JP4850587B2 - Optical equipment - Google Patents

Description

  The present invention relates to an optical apparatus such as a video camera, a digital still camera, and an interchangeable lens, and more particularly to a countermeasure technique when the optical apparatus receives an impact.

  In an optical apparatus such as a video camera, an actuator is provided for each lens in order to drive a plurality of lenses (for example, a focus lens and a zoom lens). As the actuator, a stepping motor or a voice coil motor (hereinafter abbreviated as VCM) is used for each lens from the viewpoint of driving characteristics required for the lens and miniaturization of the optical device. For example, the focus lens may be driven by VCM and the zoom lens may be driven by a stepping motor.

  When the lens is driven by the stepping motor, the lead screw is rotated by the stepping motor, and the rack engaged with the lead screw is moved in the optical axis direction. Thereby, the lens (lens holding member) connected to the rack is driven in the optical axis direction.

  In the case of using a stepping motor, the lens can be controlled to a desired position without using a position sensor by counting drive pulses applied to the motor. That is, so-called open loop control is performed. This eliminates the need for a position sensor and a circuit for processing the output, thereby miniaturizing the camera and simplifying the system.

  When using a stepping motor, a reset operation is required to move the lens to a predetermined reference position and set the pulse count value to 0 in order to match the detection position obtained by pulse counting with the lens position. It is.

  On the other hand, when using a VCM, generally, a so-called feedback control is performed in which a lens position is detected by a position sensor, and a drive signal applied to the VCM is corrected so as to eliminate a deviation between the control target position and the detected lens position. Done.

  When an impact in the optical axis direction is applied to such an optical device, the main body of the optical device moves due to the impact, but the lens supported so as to be movable in the optical axis direction within the main body is placed at the same location by the law of inertia. Try to stay. Thereby, the positional relationship between the main body of the optical device and the movable lens changes. Hereinafter, this is referred to as a lens position shift. In such a case, with respect to the lens for which feedback control is performed, the position shift of the lens is detected by the position sensor, and thus the shift is eliminated by feedback control.

  However, a lens for which open loop control is performed cannot be recovered from the shifted state because there is no means for detecting even if the lens position is shifted due to an impact. In this case, the detection position on the control by the pulse counter deviates from the actual lens position, and subsequent correct lens position control cannot be performed. As a cause of this deviation, there are generally rack deviation and self-rotation.

  The rack displacement means that when an impact is applied, the rack provided on the lens (lens holder) shifts the meshing position with respect to the lead screw meshing with the rack.

  Further, as described above, in the lens driving by the stepping motor, the rotational force generated by the motor is converted into the driving force in the optical axis direction of the lens by the engagement of the lead screw and the rack. In this case, when the optical device receives an impact, an inertial force is generated in the movable part including the lens, and a force for relatively shifting the main body and the lens position is generated. The force is transmitted to the output shaft of the stepping motor from the rack via the lead screw contrary to the normal driving of the lens, and the stepping motor rotates when the stepping motor is de-energized. This is called self-weight rotation. In recent optical devices, in order to reduce power consumption, when the lens is stopped, the power supply to the stepping motor is stopped. Therefore, such a positional deviation of the lens due to its own weight rotation becomes a problem.

  With respect to a lens for which such open loop control is performed, there is a method proposed in Patent Document 1 as a countermeasure against lens position shift due to impact. This document proposes a method of correcting a lens position by providing a position sensor to a lens driven by a stepping motor, detecting a shift amount of the lens position with respect to a target control position.

In addition to this method, it is also conceivable to provide a dedicated sensor for detecting an impact and execute the lens position resetting operation by detecting the impact.
JP-A-5-281449 (paragraphs 0023-0025, FIG. 1 etc.)

  However, as in Patent Document 1, providing a position sensor for an open loop controlled lens eliminates the merit of the open loop control main body that can be reduced in size and simplified because the position sensor is unnecessary. It is to make. In addition, providing a dedicated sensor for impact detection also increases the number of components, which similarly becomes an obstacle to miniaturization and simplification.

  An object of the present invention is to provide an optical apparatus that can cope with a positional shift of an optical element when subjected to an impact without increasing the number of parts.

