JP2000201286A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a device low-cost and thin by arranging a hologram lens off the axis between an object and an image sensor and making the light, having passed through the hologram lens incident on the image sensor after being reflected by a 1st and/or a 2nd reflection surface. SOLUTION: Lights 513 and 514 from an object are respectively made incident on hologram lens 54 and 55. An optical switch part 56 transmits the light. An optical switch part 57 cuts off the light so that only the diffracted light 515 of the light 513 from the object is repeatedly reflected by reflection part 58 and 59 of a back plate 53, a middle plates 52 and a reflection type hologram lens 510, and enters an image sensor 512. The reflection type hologram lens 510 makes the incidence on the image sensor 512 as vertical as possible. The diffracted light 516 of the light 514 from the object cut off by the optical switch part 57 impinges on the image sensor 512 through the reflection type hologram lens 511 if it is not cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera, which has various functions such as telephoto and close-up photography, and is suitable for an ultra-thin digital camera which can fit into a breast pocket.

[0002]

2. Description of the Related Art Ultra-small cameras have conventionally existed,
These are special applications with limited functions, and there are no thin card-sized cameras with the generally required functions. The reason is that in the conventional film type, a mechanism is essential in the film, and in the optical system, a mechanism such as switching between a telephoto lens and a normal lens or moving part of the lens system is necessary for focusing, etc. This is because it is difficult to reduce the thickness.

A digital camera which converts an image into an electric signal by an image sensor and stores it in a memory does not have a film and does not require a mechanical part, but the means for forming an image on the image sensor is the same as the conventional one. However, focusing or switching the magnification at telephoto requires a mechanism to replace or move the optical lens, which is one of the obstacles when trying to realize a camera with a thickness of about several millimeters. ing.

Further, even if a system having a plurality of optical systems and a switching system is assumed, there is a problem that it cannot be put to practical use because it is inevitably large and the cost increases.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a digital camera which has necessary and sufficient functions and which can be made thin at low cost.

[0006]

The basic structure of a digital camera according to the present invention has an image sensor, a hologram lens, and the like in a plane facing a subject, and is substantially perpendicular to an axis connecting the subject and the image sensor. Alternatively, if necessary, a second reflecting surface is provided, and the light that has passed through the hologram lens is reflected on the first or further second reflecting surface and then enters the image sensor, thereby enabling a reduction in thickness. In this way, the mechanism can be eliminated to reduce the thickness, but there is a concern that the optical system can be used only as a fixed focus type with a single function, and the application is limited.

In consideration of this point, the present invention further proposes a digital camera having the following structure. That is, a plurality of combinations of lens units and image sensors having different optical characteristics are provided, and the output of the image sensor is electrically selected to realize various functions within one camera.
Since a plurality of hologram lenses can be formed collectively, the cost increase is slight. However, if the use of a plurality of image sensors is still high in cost, the present invention further proposes a digital camera having the following structure.

A plurality of image forming optical systems each including a hologram lens unit having different optical characteristics and an optical switch are provided. By selecting an incident light path incident on the image sensor by the optical switch, telephoto and close-up photography are performed. It realizes various functions such as stereoscopic photography without the mechanical part. Of course, a fixed focus lens system having a different focal point is also provided, and the focusing can be performed by selecting an image forming optical system by an optical switch.

The image sensor is arranged in a plane substantially perpendicular to the axis of the subject, and a plurality of imaging optical systems are arranged around the axis so as to surround the image sensor. The image sensor is configured to be incident on the image sensor via the first or second reflection surface substantially orthogonal to the axis. In this configuration, the optical switch is composed of a liquid crystal and an analyzer or an electrochromic element that can electrically control the light transmittance, and the lens unit is composed of a hologram lens, etc., to realize a thin digital camera. it can.

Although the hologram lens is easy to duplicate, the cost is expected to be significantly reduced. However, the hologram lens is collectively arranged for each plate which is configured as having a plurality of hologram lens portions substantially on the same plane. The cost can be further reduced by replicating and manufacturing, and the purpose of realizing a low-cost digital camera can be sufficiently achieved.

