JP3047082B2 - Focus mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focusing mechanism for an optical device such as an optical disk device, a camera, a microscope, and glasses.
In particular, the present invention relates to means for achieving downsizing, low power, and high speed operation of the entire optical device by reducing the size and power consumption of the focusing mechanism and operating it at high speed.

Although glasses are usually fixed-focus optical devices, variable-focus glasses are considered here, and these glasses will be included in an optical device requiring a focusing mechanism.

[0003]

2. Description of the Related Art Heretofore, in a focusing mechanism such as an optical disk device and a camera, focus has been achieved by moving a lens.

Further, as a focusing mechanism having no moving parts,
JP-A-59-224821, JP-A-61-140920
Etc. are known.

[0005]

The focusing mechanism of the type in which the lens is moved requires a lens driving mechanism, and the mechanism is complicated, and a relatively large amount of power is required for the lens driving motor. . Therefore, in order to ensure the reliability of the movable part, a robust but large and heavy mechanism must be used, and there is a disadvantage that a power supply or a battery for supplying electric power to the motor is large and heavy.

On the other hand, a focusing mechanism of the type that has no movable portion and changes the refractive index distribution requires a large number of terminals, and has a problem that a control circuit to be connected is complicated.

An object of the present invention is to provide a simple and lightweight structure,
An object of the present invention is to provide a focusing mechanism that can be reduced in size and power consumption and that can operate at high speed.

[0008]

According to the present invention, there is provided a focusing mechanism for changing a focal length or a focal position of an optical system, comprising: a liquid crystal layer; a transparent substrate sandwiching the liquid crystal layer; A voltage drop resistor provided on the substrate from the center to the periphery, a plurality of concentric electrodes provided on the transparent substrate and connected to the voltage drop resistor, and an extraction electrode for applying a voltage to both ends of the voltage drop resistor; The present invention proposes a focusing mechanism including a lower electrode provided on one transparent substrate for applying an electric field to the liquid crystal layer between the concentric electrodes and a power supply for applying a voltage to the extraction electrode and the lower electrode.

A plurality of concentric electrodes may be arranged at unequal intervals, and the concentric electrodes may have a triangular cross section to increase the power as a lens.

[0010] An electric resistance film connecting a plurality of concentric electrodes may be provided to prevent disturbance of the electric field between the concentric electrodes.

Further, an alignment film may be provided between the lower electrode and the liquid crystal layer, or a smooth layer covering the alignment film may be provided.

When a slit is formed in the plurality of concentric electrodes from the center to the periphery and each concentric electrode is divided into a plurality of parts,
Excitation noise due to external electromagnetic waves can be reduced.

A plurality of voltage drop resistors may be provided. In this case, a plurality of slits corresponding to the number of resistors are formed in the concentric electrode from the center to the periphery.

When there are a plurality of voltage drop resistors, a structure is adopted in which concentric electrodes are divided into respective resistors and connected to form concentric electrode groups of the same number as the number of resistors. Is provided, the aberration can be further reduced.

The liquid crystal layer is not limited to a single layer, and a plurality of liquid crystal layers may be arranged in the optical axis direction of the optical system.

The orientation directions of the plurality of liquid crystal layers are arranged at right angles to each other or in the same direction depending on the purpose of handling polarized light.

If the direction of rotation of the molecules and the plane of rotation of the plurality of liquid crystal layers are made to be on the same plane, and the direction of rotation of the liquid crystal molecules is reversed, the acceptance angle of the incident light increases.

The present invention also provides an optical information storage medium, a semiconductor laser, a lens for condensing light emitted from the semiconductor laser on the optical information storage medium, and a photodetector for receiving reflected light from the optical information storage medium. The present invention proposes an optical disk device having one of the above focusing mechanisms in a part of a lens.

The present invention further proposes a camera having a lens and an image sensor or a film disposed at a focal position of the lens, the camera including any one of the above-mentioned focusing mechanisms in a part of the lens. is there. This camera has a distance sensor that measures the distance to the subject,
And a driving circuit for driving any one of the focusing mechanisms according to a signal from the distance sensor. Instead of the distance sensor, an image sensor or a defocus detector that detects blurring of an image on a film may be employed. The present invention proposes a spectacle having a lens and a lens holding frame for fixing the lens to the head, the spectacle including one of the above focusing mechanisms in a part of the lens.

[0020]

When a voltage is applied to the liquid crystal, an electric focusing mechanism having no movable parts can be constructed. In this mechanism, since there are no movable parts, the focusing mechanism is simplified, lightened, and reduced in power.

When the voltage applied to the liquid crystal has a distribution, various aberrations at the focal plane can be suppressed to a minimum.

