JPH062319U - Imaging device - Google Patents

Abstract

(57) [Abstract] [Purpose] An image pickup apparatus having a reference position setting function of a focusing lens does not require a sensor for detecting the reference position, which is not disadvantageous in terms of space and is also advantageous in power saving. An imaging device including the following is provided. [Structure] This image pickup apparatus includes a variable power lens 3, a focusing lens 6 and the like which constitute a zoom optical system, a CCD 8, a lens barrier 9 arranged in front of the optical system, and a contrast indicating a degree of focusing. It is mainly configured by a microcomputer 10 which takes in information and controls driving of the focusing lens 6 to a focus position. When setting the reference position necessary for the zoom tracking operation of the focusing lens 9, the focusing process is performed by using the pattern provided on the barrier 9 as a subject at the reference position.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image pickup apparatus, and more particularly, to an apparatus for setting a reference position of a focusing lens in an image pickup apparatus that adjusts a focus by moving a focusing lens.

[0002]

[Prior art]

 As a conventional focusing method, there is a focusing method that does not necessarily require the absolute position information of the focusing lens in the focusing operation itself, for example, an imager AF which is a focusing method using an imager. However, even in an image pickup apparatus adopting such a focusing method, there is a need for the apparatus itself to recognize the absolute position from the image pickup surface of the focusing lens in view of the image pickup function.

For example, a case of a recent high-power zoom type video camera using a rear focus type zoom lens having a multi-group lens structure that uses a zoom lens group and a focusing lens group for zooming will be described first. In order to perform zooming in the camera, it is necessary to drive the variable power lens and at the same time maintain the in-focus state. Therefore, the focusing lens is also driven to the in-focus position corresponding to each zooming position of the variable power lens. It is necessary to perform so-called zoom tracking control operation. To drive the focusing lens to the in-focus position, in order to speed up zooming, focus processing is not performed for each zooming, but to the in-focus position corresponding to each zoom position from the predetermined reference position. It is driven based on the movement amount information. That is, the movement amount information is written in the memory of the system controller in advance, and the movement amount information is read during the zoom tracking operation. Then, the lens driving stepping motor is driven by the amount of movement, and the focusing lens is moved. Therefore, the device itself must always recognize the reference position.

Further, as another object, in the case of an image pickup apparatus that determines an exposure condition by combining zoom magnification and information on a subject distance, absolute position data at the time of focusing of a focusing lens is required to obtain the subject distance. Since the absolute position is given as the amount of movement of the focusing lens from the reference position, the reference position becomes necessary. However, in an actual image pickup apparatus, the position recognized by the control unit may deviate from the actual focusing lens position due to external vibration or step-out phenomenon of the motor. Therefore, in order to always recognize the correct position of the focusing lens, for example, it was necessary to reset the focusing lens to the reference position each time the power switch was operated.

In the conventional image pickup apparatus, a photosensor for detecting the focusing lens position is provided in the lens driving peripheral portion, and a mechanism for directly detecting the driving position of the focusing lens holding frame to perform the reset operation is provided. Had adopted. FIG. 8 is a perspective view of a drive position detecting mechanism portion of the conventional focusing lens holding frame using a photo sensor. In this mechanical section, a photo interrupter 53 is used as a photo sensor. The lens holding frame 52 holding the focusing lens 51 is movably supported by the guide shaft 54 via the holder portion 52a. A shielding protrusion 52b is integrally provided on the lens holding frame 52, and the shielding protrusion 52b enters the detecting portion of the photointerrupter 53 as the lens holding frame 52 moves. The photo interrupter 53 outputs a reference position detection signal when the focusing lens 51 is positioned at a predetermined reference position.

