JP2008096610A - Automatic focusing device and adjustment method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic focusing device capable of minimizing an error between the stopped position and target specified position of a focus lens by making the distance of the movement of the focus lens longer, thereby facilitating the control of a linear motor, and to provide an adjustment method therefor. <P>SOLUTION: The driving range of the focus lens driven by the linear motor is divided into ten equal intervals from a specified position P0 to another specified position P9. After the contrast value of a subject is obtained at the specified position P0, the focus lens is moved to the specified position P5 in a rightward direction and a contrast value is obtained. Subsequently, the focus lens is moved in a leftward direction from the specified position P5 to the specified position P1 to obtain the contrast value. In the same way as above, the contrast values are obtained at all the specified positions by moving the focus lens alternately to a fifth specified position ahead in the rightward direction and a fourth specified position in the leftward direction. Then, the greatest contrast value is selected from them and the focus lens is moved to the specified position that has the greatest contrast value. Since the focus lens moves a long distance as far as a specified position at least two or more specified positions ahead, an error between the stopped position and target specified position of the focus lens after its movement can be minimized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an automatic focus adjustment device and an adjustment method thereof, and more particularly to an automatic focus adjustment device and an adjustment method thereof that adjust the position of a focus lens using a linear motor.

Since linear motors such as voice coil motors are suitable for miniaturization and weight reduction, portable electronic devices often employ an automatic focus adjustment device that drives a focus lens by a linear motor. As described in Patent Document 1, this type of automatic focus adjustment apparatus detects a focus position of a focus lens by a so-called hill-climbing method. That is, the focus lens is sequentially moved from one end to the other end of the driving range to designated positions arranged at equal intervals, and the contrast value is obtained based on the image signal from the subject at each designated position. When the contrast value obtained in this way changes from increasing to decreasing with the movement of the focus lens, the designated position immediately before starting to decrease, that is, the designated position showing the maximum contrast value is determined as the in-focus position of the subject. Then, the focus lens is moved to the designated position. In this way, the automatic focus adjustment device can focus on the subject.
JP 11-84228 A [G02B 7/11, H04N 5/232, G02B 7/11]

  However, when determining the in-focus position by the hill-climbing method, the focus lens is moved by supplying current to the linear motor while checking the position of the focus lens with the position sensor. If it is narrow, it is necessary to intermittently repeat position detection and supply of current to the linear motor. In this case, since the acceleration time and the deceleration time of the focus lens are short, it is difficult to control the acceleration / deceleration time and the output of the linear motor even with a high-performance computer. Also, if there is an interruption overhead, it becomes more difficult to stop the focus lens at the specified position. As a result, an error between the stop position after the movement of the focus lens and the target designated position becomes large, and it becomes impossible to obtain an accurate contrast value at the designated position. Therefore, an accurate in-focus position can be obtained. There is a problem that you can not. In particular, in a camera built in a portable terminal, since the driving range of the focus lens is 200 to 300 μm and the interval between adjacent designated positions is as narrow as about 10 μm, it is more difficult to stop the focus lens at the designated position. Become. For this reason, the error between the stop position after movement and the target designated position is further increased, and it becomes even more difficult to obtain an accurate in-focus position.

  Therefore, the main object of the present invention is to make it easier to control the linear motor by increasing the moving distance of the focus lens, and to reduce the error between the stop position of the focus lens and the target designated position. An automatic focus adjustment device and an adjustment method thereof are provided.

  According to the first aspect of the present invention, the focus lens driven by the linear motor (42) is stopped at a plurality of designated positions obtained by dividing the drive range of the focus lens (14) at equal intervals to obtain the contrast value. A first moving means (36, 40, 42, S15, S43, S63, S75) for moving the focus lens to a specified position at least two or more ahead in the first direction in the automatic focus adjustment device for detecting a focal position; Second moving means (36, 40, 42, S25, S53, S89) for moving the focus lens to at least two or more specified positions in the second direction opposite to the first direction, an image of the subject at each specified position Contrast value acquisition means (36, S17, S27, S45, S55, S67, S81, S93) for obtaining a contrast value from the signal, Selection means (36, S33) for selecting the maximum contrast value from the contrast value obtained by the last value acquisition means, and focusing means (36 for moving the focus lens to a designated position indicating the maximum contrast value to focus the subject) , 40, 42, S35).

  In the first aspect of the invention, the driving range of the focus lens is divided at equal intervals by a plurality of designated positions. The focus lens driven by the linear motor is moved within the driving range by the first moving means to at least two or more specified positions ahead of the first direction, or is reverse to the first direction by the second moving means. Or at least two or more positions in the second direction. At each designated position thus moved, the contrast value is obtained from the image signal of the subject by the contrast value acquisition means. Then, the maximum contrast value is selected by the selecting means from the contrast values obtained at each specified position, and the focus lens is moved by the focusing means to the specified position indicating the maximum contrast value. As a result, the focus lens can be focused on the subject.

  Unlike the case of sequentially moving to adjacent designated positions as in the hill-climbing method, the focus lens is moved to the designated position ahead by at least two or more by the first moving means or the second moving means, so the moving distance is long. Become. For this reason, it becomes easy to control the acceleration / deceleration time of the focus lens by the first moving unit or the second moving unit and the output of the first moving unit or the second moving unit. The error from the target designated position can be reduced. Accordingly, a more accurate subject contrast value can be obtained at each designated position, and thus a more accurate in-focus position of the subject can be obtained.

  According to a second aspect of the present invention, in the automatic focusing apparatus according to the first aspect, the focus lens is moved alternately in the first direction and the second direction by alternately operating the first moving means and the second moving means. , An automatic focusing device. In this case, the moving distance in the first direction and the moving distance in the second direction can be made longer than when the focus lens is moved randomly in the first direction and the second direction.