An optical apparatus according to one aspect of the present invention includes a first actuator that moves the first optical element in the optical axis direction, a second actuator that moves the second optical element in the optical axis direction, and the second actuator. position detecting means for detecting the position of the optical element, the first by an open-loop control of the actuator performed position control of the first optical element, using said detection result of said position detecting means second actuator by a control means for controlling the position of the second optical element, wherein the control unit detects for each constant period at the detected position of the by the position detecting means a second optical element, the specific In response to the occurrence of the change, an impact response operation is performed on the first optical element, and the specific change is caused by a displacement greater than a maximum drive amount that can drive the second optical element in the predetermined period. Characterized in that it is a change in the detected position when occurring in the second optical element.

  In the present invention, a specific change that has occurred in the detection position by the position detection means necessary for feedback control of the second optical element is used as a trigger for an impact handling operation related to the first optical element. For this reason, according to the present invention, there is no need to provide a position sensor or a dedicated impact sensor for the first optical element that is open-loop controlled. That is, the positional deviation generated in the first optical element due to the impact can be surely eliminated without increasing the number of components and hindering the miniaturization of the optical device and the simplification of the system.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a system configuration of an image pickup apparatus (video camera) as an optical apparatus which is an embodiment of the present invention.

  In FIG. 1, reference numeral 1101 denotes a first lens fixed to the lens barrel main body 1200, 1102 denotes a second lens that moves in the optical axis direction and performs zooming (hereinafter referred to as a zoom lens), and 1103 denotes a stop. Reference numeral 1104 denotes a third lens fixed to the lens barrel main body 1200. Reference numeral 1105 denotes a fourth lens (hereinafter referred to as “focusing function”) that moves in the optical axis direction and corrects the movement of the focal plane accompanying zooming. Is called a focus lens). These optical elements 1101 to 1105 constitute an optical system of the photographing lens unit.

  Reference numeral 1106 denotes an image sensor (hereinafter referred to as a CCD), which includes a CCD sensor or a CMOS sensor. Reference numeral 1107 denotes a CDS / AGC circuit that samples the output of the CCD 1106 and adjusts the gain. A camera signal processing circuit 1108 processes an output signal from the CDS / AGC 1107 into a signal corresponding to the recording medium 1109. The recording medium 1109 is constituted by a semiconductor memory, a hard disk, an optical disk, or the like.

  A signal from the camera signal processing circuit 1108 is sent to the recording medium 1109 and also sent to the LCD display circuit 1116. The LCD display circuit 1116 displays the signal on the LCD 1117 as an image.

  An output from the character generator 1115 is also input to the LCD display circuit 1116. The character generator 1115 generates symbols and characters representing shooting modes, shooting states, warnings, and the like. The LCD display circuit 1116 can superimpose and display an image corresponding to the signal from the camera signal processing circuit 1108 and the symbols and characters from the character generator 1115 on the LCD 1117. The camera signal processing circuit 1108, the character generator 1115, and the CCD 1106 are controlled by the microcomputer 1121.

  Reference numeral 1110 denotes a stepping motor as a first actuator that drives the zoom lens (first optical element) 1102. Reference numeral 1111 denotes a driver that drives the stepping motor 1110 by a signal from a motor control unit 1122 described later.

  Reference numeral 1112 denotes a voice coil motor (VCM) as a second actuator that drives a focus lens (second optical element) 1105. Reference numeral 1113 denotes a driver that drives the VCM 1112 by a signal from a motor control unit 1122 described later.

Reference numeral 1131 denotes a position sensor (position detection means) that detects the position of the focus lens 1105. The position sensor 1131 can be used regardless of its type, such as a variable resistance type, an optical type, and a magnetic type. The position sensor 1131 needs to have a resolution capable of detecting movement of the focus lens 1105 driven by the VCM 1112 below the minimum drive unit.

  Reference numeral 1132 denotes an A / D converter for taking the signal output from the position sensor 1131 into the microcomputer 1121. Reference numeral 1114 denotes an AF evaluation value processing circuit that extracts a high frequency component (also referred to as an AF evaluation value signal) used for focus detection from the output signal of the CDS / AGC 1107.

  Reference numeral 1118 denotes a zoom switch, which can zoom in the tele (T) direction and the wide (W) direction in accordance with the operation of the switch 1118. Reference numeral 1119 denotes an MF (manual focus) switch. By operating this switch, an AF (auto focus) mode and an MF mode can be selected alternately.

  A focus switch 1120 detects an operation position of an operation ring (not shown) for manually operating the focus lens 1105, that is, a position of the focus lens 1105.

