JP2003264845A - Lens system and image pickup apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To disperse a luminous quantity of a green color band important for a visual sense. <P>SOLUTION: The lens system 2 properly disperses a luminous quantity of a green band, provided with: a first prism lens 11 the first slope S2 of which reflects a luminous quantity made incident from an incident face S1 and a first emission face S3 of which emits the luminous quantity reflected in the first slope S2; a reflection transmission film 12 placed on the first slope S2 of the first prism lens 11 and reflecting or transmitting the luminous quantity of the green band among the luminous quantities made incident from the incident face S1 of the first prism lens 11; and a second prism lens 13 a second slope S4 of which is joined with the first slope S2 of the first prism lens 11 via the reflection transmission film 12 and a second emission face S5 of which emits the luminous quantity transmitted through the reflection transmission film 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens device and an image pickup device capable of obtaining a visually preferable picked-up image.

[0002]

2. Description of the Related Art In recent years, for example, digital still cameras, digital video cameras, camera-integrated VTRs, etc.
Electronic devices such as (video tape recorder) have become popular. In these electronic devices, miniaturization has been advanced and it has become possible to carry these devices due to high performance of, for example, a battery which is a driving power source, an electronic substrate, a magnetic tape which is a recording medium, and an optical disk. With such advances in technology, there is a demand for downsizing of a lens system including an image pickup lens system, an image pickup unit having an image pickup device, and the like.

For example, in order to miniaturize an image pickup section in an electronic device, for example, a CCD (charge-coupled device) sensor or a CMOS (complementary mental-oxide semic) is used.
It is said that it is effective to reduce the light receiving area of an image pickup device such as an onductor device) sensor, that is, to reduce the size of the image pickup device.

[0004]

However, in the image pickup section, when the light receiving area of the image pickup device is made small, each pixel becomes small and the aperture efficiency is lowered, so that the light receiving sensitivity is lowered and noise is generated in the image. May cause problems such as.

Further, in the image pickup section, when one image pickup device is used, for example, the light flux emitted from the image pickup lens or the like is made incident on the image pickup device through a color filter for visible light or the like. In this case, when obtaining the chromaticity information and the lightness information, there are problems that accurate lightness cannot be obtained, and that false colors in which the colors of pixels are blurred occur.

To solve such a problem, for example, there is a method using three image pickup devices. In this case, in the image pickup unit, the light flux emitted from the image pickup lens or the like is supplied to each image pickup element by R (red), G (green), and B.
The (blue) color filter splits the light into three optical paths and makes them incident respectively. In particular, in this image pickup unit, a light beam in the visually important green band is received by a single image pickup device, so that a visually clear image can be obtained. However, in the image pickup unit having such a configuration, generation of false colors and the like is suppressed, but the light amount of the light flux received by each image pickup device is reduced to one third by the color filter.
The following will occur and the light receiving sensitivity will decrease. Further, the problem that the optical path becomes complicated by splitting the light flux into three optical paths, the image pickup device becomes large by using three image pickup elements, and three expensive image pickup elements are used. There is also a problem that the price becomes high.

In contrast to the image pickup section using such three image pickup elements, an image pickup section using two image pickup elements has been proposed. In this case, in the image pickup section, the light flux emitted from the image pickup lens or the like is split into two optical paths by the color filter or the like and is incident on the two image pickup elements, respectively. However, in the image pickup unit having such a configuration, it is more difficult to suppress the occurrence of false colors and obtain a clear image as compared with the case where three image pickup devices are used.

Therefore, the present invention has been proposed in view of such a conventional situation, and it is possible to significantly improve the resolution by dispersing and condensing a light beam in a predetermined wavelength band. It is an object of the present invention to provide a lens device and an image pickup device having the above structure.

[0009]

To achieve this object, a lens apparatus according to the present invention has a convex surface on the object side and an incident surface on which a light beam is incident from the object side, and a light beam incident on the incident surface to the side. A first prism lens having a first inclined surface that reflects light toward the side and a first emission surface that has a convex surface on the image surface side and emits the light flux reflected by the first inclined surface; and a first prism Among the light fluxes that are arranged on the first inclined surface of the lens and are incident from the incident surface of the first prism lens, the light fluxes in the green band are reflected and the light fluxes other than the green band are transmitted, or the light fluxes in the green band are transmitted. And a reflection-transmissive film that reflects light beams other than the green band, a second slope that is joined to the first slope of the first prism lens via the reflection-transmission film, and a convex surface on the image side and reflection. Permeable membrane And a second prism lens having a second emission surface for emitting a light beam passed.

