JP3041732B2 - Color imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image pickup device using a liquid crystal element.

[0002]

2. Description of the Related Art In a color image pickup apparatus used for an endoscope or the like, a subject is sequentially irradiated with light (for example, three primary colors of red, blue, and green) separated from white light for each color component. The light reflected from the subject is imaged on the image sensor, and the accumulated charges are transferred and converted into electric signals, and color display is performed based on the electric signals. . That is, since the reflected light of each color component light has the level of the color component depending on the color of the subject, the color display of the image of the subject can be performed by synthesizing the signal of each color component level. It is.

[0003] The schematic structure of a light emitting portion of the color component light in the conventional color image pickup device applied to the endoscope will be described with reference to FIG. White light emitted from a light source 1 built in the apparatus main body passes through a convex lens 2 and is converged.

A rotary disk filter 101 driven to rotate by a motor 100 is provided with band-shaped transmission holes at regular intervals at a peripheral portion of the light-shielding plate corresponding to the optical path of the convergent light from the convex lens 2, and each of these transmission holes has Band-shaped filters 102, 103 and 104 of three primary colors of red, green and blue are provided corresponding to the rotation direction M. On the other hand, small holes 105, 106, and 107 for detecting a rotational position are provided at positions between the respective transmission holes of the rotating disk filter 101.
Photo lamp pulses are detected by flag (position) detection devices 102, 103, and 104.

Thus, the light beams passing through the filters 102, 103, 104 sequentially become red (R) light, green (G) light, and blue (B) light, and then enter the light guide fiber bundle 3, where the light guides the light. Light is emitted from the tip of the fiber bundle 3 toward a subject such as the stomach.

The light of each color reflected from the subject is received by a solid-state image pickup device (not shown) provided at the distal end of the light guide fiber bundle 3 and stored as electric charge proportional to the amount of light. Then, during the period in which light is shielded between the filters, the charge is taken out and converted into an electric signal, and color display is performed based on the signal. In addition, both ends of each filter are formed in a concave shape so as to minimize the rise and fall of the transmitted light. Further, the rotary disk filter 3 has a structure in which the light shielding area is mechanically variable. A rotary encoder is arranged, R, G, B detection signals are generated by the encoder, and the detection signals are synchronized with the detection signals. Red, green, and blue accumulated charges are read from the solid-state imaging device, and are converted into color signals.

[0007]

However, in such a conventional color image pickup apparatus, it is necessary to provide various mechanisms such as a rotary disk filter and a mechanism for driving the filter. At R,
It is necessary to execute G and B color signal conversion, but high-precision processing has been hindered by various external factors. further,
To irradiate the rotating disk filter using a 150 W to 300 W lamp, which is a light source, measures should be taken to prevent heat from being transmitted to the rotating disk filter by means of a heat ray absorption filter or motor fan, etc. Thermal measures are also required in the peripheral area.

Other major difficulties are listed below. (1) Since the motor fan is used for the heat countermeasure, the dust easily deteriorates the performance of the rotating shaft grease, and phase shift occurs in the gears and the belt of the transmission system.

(2) Uneven rotation of the rotating disk filter is likely to occur due to mechanical vibration. (3) Motors need to have high heat resistance, long life, and minimal rotation unevenness, so they always have a long life, so parts need to be replaced.

(4) Since the color signal is generated by mechanically rotating the rotary disk filter, a delay in transmission is likely to occur, which is unstable. The present invention has been made in order to solve the problems of the above-described conventional color imaging apparatus, and has a simple structure, high reliability, and stable color by generating colored light rays by electrical processing. It is an object of the present invention to provide a color imaging device capable of performing signal processing.

[0011]

Means for Solving the Problems] Therefore, written to the present invention
A color image pickup apparatus irradiates an object from a light source built in the apparatus main body via an optical fiber, and receives white light from the white light in the middle of an optical path which is reflected and received by an image pickup device .
Reflects light, having a function of light of the remaining components and transmits
Multiple dichroic mirrors and polymer matrix
It has a structure in which liquid crystal particles are dispersed.
Polymer composite with the function of switching between transmission and scattering of light
Each of which is a dichroic mirror.
Color components interposed in the optical path of the light of the color components separated by
Separation system and a machine that transmits color component light and blocks scattered light
And a diaphragm mechanism having a function in the same order.
Switch the polymer composite sequentially to the side that transmits light
Transmits color component light alternately and receives each color component light
Therefore, the electric charge accumulated in the image sensor is converted to the generation of each color component light.
Control means for controlling transfer during occurrence.
It was composed.