Further, since the voltage drop resistor for generating the voltage distribution applied to the liquid crystal is monolithically formed on the substrate holding the liquid crystal, the electric circuit connected to the outside has a simple configuration. In particular, the number of external connection terminals can be significantly reduced.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a focusing mechanism according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an external view of an embodiment of a focusing mechanism, FIG. 2 is a diagram illustrating a detailed internal structure thereof, FIG. 3 is a circuit diagram showing an electrical connection relationship of this embodiment, and FIG. It is a figure showing the characteristic of an example.

In FIG. 1, light incident on the focusing mechanism 1 is focused on a focal point 50. Based on the command signal of the focal position given to the signal processing circuit 20, the electrodes 10a, 10b,
Power is supplied to the focusing mechanism 1 through 10c to adjust the focus position.

In FIG. 2, a lower electrode 10c is attached to a substrate 18b. Although a conductive material is used for the lower electrode 10c, the lower electrode 10c is made of a material having a property of transmitting light, that is, a property of transmitting light in a wavelength band of light to be used. As this kind of translucent conductive material, an inorganic material such as ITO, a conductive organic thin film, or the like can be considered.

A liquid crystal layer 13 is formed on the lower electrode 10c. Alignment film 1
It is conceivable to form the liquid crystal layer 13 after the formation of 4b. Further, a spacer 17 is provided so as to control the thickness of the liquid crystal layer 13 and not to leak the liquid crystal layer 13 to the outside.

The substrate 18a is provided with a concentric electrode 12 facing the lower electrode 10c. A plurality of concentric electrodes 12 are provided concentrically about the optical axis, and each is connected to a different part of the voltage drop resistor 11. A voltage is applied to the voltage drop resistor 11 through the extraction electrode 10a and the extraction electrode 10b. In addition, the extraction electrode 10
An insulating film 16 is formed as necessary so that b and the concentric electrode 12 do not short-circuit with each other. The concentric electrode 12 is provided, if necessary, for the same reason as the alignment film 14b.
An alignment film 14a is formed.

As a whole, the liquid crystal is held by the substrate 18a, the substrate 18b, and the spacer 17, and an electric field is applied to the liquid crystal layer 13 from the concentric electrode 12 and the lower electrode 10c.

Next, the operation principle will be described. A voltage is applied to the voltage drop resistor 11 through the extraction electrode 10a and the extraction electrode 10b. Therefore, a voltage distribution is formed on the voltage drop resistor 11 in the radial direction from the optical axis center. This voltage distribution is determined by the radial resistance distribution of the voltage drop resistor 11.

Concentric electrode 1 connected to voltage drop resistor 11
2 has the same potential as the voltage of the voltage drop resistor 11 at the position connected to the voltage drop resistor 11. Concentric electrode 1
This is because no current flows through 2 and no voltage drop occurs in the concentric electrode 12.

By the action of the voltage drop resistor 11 and the concentric electrode 12, a voltage that changes in the radial direction is applied to the concentric electrode 12. An electric field varying in the radial direction is applied to the liquid crystal layer 13 existing between the concentric electrode 12 and the lower electrode 10c.

FIG. 3 is a drawing in which the extraction electrode 10b, the concentric electrode 12, the voltage drop resistor 11, and the extraction electrode 10a of FIG.

The AC voltage supplied from the AC source 30 is stepped down by the variable resistors 31 and 32. Each voltage signal is passed through the power amplifier 33 to the extraction electrode 10b.
And the extraction electrode 10a.

Extraction electrode 10a and extraction electrode 10b
Are different, a current flows through the voltage drop resistor 11,
A voltage drop occurs. That is, a voltage distribution occurs in the voltage drop resistor 11 in the radial direction.

Consider a case where the sectional area of the voltage drop resistor is changed in the radial direction. For example, a case where the film thickness is constant and the width is changed will be described. The fact that the cross-sectional area of the voltage drop resistor 11 changes in the radius r direction means that the resistance value per unit length of the voltage drop resistor 11 changes in the radial direction. By adjusting the width of the voltage drop resistor 11 in this manner, the radial distribution of the voltage generated in the voltage drop resistor 11 can be arbitrarily determined. Since it is easy to adjust the width while keeping the film thickness constant by photolithography, the structure is convenient for manufacturing. When the cross-sectional area of the voltage drop resistor is changed in the radial direction, characteristics of an aspherical lens or the like can be realized depending on how the voltage is distributed.

In order to minimize the aberration of the focusing mechanism, the entire aberration of the optical system to be used is calculated, and the refractive index distribution required for the focusing mechanism is obtained. For example, suppose that it was obtained as shown by the solid line in FIG. 4D. Next, from the relationship between the applied voltage and the refractive index of the liquid crystal as shown in FIG. 4C, the radial distribution of the electric field to be applied to the liquid crystal is determined as shown in FIG. 4B. If the width of the voltage drop resistor 11 is determined as shown in FIG. 4A so that the electric field distribution that realizes such low aberration is generated in the voltage drop resistor 11, the aberration of the focusing mechanism is minimized.