According to the above basic configuration, a digital system having various different functions such as telephoto and close-up photography, or eliminating the mechanism by selecting an imaging optical system having a different focal length by an optical switch, an electric switch, or the like. A camera can be realized, and a low-cost digital camera having a thickness of about several millimeters can be realized by employing a hologram lens as a lens.

[0011]

FIG. 1 shows a first embodiment of the present invention, and shows a cross-sectional structure of a main part of a digital camera 10 having an ultra-thin configuration. In the figure, the main parts of the optical system are a front plate 11, a middle plate 12, and a back plate 13.
On each plate. The front plate 11 is made of glass, has a partially transparent portion, and a transmission type hologram lens 14 is formed on the back surface of the transparent portion. The middle plate 12 is entirely made of transparent glass, and a reflection type hologram lens 15 is formed and arranged on the surface of the back plate 13. Number 16 is CCD
No. 300 is an image display unit composed of liquid crystal, No. 100 is a control unit, and No. 200
Indicates a battery, and reference numeral 400 indicates a connector portion for connection to an external device.

In FIG. 1, reflected light 17 from a subject is shown.
Is incident on the hologram lens 14 and then diffracted into a diffracted light 18, further reflected and diffracted by the reflective hologram lens 15 on the back plate 13 and incident on the image sensor 16. The surface of the back plate 13 is used as a first reflecting surface, and if it is necessary to further extend the optical path length, the back surface of the middle plate 12 is used as a second reflecting surface, and reflection is repeated between the first and second reflecting surfaces. It is configured to be incident on the sensor 16. If a reflection type hologram lens is formed in each reflection portion, and a transmission type hologram lens is formed in a portion of the middle plate 12 through which light passes, a more accurate optical system can be configured. The middle plate 12 is provided between the convergent light and the transparent portion with the intention of arranging an optical lens and a transmission hologram lens, but the second reflection surface is omitted as the back surface of the front plate 11 if unnecessary. I can do things.

The transmission type hologram lens 14 formed on the back surface of the front plate 11 is formed by pressing a mold having irregularities for forming a hologram lens against an ultraviolet curable resin applied thinly on the back surface, and curing it with ultraviolet light. I do. Optically do not diffract as off-axial type 0
Secondary light is excluded.

The reflection type hologram lens 15 formed on the back plate 13 diffracts the light in the direction in which the incident angle and the reflection angle are different from each other, thereby minimizing the mixing of the zero-order light. Also, a hologram that does not allow the diffraction direction to be incident on the subsequent reflecting portion and the image sensor 16 in unnecessary portions other than the reflecting portion 15 so as to eliminate unnecessary order diffracted light generated in the transmission hologram lens and the reflecting hologram lens, or It consists of a diffraction grating. Hologram lens 15
Is formed in the same manner as the formation of the hologram lens 14 on the front plate 11, but a thin metal particle is coated thereon by vapor deposition, sputtering or the like in order to form a reflection type. Other reflective surfaces are similarly formed by thinly coating metal fine particles.

It is assumed that the image sensor 16 is integrally formed with a filter for each primary color which composes a color so as to correspond to a color.

FIGS. 2, 3 and 4 show a digital camera which shows a second embodiment of the present invention and improves the disadvantages of the first embodiment. The digital camera of the second embodiment has substantially the same principle and structure as the digital camera of the first embodiment, but has a plurality of combinations of an optical system composed of hologram lenses having different optical functions and an image sensor. An image from a desired optical system is captured by electrically selecting the output of the image sensor. Its cross-sectional structure is the same as that of the first embodiment shown in FIG. 1 and therefore will be omitted, and FIG. 2 shows the functional elements arranged on each plate in an exploded view.