In this lens device, the reflection / transmission film reflects the light flux in the green band and transmits the light flux other than the green band among the incident light flux, or transmits the light flux in the green band and transmits the light flux other than the green band. By reflecting the light flux, it is possible to disperse only the visually important green light flux.

In this lens device, the first exit surface of the first prism lens is convex toward the image plane side, and the second exit surface of the second prism lens is convex toward the image plane side. Therefore, the dispersed light beam can be emitted in a state of being condensed on the image plane side. Therefore, in this lens device, it is possible to emit the dispersed light beam in a condensed state by the integrated lens group, and it is necessary to dispose a plurality of lenses in order to perform the spectral separation and the light collection. It can be miniaturized because it does not exist.

Further, in the image pickup apparatus according to the present invention which achieves this object, the object side has a convex surface and the incident surface on which the light beam is incident from the object side, and the light beam incident from the incident surface is reflected to the lateral side. A first prism lens having a first inclined surface for causing the image surface side to be a convex surface and a first emission surface for emitting the light beam reflected by the first inclined surface;
Of the light flux incident on the first inclined surface of the prism lens of the first prism lens, the light flux in the green band is reflected and the light flux other than the green band is transmitted, or the light flux in the green band is transmitted. A reflection-transmissive film that transmits light other than the green band and a second slope that is joined to the first slope of the first prism lens via the reflection-transmission film, and that the image side is convex. And a light beam emitted from the first emission surface of the first prism lens, and a lens system configured by a second prism lens having a second emission surface that emits the light flux that has passed through the reflective / transmissive film. A first image pickup element which receives an image of a subject by receiving light, and a second image receiving element which receives a light beam emitted from the second exit surface of the second prism lens. And an imaging unit having an imaging device.

In this image pickup device, the reflection / transmission film in the lens system reflects the light flux in the green band and the light flux other than the green band among the light fluxes incident on the lens system, or transmits the light flux in the green band. And reflecting a light beam outside the green band, the light beam in the green band emitted from the first exit surface of the first prism lens or the second exit surface of the second prism lens is converted into the first light beam in the image pickup means. The image pickup device or the second image pickup device receives light. As a result, in this imaging device,
Since the first image pickup device or the second image pickup device in the image pickup means receives only the light flux in the visually important green band, either one of the image pickup devices receives the light beam in the visually important green band. The area capable of receiving light can be increased, and the number of green pixels, which is most important in resolution, can be increased.

In this image pickup device, the first exit surface of the first prism lens in the lens system is a convex surface on the image surface side, and the second exit surface of the second prism lens is a convex surface on the image surface side. By doing so, it is possible to make the first image pickup device and the second image pickup device in the image pickup device receive the light in a state where the dispersed light flux is collected. Therefore, in this image pickup apparatus, since the lens system performs the splitting and the focusing of the light flux by the integrated lens group, it is not necessary to dispose a plurality of lenses for performing the splitting and the focusing, and the lens system and the image pickup means. It can be downsized by shortening the distance from.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings and tables. FIG. 1 shows a configuration example of this imaging device. The image pickup apparatus 1 includes a lens system 2
An image pickup section 3 for receiving the light flux condensed by the lens system 2 and converting it into an electric signal; and a signal processing section for performing processing such as converting the electric signal from the image pickup section 3 into image data such as a digital signal. 4, a memory unit 5 for storing image data and the like processed by the signal processing unit 4, a display unit 6 for displaying image data and the like processed by the signal processing unit 4, and an image processed by the signal processing unit 4. A drive unit 7 for driving the image pickup unit 3 based on data and the like, and an operation unit 8 for various inputs by the user.
And a control unit 9 that controls each unit. In addition,
In this imaging device 1, the lens system 2 is a lens device to which the present invention is applied.

The lens system 2 will be described with reference to FIG. The lens system 2 includes a diaphragm 10, a first prism lens 11, a reflective / transmissive film 12, and a second prism lens 13.

The diaphragm 10 has a thickness of about 0.2 mm, and adjusts the amount of light passing therethrough, reduces the aberration of the light emitted from the lens system 2, and increases the depth of focus. To act on.