The focal point is realized by adjusting the lens action in the liquid crystal portion. For example, when the refractive index distribution as shown by the solid line in FIG. 4D is changed to the refractive index distribution as shown by the dotted line, the focal position can be adjusted by changing the power of the lens. When the voltage difference between the extraction electrode 10a and the extraction electrode 10b is increased, as shown by the solid line in FIG. 4D, the change in the refractive index of the liquid crystal increases, and the lens effect increases.
Also, if the voltage difference between the extraction electrode 10a and the extraction electrode 10b is reduced, the change in the refractive index of the liquid crystal is reduced as shown by the dotted line in FIG. 4D, and the lens effect is reduced.

The focusing mechanism 1 shown in FIG. 1 is used singly or in combination, or combined with another lens or the like to constitute a focusing mechanism having necessary light-collecting characteristics.

As a specific circuit for controlling the voltage applied to the liquid crystal, FIG. 3 shows a circuit using an AC source 30 and variable resistors 31 and 32. The basic operation of the focusing mechanism 1 shown in FIG. explained. As a specific circuit for controlling the voltage applied to the liquid crystal, various other methods can be considered. That is,
If the signal processing circuit that supplies power to the extraction electrode 10a and the extraction electrode 10b in FIG. 2 based on the command value of the focal length in FIG. 1 is adopted in the signal processing circuit 20 in FIG.
The liquid crystal layer of FIG. 2 can be controlled. With this method, a focusing mechanism having no movable parts can be realized.

In the embodiment of FIG. 2, the alignment films 14a,
Using 14b, the molecular orientation of the liquid crystal is the same in the entire liquid crystal layer 13. That is, when forming the alignment films 14a and 14b by a method such as rubbing or oblique deposition, the direction of the fine grooves on the alignment film surface is changed to the alignment film 1
The same direction is set for 4a and 14b. By doing so, the amount of change in the refractive index of the liquid crystal due to the voltage described with reference to FIG. 4C increases, and the focus adjustment range increases.

On the other hand, the alignment film 14a in the embodiment of FIG.
And 14b, the direction of the fine grooves on the surface of the alignment film is set to be a right angle, and the molecular alignment of the liquid crystal is twisted. By doing so, although the amount of change in the refractive index is reduced, a focusing mechanism that does not depend on the polarization direction of light can be configured.

Referring to FIG. 5, an embodiment of a focusing mechanism provided with a smoothing layer according to the present invention will be described. FIG. 5 is an enlarged sectional view of this embodiment.

In FIG. 5, a lower electrode 10c and an alignment film 14b are attached to a substrate 18b. Substrate 1
8a, a smooth layer 19 provided with an alignment film 14a and a concentric electrode 12 are attached. The liquid crystal layer 13 is held on substrates 18a and 18b. Other configurations are the same as the embodiment of FIG.

In this embodiment, since the smoothing layer 19 is provided, the alignment film 14a can be smoothed and the liquid crystal can be effectively molecularly aligned. As a result, the liquid crystal operation becomes faster and the focusing operation becomes faster.

When a translucent conductive material is used for the concentric electrode 12, a part of the light passing through the substrate 18a, the substrate 18b, and the liquid crystal layer 13 passes through the concentric electrode 12, and the other light passes through the concentric electrode 12. Pass between them without transmission. After passing through the focusing mechanism 1, if the phases of these two lights are not aligned,
Diffraction of light at the concentric electrode 12 becomes strong, and the diffracted light is lost and dissipated. The diffraction loss can be reduced by appropriately selecting the thickness and the refractive index of the concentric electrode 12 and matching the phases of the light transmitted through the concentric electrode and the light not transmitted. In this way, light loss can be minimized.

An embodiment of a focusing mechanism provided with a concentric electrode connection film according to the present invention for correcting electric field disturbance will be described with reference to FIG. FIG. 6 is an enlarged sectional view of this embodiment.

In FIG. 6, a lower electrode 10c and an alignment film 14b are attached to a substrate 18b. Substrate 1
8a, a smooth layer 19 provided with an alignment film 14a and a concentric electrode 12 are attached. The liquid crystal layer 13 is held on substrates 18a and 18b.

This embodiment is a modification of the embodiment of FIG. 5 in which adjacent concentric electrodes 12 are connected to each other by a concentric electrode connecting film 12a. The concentric electrode connection film 12a is made of a light-transmitting conductive film.

As already described with reference to FIG. 3, since the voltage distribution at the voltage drop resistor 11 is transmitted in the circumferential direction by the concentric electrode 12, the concentric electrode connection film 12a in FIG.
Is too low, a current flows through the concentric electrode connection film 12a, causing a voltage drop, which may hinder the transmission of the voltage distribution in the circumferential direction. To prevent this, each material is selected so that the conductivity of the concentric electrode 12 is higher than the conductivity of the concentric electrode connection film 12a. For example, a good conductor metal such as aluminum is selected for the concentric electrode, and the concentric electrode connection film 12a is formed.
In this case, a light-transmitting conductive film such as ITO is used. Alternatively, when both have substantially the same conductivity, the thickness of the concentric electrode connection film 12a is made thinner than the thickness of the concentric electrode 12, and the resistance value of this portion is increased.