Further, FIG. 9 is a perspective view of a reference position detection mechanism portion of another conventional focusing lens holding frame using a photo sensor. Also in this mechanism unit, the photo interrupter 63 is used as a photo sensor. A lens holding frame 62 that holds the focusing lens 61 is supported by a guide shaft 64 in a forward and backward direction via a holder portion 62a. By the movement of the lens holding frame 62, the shield plate 65 fixed to the holder portion 62a of the lens holding frame 62 enters the detecting portion of the photo interrupter 63. Then, when the focusing lens 61 is located at a predetermined reference position, the photo interrupter 63 outputs a reference position detection signal.

[0007]

[Problems to be solved by the device]

 However, as described above, the conventional mechanism using the photo interrupters 53 and 63 for detecting the reset position of the focusing lens holding frames 52 and 62 requires a space for disposing the photo interrupters. However, it was an obstacle to the miniaturization of the device. Further, it is necessary to provide a blade member for shielding the focusing lens holding frame, which is not preferable because the movable member becomes large. In addition, the photo sensor consumes more electric power and is disadvantageous in terms of cost.

The present invention has been made to solve the above-described problems, and has a reference lens position setting means for a focusing lens, and a shield provided on a photosensor or a lens frame for setting the reference position. An object of the present invention is to provide an image pickup apparatus which is advantageous in terms of power saving and cost without arranging any member and therefore not being disadvantageous in space.

[0009]

[Means for Solving the Problems]

 The image pickup apparatus of the present invention includes a focusing unit that moves a focusing lens of an image pickup optical system to perform a focus adjustment, a predetermined subject provided at a front end of the image pickup optical system, and a predetermined subject described above. A reference position setting means for moving the focusing lens to a reference position for focusing is provided.

[0010]

[Action]

 When moving the focusing lens to the reference position for the focusing operation, the focusing lens is driven to focus on a predetermined subject provided at the front end of the imaging optical system, and the focusing position is set as the reference position.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an image pickup apparatus showing an embodiment of the present invention. As shown in FIG. 1, the present image pickup apparatus is an image pickup apparatus which picks up an image by an image pickup element, and uses a zoom lens having a four-group structure as an image pickup optical system. Then, an EEPROM that is a memory that stores information necessary for various image pickup processing such as zoom tracking information, a memory that stores reference position information that will be described later, a focusing unit of the image pickup optical system, and a reference of a focusing lens. A microcomputer (hereinafter, referred to as a microcomputer) 10 having a position setting unit and the like controls each control element of the image pickup apparatus. The main switch 20, which is the power switch of the present apparatus, instructs the microcomputer 10 to start and stop the control operation, and at the same time, to store and re-drive the position of each lens group, and to set the reference position and store. It is given to the microcomputer 10.

In the present image pickup apparatus, the subject light is the first group lens 2 of the fixed system, which is a zoom type imaging optical system built in the exterior body 1, the second group of the variable magnification lens supported by the lens holding frame 3a. The lens 3, the diaphragm 4, the third lens group 5 of the fixed system, the fourth lens group 6 of the focusing lens supported by the lens holding frame 6a are transmitted, and further, through the optical filter 7, the CCD 8 of the image pickup element is connected. Form an image on the image plane. Then, the image pickup signal of the subject image is input to the video circuit 12 via the image pickup signal amplifier 11 and output as a video signal to a monitor or a recording system. On the other hand, the image pickup signal from the amplifier 11 is also input to the microcomputer 10. Then, the high frequency component of the image pickup signal is extracted to obtain contrast information indicating the degree of focusing in the so-called imager AF.

In the zooming operation of the image pickup apparatus, the microcomputer 10 rotates the zoom motor 14 via the drive circuit 13 based on the zooming instruction, and drives the second group lens 3 forward and backward via the lens holding frame 3a. Done. The moving position is taken into the microcomputer 10 via the zoom encoder 19 as a zoom position. At this time, the fourth lens group 6 of the focusing lens is also driven to a position which is the in-focus position corresponding to the zoom position in order to perform the zoom tracking operation. However, the driving amount of the focusing lens is driven based on the movement amount information stored in the EEPROM in the microcomputer 10 as the displacement amount from the reference position separately set by the reference position setting means described later. . The fourth group lens 6 is driven by driving the focusing motor 16 via the drive circuit 15 to move the lens holding frame 6a forward and backward.