The first prism lens 11 has a convex surface on the object side, has positive power, and has an incident surface S1 on which a light beam is incident from the object side, and a light beam incident from the incident surface S1 is reflected to the lateral side. Along with the optical axis 4
It has a first inclined surface S2 which is a mirror surface of 5 degrees and a first emission surface S3 which has a convex surface on the image side and has a positive power and emits the light beam reflected by the first inclined surface S2. is doing.

The reflective / transmissive film 12 is disposed by being formed on the first slope S2 of the first prism lens 11. The reflective / transmissive film 12 is used for the first prism lens 1
Among the light fluxes incident from the first incident surface S1, the light flux in the green band is reflected and the light flux other than the green band is transmitted, or the light flux in the green band is transmitted and the light flux other than the green band is reflected, so-called dichroic. It's a mirror. The reflective / transmissive film 12 is formed on the first slope S2 to have a thickness of about 10 μm by a thin film forming technique such as plating or sputtering.

In the reflection / transmission film 12, the reflected or transmitted light flux in the green band has, for example, a wavelength band of 50.
The range is about 0 nm to 600 nm. On the other hand, the light flux other than the green band has a wavelength band of 400
a light flux in the blue band in the range of about nm to 500 nm,
It is a light beam in the red band or the like having a wavelength band in the range of about 600 nm to 700 nm.

The second prism lens 13 is bonded to the first slope S2 of the first prism lens 11 via the reflection / transmission film 12 and is a mirror surface inclined at 45 degrees with respect to the optical axis. It has two inclined surfaces S4 and a second emission surface S5 which is convex on the image side and emits the light flux transmitted through the reflective / transmissive film 12 together with the stay.

In the lens system 2 having the above-described structure, the reflection / transmission film 12 disperses the light beam in the green band and the other light beams among the light beams incident on the first prism lens 11. It is possible to obtain only the luminous flux in the green band that is visually important, and it is possible to improve the utilization efficiency of the luminous flux in the green band.

In this lens system 2, the first exit surface S3 of the first prism lens 11 is made a convex surface having a positive power, and the second exit surface S5 of the second prism lens 13 is made positive. Since it is a convex surface with power,
The light flux dispersed by the reflection / transmission film 12 can be focused on the image plane in a condensed state. As a result, in this lens system 2, since the dispersed light flux is emitted in a condensed state by the integrated lens group,
It is not necessary to dispose a plurality of lenses for performing the spectral separation and the condensing, and the spectral distribution and the condensing of the light flux can be realized in a size substantially equal to that of the single lens, and the size and cost can be reduced.

In the lens system 2 described above, the reflective / transmissive film 12 is formed on the first slope S2 of the first prism lens 11, but the invention is not limited to this.
For example, the reflective / transmissive film 12 may be disposed by being deposited on the second slope S4 of the second prism lens 13.

Table 1 shows specific design data of the lens system 2 described above. In Table 1, R is the radius of curvature, D is the axial distance, and N is
d is the refractive index.

[0026]

[Table 1]

The diaphragm 10 is arranged at a position corresponding to the surface number 1 shown in Table 1, and the distance on the optical axis from the first prism lens 11 is set to 10.0000 mm.

In the first prism lens 11, the entrance surface S1 corresponds to the surface number 2 shown in Table 1, and the radius of curvature of this entrance surface S1 is 7.67426 mm. Further, in this first prism lens 11, the first slope S2 corresponds to the surface number 3 shown in Table 1. Further, in the first prism lens 11, the first emitting surface S3 corresponds to the surface number 5 shown in Table 1, and the radius of curvature of the first emitting surface S3 is -9.47715 mm.

In the first prism lens 11, the refractive index is 1.49150 and the material is optical plastic such as polymethylmethacrylate (PMM).
It consists of A). In the first prism lens 11, the distance (thickness) between the entrance surface S1 and the first slope S2 on the optical axis is set to 7.5000 mm. Also the first
The distance (thickness) on the optical axis between the slope S2 and the first exit surface S3 is 5.5000 mm.

In the first prism lens 11, the entrance surface S1 and the first exit surface S3 are aspherical surfaces. These aspherical surfaces can be represented by the following known aspherical surface formula (1).