When there is no such concentric electrode connecting film 12a, as shown in FIG. 5, disturbance occurs in the direction of the electric field between the concentric electrodes. On the other hand, when the concentric electrode connection film 12a is used, an electric field is also applied to the concentric electrode connection film 12a as shown in FIG. As a result, the distribution of the electric field applied to the liquid crystal is less disturbed, and the controllability of the liquid crystal is improved.

Next, an embodiment according to the present invention of a focusing mechanism in which concentric electrodes are arranged at unequal intervals will be described with reference to FIGS. 7 and 8 are partially enlarged sectional views of the respective embodiments, and FIG. 9 is a diagram showing an external appearance common to both embodiments.

In FIG. 7, a lower electrode 10c and an alignment film 14b are attached to a substrate 18b. Also,
The substrate 18a has a smooth layer 19 provided with an alignment film 14a.
And concentric electrodes 12 are attached. Liquid crystal layer 13
Is held by the substrates 18a and 18b. Other mechanisms are the same as those in the embodiment of FIG.

In the description of the embodiment, FIG. 5 explains that light is diffracted by the concentric electrodes. In this embodiment, this diffracted light is positively used. That is, in the embodiment of FIG. 5, the phase of the light transmitted through the concentric electrode 12 and the phase of the light not transmitted are aligned to suppress the diffraction, but here, the phase is not aligned as much as possible, and the diffraction is strong. The thickness of the concentric electrode 12, the refractive index of the liquid crystal, and the like are selected so as to cause the occurrence.
A Fresnel lens is an example in which a concentric diffraction grating has a lens function. Here, similarly, the interval between the concentric electrodes 12 is changed in the radial direction so that the function of the Fresnel lens is provided. According to this method, as shown in FIG. 9, a focusing mechanism with a short focal length can be realized with a simple configuration.

FIG. 8 is a view showing a modification in which the concentric electrode 12 has a triangular cross section. When the cross-sectional shape of the concentric electrode 12 is triangular, the intensity of the diffracted light of the used diffraction order can be increased. Therefore, light can be used more effectively.

Next, referring to FIG. 10, an embodiment of a focusing mechanism in which a slit is formed in a concentric electrode according to the present invention will be described. FIG. 10 is a plan view showing the structure of the distributed voltage application portion of the present embodiment. Other configurations are the same as those described in the above embodiment.

In the embodiment shown in FIG.
1 includes a lead electrode 10a and a lead electrode 10b.
The voltage is applied through. Also, the voltage drop resistance 1
An insulating film 16 is formed on 1, and a lead electrode 10 b is attached via the insulating film 16. A concentric electrode 12b is attached to the voltage drop resistor 11, and a slit 12k is formed in the concentric electrode 12b. When such a slit is provided, excitation noise generated in the concentric electrode 12b due to an external electromagnetic wave can be reduced, and the liquid crystal can be controlled with high accuracy.

Next, an embodiment of a focusing mechanism using a plurality of voltage drop resistors according to the present invention will be described with reference to FIG.
FIG. 11 is a plan view showing the structure of the distributed voltage application portion of the present embodiment. Other configurations are the same as those described in the above embodiment.

This is the same as that described above.

In the embodiment of FIG. 11, an AC voltage is supplied to the external electrode 10a and the extraction electrode 10b by the same circuit as that of FIG. The voltage distribution generated in the voltage drop resistor 11 is transmitted to the concentric electrode 12c. At this time, a plurality of voltage drop resistors 11 are used (two in the figure), and
Each voltage drop resistor 11 is provided with each concentric electrode 12c. In this way, the stray capacitance generated in the concentric electrode 12c is reduced, and the operation is performed at a higher speed.

Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a plan view showing the structure of the distributed voltage applying unit of the embodiment of the focusing mechanism according to the present invention using a plurality of voltage drop resistors having different resistance value distributions. Other configurations are the same as those described in the above embodiment. FIG. 13 is a diagram showing a method of controlling the concave lens effect and the convex lens effect of the embodiment of FIG.

In the embodiments shown in FIGS. 1 to 3, it has been described that when the width of the voltage drop resistor 11 is properly formed, the aberration of the focusing mechanism can be reduced. This aberration reduction effect is maximized at a predetermined focal length determined at the time of design. However, as the focal length deviates from its predetermined focal length, which minimizes aberrations, some aberrations begin to occur.

Therefore, a plurality of voltage drop resistors 11 are prepared,
The distribution of the width of the resistor is determined in advance so as to minimize the aberration at a predetermined focal length. When changing the focal length and adjusting the focus while switching the voltage drop resistance to be used, the aberration can always be minimized.