  According to a third aspect of the present invention, in the automatic focusing apparatus according to the first or second aspect, the movement distances in the first direction are all the same distance, and the movement distance in the second direction is different from the movement profile in the first direction and It is an autofocus device that is all the same distance. In this case, it is only necessary to prepare one type of movement profile for each of the movement by the first movement unit and the movement by the second movement unit, so that the burden on the computer can be reduced.

  According to a fourth aspect of the present invention, in the automatic focus adjustment apparatus according to the third aspect, even when the number of designated positions is an odd number (2n-1: n is an integer of 3 or more) (2n: n is an integer of 3 or more). The moving distance in the first direction is the distance to the nth specified position, and the moving distance in the second direction is the distance to the (n-1) th specified position. Is an automatic focusing device. In this case, the first moving means advances in the first direction by n designated positions and the second moving means advances in the second direction by (n-1) designated positions, thereby alternately repeating the focus lens. Can stop only once at all specified positions and obtain a contrast value at each specified position. For this reason, the contrast value at each designated position can be efficiently obtained.

  According to a fifth aspect of the present invention, there is provided the automatic focusing apparatus according to any one of the first to fourth aspects, wherein the memory (38) and the writing means (36, S19, S29, S47, S57, S69, S83, S95), after moving to the designated position by any of the first moving means and the second moving means, it is confirmed whether or not the contrast value at the designated position is written in the memory. When it is confirmed by the confirmation means (36, S65, S79, S91) and the confirmation means that the contrast value at the designated position is written in the memory, the focus lens is moved to the next designated position without obtaining the contrast value at the designated position. Is further provided with third moving means (36, 40, 42, S63, S75, S89) for moving An automatic focusing device.

  According to the fifth aspect of the present invention, whether the contrast value at the designated position is already written in the memory by the writing means when moved to the designated position by either the first moving means or the second moving means. Confirm by confirmation means. As a result, when it is confirmed that the contrast value has already been written, the focus lens is moved to the next designated position by the third moving means without obtaining the contrast value again at the designated position. For this reason, the time until the in-focus position is obtained can be shortened.

  According to a sixth aspect of the present invention, in the automatic focus adjustment apparatus according to any one of the first to fifth aspects, the position of the focus lens when the focus lens is moved by either the first moving means or the second moving means. Position detecting means (36, 44) for detecting information at predetermined time intervals, and control means (36, S15, S15, etc.) for controlling the first moving means and the second moving means based on the position information detected by the position detecting means. S25, S43, S53, S63, S75, and S89).

  In the sixth aspect of the invention, when the focus lens is moved by the first moving means or the second moving means, the position information of the focus lens is detected by the position detecting means at predetermined time intervals. Then, the control unit is controlled based on the detected position information, and the focus lens is stopped at a predetermined designated position. In this case, since the position information can be accurately known by the position sensor 44 during the movement of the focus lens, the error between the stop position of the focus lens and the target designated position can be further reduced.

  According to a seventh aspect of the present invention, in the autofocusing apparatus according to any one of the first to sixth aspects, the display (24), the display means (36, S37) for displaying a preview image of the subject, and the focus lens It is an automatic focus adjustment device further comprising disabling means (36, S1) for disabling the display means from the start of the movement until the end of the movement of the focus lens by the focusing means.

  According to the seventh aspect of the present invention, the display means for displaying the preview image of the subject on the display is disabled before the focus lens starts moving, and the disabling of the display means is canceled after the focus lens is moved by the focusing means. In this case, since the preview image of the subject is not displayed on the display while the in-focus position is obtained, it is possible to prevent the user from feeling bad by gazing at the display screen.

  In the invention of claim 8, the focus lens driven by the linear motor (42) is stopped at a plurality of designated positions obtained by dividing the drive range of the focus lens (14) at equal intervals, and the contrast value is obtained. In the adjustment method of the automatic focusing apparatus that detects the focal position, the focus lens is moved to at least two or more specified positions in the first direction (36, 40, 42, S15, S43, S63, S75), and the focus is moved. The lens is moved to at least two or more specified positions in the second direction opposite to the first direction (36, 40, 42, S25, S53, S89), and the contrast value is obtained from the image signal of the subject at each specified position. Obtained (36, S17, S27, S45, S55, S67, S81, S93) and the maximum contrast value from the obtained contrast value A method of adjusting an automatic focus adjustment device, characterized by selecting (36, S33) and moving a focus lens to a designated position showing a maximum contrast value to focus on a subject (36, 40, 42, S35) It is. Since the operation and effect of the invention of claim 8 are the same as those of the invention of claim 1, they are omitted.

  The invention of claim 9 is the adjustment method of the automatic focusing apparatus according to claim 8, wherein the contrast value is written in the memory (38) (36, S19, S29, S47, S57, S69, S83, S95), After moving the focus lens to the designated position based on either the movement in the direction or the movement in the second direction, it is confirmed whether the contrast value at the designated position is written in the memory (36, S65, S79, S91), and when it is confirmed that the contrast value at the designated position is written in the memory, the focus lens is moved to the next designated position without obtaining the contrast value at the designated position (36, 40, 42, S63, S75, S89) is an adjustment method for the automatic focus adjustment device. Since the operation and effect of the ninth aspect of the invention are the same as those of the fifth aspect of the invention, they are omitted.