[0012]

The color component light for each color component is separated and extracted from the white light emitted from the light source by the dichroic mirror of the color separation system. Then, by applying ON / OFF control of the applied voltage of the polymer composite interposed in the optical path of each separated color component light by the control means, each color component light is alternately extracted. On the other hand, light of components other than each color component light is OF
Scattered by the polymer complex designated as F.

Next, the scattered light is removed by the aperture mechanism, and only the color component light is alternately generated. Between the generation of each color component light, the scattering is performed by turning off all the polymer composites. Since only light is emitted, light can be blocked by the aperture mechanism.

When the color separation system and the aperture mechanism are interposed in the optical path before irradiation of the object, different color component lights are sequentially irradiated on the object, and the reflected light is received by the image sensor . In addition, when interposed in the optical path of the reflected light from the subject, the reflected light is sequentially converted into color component light, then received by the image sensor, and shielded while the charge accumulated in the image sensor is being transferred. To prevent the occurrence of smear etc.
Wear.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows the configuration and principle of a color separation system 70 composed of a dichroic mirror and a polymer composite (a type of liquid crystal element). In the figure, a first group of dichroic mirrors arranged at intervals in the optical axis direction of a light beam from a light source 1 includes:
A red dichroic mirror 71 that separates and reflects red light according to spectral characteristics and transmits other color components, and a green dichroic mirror 72 that separates and reflects green light and transmits other color components similarly. And a blue dichroic mirror 73 that separates and reflects blue light and transmits other color components, both of which are arranged in the same direction with respect to the optical axis.
° installed at an angle.

Further, a second dichroic mirror group 74, which has the same configuration as the first dichroic mirror group,
The first and second dichroic mirrors 75 and 76 are arranged so as to be translated in a direction perpendicular to the optical axis from the light source.

Then, between the red dichroic mirror 74 and the green dichroic mirror 75 of the second dichroic mirror group, the green dichroic mirror 72 of the first dichroic mirror group and the green dichroic mirror of the second dichroic mirror group. The polymer composites 77, 78, 79 are disposed between the first dichroic mirror 75 and the green dichroic mirror 72 and the blue dichroic mirror 73, respectively.

The polymer composite is a light modulating material in which micron-sized liquid crystal particles are dispersed in a polymer matrix as shown in FIG. 2 , and is switched between a transparent state and a cloudy state by ON / OFF of an applied voltage. Thus, transmission and scattering of light incident on the polymer composite can be switched. Explaining the principle, when the liquid crystal has a positive dielectric anisotropy, when a voltage is applied, the ordinary light refractive index of the liquid crystal and the refractive index of a polymer (strictly, a polymer swollen by the liquid crystal) match. At this time, if the refractive indexes are strictly matched, the light transmittance can be 80% or more. Further, when no voltage is applied, the refractive index of the liquid crystal becomes larger than the refractive index of the polymer. As a result, the refractive indexes do not match, and the incident light is mainly scattered forward.

[0019] Therefore, in the color separation system of FIG. 1,
Now, the voltage applied to the polymer composite 77 is turned on, and the polymer composite
When 78 and 79 are turned off, the white light emitted from the light source 1 is reflected only by the red dichroic mirror 71 of the first dichroic mirror group, and only the red component light is transmitted. The reflected red light is reflected by the red dichroic mirror 74 of the second dichroic mirror group, passes through the polymer composite 77, and further passes through the green dichroic mirror 75 and the blue dichroic mirror 76. On the other hand, light having a color component other than red transmitted through the red dichroic mirror 71 is separated into green light and blue light by the green dichroic mirror 72, and the green light is reflected and the blue light is transmitted, but the green light is transmitted. Is scattered when entering the polymer composite 78, and blue light is scattered when entering the polymer composite 79. The scattered light as it is is reflected by the dichroic mirror and a part of the scattered light is mixed with the red light. However, the scattered light can be effectively shielded by the aperture mechanism described later. Thus, white light is extracted as red light. Similarly, when only the polymer composite 78 is turned ON, green light is separated and extracted, and when only the polymer composite 79 is turned ON, only blue light is separated and extracted.