For example, as shown in FIG. 12, two voltage drop resistors are used. In this case, as shown in FIG. 13, the voltage drop resistor 11a is designed so that the liquid crystal layer has a convex lens function when a voltage is applied to the liquid crystal, and the aberration is minimized at this time. On the other hand, the voltage drop resistor 11b is designed so that the liquid crystal layer has a concave lens effect and the aberration is minimized. The voltage distribution generated in the voltage drop resistor 11a is the concentric electrode 12d.
The voltage distribution generated by the voltage drop resistor 11b is transmitted in the circumferential direction by the concentric electrodes 12e.

According to the present embodiment, it is possible to form a focusing mechanism with extremely little aberration over a wide range of focal length.

FIG. 14 is a diagram showing the detailed internal structure of the embodiment of the focusing mechanism in which the distributed voltage applying sections according to the present invention are provided above and below the liquid crystal and the connection to the power supply.

In FIG. 14, the liquid crystal layer 13 is sandwiched between voltage distribution applying sections each composed of two concentric electrodes 12, a voltage drop resistor 11, an extraction electrode 10b, and an extraction electrode 10a. Each voltage distribution applying unit is connected to the substrate 18
a, 18b. In addition, a power supply 20b that supplies power to each voltage distribution applying unit is provided. With this configuration, the distribution of the voltage applied to the liquid crystal layer can be independently controlled by the upper and lower voltage distribution applying units. If the shape of each voltage drop resistor 11 is appropriately determined, aberration can be further reduced as compared with the case where one voltage drop resistor 11 is used.

FIG. 15 is a diagram showing a detailed configuration of an embodiment of the focusing mechanism according to the present invention for adjusting the polarization dependence by controlling the orientation directions of a plurality of liquid crystal layers.

In FIG. 15, a distributed voltage applying section 40a is formed on a substrate 18a, and an alignment film 14a is provided thereon. The distributed voltage applying unit 40a includes the voltage drop resistance 11, the extraction electrode 10a, and the extraction electrode 1 as in the past.
0b, concentric electrodes 12. On the substrate 18b, a distributed voltage applying unit 40b similar to the distributed voltage applying unit 40a and the alignment film 14b are formed. On both surfaces of the substrate 18c, a back electrode 10c and an alignment film 14c are formed. There is a liquid crystal layer 13b between the substrates 18a and 18c, and there is a liquid crystal layer 13a between the substrates 18b and 18c. Although not shown here, in practice, as in the embodiment of FIG. 2, the leakage of the liquid crystal is prevented by the spacer 17 as necessary.

When the molecular orientation of the liquid crystal layers 13a and 13b is uniform in each film, the change in the refractive index of the liquid crystal layer is maximized, and the focusing range can be expanded. However, depending on whether the direction of the amplitude of the light passing through the liquid crystal layer is the direction of the molecular orientation or the direction perpendicular thereto, there is a difference in the change in the refractive index, and the focusing function has polarization dependence. Therefore, as in the present embodiment, if a plurality of liquid crystal layers are used and the alignment films are disposed so that the molecular alignment directions of the respective liquid crystal layers are perpendicular to each other, the focusing operation can be performed over a wide range. And the polarization dependency is eliminated.

Further, the direction of the molecular orientation of the liquid crystal is adjusted to the liquid crystal layer 13a.
And 13b, the focus can be adjusted over a wider range with respect to the polarization direction of the specific light.

FIG. 16 is a partially enlarged sectional view of an embodiment of the focusing mechanism according to the present invention in which the rotation directions of the liquid crystal molecules of the plurality of liquid crystal layers are reversed and the acceptance angle of the incident light beam is enlarged.

In FIG. 16, an alignment film 1 is provided on a substrate 18a.
4a are formed, and an alignment film 14b is formed on the substrate 18b. An alignment film 14c is formed on both surfaces of the substrate 18c. A liquid crystal layer 13b is provided between the substrates 18a and 18c.
There is a liquid crystal layer 13a between the substrates 18b and 18c. The structure for applying a distributed electric field to the liquid crystal, the method for holding the liquid crystal, and the like are the same as those described above.

Using the alignment films 14a, 14b and 14c,
The directions of molecular alignment of the liquid crystal layers 13a and 13b and the plane of rotation of the liquid crystal molecules are made to be on the same plane. However, the rotation direction of the liquid crystal molecules is reversed.

In this way, almost the same focusing function can be realized for the light 60, 60a, 60b, etc., incident on the liquid crystal molecules at various angles, and the light receiving angle of the focusing mechanism can be enlarged.

FIG. 17 is a view for explaining an embodiment of the focusing mechanism according to the present invention in which the liquid crystal layer is multi-layered.