  According to a tenth aspect of the present invention, in the adjustment method of the automatic focus adjustment apparatus according to the eighth or ninth aspect, the position information of the focus lens is predetermined when the focus lens is moved in either the first direction or the second direction. Auto focus adjustment further comprising detecting at a time interval of (36, 44) and controlling movement of the focus lens (36, S15, S25, S43, S53, S63, S75, S89) based on the position information. This is a method for adjusting the apparatus. Since the operation and effect of the invention of claim 10 are the same as those of the invention of claim 6, they are omitted.

  According to an eleventh aspect of the present invention, in the adjustment method of the automatic focusing apparatus according to any one of the eighth to tenth aspects, a preview image of the subject is displayed on the display (24) (36, S37), and the focus lens is moved. This is an adjustment method for the automatic focus adjustment device, further comprising preventing the preview image from being displayed on the display from the start to the end of the movement of the focus lens to the in-focus position (36, S1). Since the operation and effect of the invention of claim 11 are the same as those of the invention of claim 7, they are omitted.

  According to the present invention, since the focus lens is moved to at least two or more specified positions ahead, the error between the stop position after the focus lens is moved and the target specified position can be reduced. Accordingly, a more accurate subject contrast value can be obtained at each designated position, and thus a more accurate in-focus position of the subject can be obtained.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  Referring to FIG. 1, a camera control circuit 10 built in a portable terminal according to a first embodiment of the present invention includes an optical unit 12, and a focus lens 14 is provided in the optical unit 12. The optical image of the subject is projected onto the light receiving surface of the CCD 16 through the focus lens 14. On the light receiving surface of the CCD 16, a charge corresponding to the optical image of the subject, that is, an image signal is generated by photoelectric conversion. The generated image signal is converted into image data which is digital data by the A / D conversion circuit 18 and then applied to the image signal processing circuit 20. The image signal processing circuit 20 performs a series of processes of white balance adjustment, color separation, gamma correction, and YUV conversion on the given image data, and generates YUV image data (YUV image data). The generated YUV image data is taken into the buffer memory 22 and then displayed on the liquid crystal display 24 as a preview image.

  The recording / reproducing processing circuit 26 takes in the YUV image data from the buffer memory 22, writes the fetched YUV image data into the recording memory 28, reads out the YUV image data from the recording memory 28, and puts the subject image on the liquid crystal display 24. Or display.

  The image signal output from the CCD 16 is also given to a high pass filter (HPF) 30. The high pass filter 30 extracts a high frequency component from the luminance signal of the image signal, and supplies the extracted high frequency component to the A / D conversion circuit 32. The A / D conversion circuit 32 converts the high-frequency component from an analog signal to digital data, and then gives it to the autofocus signal detection circuit 34. The autofocus signal detection circuit 34 obtains a contrast value from the high frequency component converted into digital data. Specifically, the absolute value of the high frequency component is taken and the peak is detected. The obtained contrast value is given to the computer 36 and written into the memory 38. Here, the focus state is detected using the high-frequency component of the luminance signal for the following reason. That is, an image captured in a focused state has a larger luminance difference between adjacent pixels than an image captured in an out-of-focus state, so that a high-frequency component is included in the luminance signal. For this reason, if the high frequency component contained in the luminance signal is evaluated, the in-focus state can be evaluated. Although the high-pass filter 30 is used in this embodiment, a band-pass filter (BPS) can be used depending on the imaging target.

  In the memory 38, linear motors at the time of acceleration and deceleration according to the moving direction and moving distance of the focus lens 14 as well as the designated positions for obtaining the contrast value necessary for detecting the in-focus state and the movement order thereof. 42 drive control programs (hereinafter referred to as “movement profiles”) are also written.

  Therefore, the computer 36 reads the designated positions for obtaining the contrast value, their movement order, and the movement profile from the memory 38. Then, based on the read movement profile, the motor driving circuit 40 is controlled to drive the linear motor 42 provided in the optical unit 12, so that the focus lens 14 is set according to a preset order. Move to. Further, the computer 36 reads the contrast value obtained at each designated position from the memory 38 and selects the maximum contrast value from them. Then, by controlling the motor drive circuit 40 to drive the linear motor 42, the focus lens 14 is moved to a designated position showing the maximum contrast value, that is, a focus position. In addition, a position sensor 44 that detects position information of the moving focus lens 14 and supplies the position information to the computer 36 is also provided in the optical unit 12.

  Next, the configuration of the optical unit 12 included in the camera control circuit 10 will be described with reference to FIG. The optical unit 12 includes a cylindrical lens holder 52 extending in the direction of the optical axis 50, and the focus lens 14 is accommodated in the lens holder 52. A support base 54 that supports the focus lens 14 is provided below the lens holder 52, and a shaft 56 that is provided in parallel with the optical axis 50 of the focus lens 14 passes through the support base 54. For this reason, the support base 54 can move to the left and right along the shaft 56, and the focus lens 14 can also move to the left and right in the direction of the optical axis 50 in the lens holder 52. In FIG. 2, only one set of shaft 56 and support base 54 is shown, but another set of shaft 56 and support base 54 is provided on the back side of the sheet in parallel with this shaft 56. The shaft 56 provided on the back side also penetrates the support base 54 that supports the focus lens 14. For this reason, the focus lens 14 can be stably moved left and right in the direction of the optical axis 50 by the two sets of the shaft 56 and the support base 54.

  A drive coil 42 a is attached to the upper surface of the lens holder 52. A magnet 42b is provided between the yoke 60 fixed to the housing 58 and the drive coil 42a, and the linear motor 42 is constituted by the drive coil 42a and the magnet 42b. When a drive current is supplied to the drive coil 42a, a drive force parallel to the optical axis 50 is generated in the drive coil 42a due to the interaction between the magnetic field formed by the magnet 42b and the current flowing through the drive coil 42a. For this reason, the focus lens 14 can be moved left and right along the shaft 56. A position sensor 44 made of a photo interrupter or the like is also provided on the upper surface of the lens holder 52. The position sensor 44 detects position information of the focus lens 14 and provides the detected position information of the focus lens 14 to the computer 36 at predetermined time intervals.