In FIG. 2, three sets of a hologram lens and an image sensor are shown. The front plate 21 is a partially transparent glass substrate, and a plurality of transmission hologram lenses are formed on the back surface of the transparent portion group of openings 24. The middle plate 22 has transparent groups 25 and 28 through which light passes.
A light reflecting portion group 26 is formed and arranged on the back surface. The reflection portion group 27 is formed on the surface of the back plate 23, and the image display portion 300 is disposed. The reflected light from the subject passes through the aperture group 24 and the hologram lens on the back surface thereof, passes through the transparent group 25, and is repeatedly reflected by the reflection groups 27 and 26, and then passes through the transparent group 28 and passes through the image sensor. The light enters the group 29. The transparent section groups 25 and 28 can be formed as transmission hologram lenses, and the reflection section groups 26 and 27 can be formed as reflection hologram lenses. The number of reflecting portions and the like are appropriately adjusted according to the size of the optical path required by the optical system.

Although the number of hologram lenses is dramatically increased as compared with the first embodiment, there is no practical problem in view of the fact that the configuration shown in FIG. It is possible to realize a digital camera with a variety of functions despite its thin structure while keeping the cost down by a certain degree. However, at this stage, the cost of the image sensor group 29 cannot be ignored, so that the cost may be considerably increased in this respect.

FIG. 3 shows a digital camera 3 according to the second embodiment.
0 shows an external view as viewed from the subject side. Reference numeral 24 denotes an opening group, reference numeral 400 denotes a connector for connection to an external device,
Reference numeral 500 denotes a power switch, reference numeral 600 denotes a function switch, reference numeral 700 denotes a shutter switch, and reference numerals 800 and 900 denote an ultrasonic transmission unit and a reception unit for detecting a distance to a subject.

FIG. 4 shows a digital camera 3 according to the second embodiment.
0 is a functional block diagram. The imaging optical system group including the transmission type hologram lens on the front plate 21 and the hologram lens on the middle plate 22 and the back plate 23 is indicated by numeral 41, and the image sensor group is indicated by numeral 2.
9. Images from optical systems having different functions are selected by an electric switch 42 and stored in a memory 43.

FIGS. 5 to 8 are views for explaining a digital camera according to a third embodiment of the present invention, and show an example in which the number of image sensors is reduced to reduce the cost. FIG.
3 shows a cross-sectional structure of a main part of the digital camera 50 configured to be ultra-thin. In this figure, the main part of the optical system is formed on each of a front plate 51, a middle plate 52, and a back plate 53. The front plate 51 is made of glass, has a partially transparent portion, and transmission type hologram lenses 54 and 55 are formed on the back surface of the transparent portion. On the middle plate 52, optical switches 56 and 57 formed by electrochromic elements are formed at positions corresponding to the paths of the diffracted lights 515 and 516 from the hologram lenses 54 and 55. Are formed and arranged by vapor deposition of metal fine particles. Further, diffracted lights 515 and 516 are provided on the surface of the back plate 53.
Of the reflection portions 58, 59, 510, and 511 are disposed. If necessary, the reflection section can be constituted by a reflection type hologram lens, and reference numerals 510 and 511 in the figure denote reflection type hologram lenses. Reference numeral 512 denotes a CCD image sensor, reference numeral 300 denotes an image display unit composed of liquid crystal, reference numeral 100 denotes a control unit, reference numeral 200 denotes a battery,
Numeral 400 indicates a connector unit for connection to an external device.

The transmission-type hologram lenses 54 and 55 formed on the back surface of the front plate 51 are pressed against an ultraviolet-curing resin thinly coated on the back surface with a mold having irregularities for forming a hologram lens, and are cured by ultraviolet rays. Formed. Optically, zero-order light that is not diffracted as an off-axial type is excluded.

The optical switch units 56 and 57 are formed by enclosing a transparent electrode pattern and an electrochromic working fluid, and are capable of transmitting or blocking light depending on the voltage and polarity applied between the electrodes. The aperture effect is enabled by controlling the transmission area as shown by. Since the technique is a well-known technique, detailed description of the principle and structure will be omitted.

The reflection type hologram lenses 510 and 511 formed on the back plate 53 diffract light in directions different from the incident angle and the reflection angle to minimize the mixing of zero-order light. Further, in unnecessary portions other than the reflection portion, holograms or diffractions which do not allow the diffraction direction to enter the subsequent reflection portion and the image sensor 512 so as to eliminate unnecessary orders of diffracted light generated in the transmission hologram lens and the reflection hologram lens. Consists of a lattice.