On the other hand, in the focusing operation, the fourth lens group 6 is moved back and forth through the drive circuit 15 and the focusing motor 16 which are focusing means, and the focusing position is detected by the contrast information obtained at that time, and the focusing position is detected. This is performed by driving the fourth lens group 6 to the in-focus position.

At the front ends of the first to fourth lens groups 2 to 6 of the image pickup optical system, there is provided a lens barrier 9 which is a reference position setting means capable of shielding the optical system. The reference position setting of the focusing lens in the apparatus of this embodiment is performed by setting the slits 9a and 9b (see FIG. 3) provided on the lens barrier 9 as an object when the lens barrier 9 is in a closed state as described later. Then, the focusing lens detects the position where it is focused on the slits 9a and 9b. The lens barrier 9 is opened and closed by the barrier drive motor 17 via the drive circuit 16 by the microcomputer 10.

FIG. 2 is a perspective view of the lens barrier mechanism section. As shown in the figure, the lens barrier 9 is axially supported by a frame 21 screwed to the exterior body 1. A barrier drive motor 17 is fixed to the frame 21, and a position where the lens barrier 9 closes the opening 1a for the optical system provided in the exterior body 1 via gears 22 and 23. It is driven to open and close to the open position. Further, the lens barrier 9 is provided with a plurality of vertical slits 9a and 9b which are subject patterns for setting a reference position, and an LED 18 for illuminating the slits 9a and 9b. It is arranged. The slits 9a, 9b and the like are arranged within the range of the lens opening area 2a of the image pickup optical system.

Details of the slits 9a and 9b will be described with reference to FIGS. FIG. 3 is a rear view of the lens barrier 9 as seen from the optical system side. As shown in FIG. 4 which is a BB cross section of FIG. 3, the LED 18 emits light in the direction in which the slits 9a and 9b are present. And is fixed by a holding member 9f. The light from the LED 18 is transmitted through a white semi-transparent diffusion / transmission member 9e formed by two-color molding inside the barrier 9 and reflected by the inclined reflecting surfaces 9a ', 9b' of the slits 9a, 9b. The object light for setting the reference position is introduced into the optical system of the first lens group 2 and below.

When the outside is bright, the LED 18 is turned off to save power, and external light is taken in through the opposing slits 9c and 9d. Similarly, the first group lens is used as the subject light for setting the reference position. It is introduced into the optical system of 2 or less. The detection of the external brightness and the determination of turning off the light are performed by the photometric information of a separately provided photometric device. Further, although the reference position can be set even in a dark environment by using the LED 18 as described above, the slits 9c and 9d emit light when used in such a dark environment. As a result, the standby state for shooting can be confirmed from outside the barrier 9.

The slits 9a and 9b need to be in the vertical direction as described above because the scanning direction of the CCD 8 is horizontal. The width b and the pitch p of the slits 9a 1 and 9b need to be set within a range that does not exceed the limit resolution of the optical system and the CCD 8. Further, the light transmissive portion of the barrier 9 is formed so as to be filled with the white translucent diffusion transmissive member 9e. The reason is that when the slit portion has a gap, the external scenery is transmitted when the reference position detection is set. , There is a risk of treating it as a subject.

Next, the setting operation of the reference position of the focusing lens, that is, the reset operation in the image pickup apparatus of the present embodiment configured as described above will be described. When setting the reference position, the lens barrier 9 is closed, and first, the second lens group 3 of the zoom lens is driven to the wide end position. However, the movement to the wide end position may be a position near a predetermined wide end position. Then, the slits 9a and 9b of the lens barrier 9 are set as the subject at the time of detecting the reference position, and the subject light passes through the optical system and forms an image on the CCD 8. Therefore, while driving the fourth lens group 6 which is a focusing lens, the image pickup signal of the subject is taken into the microcomputer 10, and the position showing the peak of the value of the contrast information obtained from the image pickup signal is set as the in-focus position. The focus position is stored in the memory of the microcomputer 10 as a reference position, and the setting of the reference position is completed.