[0020] Next will be described on the basis of the throttle mechanism 3 for shielding the scattered light mentioned above. The aperture mechanism 80 includes a convex lens 81 disposed downstream of the color separation system 70 and an aperture 82 having a small hole 82a formed in an optical axis portion.

That is, since the color component light transmitted through the color separation system 70 is parallel light, it passes through the small hole 82a when converged by the convex lens 81, but scattered light passes through the convex lens 81 because it has no directionality. The number of the small holes 82a is extremely small, and the light is substantially blocked.

When all of the polymer composites 77, 78, and 79 are turned off in the color separation system 70, only the scattered light is generated. Therefore, a light-shielded state is obtained, and the same function as the optical shutter is obtained.

FIG. 4 shows the color separation system 70 and the aperture mechanism.
Shows an embodiment of a color imaging apparatus according to the present invention using a 80, the apparatus main body A, similar to the prior art as a light emitting portion
A light source 1 and a convex for converging a light beam emitted from the light source 1
The lens 2 is provided, and the converged light beam is transmitted to the apparatus main body A.
Of the light guide fiber bundle 3 with the end introduced into the
Although it is incident on the rear end face, between the light source 1 and the convex lens 2
The color separation system 70 and the aperture mechanism 80 are interposed in the same order.
Have been.

The light guide fiber bundle 3 is incorporated.
The light guide fiber bundle 3 is provided at the tip of the optical fiber 8.
Diffuses the light emitted from the exit light surface at the tip to cover a wide area
When the illumination lens 9 for irradiating the subject is attached,
And the reflected light of the light applied to the subject enters and converges.
The objective lens 10 to receive the light passing through the objective lens 10
Solid-state image sensor 11 that emits light and stores it as electric charge proportional to the amount of light
Is installed.

The solid-state imaging device 11 has a tag
As described later, the light-shielding period
The charge extraction signal CDP generated in the middle of the optical fiber 8
The signal is input through a signal output line 13
The charge of each color stored in the solid-state image sensor 11 is taken out.
And a signal provided in the optical fiber 8 as an electric video signal.
The signal is input to the signal processing unit
It is.

The signal processing section is constituted by each circuit described later.
Have been. Based on the clock pulse from crystal oscillator 15,
Of the television image signal from the synchronization signal generator 16
Field with high-level pulse width synchronized with period
Reference pulse V. BLKP is the timing pulse signal
It is output to the generator 12.

The timing pulse signal generating section 12
Polymer composite drive pulse based on Lus V · BLKP
And a charge accumulation pulse CDP to form a polymer composite drive.
The driving pulse is supplied to the polymer composite driving section 90 by the charge storage pulse C.
DP are output to the solid-state imaging device 11, respectively. In addition, crystal oscillation
15, Synchronous signal generator 16, Timing pulse signal generator
12, and the polymer composite drive unit 90 is a control means in the present invention.
Make up the steps.

The polymer composite driving section 90 is provided with the polymer
Based on the composite drive pulse, as shown in FIG.
V. The high level is alternately synchronized with the high level period of BLKP.
Red light transmission pulse RSP, green light transmission pulse
Lus GSP, blue light transmission pulse BSP
The child composites 77, 78, and 79 are sequentially output. Also, all high
By turning off the voltage applied to the child complexes 77, 78, and 79,
A light blocking period is obtained. For this reason, use an optical shutter
It is not necessary to form a light shielding pulse as in the case.

Thus, the white light emitted from the light source 1
Is the polymer composite 7 to which the transmission pulse of each color is input.
Red light, green light and blue light are emitted alternately by 7, 78 and 79
These are the light guide fiber bundle 3 and the illumination lens.
The subject is illuminated through the camera 9. Then, the transparency of each color is
High level synchronized with overpulse
The charge accumulation pulse CDP output to the image element 11 causes
The reflected light of the illumination light of each color passes through the objective lens 10
The charge received by the element 11 is proportional to the amount of light for each pixel of the image.
Is accumulated.