[0031]

[Equation 1]

In this equation (1) for the aspherical surface, Z
Is the coordinate in the optical axis direction, which is the origin of the intersection of the aspherical surface and the optical axis, and X is the coordinate in the direction passing through the origin and orthogonal to the optical axis.
C is a paraxial curvature 1 / R. Therefore, the aspherical surface has a radius of curvature R near the optical axis, a conic constant α ₁ ,
Aspherical coefficient α _{4 of} the aspherical terms of the 6th, 6th, 8th and 10th orders,
It can be determined by α ₆ , α ₈ and α ₁₀ .

In this case, the entrance surface S1 and the first exit surface S
The conical constant α _{1 of} 3 and the aspherical surface coefficients α ₄ , α ₆ , α ₈ and α ₁₀ of the 4th-order, 6th-order, 8th-order and 10th-order aspherical terms are shown in Table 2 below.

[0034]

[Table 2]

In the second prism lens 13, the second
The slope S4 corresponds to the surface number 4 shown in Table 1. Further, in the second prism lens 13, the second emission surface S5 is the first emission surface S3 of the first prism lens 11.
Similarly, the surface number 5 shown in Table 1 corresponds, and the radius of curvature of the second exit surface S5 is also set to -9.47715 mm. The refractive index of the second prism lens 13 is the first
Similar to the prism lens 11 of 1., it is 1.49150, and the material thereof is optical plastic such as polymethylmethacrylate (PMMA). In the second prism lens 13, the distance (thickness) between the second slope S4 and the second exit surface S5 on the optical axis is 5.5000.
It is set to mm.

Further, in the second prism lens 13, the second exit surface S5 is also aspherical. Also in this case, the conical constant α _{1 of} the second exit surface S5 and the quartic
Aspherical coefficient α _{4 of} the 6th, 8th and 10th aspherical terms,
α ₆ , α ₈ and α ₁₀ are as shown in Table 2 above.

In the lens system 2 having the above construction, the first
The light flux incident from the incident surface S1 of the prism lens 11 is reflected or transmitted in the state where the wavelength band is selected by the reflection / transmission film 12, and the reflected light flux is the first emission surface S3 of the first prism lens 11. The light beams emitted and transmitted by the second prism lens 13 are emitted from the second emission surface S5 of the second prism lens 13 and are focused on the image plane. At this time, in this lens system 2, the distance between the first exit surface S3 of the first prism lens 11 and the image plane on the optical axis, and the second exit surface S5 of the second prism lens 13 The distance from the image plane on the optical axis is 5.0804 mm.

Here, a coma aberration diagram of the lens system 2 designed with such design data is shown in FIG. 3, and a spot diagram is shown in FIG. As can be seen from FIG. 3, the lens system 2 is satisfactorily high-order corrected for coma by adopting the configuration based on the design data as described above.

Then, the luminous flux emitted in the state of being split into the luminous flux in the green band and the luminous flux other than the green band by the lens system 2 is received by the image pickup section 3.

As shown in FIG. 1, the image pickup unit 3 receives the light flux emitted from the lens system 2 at the position where the light flux emitted from the lens system 2 is imaged, thereby receiving the image of the subject. For example CCD (charge-coupled devic
e) Sensors and CMOS (complementary mental-oxide)
An image pickup device 14 such as a semiconductor device) sensor is arranged. Specifically, as can be seen from Table 1, the first prism lens 11 in the lens system 2
At the position of 5.0804 mm on the optical axis from the first exit surface S3 to the image plane side.
Is the second exit surface S of the second prism lens 13.
The second image pickup device 14b is arranged at a position of 5.0804 mm on the optical axis from 5 to the image plane side.

In this image pickup unit 3, the first image pickup device 14a and the second image pickup device 14b are the lens system 2
A photoelectric conversion element that converts the light beam emitted and received by the device into an electric signal, etc., and has a plurality of pixels in the imaging area that receives the light beam, and an electric signal that is output according to the amount of light received by each of these pixels. And the subject image formed in the imaging region is photoelectrically converted.

In the image pickup section 3, one of the first image pickup element 14a and the second image pickup element 14b receives the light flux in the green band split by the lens system 2, and the other. Will receive a light beam outside the green band. As a result, in the image pickup unit 3, since either one of the first image pickup device 14a and the second image pickup device 14b independently receives only the luminous flux in the green band which is visually important, It is possible to improve the utilization efficiency of the luminous flux in the band.