In the present embodiment, the reference position is set at the wide end position for zooming, but this is done for the lens barrier 9 arranged immediately before the optical system as described above. This is because zooming needs to be in the vicinity of the wide end in order to be able to focus on the subject. In other words, if an optical system that can focus in front of the lens in the wide and tele range is used, the movable range of the focusing lens becomes large and the optical system is not practical.

It is necessary to select whether to perform the reset operation when the main switch 20 is turned on or when the main switch 20 is turned off. It is reasonable to make this choice based on what the preferred function of the product is. However, when the fourth group lens 6 is reset when the main switch 20 is turned on, there is a problem that it takes time to reset depending on the zoom state when the main switch was turned off last time. That is, if the second lens group 3 which is a variable power lens was in the tele position when the main switch 20 was turned off last time, the variable power is changed as a preparatory operation when the reset operation is performed when the main switch 20 is turned on next time. The lens has to be moved to the wide-angle end, which requires waiting time.

Therefore, in the present embodiment, when the main switch 20 is turned off, the second lens group 3, which is a variable power lens, is moved to the wide end. If resetting is performed in this way, when the main switch 20 is turned on, the fourth group lens 6 can be immediately reset without moving the variable power lens. In this case, the barrier 9 remains closed during the focusing operation of the reference position of the fourth lens group 6, but this time is not so long because only the focusing process is being performed. Further, when the main switch 20 is off, the zoom position is stored before moving the second lens group 3 to the wide end, and after the reset operation immediately after the main switch 20 is turned on, the storage position is again set. Up to this point, the second group lens 3 is driven to improve usability. .

Next, the reset processing operation of the focusing lens will be described with reference to the flowchart of FIG. First, when the main switch 20 is turned off in step S1, the barrier 9 is closed (step S2). Then, the current zoom position is detected and stored in the memory of the microcomputer 10 (step S3), and zoom driving is performed to move to the wide end (step S4) to turn off the power.

Next, when the main switch 20 is turned on (step S5), the functions of all image pickup systems are put into operation (step S6). Then, the pattern LED 18 is turned on until the lens barrier 9 is closed (step S7), and the fourth group lens 6 is reset-driven to execute the reset operation (step S8). Then, the focus determination is performed based on the contrast information when the pattern of the slits 9a and 9b of the lens barrier 9 is the subject (step S9). At this time, the second lens group 3 remains in the wide end position when the main switch 20 is turned off.

When the in-focus position of the second lens group 3, which is a focusing lens, is detected, the position information is stored in the memory of the microcomputer 10 as reference position information (step S 10) and the pattern LED 18 is turned off. (Step S11). Then, the second group lens 3 is driven to the zoom position before the main switch 20 is turned off, and at the same time, the fourth group lens 6 is driven to the zoom tracking position corresponding to the zoom position with reference to the reference position. (Step S12). Therefore, the lens barrier 9 is opened to enable image pickup (step S13), and this routine ends.

Next, as a modified example of the reset process of the focusing lens of the image pickup apparatus of the present embodiment, a description will be given of a case where the reset process is performed when the main switch 20 is off. The configuration of the apparatus of this modification is the same as that of the above-mentioned embodiment.

The reset processing operation of the focusing lens of this modification is shown in the flowchart of FIG. 7. The operation of driving the zoom from step S21 to step S24 to the wide end is performed from step S1 of FIG. This is the same as the processing up to step S4. Subsequently, as a processing operation between step S25 and step S30, the pattern LED 18 is turned on with the lens barrier 9 kept closed, and the focusing lens reset operation is executed. Then, after the reference position information is stored in the memory of the microcomputer 10, the zoom drive is performed to the zoom position before the main switch 20 is turned off. A series of these operations is the same as the processing from step S7 to step S12 in FIG. Then, in step S31, the function of the image pickup system is turned off, and this routine ends.