Further , each transmitted pulse RSP, GSP, BS
The applied voltage to the polymer composite 77, 78, 79 between P is OF
When it becomes F, it is shaded and the illumination to the subject is cut off.
You. On the other hand, during the light-blocking period in which the illumination is cut off,
Charge accumulated by receiving the color component light of
11 Transferred to internal storage. Here, the solid-state imaging device 11
The configuration will be described. In this embodiment, a solid-state imaging device is used as a solid-state imaging device.
A frame transfer CCD is used. In CCD, the signal charge
The two states of accumulation and transfer are alternately repeated. So
Here, one field accumulated in the photosensitive unit that directly receives light
Instantaneous charge during a part of the vertical blanking period
Transfer to department. One field worth of power transferred to the storage
The load corresponds to one scan line during part of the horizontal blanking period.
Are transferred to the line transfer section by
Signal charge is immediately transferred to the output terminal at standard speed
The standard TV signal from the output terminal.
ing. By the way, in the case of a color imaging device, a thin optical fiber
Since the CCD is mounted on the tip of the bar, the light receiving area of the CCD
In order to increase the light receiving efficiency,
Advantages of frame system with structure completely separated from stacking part
It is. However, when using the frame method,
Even if the data is transferred at high speed, the transfer
If light is irradiated inside, the light is inevitably covered. Transfer
If light is mixed in, the correct signal cannot be obtained and
A. Therefore, the transfer of electric charge to the storage section is performed.
To ensure that the CCD is not illuminated during transport,
A light-blocking period is provided.

The photosensitive section and the storage section are alternately arranged in the horizontal direction.
In the interline CCD, the C
Even if the CD is irradiated with light, it is almost affected by the light
There is almost no need to block light during transfer,
Resolution because efficiency is reduced to less than half of the frame method
Inferior.

Returning to FIG . 4, the accumulation of the solid-state image pickup device 11 will be described.
The electric charge transferred to the unit is converted into an electric video signal,
Output to the buffer amplifier 17 via the outgoing line 14,
17 removes noise. And the timing
The red (R), green (G),
Pulses RGP and GG corresponding to each blue (B) video signal
P and BGP are output to the analog switch 18 for each field.
Is forced. The analog switch 18 controls these pulses RG
P, GGP, BGP sequentially correspond to each color video signal red
Color process circuit 19, green process circuit 20, blue
The switching operation is performed so as to output to the process circuit 21. This result
As a result, the analog video signal of each color is once converted to an A / D converter 2 once.
Converted to digital video signal by 2, 23, 24, red
Field memory 25, green field memory 26, blue
It is stored in the color field memory 27.

Then, the field memories 25 for each color,
The digital video signal of each color stored in 26 and 27 is used for each color.
D / A converters 28, 29, 30
Is converted to a color TV signal through the matrix circuit 31.
The color is displayed on the John monitor 32 (see FIG. 5).

As described above, the color separation system 70 and the aperture mechanism 80
Alternate color component light for each color component by electronic control using
Can be generated in the color filter
No moving mechanism is required, and the durability of the driving mechanism and replacement of parts
The problem can be avoided and the size can be reduced.
And semi-permanent stability
Image of the subject can be obtained. In addition, the polarization conversion element
Less decrease in transmittance due to the use of polarized light
Can obtain bright and clear images, diagnostic
It also leads to improved accuracy.

In this embodiment, the polymer composite driving section 90
From each of the polymer composites 77, 78 and 79 to the corresponding pulse R
SP, GSP and BSP are output independently, but polymer
The drive unit 90 combines these pulses in series.
Motion pulse from one output line
When the serial drive pulse is input to the portion near 11
The polymer composites 77, 78, 79 corresponding to each pulse sequentially
Distribution circuit (formed with one chip element)
May be interposed.

FIG . 6 shows the color separation system 70 and the aperture mechanism.
80 and the middle part of the optical fiber 8 (generally, an optical fiber
Operation unit for driving the insertion of the
An optical lens group 41 is provided. Configuration of other parts
And the functions and effects are the same as in the previous embodiment.
Compact color separation system 70 and aperture mechanism 80 in operation unit
Can be stored.

The color separation system 70 and the aperture mechanism 80
At the tip of the light guide fiber bundle 3 as shown in FIG.
And the illumination lens 9 may be provided.
Is located outside the illumination lens 9 as shown in FIG.
(Interval).