The image sensor 512 is integrated with a filter for each primary color that composes a color so as to correspond to a color. However, since the image sensor 512 is a well-known element, its description is omitted.

Referring to FIG.
14 are incident on the hologram lenses 54 and 55, respectively. The optical switch 56 permits light transmission, and the optical switch 57 is light-blocked.
Only the light is repeatedly reflected by the reflection portions 58, 59, and 510 of the back plate 53 and the middle plate 52, and finally enters the image sensor 512. The last reflection unit 510 is a reflection type hologram lens, and the image sensor 5
12 is made to be as vertical as possible. Incident light 5 blocked by optical switch 57
The 14th diffracted light 516 enters the image sensor 512 via the reflective hologram lens unit 511 if it is not blocked.

FIG. 6 shows a front plate 51, a middle plate 52, and a back plate 53 in the third embodiment in a developed view. The front plate 51 is partially formed of glass having a group of transparent openings 61, and a transmission type hologram lens is arranged on the back surface of the group of six openings 61 shown in FIG. 6 so as to substantially surround the image sensor 512. Have been. Each hologram lens has a different optical function and constitutes a lens group that enables close-up photography, normal photography, telephoto photography, wide-angle photography, designated direction photography, stereoscopic photography, and the like. Image sensor 512 for telephoto shooting
Therefore, it is arranged at a position distant from the image sensor 512, and is configured to be repeatedly reflected and incident on the image sensor 512.

An optical switch group 62 is formed on the surface of the middle plate 52, and concentric transparent electrodes are formed as shown in FIG. It is configured so that opening control can be performed in addition to control of shutoff.

As described with reference to FIG. 5, the back plate 53 has a reflecting portion group and a reflective hologram lens group 6 as described above.
3, and an image display unit 300 is further arranged.

If the hologram lens alone does not have a sufficient function as an imaging optical system, the image sensor 5
Normal optical lenses can be collectively arranged on the middle plate 52 immediately before the light enters the optical system 12, and the optical lenses can be placed on the middle plate 52 at a position where the optical switch is arranged.

In the above example, the first reflecting surface is constituted by the back plate 53 surface and the second reflecting surface is constituted by the middle plate 52 back surface. However, the transmission type hologram lens and the optical switch are integrated on the front plate 51 back surface. It is also possible to transfer the reflecting portion group formed on the back surface of the middle plate 52 to the back surface of the front plate 51 so that the back surface of the front plate 51 can be used as the second reflecting surface. Cost reduction becomes possible.

FIG. 7 is an external view of the third embodiment of the present invention as viewed from the subject side. A group of openings 61 to six hologram lenses, an ultrasonic transmitter 800 and a receiver 900 for measuring the distance to a subject, a power switch 500, a function switch 600, a shutter switch 70
0, a connection connector 400 to an external device and the like are shown.

FIG. 8 shows a functional block diagram of the third embodiment. The light that has entered the imaging optical system group 81 including each hologram lens is selected by the optical switch group 62, enters the image sensor 512, is converted into an electric signal, and is stored in the memory 82.
Is stored in The function switch 600 instructs selection of telephoto, proximity, or normal photographing, or image display.

The image forming optical system 81 including the hologram lens is of a fixed focus type having no mechanism. There is an imaging optical system that includes a fixed-focus hologram lens that has been focused in advance according to the type of camera, and the imaging optical system is selected in conjunction with the ultrasonic distance measurement and focused. You can get clear photos. Numerals 800 and 900 denote an ultrasonic transmitting unit and a receiving unit, respectively. Further, it is also possible to simply detect the distance to the subject, attach the information to the image, and obtain a correct image by digital processing based on the distance information after photographing. In that case, further accuracy can be expected according to the method of Japanese Patent Application No. 10-191069 described later.