According to the present modification, since the reset process is always performed when the main switch 20 is turned off, the resetting operation of the focusing lens is not necessary when the main switch 20 is turned on, and the waiting time is not required. , You can immediately start shooting. As yet another modified example, the reset process may be executed when the main switch is turned on or off to perform a more reliable reset operation of the focusing lens.

It is also possible to use a designed pattern instead of the slits 9a and 9b of the lens barrier 9 of the image pickup apparatus of the above-mentioned embodiment. For example, a logo mark as shown in FIG. 5 may be used. In addition, as a substitute for the LED 18 of the above-described embodiment, the light of a tally lamp that indicates that an image is being captured may be used to reduce the number of components. Further, the lens barrier may be a multi-layered barrier, and the plurality of barriers may be held in a half-opened state at the time of reset processing, and the half-opened barrier may be used as a subject at the time of reset processing. It is also possible to propose a modification. Further, in an image pickup apparatus using a liquid crystal plate as a lens barrier, it is possible to display a vertical line on the liquid crystal during the reset process and use it as a subject for resetting the focusing lens. . Further, the focusing lens reference position setting means of the present invention, that is, the image pickup device to which the reset device is applied, is an image pickup device having a focusing function using a silver salt film, or driven by a zoom cam or a focusing cam. The present invention can also be applied to an image pickup apparatus having an image pickup optical system.

[0031]

[Effect of device]

 As described above, in the image pickup apparatus of the present invention, the reference position of the focusing lens is set by focusing on the predetermined object provided at the front end of the image pickup optical system. It eliminates the need for a photo sensor for setting the required reference position and a shielding member provided on the lens frame, and is not disadvantageous in terms of space, and it is advantageous in terms of power saving and cost as well. It has various effects.

[Brief description of drawings]

FIG. 1 is a block diagram of an image pickup apparatus showing an embodiment of the present invention.

FIG. 2 is a perspective view of a lens barrier mechanism unit incorporated in the image pickup apparatus shown in FIG.

FIG. 3 is a rear view of the lens barrier of FIG. 2 seen from the imaging optical system side.

4 is a sectional view taken along line BB of FIG.

5 is a logo mark pattern showing a modification of the lens barrier pattern shown in FIG.

FIG. 6 is a flowchart of a focusing lens reset process of the image pickup apparatus of FIG.

7 is a flowchart of a reset process showing a modification of the focusing lens reset process of the image pickup apparatus shown in FIG.

FIG. 8 is a perspective view of a reference position detection mechanism section of a focusing lens in a conventional imaging device.

FIG. 9 is a perspective view of a reference position detection mechanism section of a focusing lens in another conventional imaging apparatus.

[Explanation of symbols]

2 …………………… First group lens (imaging optical system) 3 …………… Second group lens (imaging optical system) 4 ………………… Aperture (imaging optical system) 5…. ……………… Third group lens (imaging optical system) 6 ……………… Fourth group lens (focusing lens, imaging optical system) 8 ……………… CCD (focusing means) 9a , 9b ……… Barrier slit (subject) 10 …………… Microcomputer (reference position setting means, focusing means) 15 …………… Drive circuit (focusing means) 16 ………… ……… Focusing motor (focusing means) 29a, 29b …………… Logo mark (subject)

Claims (1)

[Scope of utility model registration request] 1. A focusing means for adjusting a focus by moving a focusing lens of an image pickup optical system, a predetermined subject provided at a front end of the image pickup optical system, and a focus for the predetermined subject. An image pickup apparatus comprising: a reference position setting unit that moves the focusing lens to a reference position.