JP3907222B2 - Video equipment system and interchangeable lens - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to video equipment such as a video camera system in which lenses can be exchanged.
[0002]
[Prior art]
An interchangeable lens and camera body used in a conventional video apparatus such as a video camera system will be described with reference to FIG.
[0003]
A conventional lens unit (interchangeable lens) 920 capable of zooming has a zoom lens 901 and a correction lens 902 that corrects a focal position shift at the time of zooming, which are mechanically connected by a cam 903, so that zooming operation is performed. When manually or electrically operated, the zoom lens 901 and the correction lens 902 are interlocked with each other in a predetermined positional relationship.
[0004]
In such a lens system, the front lens is the focusing lens 900, and focusing is performed by moving in the optical axis direction. The light that passes through these lens groups forms an image on the imaging surface of the imaging element 905 of the camera body 921, is photoelectrically converted into an electrical signal, and is output as a video signal. The video signal is subjected to predetermined signal processing by a video signal processing circuit 907 and converted into a standard television signal.
[0005]
At the same time, the video signal is also input to the AF signal processing circuit 908. The AF signal processing circuit 908 extracts a high frequency component from the video signal and takes it into the microcomputer 909 as an AF evaluation value. The microcomputer 909 determines the motor drive direction so that the focusing speed and AF evaluation value corresponding to the degree of focus increase, and sends the speed and direction of the focus motor 930 to the focus motor driver 931 in the lens unit. Then, the focusing lens 900 is driven.
[0006]
The state of the zoom switch 910 is read into the microcomputer 909, and the microcomputer 909 determines the drive direction and drive speed of the zoom lens 901 according to the operation state of the zoom switch 910, and sends it to the zoom motor driver 933 in the lens unit. The zoom lens 901 is driven via the zoom motor 932.
[0007]
The camera main body 921 can replace the lens unit 920, and can expand the photographing range by connecting another lens unit.
[0008]
By the way, in recent cameras, in order to reduce the size and focus on a short-distance subject, the correction lens is no longer mechanically interlocked with a cam, and the movement locus of the correction lens is stored in advance in the microcomputer as lens cam data. A so-called inner focus type lens structure in which the correction lens is driven based on the lens cam data and the focus is adjusted by the correction lens has been proposed and put into practical use.
[0009]
A video camera having an inner focus type lens configuration already in practical use will be described with reference to FIG.
[0010]
The image light from the subject is fixed to a first lens group 801 that is fixed from the front of the optical axis, and a second lens group (variable lens) 802 that moves in the direction of the optical axis to perform zooming. The third lens group 804 passes through a fourth lens group (correction lens) 805 that has both a focus adjustment function by moving alone in the optical axis direction and a correction function that corrects the movement of the focal plane due to zooming. The image is formed on an image sensor 806 such as a CCD.
[0011]
Image light on the image sensor is photoelectrically converted, amplified to an optimal level by an amplifier 809, input to the camera signal processing circuit 812, converted into a standard television signal, and simultaneously input to the AF signal processing circuit 813. . When the AF switch 831 is off and the zoom switch 830 is pressed, the AF evaluation value generated by the AF signal processing circuit 813 is scaled in the tele or wide pressed direction. Accordingly, by sending a signal to the zoom motor driver 822, the zoom lens 802 is driven via the zoom motor 821, and at the same time, a signal is sent to the focus motor driver 826 by the control unit 819 based on the lens cam data 820. The magnification change operation is performed by moving the correction lens 805.
[0012]
When the AF switch 831 is on and the zoom switch 130 is pressed, the determination result of the in-focus state can be used, so the control unit 819 stores the lens cam data stored in advance in the lens microcomputer. Referring to not only 820 but also the AF evaluation value, the zooming operation is performed while maintaining the position where the AF evaluation value is maximized. When the AF switch 831 is on and the zoom switch 830 is not pressed, the AF control unit 817 sends a signal to the focus motor driver 826 so that the AF evaluation value becomes maximum, and the correction is performed via the focus motor 825. An automatic focus adjustment operation is performed by moving the lens 805.