  The optical image of the subject is projected onto the light receiving surface of the CCD 16 through the focus lens 14, and is converted into charges corresponding to the optical image of the subject by photoelectric conversion on the light receiving surface, thereby generating an image signal. An optical filter 62 that cuts off ultraviolet rays is provided between the focus lens 14 and the CCD 16.

  Next, the drive current supplied to the linear motor 42 and the moving speed of the focus lens 14 when the focus lens 14 is moved from the specified position P0 to the specified position P5 will be described with reference to FIG. Here, the designated positions from the designated position P0 to the designated position P5 are arranged on the straight line at equal intervals.

  A constant current is supplied to the linear motor 42 from the first designated position P0 to just before reaching the target designated position P5, and a reverse current is supplied in pulses before the designated position P5. Is rapidly reduced to zero.

  When such a drive current is passed through the linear motor 42, the moving speed of the focus lens 14 gradually increases from zero and becomes constant near the designated position P1, for example. Thereafter, the robot moves to a position before the designated position P5 at a constant speed. When moving at a constant speed, the position information of the focus lens 14 is detected by the position sensor 44 at predetermined time intervals. When the computer 36 detects that the focus lens 14 has come before the specified position P5 based on the position information of the focus lens 14 given from the position sensor 44, the drive current in the direction opposite to that in the past is pulsed. To the linear motor 42. As a result, the moving speed of the focus lens 14 rapidly decreases and stops at the designated position P5.

  As in the prior art, the focus lens 14 is moved from the designated position P0 to the designated position P1 and stopped, and then moved from the designated position P1 to the designated position P2 to be stopped. Unlike the case where the focus lens 14 is moved, it can be moved from the designated position P0 to the designated position P5 without stopping on the way, so that the moving speed can be increased for a certain period of time. I can know. As a result, the time control and output control of the acceleration time and the deceleration time are facilitated without using a high-speed computer, and even if there is an interruption overhead, the control of the linear motor is not affected. The error between the stop position and the target designated position P5 can be reduced.

  With reference to FIG. 4, a method of moving the focus lens 14 in the case where there are ten designated positions, that is, an even number, from the designated position P0 to the designated position P9 will be described. When moving forward, move 5 specified positions to the right (plus) from the current specified position, and when moving backward, move 4 specified positions to the left (minus) from the current specified position The movement of the focus lens 14 is shown for the case where it is made to do so. Here, the distance from the designated position P0 to the designated position P9 corresponds to the driving distance of the focus lens 14, and the designated positions from the designated position P1 to the designated position P8 arranged therebetween are arranged on the straight line at equal intervals. ing.

  First, after obtaining the contrast value of the designated position P0 in the first step (displayed by a white circle, the same applies hereinafter), in the second step, the designated position P0 is advanced to the right by five designated positions from the designated position P0 to the designated position. The contrast value of P5 is obtained. In the third step, the designated position P5 returns to the left by four designated positions from the designated position P1 to obtain the contrast value at the designated position P1. In the fourth step, the process proceeds rightward by five designated positions from the designated position P1 to the designated position P6, and the contrast value at the designated position P6 is obtained. Similarly, the focus lens 14 reaches the designated position P9 in the tenth step while alternately repeating the forward movement and the backward movement, and obtains the contrast value of the designated position P9. With this operation, the focus lens stops once at all the designated positions from the designated position P0 to the designated position P9, so that the contrast values at all the designated positions can be obtained.

  Next, the contrast values at the designated positions from the designated position P0 to the designated position P9 are compared, and the designated position with the maximum contrast value is determined. Since the designated position where the contrast value is maximized is the focus position, the linear motor 42 is driven to move the focus lens 14 to the focus position, and the focus lens 14 is focused on the subject.

  Next, the computer 36 moves the focus lens 14 according to the flow shown in FIGS. 5 and 6 to obtain the contrast value at each designated position, and executes processing for moving the focus lens 14 to the in-focus position. First, in step S1, the preview display is turned off. As a result, the preview image of the subject is not displayed on the liquid crystal display 24. The preview display is turned off as described above. When the focus lens 14 is moved back and forth in order to obtain the in-focus position, the image of the subject displayed on the liquid crystal display 24 is increased in a short time. This is to prevent the user from feeling uneasy by gazing at the screen of the liquid crystal display 24 because it repeatedly decreases.

  In step S3, the designated position for detecting the in-focus state written in the memory 38, the order of the designated positions for obtaining the contrast value, and the movement profile are read out. In step S5, the variable n is set to zero. In step S7, the linear motor 42 is driven to move the focus lens 14 to the designated position P0 that is the origin. At this time, the computer 36 grasps the current position of the focus lens 14 based on the position information given from the position sensor 44 at predetermined time intervals, and controls the current flowing through the linear motor 42 to the designated position P0. The focus lens 14 is stopped. In step S9, the high-frequency component obtained by the high-pass filter 30 from the subject image signal obtained through the focus lens 14 is A / D converted, and then the contrast value at the designated position P0 is obtained. In step S11, the contrast value at the designated position P0 is written in the memory 38.