  Reference numeral 1125 denotes a storage unit that stores focus cam data used for zoom tracking for correcting image plane fluctuations accompanying zooming. The focus cam data is data of the position of the focus lens 1105 according to the position of the zoom lens 1102 and the subject distance.

A zoom control unit 1124 outputs a command signal to the motor control unit 1122 to move the zoom lens 1102 in accordance with the operation of the zoom switch 1118. At this time, the zoom control unit 1124 outputs a command signal to the motor control unit 1122 so as to move the focus lens 1105 to a position according to the focus cam data 1125. Further, when the MF mode is selected by the MF switch 1119, the zoom control unit 1124 outputs a command signal to the motor control unit 1122 to move the focus lens 1105 to a position corresponding to the detection signal from the focus switch 1120. . When the zoom control unit 1124 detects that the infinite switch 1126 is turned on, the zoom control unit 1124 outputs a command signal to the motor control unit 1122 to forcibly move the focus lens 1105 to the infinity position.

  Reference numeral 1123 denotes an AF control unit which outputs a command signal to the motor control unit 1122 so as to move the focus lens 1105 to a position where the AF evaluation value signal obtained from the AF evaluation value processing circuit 1114 is maximized, that is, a focus position. . Thereby, AF control is performed.

  The motor control unit 1122 controls the driving of the stepping motor 1110 via the driver 1111 in accordance with a command signal from the zoom control unit 1124. The control at this time is open loop control. In the open loop control, the drive pulses given to the stepping motor 1110 are counted, and the stepping motor 1110 is driven until the count value matches the target count value. Thereby, the position of the zoom lens 1102 is controlled.

Here, in order to accurately obtain the position of the zoom lens 1102 by counting the drive pulses, the zoom lens 1102 is moved to a predetermined reference position for position control, and a reset operation for setting the pulse count value there to zero is performed. is required. As a result, the detection position obtained by the pulse count matches the movement amount (position) of the zoom lens 1102 from the reference position.

  For this reason, a zoom reset sensor 1150 is provided. As the zoom reset sensor 1150, for example, a photo interrupter is used. In this case, the photo interrupter is arranged so that the zoom lens 1102 (actually a member that holds this lens) that has reached the reference position enters between the light projecting unit and the light receiving unit of the photo interrupter. When the zoom lens 1102 enters between the light projecting unit and the light receiving unit, the light from the light projecting unit that has been irradiated to the light receiving unit is blocked and does not reach the light receiving unit. It is possible to detect that the zoom lens 1102 has reached the reference position by changing the output signal from the photo interrupter by switching between the light receiving state and the non-light receiving state.

  This reset operation is performed not only at the timing when the image pickup apparatus is powered on, but also when an impact determination described later is performed. As the zoom reset sensor 1150, various devices such as a photo reflector and an electrical switch that is mechanically turned on can be used.

  In addition, the motor control unit 1122 controls driving of the VCM 1112 via the driver 1113 in accordance with command signals from the zoom control unit 1124 and the AF control unit 1123. The control at this time is feedback control. In the feedback control, the drive signal applied to the VCM 1112 is controlled so that the position information of the focus lens 1105 detected by the position sensor 1131 matches the target position according to the command signal from the zoom control unit 1124 or the AF control unit 1123. . Thereby, the position of the focus lens 1105 is controlled.

  Next, a mechanical configuration example of the taking lens unit in the present embodiment will be described with reference to FIG.

  In FIG. 2, reference numerals 1101 to 1106 denote the lens, diaphragm, and CCD shown in FIG. Further, 1110 is a stepping motor shown in FIG. 1 and 1112 is a VCM. Further, reference numeral 1131 denotes the position sensor shown in FIG. 1, and reference numeral 1150 denotes a zoom reset sensor.

  A zoom lens holding member 107 holds the zoom lens 1102. As indicated by an arrow A in the drawing, a part of the zoom lens holding member 107 enters between the light projecting portion and the light receiving portion of the zoom reset sensor (photo interrupter) 1150, so that the zoom lens 1102 is at the reference position. It is detected.

Reference numeral 109 denotes a lead screw connected to the output shaft of the stepping motor 1110. A rack 108 is attached to the zoom lens holding member 107 and meshes with (engages with) the lead screw 109. The lead screw 109 is disposed on the upper side (lower side in the drawing) of the lens unit so as to extend in the optical axis direction of the lens unit.