[0013]
For this reason, this type of lens configuration is no longer the mainstream method for clip-on (non-replaceable) lens type video cameras, and it is more attractive if the same configuration is used for interchangeable lens type lenses. A simple video camera system can be realized. However, the inner focus in the interchangeable lens system has several problems to be solved and has not yet been put into practical use.
[0014]
[Problems to be solved by the invention]
In this inner focus type interchangeable lens system, the distance from the focus lens (correction lens) group to the image sensor (back focus: BF) may vary due to the accuracy of structural parts, mounting errors, and the like. In order to affect the zooming operation, the focus lens group needs to recognize an accurate origin as a driving reference based on the lens cam data. Normally, this position recognition is performed by measuring the dispersion value based on the reference position of the correction lens (the position obtained by the reference position detection means) at the time of manufacture, and storing it as a correction value in the nonvolatile memory of the microcomputer. This correction value is read and corrected based on the drive end position to determine the origin.
[0015]
In addition, there is a problem that BF changes with changes in environmental temperature or the like. To solve this problem, as shown in Japanese Patent Laid-Open No. Hei 6-289275, a temperature detecting means is provided and a zoom trace curve is set. Methods such as sequential change control according to the ambient temperature have been proposed.
[0016]
However, the control proposed above is effective only for the video camera of the sticking lens method, and does not solve the problem in the case of the interchangeable lens method.
[0017]
That is, the problem of many combinations of the camera body and the lens unit is newly added.
[0018]
The present invention solves the above-mentioned problems in the interchangeable lens type video device system, and can perform any zooming operation and focusing operation under any combination of any interchangeable lens and video device body and under any use conditions. A system is provided.
[0019]
[Means for Solving the Problems]
The invention according to claim 1 is a zoom lens, a correction lens that corrects a change in a focal position due to movement of the zoom lens, a storage unit that stores a positional relationship between the zoom lens and the correction lens, and the first lens An inner focus type interchangeable lens having control means for controlling movement of the correction lens in accordance with movement of the variable magnification lens based on information stored in one storage means, and detachable from the interchangeable lens, A camera body having a flange back correction information supply means for storing flange back correction information unique to the camera body caused by the camera body and supplying the information to the interchangeable lens by communication , the video equipment system comprising: the interchangeable lens and the flange back correction information received from the camera body, the correction lens using the information stored in said storage means A video device system characterized by comprising a correction means for controlling the movement.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0034]
FIG. 1 is a diagram showing a configuration of a video equipment system as an embodiment of the present invention. The lens unit 127 (interchangeable lens) is configured to be detachable from the camera body 128.
[0035]
The image light from the subject includes a first lens group 101 fixed from the front of the optical axis, a second lens group (variable lens) 102 that performs zooming by moving in the optical axis direction, a diaphragm 103, and a fixed lens. The third lens group 104 is a fourth lens group (correction lens) 105 having both a focus adjustment function by itself and a correction function for correcting the movement of the focal plane due to zooming by moving in the optical axis direction. Then, an image is formed on the image sensor 106 such as a CCD.
[0036]
The absolute positions of the second lens 102 and the fourth lens 105 are detected by absolute position detection devices 102A and 105A such as encoders, and the detection information is supplied to the microcomputer 116.
[0037]
The image light on the image sensor is photoelectrically converted, amplified to an optimum level by the amplifier 109, input to the camera signal processing circuit 112, converted to a standard television signal, and simultaneously input to the AF signal processing circuit 113. . The AF evaluation value generated by the AF signal processing circuit 113 is read by the data read program 115 in the main body microcomputer 114 and transferred to the lens microcomputer 116 by communication. Although not described below, information is transmitted between the main body microcomputer 114 and the lens microcomputer 116 by electrical communication.
[0038]
Further, the main body microcomputer 114 reads the state of the zoom switch 130 and the AF switch 131 and sends the state of the switch to the lens microcomputer 116. In the lens microcomputer 116, when the AF switch 131 is off and the zoom switch 130 is pressed according to information from the main body microcomputer 114, the second lens group 102 is driven in the tele or wide pressed direction. Therefore, by sending a signal to the zoom motor driver 122 based on the lens cam data 120 stored in advance in the lens microcomputer, the zoom lens 121 is driven via the zoom motor 121 and at the same time, The stored lens cam data 120 is used to send a signal to the focus motor driver 126 based on the program 119 to move the correction lens 105 via the focus motor 125, thereby performing a scaling operation.