  In step S13, the variable n is set to (n + 5), and in step S15, the linear motor 42 is driven to move the focus lens 14 rightward by five designated positions and move to the designated position Pn. In this embodiment, the variable n is an integer of 3 or more. In step S17, the contrast value at the designated position Pn is obtained from the image signal of the subject in the same manner as in step S9. In step S19, the contrast value at the designated position Pn is written in the memory 38. In step S21, it is determined whether or not the variable n is 9. The case where “YES” is determined will be described later. On the other hand, if it is determined as “NO”, that is, if the variable n is not 9, the focus lens 14 has not yet reached the position P9 which is the last designated position, and the process proceeds to step S23.

  Next, in step S23, the variable n is set to (n-4). In step S25, the linear motor 42 is driven to move the focus lens 14 backward by four designated positions and move to the designated position Pn. Let In step S27, the contrast value at the designated position Pn is obtained from the image signal of the subject in the same manner as in step S9. In step S29, the contrast value at the designated position Pn is written in the memory 38, and the process returns to step S13.

  If “YES” is determined in the step S21, that is, if it is determined that the focus lens 14 has reached the last designated position P9, the process proceeds to a step S31. In step S31, the contrast values of all the specified positions from the specified position P0 to the specified position P9 obtained in steps S9, S17, and S27 are read from the memory 38. In step S33, the read contrast values are compared with each other to select the maximum contrast value, and the designated position indicating the maximum contrast value is determined. In step S35, the focus lens 14 is moved to the designated position determined by driving the linear motor 42. As a result, since the focus lens 14 can be moved to the in-focus position, the preview display turned on in step S37 and output from the image signal processing circuit 20 to end the preview display turned off in step S1. A preview image of the subject is displayed on the liquid crystal display 24 via the buffer memory 22. Thereafter, the autofocus control operation is terminated.

  In this embodiment, when moving forward, the vehicle always moves right by 5 designated positions, and when moving backward, it always moves left by 4 specified positions. As described above, since a plurality of designated positions are included between the designated positions for obtaining the contrast value, the moving distance of the focus lens 14 becomes long. Therefore, it becomes easy to control the time to accelerate / decelerate the focus lens 14 by the linear motor 42 and the output of the linear motor 42, and the stop position of the focus lens 14 and the target designated position can be controlled even if the computer 36 has low capability. The error can be reduced. Accordingly, it is possible to obtain a more accurate contrast value of the subject at each designated position, and thus a more accurate in-focus position of the subject.

  Further, since the forward and backward movement amounts are constant, it is only necessary to prepare one type of movement profile for each of forward and backward movements, so that the burden on the computer 36 can be reduced.

  In this embodiment, the focus lens 14 stops at ten designated positions from the designated position P0 to the designated position P9, that is, even (2n) designated positions. Therefore, when n is an integer greater than or equal to 3, when moving forward, it proceeds to the right by n specified positions, and when moving backward, it returns alternately to the left by specified positions (n-1). As a result, the focus lens 14 can be stopped only once at all designated positions, and the contrast value can be obtained at all designated positions. For this reason, the contrast values of all the designated positions can be obtained efficiently.

  Note that the movement amount is not limited to the combination of n designated positions and (n-1) designated positions. For example, the movement amount is designated by (n + 1) designated positions (n-1), designated positions ( It is sufficient that the amount of movement in the right direction and the amount of movement in the left direction are equal to or more than two designated positions, such as n-1) pieces and designated positions (n-2) pieces. Further, it is not necessary to alternately repeat the forward movement and the backward movement. The forward movement and the backward movement may be performed after a plurality of forward movements, or the reverse movement may be performed after the forward movement. However, depending on the combination of movement amounts, there may be a designated position where the focus lens 14 does not stop, or it may stop several times at the same designated position. Handling in the case of stopping at the same designated position a plurality of times will be described in a third embodiment to be described later.

  Next explained is the second embodiment of the invention. Also in the case of the second embodiment, the configuration of the camera control circuit 10 of FIG. 1 used in the description of the first embodiment, the configuration of the optical unit 12 of FIG. 2, and the illustration of FIG. In the explanation of the examples, those figures and the explanation thereof are omitted.

  With reference to FIG. 7, a method of moving the focus lens 14 will be described in the case where there are 11 designated positions from the designated position P0 to the designated position P10, that is, an odd number. When moving forward by 6 specified positions from the current specified position when moving forward, and moving left by 5 specified positions from the current specified position when going back, The movement of the focus lens 14 is shown. Here, the distance from the designated position P0 to the designated position P10 corresponds to the drive distance of the focus lens 14, and the designated positions from the designated position P1 to the designated position P9 arranged therebetween are arranged at equal intervals on a straight line. ing.

  First, after obtaining the contrast value at the designated position P0 in the eleventh step, the process proceeds to the right by six designated positions from the designated position P0 to the designated position P6 in the twelfth step to obtain the contrast value at the designated position P6. In the thirteenth step, the designated position P6 returns to the left by five designated positions from the designated position P6 to obtain the contrast value at the designated position P1. In the fourteenth step, the designated position P1 is advanced to the right by 6 designated positions from the designated position P1 to obtain the contrast value at the designated position P7. Similarly, the focus lens 14 reaches the designated position P5 in the 21st step while alternately repeating the forward movement and the backward movement, and obtains the contrast value of the designated position P5. In this embodiment, the focus lens 14 reaches the end not at the specified position P10 but at the specified position P5. In this way, the focus lens 14 stops once at all the designated positions from the designated position P0 to the designated position P10, so that the contrast values at all the designated positions can be obtained.

  Next, the contrast values at the designated positions from the designated position P0 to the designated position P10 are compared with each other, and the designated position having the maximum contrast value is determined. Since the designated position where the contrast value is maximized is the focus position, the linear motor 42 is driven to move the focus lens 14 to the focus position, and the focus lens 14 is focused on the subject.