The image display section 300 is composed of a liquid crystal and is used for a finder at the time of photographing or for displaying an image after photographing. If the image display unit 300 is a touch sensor type and is used also as an input unit, the function switch 600
Can be omitted and operability can be improved. The connector 400 for external connection is used for transferring a captured image to an external device or for other purposes. If it is a photoelectric connection device other than the mechanical connection device, it can be configured more compactly. The control unit 100 receives an instruction from an external device via the power switch 500, the function switch 600, the shutter switch 700, or the like, or the connector 400, and receives the instruction from the external device.
0 controls the overall operation.

FIG. 9 shows a cross section of a main part of a digital camera 90 according to a fourth embodiment. The image sensor 97 is of a monochrome type and has a hologram lens 91 corresponding to the primary colors constituting the color, a wavelength pass filter 92 corresponding to the primary colors, and an optical switch unit 93, and captures images corresponding to the respective primary colors at different times. It is a method. That is, the hologram lens 91 and the wavelength pass filter 92 are provided with image forming optical systems corresponding to the three primary colors of red, green, and blue constituting a color.
Is used to select each primary color. Number 94,
Reference numerals 95 and 96 denote reflecting portions, respectively.

Although the application is not suitable for a fast-moving subject, there is no inconvenience for a stationary subject, and the hologram lens can be designed for each primary color, so that there is an advantage that the design becomes easy and the resolution can be improved. Since a large number of imaging optical systems are required, there is a disadvantage that the types of functions are limited in one camera. Focusing on the fact that the cost can be reduced, the present invention can also be applied to a stationary monitoring imaging device.

As described above, the configuration of the digital camera according to the present invention has been described with reference to the embodiments.
An imaging optical system having various different functions is provided in a single digital camera, and can be selected by an optical switch. The cost increase due to having a plurality of imaging optical systems is that the imaging optical system is formed by hologram lenses and a plurality of hologram lenses are formed collectively for each plate, and the optical switch is also formed by the same process for each plate. It was shown that it can be solved by forming them all at once.

Another feature is that it is possible to form a large part by a thin film process similar to the formation of a semiconductor integrated circuit by omitting all the mechanical parts, thereby enabling ultra miniaturization and cost reduction. For this reason, all imaging optics had to be fixed focus, but multiple optics were equipped with imaging optics in accordance with the distance to the subject and automatically selected according to the distance to the subject In addition, it has made it possible to hold multiple telephoto lenses with different magnifications.

As described above, according to the present invention, a small and ultra-thin general-purpose digital camera can be realized at low cost. However, the remaining distortion due to the simplification of the optical system and the distortion peculiar to the hologram lens. And other problems such as distortion and chromatic aberration. This is a problem that can be practically solved because an imaging optical system including a hologram lens can be optimally designed and a multilayer hologram lens can be employed as shown in the present invention. However, inadequate adjustments tend to remain due to difficulties in optimizing the adjustment by manufacturing and arranging a plurality of imaging optical systems at once, and priority is given to minimizing hardware costs. If so, it is desirable to optimize it taking into account the digital processing after photographing. For example, a predetermined calibration figure is prepared and the image after passing through each imaging optical system is photographed, and each ideal pixel is compared with an ideal image for each primary color and each pixel, and each pixel is moved to the next position after photographing. Japanese Patent Application No. 10-22810 may obtain information on how to expand or compress the value of each pixel for each device, store the information in a memory, and correct the information. Alternatively, similarly, a correction method according to Japanese Patent Application No. 10-191069, which enables correction in the spatial frequency domain from a calibration graphic, can be adopted.

The enhancement of image quality by these digital processes has a function of bringing an insufficient imaging optical system closer to an ideal system, and simplifies the adjustment work in the manufacturing process of a digital camera and uses it with insufficient settings. Alternatively, it is possible to use a low-cost optical system although the quality is reduced, and the cost can be reduced. Therefore, if used in conjunction with the present invention, the object of the present invention can be sufficiently realized.

[0042]

According to the present invention, it is possible to realize a low-priced digital camera which is thin, small, excellent in productivity and has various functions generally required.