[0039]
In the type in which the correction lens (focus lens) is behind the optical axis as in the embodiment, the control position of the correction lens in the state in which the focus at the time of zooming is maintained varies depending on the subject distance. As shown in FIG. 4, the lens cam data 120 stores the movement position of the correction lens 105 for each of a plurality of absolute positions of the variable magnification lens 102 and for each subject distance (absolute position). Reference numeral 119 determines the rotation direction and rotation speed of the correction lens motor 125 using lens cam data selected by the absolute position information of the variable magnification lens 102 and the correction lens 105 detected by the position detection devices 102A and 105A.
[0040]
When the AF switch 131 is on and the zoom switch 130 is pressed (on), control based on detection of the in-focus state can be performed. The control unit 119 refers to not only the lens cam data 120 stored in advance in the lens microcomputer but also the AF evaluation signal sent from the main body microcomputer 114, and performs a zooming operation while maintaining the position where the AF evaluation value becomes maximum. I do. When the AF switch 131 is on and the zoom switch 130 is not pressed, the AF control unit 117 sends a signal to the focus motor driver 126 so that the AF evaluation value signal sent from the main body microcomputer 114 is maximized. An automatic focus adjustment operation is performed by moving only the correction lens 105 via the focus motor 125.
[0041]
In the front lens focus type lens system, an independent correction lens is provided for the variable magnification lens, and the variable magnification lens and the correction lens are coupled by a mechanical cam ring. Therefore, for example, when a knob for manual zoom is provided on this cam ring, and the focal length is changed manually, the cam ring will follow the rotation no matter how fast the knob is moved, and it will be corrected with the variable power lens. Since the lens moves along the cam groove of the cam ring, the above operation does not cause blur as long as the focus lens is in focus.
[0042]
On the other hand, in the control of the inner focus type lens system as in the embodiment, when the zooming operation is performed while maintaining the in-focus state, the locus information of FIG. 4 is stored as the lens cam data 120 in the lens microcomputer 116. In addition, it is necessary to read movement locus information of the correction lens from the cam data in accordance with the positions of the variable power lens and the correction lens, and to move the correction lens based on the information.
[0043]
Now, with respect to the driving of the correction lens based on the lens cam data as described above, the origin for ensuring an accurate BF must be determined. The origin is determined by correcting with a predetermined correction value based on the set reference position.
[0044]
The predetermined correction value here is a total value of the correction value possessed by the lens unit (interchangeable lens) itself and the correction value transmitted from the camera body.
[0045]
The correction value possessed by the lens unit itself is a total value of a fixed value due to variations or the like generated at the stage of manufacturing the lens unit and a variable value due to a temperature change or the like on the lens unit side.
[0046]
Similarly, the correction value transmitted from the camera body is a total value of a fixed value due to variation or the like generated at the stage of manufacturing the camera body and a variable value caused by a temperature change on the camera body side.
[0047]
Next, the automatic focus adjustment operation of the AF control unit 117 when the zooming operation is not performed in the lens microcomputer 116 in the lens unit will be described with reference to FIG.
[0048]
After AF activation (A1), hill climbing control (A2) is performed by controlling the direction of the motor 125 while applying speed control according to the level of the sharpness evaluation value sent from the camera body. Next, the top of the mountain is judged (A3) based on the amount of change in the sharpness evaluation value, the point is stopped at the highest level, and the restart standby (A4) is entered. In the restart standby, it is detected that the level of the sharpness evaluation value has dropped, and restart (A5) is performed.
[0049]
Next, the relationship of the movement of the zoom lens 102 and the correction lens 105 when performing the zoom operation will be described.
