electrical signal output from the sensor;
Detecting means for detecting an opening / closing operation amount of the iris based on the electric signal amplified by the amplifying means;
A sensitivity switching means for switching the sensitivity of the sensor with respect to a predetermined operation amount of the iris;
With
The sensitivity switching means is
Corresponding to the presence or absence of the connection of the predetermined resistor in the resolution switching means, switching between the first sensitivity when the resistor is connected and the second sensitivity when the resistor is disconnected,
The change amount of the electrical signal after the sensitivity is switched with respect to the predetermined operation amount of the iris is configured to be equal between the first sensitivity and the second sensitivity.
The iris control device according to claim 1.
An iris control method for applying a pulse signal to an actuator and controlling the opening / closing operation of the iris according to a duty ratio of the pulse signal,
As the actuator,
An inductor having S and N poles magnetized on its outer surface;
A drive coil arranged to face the outer surface of the inductor;
A drive circuit for applying a drive voltage to the drive coil;
Use
A control step for controlling the opening and closing operation of the iris with different resolutions;
A resolution switching step of switching the iris opening / closing operation in a precise manner in association with the iris opening diameter, and finely switching the opening diameter as it decreases.
With
The resolution switching step includes
A first switching step of switching the drive voltage to be applied to the drive coil by switching presence / absence of connection of a predetermined resistor to the drive coil on the supply path of the drive voltage to the drive coil; A second switching step for switching between application and interruption of the pulse signal applied to the drive coil;
Use
In the first switching step,
When the opening diameter of the iris is smaller than a predetermined opening diameter, the predetermined resistance is connected to the drive coil, while when the opening diameter of the iris is larger than the predetermined opening diameter, Cutting off the connection of the predetermined resistor to the drive coil;
In the second switching step,
It is configured to switch the duty ratio of the pulse signal in accordance with switching of the opening diameter of the iris and the connection of the resistor of the first switching step,
The duty ratio of the pulse signal at the predetermined opening diameter is larger than when the resistor is disconnected when the resistor is connected,
And, in a range where the opening diameter is small via the predetermined opening diameter, the change of the duty ratio of the pulse signal with respect to the change of the opening diameter of the iris is made larger than the large range via the predetermined opening diameter.
An iris control method characterized by the above.

An iris operation amount detection step for outputting an electrical signal corresponding to the iris opening / closing operation amount;
An amplification step for amplifying the electrical signal detected through the iris operation amount detection step;
A feedback control step of feedback-controlling the opening / closing operation amount of the iris based on the electrical signal amplified in the amplification step,
The amplification step comprises:
In association with the presence / absence of connection of the predetermined resistor in the resolution switching step, the amplification degree is increased when the iris opening diameter is smaller than the predetermined opening diameter than when the iris opening diameter is larger than the predetermined opening diameter. By switching the amplification degree of the electric signal, the amount of change in the electric signal after the amplification with respect to the predetermined operation amount of the iris becomes smaller and smaller in the range in which the opening diameter becomes larger via the predetermined opening diameter. Equal in range,
The iris control method according to claim 4, wherein:
An iris operation amount detection step for outputting an electrical signal corresponding to the iris opening / closing operation amount;
An amplification step for amplifying the electrical signal detected through the iris operation amount detection step;
A feedback control step of feedback-controlling the opening / closing operation amount of the iris based on the electrical signal amplified in the amplification step;
A sensitivity switching step of switching the detection sensitivity of the iris operation amount detection step;
With
The sensitivity switching step includes
Corresponding to the presence or absence of connection of the predetermined resistor in the resolution switching step, switching between the first sensitivity when the resistor is connected and the second sensitivity when the resistor is disconnected,
The amount of change in the electrical signal after the sensitivity is switched is equal between the first sensitivity and the second sensitivity with respect to the predetermined operation amount of the iris.
The iris control method according to claim 4, wherein:

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