In FIG. 17, liquid crystal layers 13a to 13d are formed between substrates using substrates 18a to 18e. On each of the substrates, a distribution voltage applying section for the liquid crystal as described above is formed, and an alignment film is formed.

As described above, when the liquid crystal film is multi-layered, the focal region can be expanded. The operation speed of the liquid crystal depends on the thickness of the liquid crystal layer, and the thinner the film, the faster the operation. Therefore, by increasing the number of liquid crystal layers while ensuring a necessary amount of focusing, and reducing the thickness of each liquid crystal layer, the focusing function can be speeded up.

In addition, for example, the liquid crystal layers 13a and 13b
Are arranged such that the molecular orientation directions are perpendicular to each other, as in the liquid crystal layers 13a and 13b in FIG.
The liquid crystal layers 3a and 13c have liquid crystal layers 13b and 13b in FIG.
And 13d, like the liquid crystal layers 13a and 13b in FIG.
The rotation plane of the liquid crystal is set in the opposite direction. As described above, by appropriately combining the relationship between the molecular orientations of the liquid crystal shown in FIG. 15 and the relationship between the molecular orientations of the liquid crystal shown in FIG.

FIG. 18 is a block diagram showing a system configuration of another embodiment in which the focusing mechanism of the present invention is applied to an optical disk device.

In FIG. 18, light emitted from a semiconductor laser 71 is converted into parallel light by a lens 72, passes through a beam splitter 74, is reflected by a rising mirror 75, passes through the focusing mechanism 1, and passes through an objective lens 76. To form a focal point on the optical disk 81 rotated by the motor 80. The reflected light from the optical disk 81 returns to the original path, is reflected by the beam splitter 74,
The light is condensed by the lens 73 and enters the photodetector 77. The signal from the photodetector 77 is amplified by a preamplifier 87.
The photodetector 77 is divided into several parts. The signal processing circuit 85 processes these signals to generate necessary read signals and servo signals. The read signal is output to the outside through the interface 84. The signal processing circuit 85 turns on and off the semiconductor laser 71 through the amplifier 86.
The control of the focusing mechanism 1, the control of the motor 80, and the movement of the housing 90 holding the optical system are controlled. A rail mechanism 83 is attached to the housing 90, and a rail 82 is provided.
Together with it constitutes a rectilinear moving mechanism. The housing 90 is propelled by a linear motor (not shown) or the like.

At the time of writing to the optical disk 81, based on external information obtained through the interface 84,
The signal processing circuit 85 causes the semiconductor laser 71 to blink.
Alternatively, although not shown, the magnetic flux density in the vicinity of the point of the optical disk 81 where the light is irradiated is changed by an electromagnet or the like.

With such a configuration, the mechanical movable portion can be eliminated from the focusing mechanism of the optical disk device, and the access can be sped up by downsizing the optical disk device, saving energy, and reducing the weight of the mechanical movable portion.

FIG. 19 is a block diagram showing a system configuration of another embodiment in which the present invention is applied to a video camera.

In FIG. 19, the light from the subject 135 passes through the lens 100 and the focusing mechanism 1, and then forms an image on the image sensor 105. Image sensor 10
The electric signal from 5 is sent to the signal processing circuit 110 and further sent to the head 115. A part of the tape 116 stored in the cassette 117 is in contact with the head 115, and a signal is recorded on the tape 116.

A part of the signal from the image sensor 105 is sent to the display device 106 via the signal processing circuit 110 to form an image. This image is observed by the photographer's naked eyes 99 via an appropriate finder lens 101.

The mechanism including the signal processing circuit is driven by the power supply 119. Further, the mechanism system is housed in the housing 130.

For example, when the subject 135 moves, the image on the image sensor 105 may be out of focus. In such a case, since a high-quality image cannot be recorded, a focusing mechanism is required.

The output from the image sensor 105 is taken into the signal processing circuit 110, and the focus state on the image sensor 105 is detected. The focus detection algorithm is
Although many methods are conceivable, for example, there is a method of performing frequency analysis of an output from the image sensor 105. This is a detection method in which the focus is good when the highest frequency component is output among the frequency components.

The focusing mechanism 1 based on the focus detection signal
To supply drive power to adjust the focus without mechanically moving parts. Alternatively, a separate distance detector 107 may be provided to supply driving power to the focusing mechanism 1 to adjust the focus without a mechanically movable part. A dial is provided on the housing 130 to supply driving power to the focusing mechanism 1 so that the photographer can manually adjust the focus as needed, and the focus is adjusted without a mechanically movable part.

According to this method, the focusing operation can be performed without a mechanical movable part, and the operation can be speeded up, the size of the apparatus can be reduced, and the power supply 119 can be simplified. Weight reduction and improved reliability are achieved.