[0050]
In the lens system configured as shown in FIG. 1, since the correction lens 105 has both a correction function at the time of zooming and a focus adjustment function, the lens is focused on the imaging surface of the image sensor 106 even if the focal lengths are equal. Therefore, the position of the variable magnification lens 105 varies depending on the subject distance. When the subject distance is changed at each focal length, the position of the correction lens 105 for focusing on the imaging surface is continuously plotted as shown in FIG. During zooming, if the locus shown in FIG. 5 is selected according to the subject distance and the correction lens 105 is moved along this locus, zooming without blurring becomes possible.
[0051]
Next, a communication operation for transmitting predetermined information of the camera body to the lens unit (interchangeable lens) side will be described.
[0052]
First, the configuration will be described with reference to FIG. BF variation information generated due to the accuracy of structural parts, attachment errors, and the like is measured as variation measurement data in the manufacturing stage of the camera body, and then written in the rewritable memory means 142. Changes in the environmental temperature that occur during the shooting operation of the video equipment are measured by the temperature sensor 140 in the camera main body 128 and converted into BF change data by the operation program of the temperature compensation control unit 141 in the main body microcomputer 114. The above two types of information are transmitted from the camera body 128 to the lens unit 127 at a timing determined by the communication means, and a predetermined process is performed as a correction value in the control unit 119.
[0053]
Next, the flow of processing will be described with reference to FIG. In this example, the camera body is the master and the lens unit is the slave, and the camera body and the lens unit communicate in synchronization with the clock output on the camera body side. Whether the initial communication or subsequent sequential communication is determined based on the identification information.
[0054]
The flowchart in FIG. 5A is a communication flow on the camera body side. After the power is turned on (B0), first, it is checked whether the lens unit is attached (B1). If it is attached, initial information is set (B2), and initial communication is performed immediately (once) (B3). In the initial communication, BF variation measurement data is transmitted to the lens unit 127 as one of the initial information.
[0055]
Further, during the operation after the mounting, after the completion of the initial communication, as shown in FIG. 5B, a communication start interrupt is sequentially applied (B5). In accordance with this, the lens mounting state is also checked (B6). If it is mounted, sequential information is set (B7) and sequential communication is performed (once) (B8). In sequential communication, BF change data due to temperature change is transmitted to the lens unit as one piece of sequential information. Conversely, when the lens unit is removed, the lens is put on standby.
[0056]
On the other hand, FIG. 5C shows a communication flow on the lens unit side which is the information receiving side. Most processing of the lens microcomputer 127 in the lens unit is spent on AF and lens movement control. When communication between the camera body and the lens unit is completed at a certain timing, a communication completion interrupt is issued. Over (B10), processing is performed temporarily. The process is simple. In the case of initial communication (B11), initial information, that is, variation measurement data is transferred to the memory 1 (B12). In the case of sequential communication, sequential information, that is, change data is transferred to the memory 2 (B14). . Then, the interrupt process is completed.
[0057]
The data in memory 1 and memory 2 written here is used as a correction value for lens cam data in lens movement control by a program.
[0058]
Next, how the correction value data is used in the lens movement control process will be described.
[0059]
The lens microcomputer 116 stores the lens cam data 120 of FIG. 1 as ideal values (design values) as shown in FIG. This is subjected to the following calculation for correction. If the initial value transmitted from the camera is a1 and the sequential value is a2, it is a1 + a2 correction value. If this value is positive, BF is longer than the ideal value, so FIG. 4 (b). Thus, the lens cam data indicated by the dotted line obtained by subtracting this amount is shifted in parallel (downward) and reread. By performing lens movement control using the new data that has been replaced, accurate zooming without blurring can be performed.
[0060]
Naturally, if the correction value is negative, the BF is contracted from the ideal value, and the lens cam data is read by being shifted upward in parallel.
[0061]
In the procedure described above, correction values (fixed) related to manufacturing variations are transmitted by initial communication that is performed once when the lens unit is replaced or when the power is turned on, and sometimes by subsequent sequential communication. The correction value (fluctuation) that changes every moment is transmitted sequentially and summed on the lens unit side to obtain the origin, but in the other method, both fixed and fluctuation correction values are summed on the camera body side. Alternatively, the origin may be obtained by transmitting only by sequential communication.