  Next, the computer 36 moves the focus lens 14 in accordance with the flow shown in FIGS. 8 and 9 to obtain the contrast value at each designated position, and executes processing for moving the focus lens 14 to the in-focus position. Since the first step S1 to step S11 are the same as the step S1 to step S11 shown in FIG. 5, the same numbers are given and the description thereof is omitted.

  In step S41, the variable n is set to (n + 6), and in step S43, the linear motor 42 is driven to move the focus lens 14 rightward by six designated positions and move to the designated position Pn. In this embodiment, the variable n is an integer of 3 or more. In step S45, the contrast value at the designated position Pn is obtained from the image signal of the subject in the same manner as in step S9. In step S47, the contrast value at the designated position Pn is written in the memory 38. In step S49, it is determined whether the variable n is 5. The case where “YES” is determined will be described later. On the other hand, if “NO” is determined, that is, if the variable n is not 5, the focus lens 14 has not yet reached the last designated position P5, and thus the process proceeds to step S51.

  Next, in step S51, the variable n is set to (n-5), and in step S53, the linear motor 42 is driven to move the focus lens 14 backward by five designated positions and move to the designated position Pn. . In step S55, the contrast value at the designated position Pn is obtained from the image signal of the subject in the same manner as in step S9. In step S57, the contrast value at the designated position Pn is written in the memory 38, and the process returns to step S41.

  If “YES” is determined in the step S49, that is, if it is determined that the focus lens 14 has reached the last designated position P5, the process proceeds to a step S59. In step S59, the contrast value at each specified position from the specified position P0 to the specified position P10 obtained in steps S9, S45, and S55 is read from the memory 38.

  Since the next step S33 to the last step S37 are the same as the step S33 to step S37 shown in FIG. 6, the same numbers are given and the description thereof is omitted.

  In this embodiment, when moving forward, it always proceeds rightward by 6 specified positions, and when moving backward, it always returns leftward by 5 specified positions. Accordingly, as in the case of the first embodiment, since a plurality of designated positions are included between designated positions for obtaining the contrast value, the moving distance of the focus lens 14 becomes long. Therefore, it becomes easy to control the time to accelerate / decelerate the focus lens 14 by the linear motor 42 and the output of the linear motor 42, and the stop position of the focus lens 14 and the target designated position can be controlled even if the computer 36 has low capability. The error can be reduced. Accordingly, it is possible to obtain a more accurate contrast value of the subject at each designated position, and thus a more accurate in-focus position of the subject.

  Further, since the forward and backward movement amounts are constant, it is only necessary to prepare one type of movement profile for each of forward and backward movements, so that the burden on the computer 36 can be reduced.

  In this embodiment, the focus lens 14 stops at eleven, ie, odd (2n-1) designated positions from the designated position P0 to the designated position P10. Therefore, when n is an integer greater than or equal to 3, when moving forward, it proceeds to the right by n specified positions, and when moving backward, it returns alternately to the left by specified positions (n-1). As a result, the focus lens 14 can be stopped only once at all designated positions, and the contrast value can be obtained at all designated positions. For this reason, even when the number of designated positions for obtaining the contrast is an odd number, the contrast value at each designated position can be obtained efficiently. However, the designated position that reaches the end in this case is not the designated position at the right end but the designated position in the center.

  Note that the movement amount is not limited to the combination of n designated positions and (n-1) designated positions. For example, the movement amount is designated by (n + 1) designated positions, n designated positions, and designated positions (n-1). The amount of movement in the right direction and the amount of movement in the left direction, such as the number of pieces and the number of designated positions (n−2), need only be equal to or more than two designated positions. Further, it is not necessary to alternately repeat the forward movement and the backward movement, and the backward movement may be performed after moving forward a plurality of times, or the reverse movement may be performed a plurality of times after moving forward. However, depending on the combination of movement amounts, there may be a designated position where the focus lens 14 does not stop, or it may stop several times at the same designated position. Handling in the case of stopping at the same designated position a plurality of times will be described in a third embodiment to be described later.

  Furthermore, a third embodiment of the present invention will be described. Also in the case of the third embodiment, the configuration of the camera control circuit 10 of FIG. 1 used in the description of the first embodiment, the configuration of the optical unit 12 of FIG. 2, and the illustration of FIG. In the explanation of the examples, those figures and the explanation thereof are omitted.

  Referring to FIG. 10, when moving the focus lens 14 to eleven designated positions from the designated position P0 to the designated position P10, unlike the case of the second embodiment, from the current designated position when proceeding forward. The focus lens 14 is moved to the right by dividing it into three designated positions twice. On the other hand, when returning to the back, the focus lens 14 is moved to the left by 5 designated positions from the current designated position, as in the second embodiment. Here, as in FIG. 7, the distance from the designated position P0 to the designated position P10 corresponds to the driving distance of the focus lens 14, and each designated position from the designated position P1 to the designated position P9 arranged therebetween is They are arranged at regular intervals on a straight line.

  First, after obtaining the contrast value at the designated position P0 in the thirty-first step, the process proceeds to the right by three designated positions from the designated position P0 to the designated position P3 in the thirty-second step to obtain the contrast value at the designated position P3. . In a thirty-third step, the process proceeds further to the right by three designated positions from the designated position P3 to the designated position P6, and the contrast value at the designated position P6 is obtained. Next, in a thirty-fourth step, the process returns to the left by five designated positions from the designated position P6 to the designated position P1, and the contrast value at the designated position P1 is obtained. In a thirty-fifth step, the process proceeds rightward by three designated positions from the designated position P1 to the designated position P4, and the contrast value at the designated position P4 is obtained. Similarly, the focus lens 14 returns to the designated position P3 in the 40th step while alternately repeating two forwards and one backward.