[Brief description of the drawings]

FIG. 1 shows a cross section of a main part of an optical system according to a first embodiment.

FIG. 2 shows a layer configuration of a main part of an optical system according to a second embodiment.

FIG. 3 shows an appearance of a second embodiment.

FIG. 4 shows a functional block diagram of a second embodiment.

FIG. 5 shows a cross section of a main part of an optical system according to a third embodiment.

FIG. 6 shows a layer configuration of a main part of an optical system according to a third embodiment.

FIG. 7 shows an appearance of a third embodiment.

FIG. 8 shows a functional block diagram of a third embodiment.

FIG. 9 shows a cross section of a main part of an optical system according to a fourth embodiment.

[Explanation of symbols]

10. Digital camera of the first embodiment, 11 ...
・ Front plate, 12 ・ ・ ・ Middle plate, 13 ・ ・ ・ Back plate, 14 ・ ・ ・
Hologram lens, 15: reflection hologram lens, 16: image sensor, 17: reflected light from subject, 18: diffracted light 21: front plate, 22: middle plate 23 ..Back plate, 24 ... Opening group, 25,28..Transparent part group, 26,2
7. Reflecting unit group 29 image sensor group 30 Digital camera of second embodiment 41 41
An imaging optical system group, 42 an electric switch, 43 a memory 50 a digital camera of the third embodiment, 51
・ Front plate, 52 ・ ・ ・ Middle plate, 53 ・ ・ ・ Back plate, 54, 55
..Hologram lenses, 56 and 57.
58, 59-reflection unit, 510, 511-reflection type hologram lens, 512-image sensor, 513, 514-light from subject, 51
5,516 ··· diffracted light, 61 ··· aperture group,
62: Optical switch group, 63: Reflecting unit group 81: Image forming optical system group, 82: Memory 90: Digital camera of the fourth embodiment, 91 ...
・ Hologram lens, 92: wavelength pass filter, 93: optical switch unit, 94,
95, 96... Reflection unit, 97... Image sensor 100... Control unit, 200... Battery, 300... Image display unit, 400.
Connector 500 Power switch, 600 Function switch, 700 Shutter switch
800: Ultrasonic transmitter, 900: Receiver

Claims (8)

[Claims] An image sensor, a hologram lens, a first and / or a second reflection surface disposed in a plane substantially orthogonal to an axis with respect to a subject, and the hologram lens is positioned between the axis of the subject and the image sensor. A digital camera which is arranged so as to be deviated and which is configured such that incident light passing through the hologram lens is reflected by the first and / or second reflecting surfaces and then incident on the image sensor to enable a thin structure. 2. The digital camera according to claim 1, wherein the first or second reflection surface includes a reflection type hologram lens. 3. The digital camera according to claim 1, further comprising: a plurality of combinations of an image forming optical unit including a hologram lens having a different optical function and an image sensor; Digital camera characterized by selective image capture 4. The digital camera according to claim 1, wherein the plurality of imaging optical systems, each of which comprises an electrically controllable optical switch and a hologram lens, and each of which has a different optical function, comprises: The image sensor is disposed about an axis connecting the sensor and the subject, and is reflected by first and / or second reflecting surfaces disposed substantially orthogonal to the axis and transmitted through the imaging optical system. Digital camera characterized in that the image is selected by an optical switch and captured by an optical switch 5. The digital camera according to claim 4, wherein the optical switch is constituted by an element capable of controlling the light transmittance in a piecewise manner, and in addition to the function of selecting the image forming optical system, the aperture control of the image forming optical system. Digital camera characterized by performing 6. A digital camera according to claim 3, wherein a plurality of hologram lenses are collectively formed for each substrate constituting the digital camera. 7. The digital camera according to claim 3, wherein the image sensor is for monochrome, and a hologram lens for the primary color and a pass filter of a primary color wavelength necessary for forming a color image are provided independently of each other. A digital camera having an imaging optical system and forming a color image by sequentially capturing images of primary colors at different times. 8. A digital camera according to claim 1, further comprising a distance detector to a subject.