Further, in the image pickup section 3, either one of the first image pickup element 14a and the second image pickup element 14b independently receives only the light flux in the green band, which is visually important. The light receiving sensitivity for the pixel to receive a light flux in the green band is improved. As a result, this imaging unit 3
Then, when one of the first image pickup device 14a and the second image pickup device 14b converts the luminous flux in the green band into an electric signal, a state in which the level of the electric signal corresponding to green is increased. Will be output.

The signal processing unit 4 is a DSP (Digital Signal Processor) or the like that performs signal processing such as converting the electric signal output from the image pickup unit 3 into a digital signal such as image data, and the like, depending on the level of the electric signal. The digital signal is output to the memory unit 5, the display unit 6, the drive unit 7, the control unit 9, and the like.

The memory section 5 stores the digital signal processed by the signal processing section 4 as image data. As the memory unit 5, for example, a DRAM (Dynamic Random Acces
s Memory) and RAM (Random Access Memory).

The display unit 6 includes, for example, an LCD (liquid cry
stal display) etc. This LCD has a liquid crystal panel that performs light modulation and a backlight that illuminates the liquid crystal panel from the back, and illuminates the liquid crystal panel with the backlight according to a control signal from the control unit 9 and the signal processing unit. A pattern based on the image data output from the image pickup device 4 or the like is displayed on the liquid crystal panel, and the liquid crystal panel modulates the illumination light from the backlight to display the subject image formed in the image pickup area of the image pickup device 14.

The drive unit 7 is, for example, a drive mechanism such as an actuator, and the image pickup unit 3 and the like for appropriately adjusting the color tone based on the image data from the signal processing unit 4 and the control signal from the control unit 9. Drive.

The operation section 8 allows the user to perform various operations of the image pickup apparatus 1.

The control unit 9 is, for example, a CPU (Central Proc
essing unit) and the like, recording image data from the image pickup unit 3 in the memory unit 5 according to an input signal from the operation unit 7, displaying image data from the image pickup unit 3 on the display unit 6, The imaging unit 3, the signal processing unit 4, the memory unit 5, the display unit 6, the driving unit 7, and the like are controlled so that the imaging unit 3 can appropriately image the subject.

In the image pickup apparatus 1 having the above-described structure, the reflection / transmission film 12 in the lens system 2 separates the light flux entering the lens system 2 into the light flux in the green band and the other light flux. , The green light flux emitted from the lens system 2 is transferred to the first image pickup device 14a in the image pickup unit 3.
Alternatively, either one of the second image pickup devices 14b is designed to receive light independently.

As a result, in the image pickup apparatus 1, the light flux in the green band split by the lens system 2 is supplied to either the first image pickup element 14a or the second image pickup element 14b in the image pickup section 3. However, since the light is received independently, it is possible to increase the area of the pixel in the image pickup region that can receive the light flux of the visually important green band.

Further, in this image pickup apparatus 1, since either one of the first image pickup device 14a and the second image pickup device 14b in the image pickup unit 3 independently receives the light flux in the green band, the visual sense is achieved. It is possible to improve the utilization efficiency of the light flux of the green band that is important above, and improve the light receiving sensitivity of the pixels in the imaging region to receive the light flux of the green band that is visually important.

Therefore, in this image pickup apparatus 1, since either one of the two image pickup elements outputs the electric signal corresponding to the green color from the image pickup section 3 in a state of being raised in level, the resolution is the most important. It is possible to display a subject image with an increased number of green pixels, which is represented by the above, on the display unit 6, and it is possible to improve the resolution of green in particular and obtain visually clear image data.

In this image pickup device 1, clear lightness information and chromaticity information of green, which are visually important, are obtained without using three image pickup elements as in the conventional case, and false colors of green are suppressed. Therefore, it is possible to obtain a visually clear image even with the two image pickup elements.

In this image pickup apparatus 1, since the lens system 2 only splits the optical path into two, the structure is relatively simple as compared with the case where three image pickup elements are used to split into three optical paths. A high-quality image can be obtained, and the number of members used for the lens system 2 and the imaging unit 3 can be reduced, so that the cost can be reduced.