[0062]
Now, BF variations and fluctuations are not only in the camera body, but of course in the lens unit itself. Therefore, if correction is finally performed by adding a value to be corrected by the lens unit itself to the correction value transmitted from the camera body, more ideal correction is performed.
[0063]
FIG. 2 schematically shows only the lens unit in an embodiment further improved from the above viewpoint. In addition to the configuration of FIG. 1, this configuration has a memory means 242 for storing variation measurement values in the lens itself, a temperature sensor 240 and a conversion means 241 for correction values, and performs the same processing. Made. Further, a rewriting means 243 for changing data in the memory means for storing the variation measurement value is added, and the contents can be changed by the user by performing a predetermined operation.
[0064]
Assuming that the values stored in the memory means 242 and the output values of the converting means 241 are b1 and b2, respectively, a1 + a2 + b1 + b2 is added to the final correction value in addition to the above-described a1 and a2. If this is the case, it will be the most ideal correction.
[0065]
The correction value obtained as described above can achieve the purpose of accurately following the cam locus of the lens cam data.
[0066]
【The invention's effect】
As described above, according to the present invention, the memory means for storing the positional relationship between the variable power lens and the correction lens in the interchangeable lens, and the control means for controlling the movement of the correction lens in the movement of the variable power lens based on the memory contents. Assuming that the interchangeable lens receives correction information on temperature and manufacturing variation in the camera body, and corrects the movement control based on the memory contents, the correct movement control of the correction lens can be performed. Thereby, the focus can be accurately maintained. Particularly important is the deviation from the reference value of the back focus, but in the present application, movement control can be performed with the deviation corrected.
[0067]
Further, according to the present invention, the movement control correction based on the correction information is performed by shifting the memory contents, so that the correction control can be easily performed.
[0068]
Further, according to the present invention, since the second memory means for correcting the memory contents is provided in the interchangeable lens itself, it is possible to store correction information unique to the interchangeable lens, and to accurately control the movement of the corrective lens.
[Brief description of the drawings]
FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention. FIG. 2 is a diagram showing the overall structure of the embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of the embodiment of the present invention. FIG. 4 is a diagram for explaining an embodiment of the present invention. FIG. 5 is a diagram for explaining an operation of the embodiment of the present invention. FIG. 6 is a diagram showing a configuration of a conventional example. Diagram [Description of symbols]
101 Variable lens 105 Correction lens 114 Main body microcomputer 116 Lens microcomputer 127 Lens unit 128 Camera body

Claims (4)

A variable power lens,
A correction lens that corrects a change in the focal position due to the movement of the zoom lens;
Storage means for storing a positional relationship between the zoom lens and the correction lens;
An inner focus type interchangeable lens having control means for controlling movement of the correction lens in accordance with movement of the variable power lens based on information stored in the storage means;
Is detachable and the interchangeable lens, and stores the camera-specific flange back correction information resulting from the camera body, and a camera body having a flange back correction information supplying means for supplying to the interchangeable lens through communication Video equipment system,
The video equipment system, wherein the interchangeable lens includes a correction unit that controls movement of the correction lens using the flange back correction information received from the camera body and information stored in the storage unit. The video equipment system according to claim 1 , wherein the camera body includes an environment detection unit, and the flange back correction information is information related to a flange back position corresponding to a detection result of the environment state detection unit. In an interchangeable lens that can be attached to and detached from a plurality of camera bodies having flange back correction information supply means for storing flange back correction information unique to the camera body caused by the camera body and supplying the information to the interchangeable lens by communication .
A variable power lens,
A correction lens that corrects a change in the focal position due to the movement of the zoom lens;
Storage means for storing a positional relationship between the zoom lens and the correction lens;
Control means for controlling the movement of the correction lens according to the movement of the variable power lens based on the information stored in the storage means,
An interchangeable lens comprising correction means for controlling movement of the correction lens using the flange back correction information received from the camera body and information stored in the storage means. 4. The interchangeable lens according to claim 3, wherein the camera body includes environment detection means, and the flange back correction information is information relating to a flange back position corresponding to a detection result of the environment state detection means.

Images