Further, as an application of the focusing operation, it is conceivable to eliminate the mechanical movable part from the zoom operation. That is, the size of the image of the object 135 on the image sensor 105 is determined by the total focal length of the optical system such as the lens 100 and the focusing mechanism 1. When the focal length of the focusing mechanism 1 is changed, the size of the image can be changed, and the mechanical movable part can be eliminated from the zoom operation. However, in this case, it is necessary to provide another focusing mechanism or to provide a plurality of focusing mechanisms 1 to perform both the focusing operation and the zoom operation simultaneously. The zoom operation is mainly performed by the photographer operating a dial provided on the housing 130.

According to this method, the mechanical movable part can be eliminated from the zoom operation, the operation speed is increased, the size of the apparatus is reduced, and the power supply 119 is simplified.
Weight reduction and improved reliability are achieved.

FIG. 19 shows an example in which the focusing mechanism described with reference to FIGS. 1 to 17 is applied to a video camera. In addition to this, films and images of a photographic camera, video camera, TV camera, etc. The present invention can be applied to cameras, microscopes, telescopes, laser printer optical systems, and other optical devices that require focusing, in which sensors and the like are combined with lenses. It will be easily understood that when the present invention is applied to these devices, as in the case of the video camera, miniaturization, energy saving, weight reduction, and the like of the devices can be achieved.

Also, as a spectacle lens, FIGS.
When the focusing mechanism 1 described above is used, the degree of the eyeglass lens can be continuously changed. further,
A dial for adjusting the focus of the focusing mechanism 1 is attached to a frame of glasses together with a power supply and a drive circuit. According to this method, the user of the glasses can freely change the degree of the glasses. For this reason, the user of the glasses can adjust the so-called degree of the glasses to an optimal lens state when reading a work document or playing an outdoor sport, for example.

[0095]

According to the present invention, it is possible to obtain a focusing mechanism that has a simple and lightweight structure, can be reduced in size and weight, and can be operated at high speed and has no mechanical and mechanical moving parts.

When this focusing mechanism is applied to an optical disk device or other device having an optical system that requires focusing, the size of the entire device can be reduced, the operation speed can be increased, energy can be saved, and weight can be reduced. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an appearance of an embodiment of a focusing mechanism according to the present invention.

FIG. 2 is a diagram illustrating a detailed internal structure of the embodiment of FIG. 1;

FIG. 3 is a circuit diagram showing an electrical connection relationship of the embodiment of FIG.

FIG. 4 is a diagram showing characteristics of the embodiment of FIG. 1;

FIG. 5 is a diagram illustrating an embodiment of a focusing mechanism provided with a smoothing layer according to the present invention.

FIG. 6 is a diagram illustrating an embodiment of a focusing mechanism provided with a concentric electrode connection film according to the present invention for correcting disturbance of an electric field.

FIG. 7 is a diagram illustrating an embodiment of a focusing mechanism according to the present invention in which concentric electrodes are arranged at unequal intervals.

FIG. 8 is a view for explaining an embodiment of a focusing mechanism in which the cross section of the concentric electrode is triangular according to the present invention.

FIG. 9 is a diagram showing an appearance common to the embodiments of FIGS. 7 and 8;

FIG. 10 is a diagram illustrating an embodiment of a focusing mechanism in which a slit is formed in a concentric electrode according to the present invention.

FIG. 11 is a diagram illustrating an embodiment of a focusing mechanism using a plurality of voltage drop resistors according to the present invention.

FIG. 12 is a diagram illustrating an embodiment of a focusing mechanism according to the present invention using a plurality of voltage drop resistors having different resistance value distributions.

13 is a diagram illustrating a method for controlling the convex lens effect and the concave lens effect of the embodiment of FIG.

FIG. 14 is a diagram illustrating an embodiment of a focusing mechanism in which distributed voltage applying units according to the present invention are provided above and below liquid crystal.

FIG. 15 is a diagram illustrating an embodiment of a focusing mechanism according to the present invention for adjusting polarization dependence by controlling the orientation direction of a plurality of liquid crystal layers.

FIG. 16 is a diagram illustrating an embodiment of a focusing mechanism according to the present invention in which the rotation directions of liquid crystal molecules in a plurality of liquid crystal layers are reversed to increase the acceptance angle of an incident light beam.

FIG. 17 is a diagram for explaining an embodiment of a focusing mechanism according to the present invention in which a liquid crystal layer is multilayered.

FIG. 18 is a block diagram showing a system configuration of another embodiment in which the focusing mechanism of the present invention is applied to an optical disc device.