Further, in this image pickup apparatus 1, the lens system 2
First exit surface S3 of the first prism lens 11 at
Is a convex surface having a positive power, and the second exit surface S5 of the second prism lens 13 is a convex surface having a positive power, so that the imaging unit in a state where the dispersed light flux is condensed. The first image pickup device 14a and the second image pickup device 14b in No. 3 can receive light.

Therefore, in the image pickup apparatus 1, the lens system 2 performs the light beam splitting and the light focusing by the integrated lens group, and the light beam splitting and the light focusing can be realized in substantially the same size as the single lens. The distance between the lens system 2 and the image pickup unit 3 can be shortened to achieve miniaturization, and the cost can be reduced because it is not necessary to dispose a plurality of lenses for performing the spectrum and the light collection.

In the above-described embodiments, the lens system 2 having the diaphragm 10 between the subject and the first prism lens 11 has been described as an example, but the present invention is not limited to this. Instead, the lens system 20 shown in FIG. 5 may have a structure in which a diaphragm is provided inside. Since the lens system 20 is used in a portion equivalent to the lens system 2 in the above-described image pickup apparatus 1, description of the image pickup apparatus using the lens system 20 will be omitted.

Here, a specific configuration, numerical values, etc. of the lens system 20 will be given. In this lens system 20,
It is not necessarily limited to the following examples. The design data of the lens system 20 shown in FIG. 5 are as shown in Table 3 below. In Table 3, R is the radius of curvature, D is the axial distance, and Nd
Is the refractive index.

[0060]

[Table 3]

This lens system 20 is arranged in order from the subject side.
The first prism lens 21, the diaphragm 22, the reflective / transmissive film 23, and the second prism lens 24 are included.

The first prism lens 21 has an incident surface T1 having a convex surface on the object side and having positive power, and a light beam incident from the object side, and a light beam incident from the incident surface T1 reflected to the side. In addition, the first inclined surface T2 is inclined at 45 degrees with respect to the optical axis, and the image surface side is a convex surface to have positive power and emit the light flux reflected to the side by the first inclined surface T2. It has the 1st outgoing radiation surface T3.

In this first prism lens 21,
The incident surface T1 corresponds to the surface number 1 shown in Table 3, and the radius of curvature of this incident surface 1 is set to 13.44617 mm. In addition, in the first prism lens 21,
The first slope T2 corresponds to the surface number 2 shown in Table 3. Furthermore, in this first prism lens 21,
The first exit surface T3 corresponds to the surface number 4 shown in Table 3, and the radius of curvature of the first exit surface T3 is -7.3613.
It is set to 1 mm.

In the first prism lens 21, the refractive index is 1.49150 and the material is optical plastic such as polymethylmethacrylate (PMM).
It consists of A). In the first prism lens 21, the distance (thickness) on the optical axis between the incident surface T1 and the first inclined surface T2 is set to 5.0000 mm. The distance (thickness) on the optical axis between the first slope T2 and the first exit surface T3 is set to 5.0000 mm.

In the first prism lens 21, the entrance surface T1 and the first exit surface T3 are also aspherical surfaces, like the first prism lens 11 in the lens system 2. These aspherical surfaces can also be represented by the above-described known aspherical surface formula (1).

First, the prism lens 21
Conical constant α of the projection surface T1 and the first exit surface T3₁, And
Aspherical coefficients of 4th, 6th, 8th and 10th aspherical terms
α_Four, Α ₆, Α₈, Α₁₀Is as shown in Table 4 below.
is there.

[0067]

[Table 4]

The diaphragm 22 is arranged on the first slope T2 of the first prism lens 21 as, for example, a black coating film having an opening for adjusting the amount of light and has a thickness of about several microns. There is. As a result, the amount of light flux incident from the incident surface T1 is adjusted, and the aberration when emitted from the lens system 21 is reduced.

The reflective / transmissive film 23 is arranged by being formed on the first slope T2 of the first prism lens 21 through the diaphragm 22. The reflection / transmission film 23 reflects the light flux in the green band and transmits the light flux other than the green band or transmits the light flux in the green band among the light fluxes incident from the incident surface T1 of the first prism lens 21. Together with this, it is a so-called dichroic mirror that reflects light beams other than the green band. The reflective / transmissive film 23 is formed on the first slope T2 to have a thickness of about 10 μm by a thin film forming technique such as plating or sputtering.