  Reference numeral 111 denotes a focus lens holding member that holds the focus lens 1105. Reference numeral 112 denotes an air core coil constituting the VCM 1112, which is fixed to the focus lens holding member 111. Reference numeral 113 denotes a yoke constituting the VCM 1112, and reference numeral 114 denotes a magnet constituting the VCM 1112.

  Reference numeral 115 denotes a magnetic or optical scale constituting the position sensor 1131, which is fixed to the focus lens holding member 111. Reference numeral 116 denotes a magnetic or optical detection head constituting the position sensor 1131, which is fixed to the barrel main body 1200.

  When the scale 115 moves relative to the detection head 116 together with the focus lens holding member 111, the detection head 116 detects a change in magnetic field and a change in light shielding / transmission that occur at a predetermined period of movement. The detection head 116 outputs a pulse signal in accordance with changes in the magnetic field and light shielding / transmission. Further, the detection head 116 can detect a change in a plurality of magnetic fields having different phases and a change in light shielding / transmission. By comparing the two pulse trains obtained in this way, the moving direction of the focus lens holding member 111 can also be detected.

  Therefore, the position of the focus lens 1105 (focus lens holding member 111) can be detected by increasing or decreasing the pulse signal output from the detection head 116 according to the moving direction from the predetermined reference position. For the position sensor 1131 having this configuration, the focus lens is moved to a predetermined reference position so that the detection position obtained by the pulse count matches the focus lens position, and the pulse count value at that position is set to zero. A reset operation is required.

For this reason, when an impact that causes a displacement of the zoom lens is applied, the displacement of the focus lens similarly occurs. In this embodiment, this phenomenon is used to detect the occurrence of displacement of the zoom lens (that is, the impact), and the change in the detection position by the position sensor 1131 originally provided for detecting the position of the focus lens. It is detected by monitoring. Then, the zoom lens resetting operation is performed with the detection (impact determination) as a trigger.

  Hereinafter, the impact presence / absence determination and the zoom lens reset operation as the impact handling operation executed by the motor control unit 1122 in the microcomputer 1121 will be described with reference to the flowcharts of FIGS. These impact determination and reset operations are executed according to a computer program stored in a memory in the microcomputer 1121.

  The motor control unit 1122 starts a predetermined initialization process in step (hereinafter abbreviated as S) 301 in FIG. 3. In S302, the position sensor 1131 is used to detect the current position PFnow of the focus lens. In S303, the detected current focus lens position PFnow is substituted into the previous focus lens position PFold.

  In the processing described later, a difference between the current focus lens position PFnow and the previous focus lens position PFold detected in the previous routine is obtained, and the presence / absence of an impact is determined based on the magnitude of the difference value. However, the current focus lens position PFnow is substituted for the previous focus lens position PFold in the first S303 so that the impact determination (determination that an impact has been received) is not mistakenly performed in the first difference value calculation (the difference value is 0). Becomes). In S304, the initialization process ends.

Next, the motor control unit 1122 starts an impact presence / absence determination process executed in a predetermined setting cycle (routine) in S305 of FIG. As the setting cycle (predetermined cycle) , a cycle suitable for detection of instantaneous displacement of the focus lens due to impact, for example, 100 μs is set.

In S306, the motor control unit 1122 detects the current focus lens position PFnow using the position sensor 1131. In S307, the absolute value of the difference between the current focus lens position PFnow and the previous focus lens position PFold is calculated and set as a position change amount PFdif (displacement) .

  The reason why the position change amount PFdif is an absolute value is that it is only necessary to know the change amount (impact presence / absence) of the focus lens position in the impact presence / absence determination, and the change direction (impact direction) is not necessary.

  In S308, the current focus lens position PFnow is stored in the previous focus lens position PFold for the next calculation.

  In S309, it is determined whether or not the position change amount PFdif has exceeded a set value (predetermined value), that is, whether or not a specific change has occurred in the detection position of the focus lens. This set value is set to be larger than the maximum drive amount that the focus lens can be driven within one cycle of the execution cycle of the impact determination routine in normal focus lens operation. This is to enable the impact determination to be performed regardless of whether the normal focus lens operation is performed.

Further, the set value may be set to a value smaller than the amount of displacement (maximum displacement) of the focus lens when the imaging apparatus receives an impact that causes displacement of the zoom lens. Thereby, it can be determined that the zoom lens has received an impact that causes a positional shift, not the focus lens.