  However, in the thirty-second step, the focus lens 14 is moved to the designated position P3, and the contrast value at the designated position P3 is obtained. For this reason, it is not necessary to obtain the contrast value at the designated position P3 again in the 40th step (displayed by a black circle, the same applies hereinafter). Therefore, in the forty-first step, the robot advances rightward by three designated positions from the designated position P3 and moves to the designated position P6. However, since the contrast value of the designated position P6 has already been obtained in the 33rd step, it is not necessary to obtain the contrast value of the designated position P6 even in the 41st step. Similarly, it is not necessary to obtain the contrast value of the designated position P4 moved in the 43rd step and the contrast value of the designated position P7 moved in the 44th step. In step 45, the process proceeds to the designated position P10, and the contrast value at the designated position P10 is obtained. By this operation, the focus lens 14 stops at all the designated positions from the designated position P0 to the designated position P10, so that the contrast values at all the designated positions can be obtained.

  Next, the contrast values at the designated positions from the designated position P0 to the designated position P10 are compared with each other, and the designated position having the maximum contrast value is determined. Since the designated position where the contrast value is maximized is the focus position, the linear motor 42 is driven to move the focus lens 14 to the focus position, and the focus lens 14 is focused on the subject.

  Next, the computer 36 moves the focus lens 14 according to the flow shown in FIGS. 11 to 13 to obtain the contrast value at each designated position, and executes processing for moving the focus lens 14 to the in-focus position. Since the first step S1 to step S11 are the same as the step S1 to step S11 shown in FIG. 5, the same numbers are given and the description thereof is omitted.

  In step S61, the variable n is set to (n + 3). In step S63, the linear motor 42 is driven to move the focus lens 14 rightward by three designated positions and move to the designated position Pn. In this embodiment, the variable n is a positive integer. In step S65, it is determined whether or not the contrast value at the designated position Pn has already been written in the memory 38. As a result, if "YES" is determined, the process proceeds to step S73 described later. On the other hand, when it is determined as “NO”, that is, when the contrast value at the designated position Pn is not written in the memory 38, in the same manner as in the case of Step S9, in step S67, the image of the designated position Pn is obtained. Find the contrast value. In step S69, the contrast value at the designated position Pn is written in the memory 38. In step S71, it is determined whether or not the variable n is 10. This determination is performed only when the contrast value of Pn is written in the memory 38 in step S69, and when it is determined “YES” in step S65, the variable n is not 10, so it is not performed. As a result, if "YES" is determined, the process proceeds to step S97 described later. On the other hand, if “NO” is determined, that is, if the variable n is not 10, it is determined that the designated position P10 to be reached last is not reached yet, and the process proceeds to step S73.

  In step S73, the variable n is set to (n + 3) again. In step S75, the linear motor 42 is driven to further move the focus lens 14 rightward by three designated positions and move to the designated position Pn. . In step S79, it is determined whether or not the contrast value at the designated position Pn has already been written in the memory 38. As a result, if "YES" is determined, the process proceeds to step S87 described later. On the other hand, when it is determined as “NO”, that is, when the contrast value at the designated position Pn is not written in the memory 38, in the same manner as in step S9, in step S81, the image of the designated position Pn is obtained from the subject image signal. Find the contrast value. In step S83, the contrast value at the designated position Pn is written in the memory 38.

  In step S85, it is determined whether the variable n is 10. This determination is performed only when the contrast value at the designated position Pn is written in step S83, and when it is determined “YES” in step S79, the variable n is not 10, so it is not performed. As a result, if “YES” is determined, it will be described later. On the other hand, if “NO” is determined, that is, if the variable n is not 10, it is determined that the designated position P10 to be reached last is not reached yet, and the process proceeds to step S87.

  Next, in step S87, the variable n is set to (n-5), and in step S89, the linear motor 42 is driven to move the focus lens 14 backward by five designated positions and move to the designated position Pn. Let In step S91, it is determined whether or not the contrast value at the designated position Pn has already been written in the memory 38. As a result, if “YES” is determined, the process returns to step S61 described above. On the other hand, if it is determined as “NO”, that is, if the contrast value at the designated position Pn is not written in the memory 38, in the same manner as in step S9, in step S93, the image of the designated position Pn is obtained from the subject image signal. Find the contrast value. In step S95, the contrast value at the designated position Pn is written in the memory 38, and the process returns to step S61.

  If “YES” is determined in step S71 and step S85, that is, if the contrast value is obtained by reaching the last-specified position P10, the process proceeds to step S97. In step S97, the contrast values of all the specified positions from the specified position P0 to the specified position P10 obtained in steps S9, S67, S81, and S93 are read from the memory 38.

  Since the next step S33 to the last step S37 are the same as the step S33 to step S37 shown in FIG. 6, the same numbers are given and the description thereof is omitted.

  In this embodiment, when the focus lens 14 stops again at the designated position where the contrast value has already been obtained, the focus lens 14 is moved to the next designated position without obtaining the contrast value again at the designated position. For this reason, the time until the in-focus position is obtained can be shortened.

  Further, when moving forward, it is divided into two times, each proceeding to the right by three specified positions, and when moving backward, it always returns to the left by five specified positions. For this reason, since a plurality of designated positions are included between the designated positions for obtaining the contrast value, the moving distance of the focus lens 14 becomes long. Therefore, it becomes easy to control the time for accelerating / decelerating the focus lens 14 by the linear motor 42 and the output of the linear motor 42, and the stop position of the focus lens 14 and the target designated position can be controlled even if the computer 36 has low capability. The error can be reduced.