At this time, the light flux in the green band reflected or transmitted by the reflective / transmissive film 23 has a wavelength band in the range of about 500 nm to 600 nm, for example. On the other hand, the light beam other than the green band is, for example, a light beam in the blue band having a wavelength band in the range of about 400 nm to 500 nm, a light beam in the red band having a wavelength band in the range of about 600 nm to 700 nm, and the like.

The second prism lens 24 is joined to the first inclined surface T2 of the first prism lens 21 via the diaphragm 22 and the reflective / transmissive film 23, and is oblique to the optical axis.
It has a second inclined surface T4 which is a mirror surface of 5 degrees and a second emission surface T5 which has a convex surface on the image side and has a positive power and which emits the light flux transmitted through the reflection / transmission film 23. There is.

In this second prism lens 24,
The second slope T4 corresponds to the surface number 3 shown in Table 3. Further, in the second prism lens 24, the second emission surface T5 corresponds to the surface number 4 shown in Table 3 like the third emission surface T3 of the first prism lens 21, and The radius of curvature of the second exit surface T5 is -7.3613.
It is 1 mm. The refractive index of the second prism lens 24 is
1.49150, and the material is optical plastic such as polymethylmethacrylate (PMMA). In the second prism lens 24, the distance (thickness) on the optical axis between the first inclined surface T4 and the second emission surface T5 is set to 5.0000 mm.

Further, in the second prism lens 24, the second emission T5 is also an aspherical surface, like the second emission surface S5 of the second prism lens 13 of the lens system 2. Also in this case, the conical constant α _{1 of} the second exit surface T5 and the aspherical surface coefficients α ₄ , α ₆ , α ₈ , α ₁₀ of the _4th , _6th , _8th , and _10th aspherical terms are as described above. It is as shown in Table 4.

Also in the lens system 20 having the above-described structure, as in the lens system 2, the luminous flux incident from the incident surface T1 of the first prism lens 21 is adjusted in the diaphragm 22 and the reflection / transmissive film 23 is formed together with the light. In the state where the wavelength band is selected, the light flux is reflected or transmitted, the reflected light flux is emitted from the first exit surface T3 of the first prism lens 21, and the transmitted light flux is transmitted to the second prism lens 24 of the second prism lens 24. Are emitted from the emission surface T5 and are imaged on the image plane. At this time, in this lens system 20, the first prism lens 21
On the optical axis between the first exit surface T3 and the image plane at
And the second exit surface T of the second prism lens 24.
5 and the image plane on the optical axis are each 8.6817 m
It is set to m.

Similar to the lens system 2, the coma aberration diagram of the lens system 20 is shown in FIG. 6 and the spot diagram thereof is shown in FIG. As can be seen from FIG. 6, even with the lens system 20, coma aberration is favorably corrected to a higher order by adopting the configuration as the design data described above.

Also in this lens system 20, as in the lens system 2, the reflection / transmission film 23 separates the light flux in the green band and the other light flux from the light flux incident on the first prism lens 21. Therefore, only the luminous flux in the green band which is visually important can be obtained, and the utilization efficiency of the luminous flux in the green band can be improved.

Also in this lens system 20, the first projected surface T3 of the first prism lens 21 is a convex surface having positive power, and the second exit surface T5 of the second prism lens 24 is positive. Since it is a convex surface having power, it is possible to form an image on the image plane in a state in which the light flux dispersed by the reflection / transmission film 23 is condensed. This allows
In this lens system 20, the combined lens is used to emit the dispersed light beam in a condensed state, and it is not necessary to dispose a plurality of lenses for performing the spectrum separation and the light collection. The light beam can be dispersed and condensed in a size almost equal to that of a single lens, and downsizing and cost reduction can be achieved.

Further, in this lens system 20, the diaphragm 22
Since it is provided inside, it is not necessary to dispose a diaphragm between the subject and the first prism lens 21,
Further size reduction can be achieved.

In the lens system 20 described above, the reflective / transmissive film 23 is provided on the second slope T2 of the first prism lens 21.
However, the present invention is not limited to this. For example, the reflective / transmissive film 23 is formed on the second prism lens 24.
It may be arranged by forming a film on the second slope T4.

The lens device to which the present invention is applied has been described in the above-mentioned embodiment by taking an example in which the image pickup device 1 in which the image pickup device 14 receives light on the image plane is used. The present invention is not limited to this, and can be applied to, for example, color separation of a projection device such as a liquid crystal projector by performing light reception on the image plane by a liquid crystal panel or the like.