  If the position change amount PFdif is larger than the set value, it is determined that an impact has been received, and the process proceeds to S310. In S310, the motor control unit 1122 operates the stepping motor 1110 to move the zoom lens to the reference position. That is, a reset operation as an impact response operation is performed. When the zoom reset sensor 1150 detects that the zoom lens reaches the reference position, the zoom lens is stopped. Then, the process returns from S311 to S305.

  On the other hand, when the position change amount PFdif is smaller than the set value in S309, the process proceeds to S311 and returns to S305.

  By performing the above processing, the zoom lens whose position is controlled by the open loop control of the stepping motor can be automatically and quickly returned to the normal state from the misaligned state of the zoom lens caused by the impact. Therefore, it is possible to prevent the image blur due to the displacement of the zoom lens (the displacement of the focus lens according to the focus cam data) from occurring continuously.

  In addition, since no new position sensor or impact sensor is added, the increase in the number of components and the complexity of the system can be avoided, and the lens position can be controlled with a simple configuration that does not use the position sensor that the open loop control of the stepping motor has Can take advantage of the original advantages. And the cost can be reduced by simplifying the system.

  As described above, it is possible to realize an imaging apparatus that is small in size, high in impact resistance, and inexpensive.

  In the present embodiment, the case where the reset operation is performed so as to return the zoom lens to the reference position as the shock handling operation has been described. However, in the present invention, warning information indicating that a displacement has occurred in the zoom lens due to an impact may be output without performing the reset operation.

  In this case, as shown in FIG. 5, in S310 ′, the motor control unit 1122 causes the LCD 1117 to display a warning through the microcomputer 1121, the character generator 1115, and the LCD display circuit 1116, for example. A warning sound may be generated from a speaker. Then, the process proceeds to S311.

  Such warning display and warning sound generation are also shock handling operations relating to the first optical element according to the present invention. This warning may be one that prompts the photographer to perform a switch operation to instruct a power-on operation or a zoom lens resetting operation. As a result, the zoom lens can be reset through a user operation, and the zoom lens can be quickly returned to the normal state from the misalignment state.

  In the above embodiment, the zoom lens is driven by the stepping motor and the focus lens is driven by the VCM. However, the present invention is not limited to this case and can be applied. For example, the present invention can be applied to a case where the focus lens is driven by a stepping motor or a vibration type motor and the zoom lens is driven by a VCM or a DC motor. Furthermore, in the present embodiment, a video camera with an integrated lens has been described, but the present invention can also be applied to other optical devices such as a digital still camera and an interchangeable lens.

1 is a system configuration diagram of an imaging apparatus that is an embodiment of the present invention. Schematic which shows the mechanical structure of the imaging lens part in the imaging device of an Example. 6 is a flowchart illustrating a procedure of initialization processing in the imaging apparatus according to the embodiment. 6 is a flowchart illustrating a procedure of impact presence / absence determination and reset operation in the imaging apparatus of the embodiment. 6 is a partial flowchart illustrating a procedure of a warning operation in the imaging apparatus according to the embodiment.

Explanation of symbols

107 Zoom lens holding member 108 Rack 109 Lead screw 111 Focus lens holding member 1102 Zoom lens 1105 Focus lens 1110 Stepping motor 1112 Voice coil motor 1121 Microcomputer 1122 Motor controller 1131 Position sensor 1150 Zoom reset sensor

Claims (5)

A first actuator for moving the first optical element in the optical axis direction ;
A second actuator for moving the second optical element in the optical axis direction ;
Position detecting means for detecting the position of the second optical element;
Wherein the open-loop control of the first actuator performs the position control of the first optical element, a detection result control controlling the position of the second optical element by the second actuator with the position detecting means Means,
Said control means, said detected by the position detecting means in every fixed cycle at the detection position of the second optical element, in response to the change in the specific occurs, the shock responsive operation relating to the first optical element And
The specific change is a change in a detection position when a displacement larger than a maximum driving amount by which the second optical element can be driven in the predetermined period occurs in the second optical element. machine.   2. The optical apparatus according to claim 1, wherein the impact handling operation is an operation of driving the first optical element to a reference position in position control by the first actuator.   The optical apparatus according to claim 1, wherein the impact handling operation is an operation of outputting warning information.   The specific change is a change in a detection position smaller than a maximum displacement that can be generated in the second optical element by the impact when the first optical element is displaced by the impact. The optical apparatus described in 1. The first actuator is a stepping motor;
5. The optical apparatus according to claim 1, wherein the stepping motor drives the first optical element via a lead screw and a rack engaged with the lead screw. .