FIG. 19 is a block diagram showing a system configuration of another embodiment in which the focusing mechanism of the present invention is applied to a video camera.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Focusing mechanism 10a Leader electrode 10b Leader electrode 10c Lower electrode 11 Voltage drop resistor 11a Voltage drop resistor 11b Voltage drop resistor 12 Concentric electrode 12a Concentric electrode connection film 12b Concentric electrode 12c Concentric electrode 12d Concentric electrode 12e Concentric electrode 12k Slit 13 Liquid crystal layer 13a Liquid crystal layer 13b Liquid crystal layer 13c Liquid crystal layer 13d Liquid crystal layer 14a Alignment film 14b Alignment film 14c Alignment film 16 Insulation film 17 Spacer 18a Substrate 18b Substrate 18c Substrate 19 Smooth layer 20 Signal processing circuit 20b Power supply 30 AC source 31 Variable resistance 32 Variable resistance 33 power amplifier 40a distributed voltage applying unit 50 focal point 60 light 60a light 60b light 71 semiconductor laser 72 lens 73 lens 74 beam splitter 75 mirror 76 objective lens 77 photodetector 80 motor 81 Disk 82 rail 83 rail mechanism 84 interface 85 signal processing circuit 86 amplifier 87 preamplifier 90 housing 99 photographer's naked eye 100 lens 101 lens 105 image sensor 106 display device 107 distance detector 110 signal processing circuit 115 head 116 tape 117 cassette 119 power supply 130 housing 135 subject

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FIG11B 7/095 (72) Inventor Atsushi Ichikawa 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Hitachi, Ltd. Machinery Research Laboratory Hitachi, Ltd. (56) References Special 1986-140920 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/13 505 G02B 3/00 G02B 3/04

Claims (18)

(57) [Claims] 1. A focusing mechanism for changing a focal length or a focal position of an optical system, comprising: a liquid crystal layer; a transparent substrate sandwiching the liquid crystal layer; and a first transparent substrate provided from a center to a periphery. A voltage drop resistor, a plurality of concentric electrodes provided on the first transparent substrate and connected to the voltage drop resistor, an extraction electrode for applying a voltage to both ends of the voltage drop resistor, and a second transparent substrate. A focusing mechanism, comprising: a lower electrode for applying an electric field to the liquid crystal layer between the concentric electrode and a power supply for applying a voltage to the extraction electrode and the lower electrode. 2. The focusing mechanism according to claim 1, wherein a plurality of concentric electrodes are arranged at unequal intervals. 3. The focusing mechanism according to claim 2, wherein a cross section of the plurality of concentric electrodes is formed in a triangular shape. 4. The focusing mechanism according to claim 1, further comprising an electric resistance film connecting between the plurality of concentric electrodes. 5. The focusing mechanism according to claim 1, wherein an alignment film is provided between the lower electrode and the liquid crystal layer. 6. The focusing mechanism according to claim 5, further comprising a smoothing layer covering the alignment film. 7. The focusing mechanism according to claim 1, wherein a slit is formed in the plurality of concentric electrodes from a center to a periphery, and each concentric electrode is divided into a plurality of concentric electrodes. Focus mechanism. 8. The focusing mechanism according to claim 7, wherein a plurality of the voltage drop resistors are provided, and a plurality of slits corresponding to the number of the voltage drop resistors are formed in the concentric electrode from the center toward the periphery. Features a focusing mechanism. 9. The focusing mechanism according to claim 1, wherein a plurality of the voltage drop resistors are provided, and the concentric electrodes are separately connected to the respective resistors, and the number of the resistors and A focusing mechanism comprising the same number of concentric electrode groups, wherein the power supply comprises the same number of individual power supplies as the number of the resistors. 10. The focusing mechanism according to claim 1, wherein said liquid crystal layer comprises a plurality of liquid crystal layers arranged in an optical axis direction of said optical system. Focus mechanism. 11. The focusing mechanism according to claim 10, wherein said plurality of liquid crystal layers are arranged so that their alignment directions are at right angles to each other. 12. A focusing mechanism according to claim 10, wherein said plurality of liquid crystal layers are arranged so that their alignment directions are the same. 13. The focusing mechanism according to claim 10, wherein the plurality of liquid crystal layers have the same molecular alignment direction and the same plane of rotation, and the rotation direction of the liquid crystal molecules is reversed. Focus mechanism. 14. An optical information storage medium, comprising a semiconductor laser, a lens for condensing light emitted from the semiconductor laser on the optical information storage medium, and a photodetector for receiving reflected light from the optical information storage medium. An optical disk device, comprising: the focusing mechanism according to claim 1 as a part of the lens. 15. A camera having a lens and an image sensor or a film disposed at a focal position of the lens, wherein a part of the lens includes the focusing mechanism according to any one of claims 1 to 13. A camera characterized in that: 16. The camera according to claim 15, wherein a distance sensor for measuring a distance to a subject, and a focusing mechanism according to claim 1 driven by a signal from the distance sensor. And a driving circuit. 17. The camera according to claim 15, wherein a defocus detector that detects blur of an image on the image sensor or the film, and a signal from the defocus detector are provided.
4. A camera, comprising: a driving circuit that drives the focusing mechanism according to claim 3. 18. A pair of glasses having a lens and a lens holding frame for fixing the lens to a head, wherein a part of the lens includes the focusing mechanism according to claim 1. Description: Glasses.