[0081]

As is apparent from the above description, according to the present invention, the reflective / transmissive film selectively reflects or transmits only the light flux in the green band to disperse the light beam, so that the visually important green band It is possible to obtain a lens device and an imaging device in which only the light flux can be obtained and the utilization efficiency of the green light flux is improved.

Further, according to the present invention, since the dispersed light flux is emitted in the condensed state by the integrated lens group, a plurality of lenses are arranged for the spectral separation and the light condensation. Therefore, it is possible to obtain a lens device and an imaging device that are downsized and reduced in cost.

Further, according to the present invention, one of the first image pickup device and the second image pickup device in the image pickup device independently receives the light flux in the green band split by the lens device. Therefore, it is possible to increase the area where the luminous flux of the green band which is visually important can be received.
Further, according to the present invention, it is possible to improve the utilization efficiency of the luminous flux in the green band that is visually important and the light receiving sensitivity of the luminous flux in the green band that is visually important in the imaging unit. Therefore, according to the present invention, it is possible to display image information in which the number of green pixels, which is the most important factor in resolution, is increased, and in particular, an imaging device capable of improving the resolution of green and displaying a visually clear image. Is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an image pickup apparatus according to the present invention.

FIG. 2 is a configuration diagram showing the lens device.

FIG. 3 is a coma aberration diagram of the lens device.

FIG. 4 is a spot diagram of the lens apparatus.

FIG. 5 is a configuration diagram showing another example of the lens device according to the present invention.

FIG. 6 is a coma aberration diagram of the lens device.

FIG. 7 is a spot diagram of the lens apparatus.

[Explanation of symbols]

1 imaging device, 2, 20 lens system, 3 imaging unit, 4
Signal processing unit, 5 memory unit, 6 display unit, 7 drive unit,
8 operation unit, 9 control unit, 10 diaphragm, 11 first prism lens, 12 reflective / transmissive film, 13 second prism lens, 14a first image pickup device, 14b second image pickup device

Claims (4)

[Claims] 1. An incident surface having a convex surface on the object side and a light beam incident from the object side, a first inclined surface for reflecting the light beam incident from the incident surface to a lateral side, and an image surface side convex surface. And a first prism lens having a first emission surface that emits the light beam reflected by the first slope, and the first prism lens is disposed on the first slope of the first prism lens. Reflective transmission that reflects the light flux in the green band and transmits the light flux other than the green band, or transmits the light flux in the green band and reflects the light flux other than the green band, out of the light flux incident from the incident surface of the prism lens of A film, a second inclined surface joined to the first inclined surface of the first prism lens via the reflection / transmission film, and a convex surface on the image side, and emits a light flux transmitted through the reflection / transmission film. First Lens system and a second prism lens having a light exit surface. 2. A diaphragm is provided between the subject and the incident surface of the first prism lens, and / or between the first inclined surface of the first prism lens and the reflective / transmissive film. The lens device according to claim 1. 3. An incident surface having a convex surface on the object side and a light beam incident from the object side, a first inclined surface for reflecting the light beam incident from the incident surface to a lateral side, and an image surface side convex surface. And a first prism lens having a first emission surface that emits the light beam reflected by the first slope, and the first prism lens is disposed on the first slope of the first prism lens. Reflective transmission that reflects the light flux in the green band and transmits the light flux other than the green band, or transmits the light flux in the green band and reflects the light flux other than the green band, out of the light flux incident from the incident surface of the prism lens of A film, a second inclined surface joined to the first inclined surface of the first prism lens through the reflection / transmission film, and a convex surface on the image surface side, which emits a light flux transmitted through the reflection / transmission film. 2 out A first prism for receiving an image of a subject by receiving a light beam emitted from a first exit surface of the first prism lens, and a lens system including a second prism lens having a projection surface. The image pickup device and the second prism lens
And an image pickup unit having a second image pickup element for receiving an image of a subject by receiving the light flux emitted from the exit surface of the image pickup device. 4. The lens system includes the subject and the first lens.
Between the entrance surface of the prism lens and / or the first
The image pickup device according to claim 3, wherein a diaphragm is disposed between the first inclined surface of the prism lens and the reflective / transmissive film.