Furthermore, since the amount of movement when moving forward is the same as that for three designated positions, the moving profile for forward movement can be made common. Therefore, since the number of necessary movement profiles can be reduced, the burden on the computer 36 can be reduced. However, for example, the amount of movement may be changed such that the first advancement proceeds rightward by three designated positions and the second advancement proceeds right by two designated positions. Further, the number of times of movement when moving forward is not limited to two, and may be three or more. Furthermore, not only when moving forward, but also when moving backward, the amount of movement and the number of movements may be changed.

It is a block diagram which shows an example of a structure of the camera control circuit of 1st Example of this invention. It is a block diagram which shows an example of a structure of an optical unit. It is an illustration figure which shows the drive current of a linear motor, and the moving speed of a focus lens. It is an illustration figure which shows the movement order of the focus lens in 1st Example. It is a flowchart which shows a part of operation | movement of the computer of 1st Example. It is a flowchart which shows a part of other operation | movement of the computer of 1st Example. It is an illustration figure which shows the movement order of the focus lens in 2nd Example. It is a flowchart which shows a part of operation | movement of the computer of 2nd Example. It is a flowchart which shows another part of operation | movement of the computer of 2nd Example. It is an illustration figure which shows the movement order of the focus lens in 3rd Example. It is a flowchart which shows a part of operation | movement of the computer of 3rd Example. It is a flowchart which shows a part of other operation | movement of the computer of 3rd Example. It is a flowchart which shows a part of others of operation | movement of the computer of 3rd Example.

Explanation of symbols

10 ... Camera control circuit 16 ... CCD
24 ... Liquid crystal display 34 ... Autofocus signal detection circuit 36 ... Computer 38 ... Memory 40 ... Motor drive circuit 42 ... Linear motor 44 ... Position sensor

Claims (11)

In an automatic focus adjustment apparatus that detects a focus position by stopping the focus lens driven by a linear motor and obtaining a contrast value at a plurality of designated positions obtained by dividing the drive range of the focus lens at equal intervals.
First moving means for moving the focus lens to the designated position at least two or more ahead in the first direction;
Second moving means for moving the focus lens in the second direction opposite to the first direction to the designated position at least two or more ahead;
Contrast value obtaining means for obtaining a contrast value from an image signal of a subject for each designated position;
Selecting means for selecting a maximum contrast value from the contrast value obtained by the contrast value acquiring means; and focusing means for moving the focus lens to the designated position indicating the maximum contrast value to focus on the subject. An automatic focusing device, comprising:   2. The automatic focus adjustment apparatus according to claim 1, wherein the focus lens is alternately moved in the first direction and the second direction by operating the first movement unit and the second movement unit alternately. 3.   3. The automatic focusing apparatus according to claim 1, wherein the moving distances in the first direction are all the same distance, and the moving distances in the second direction are different from the moving profile in the first direction and are all the same distance. .   Whether the number of designated positions is odd (2n-1: n is an integer greater than or equal to 3) or even (2n: n is an integer greater than or equal to 3), the moving distance in the first direction is n ahead. 4. The automatic focus adjustment apparatus according to claim 3, wherein the distance is a distance to a designated position, and the moving distance in the second direction is a distance to the designated position that is (n−1) ahead. 5. memory,
Writing means for writing the contrast value obtained by the contrast value obtaining means into the memory;
After moving to the designated position by either the first moving means or the second moving means, confirmation means for confirming whether the contrast value at the designated position is written in the memory, and by the confirmation means When it is confirmed that the contrast value at the designated position is written in the memory, a third moving unit is further provided for moving the focus lens to the next designated position without obtaining the contrast value at the designated position. 5. An automatic focusing apparatus according to any one of claims 1 to 4. Position detecting means for detecting position information of the focus lens at a predetermined time interval when the focus lens is moved by any one of the first moving means and the second moving means; and detected by the position detecting means. 6. The automatic focus adjusting apparatus according to claim 1, further comprising a control unit that controls the first moving unit and the second moving unit based on the position information that has been set. display,
Display means for displaying a preview image of the subject on the display; and disabling means for disabling the display means from the start of movement of the focus lens to the end of movement of the focus lens by the focusing means. Item 7. The automatic focusing apparatus according to any one of Items 1 to 6. Adjustment of an automatic focus adjustment device that detects a focus position by obtaining a contrast value by stopping the focus lens driven by a linear motor at a plurality of designated positions obtained by dividing the drive range of the focus lens at equal intervals. In the method
Moving the focus lens to the designated position at least two or more points in the first direction;
Moving the focus lens to the specified position at least two or more ahead in a second direction opposite to the first direction;
Obtain a contrast value from the image signal of the subject for each specified position,
An automatic focus adjustment apparatus, wherein a maximum contrast value is selected from the obtained contrast values, and the focus lens is moved to the designated position indicating the maximum contrast value to focus on the subject. Method. Write the contrast value into the memory;
Whether or not the contrast value at the designated position is written in the memory after the focus lens is moved to the designated position based on either the movement in the first direction or the movement in the second direction. And confirming that the contrast value at the designated position is written in the memory, further moving the focus lens to the next designated position without obtaining the contrast value at the designated position. The adjustment method of the automatic focus adjustment apparatus of Claim 8 provided. The position information of the focus lens is detected at a predetermined time interval when the focus lens is moved in either the first direction or the second direction, and the focus lens is moved based on the position information. The method of adjusting an automatic focusing apparatus according to claim 8 or 9, further comprising controlling Further comprising: displaying a preview image of the subject on a display; and not displaying the preview image on the display from the start of movement of the focus lens until the end of movement of the focus lens to the in-focus position. The adjustment method of the automatic focus adjustment apparatus in any one of Claims 8 thru | or 10.

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