In the above embodiment, the illumination light to the subject is
Was used as the color component light, but illumination was performed with white light, and reflected light was
The same effect can be obtained by transmitting the light as the next color component light.
An example of such a system will be described below.

FIG . 9 shows a color separation system 70 and an aperture mechanism 80.
Is disposed between the objective lens 10 and the solid-state imaging device 11.
It is. FIG. 10 shows a color separation system 70 and an aperture mechanism.
80 outside the objective lens 10 (between the subject)
It is a thing.

Further, both the illumination light and the reflected light to the subject
The color components may be overlapped with each other, examples of which are shown below.
You. FIG. 11 shows that the color separation system 70 and the aperture mechanism 80 are illuminated.
It is formed so as to straddle the lens 9 and the objective lens 10, and is fixed.
FIG.
The color separation system 70 and aperture mechanism 80 formed in the upper size
To the outside of the illumination lens 9 and the objective lens 10
In the middle).

[0041]

As described above, according to the present invention, color separation comprising a dichroic mirror and a polymer composite is performed.
The combination of the system and aperture
Since the image sensor is configured to generate light alternately for each component and receive light on the image sensor, a high-brightness, high-contrast ratio photographed image can be obtained, and a rotary drive mechanism for the color filter is not required. The problem can be avoided, the size can be reduced, and the problem of vibration and rotation unevenness of the drive mechanism can be avoided. Therefore, a stable photographed image can be obtained semi-permanently.

[Brief description of the drawings]

FIG. 1 consists of a dichroic mirror and a polymer composite
Configuration diagram of color separation system

FIG. 2 is a diagram showing the configuration and principle of a polymer composite

FIG. 3 is a diagram showing a configuration principle of an aperture mechanism.

FIG. 4 shows an embodiment of the present invention using the above color separation system.
Configuration diagram showing an embodiment of a color imaging device

FIG. 5 is a time chart showing a signal state of each unit of the embodiment .
To

FIG. 6 is a configuration diagram of a main part of a second embodiment.

FIG. 7 is a configuration diagram of a main part of a third embodiment.

FIG. 8 is a configuration diagram of a main part of a fourth embodiment.

FIG. 9 is a configuration diagram of a main part of a fifth embodiment.

FIG. 10 is a configuration diagram of a main part of a sixth embodiment.

FIG. 11 is a configuration diagram of a main part of a seventh embodiment.

FIG. 12 is a configuration diagram of a main part of an eighth embodiment.

13A and 13B are diagrams showing a configuration of a conventional example, and FIG.
Figure, (b) is a front view

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 4 Polarization conversion element 5 Liquid crystal element 8 Optical fiber 11 Solid-state image sensor 12 Timing pulse signal generator 15 Crystal oscillator 16 Synchronous signal generator 70 Color separation system 80 Aperture mechanism 90 Polymer composite drive

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI H04N 9/07 H04N 9/07 A (58) Investigated field (Int.Cl. ⁷ , DB name) G02B 23/24 A61B 1 / 04 370 G02B 23/26 G02F 1/13 505 H04N 7/18 H04N 9/07 G02B 27/10 G02F 1/1335 525

Claims (1)

(57) [Claims] An image pickup device receives reflected light of each color component of light applied to a subject, transfers the accumulated electric charge, converts the electric charge into an electric signal, and performs color conversion based on the electric signal of the color component. In a color image pickup apparatus for displaying images, a light source built in the apparatus main body is illuminated to an object via an optical fiber, reflected light is received by an image pickup device, and the light passes through a white light.
Reflects the light of each color component and transmits the light of the remaining components
Dichroic mirrors with functions and polymer
Structure with liquid crystal particles dispersed in Trix
Has the function of switching light transmission and scattering by control
Polymer composite, and the polymer composite is
Each of the light paths of the color components separated by the Ick mirror
Interposed color separation system and color component light transmitted and scattered light
Is interposed in the same order with the aperture mechanism that has the function of blocking light
At the same time, the polymer composite is sequentially placed on the side that transmits light.
Switch to allow each color component light to pass through alternately, and
The electric charge accumulated in the image sensor by the light
Control means for controlling transfer between generations of spectral light.