JPH0616142B2 - Lens forming device - Google Patents

Description

The present invention relates to a lens element, and more particularly to a lens forming device capable of arbitrarily changing the focal length thereof.

In order to make the focus of a lens that has been used conventionally variable, it is necessary to change either the curvature, thickness, or refractive index of the lens, but in the conventional method, any change amount except for the mechanical zoom lens Is also small, and the focus variable range is small. When an electro-optical material or liquid crystal is used, the use is limited because it depends on the polarization of light. Further, as a gradient index lens, for example, there is a self-occ lens, but in order to change the focal length of this type of lens, several combinations are required, and a mechanism for changing the mutual interval between them,
It has a drawback that the holding mechanism becomes complicated.

On the other hand, the applicant of the present application, in Japanese Patent Application No. 58-67026, makes the refractive index distribution variable by controlling the amount of heat given to the medium by generating a refractive index distribution in the medium by heat. An element that changes the focal length according to the distribution has been disclosed. In particular, the effect of this element is not only that it can provide a device having a lens effect corresponding to a size of several tens of μm, which has been impossible in the past, and that the focal length is further changed. Therefore, for example, it becomes possible to achieve focus control in a minute area or a variable focal length device as a plurality of minute lens arrays.

The shape of the refractive index distribution formed in the medium of the element is such that the refractive index changes with respect to the amount of heat of the medium, that is, the value of the refractive index becomes larger when the medium is heated. Or smaller. When the value of the refractive index of the medium decreases as the temperature rises, the shape of the refractive index distribution is mountain-shaped (convex) centered on the position where heat is applied to the medium.
It becomes the shape of. On the other hand, when the value of the refractive index of the medium increases as the temperature rises, the shape of the refractive index distribution has a valley shape (concave shape) around the position where heat is applied to the medium. Therefore, the light beam incident on such a mountain-shaped refractive index distribution becomes a divergent light beam after exiting from the refractive index distribution, and such a mountain-shaped refractive index distribution acts as a concave lens. Further, the light flux incident on the valley-shaped refractive index distribution becomes a convergent light flux after exiting from the refractive index distribution, and such a valley-shaped refractive index distribution acts as a convex lens.

As described above, whether the element functions as a convex lens or a concave lens is uniquely determined by the characteristics of the medium. Therefore, the change in the refractive index is large with respect to the temperature change,
Since most of the media suitable for the above-mentioned element are media whose refractive index decreases with increasing temperature (hereinafter referred to as a medium having a negative refractive index temperature coefficient), the function of a concave lens as a lens I had no choice.

An object of the present invention is to improve the above-mentioned drawbacks and to provide a lens forming apparatus capable of obtaining a positive lens or a negative lens without depending on the temperature coefficient of the refractive index of the medium.

In the lens forming apparatus according to the present invention, the means for simultaneously forming a plurality of refractive index distributions at a plurality of positions in the medium whose refractive index changes due to temperature change has a positive index when forming a plurality of refractive index distributions. If the medium has a temperature coefficient of refraction index of, the light flux that has passed through the medium is formed with a place where it can be subjected to divergence action, or if the medium has a temperature coefficient of negative refraction index, the medium is changed. It is set so as to form a portion in the medium where the passing light flux can be subjected to a converging action. Efficiently extracting the light flux that has been affected by the lens by providing a lighting unit that selects only this location and passes the light flux, or a means that extracts only the light flux that has passed through this location and blocks the other light flux. To do.

Further, also in the lens forming method and apparatus according to the present invention, the power of the lens obtained by the element can be changed by controlling the amount of heat applied to the medium and changing the shape of the refractive index distribution. Is.

As the heat effect medium used in the lens forming device according to the present invention, liquids having a negative temperature coefficient of refractive index such as ethyl alcohol, benzene, ethyl ether, methylene iodide, water, and carbon tetrachloride eto can be used. is there.

In the description of the present invention described in detail below with reference to the drawings, a medium having a negative temperature coefficient of refractive index will be described as an example of the medium, but the present invention also applies to a medium having a positive temperature coefficient of refractive index. It goes without saying that it is applicable.

First, the applicant will describe the principle of the variable focus effect using the element disclosed in Japanese Patent Application No. 58-67026.

1 (A) and (B) are diagrams showing the principle of the element, and FIG. 1 (A)
Is a side view thereof, and FIG. 1 (B) is a plan view of the same. First
1A and 1B, an element is a transparent protective plate 1, a thermal effect medium 2 having a negative temperature coefficient of a refractive index that forms a refractive index distribution by heat, an insulating layer 3, a heating resistor 4, an electrode 5 , A transparent substrate 6. Due to the heat generated when a voltage is applied to the heating resistor 4, a refractive index distribution 10 having a mountain-shaped (convex) uniform refractive index distribution around the heating position is formed in the heat effect medium 2. To be done. When the light beam 7 is incident on this portion, the wavefront is converted and the light beam 9 is emitted as if diverging from the point 8.
The distance from the boundary surface of the heat effect medium to the divergence origin (or the convergence point) 8 is f, and this is defined as the focal length.

FIG. 2 is a diagram for explaining the input voltage applying means for the variable focal length element described in FIG. 1, one of the heating resistors 4 is connected via the electrode 5 to the voltage applying means 11, and the other is grounded. It is held at a constant potential. When a voltage is applied to the heating resistor 4 by the voltage applying means as shown in FIG. 2, a current flows in the heating resistor 4 and the refractive index distribution is formed in the thermal effect medium as described above. In this case, the heat generation amount is changed by changing the applied voltage or the pulse application time of the periodic pulse voltage. As a result of the change in the amount of heat generation, the refractive index distribution also changes in the thermal effect medium. Therefore, the focal length f shown in FIG. 1 becomes variable.

1 and 2 show an example of a transmission type variable focal length element, while FIG. 3 shows an example of an element capable of widening the range of change of the focal length, 1 is a transparent protective plate such as glass, Two
Is a heat-effect medium such as ethyl alcohol, 3 is an insulating layer such as SiO ₂ , 4 is a heating resistor such as HfB ₂ , 5 is an electrode, and 6 is an insulating substrate. Reference numeral 13 is a light reflecting layer such as Al formed on the insulating layer of SiO ₂ . When a parallel light flux 15 is incident on this element, the wavefront is converted by the refractive index distribution 10 and reflected by the light reflection layer 13, and then the refractive index distribution 10
Thus, the wavefront is converted, and the light beam 16 is emitted as if diverging from the divergence origin 14. When the size of the heating resistor is 50 μm × 50 μm and the resistance value is 67Ω and a DC voltage of about 2.5 V is applied, a concave lens effect of f≈−0.6 mm and NA≈0.16 was observed. Lower the voltage below 2.5V,
It was also observed that when the power consumption of the heater was reduced, the focal length became longer as shown in FIG. In FIG. 4, the vertical axis represents the focal length and the horizontal axis represents the power consumption of the heater. In the above example, ethyl alcohol was used as the heat effect medium, but the same effect could be confirmed by using a liquid such as water or isopropyl alcohol instead.

FIG. 5 is a view for explaining an embodiment of the present invention, and FIG. 5 is a sectional view showing the constitution of the element. The structure of the figure is basically the same as that of the element shown in FIG. 3, and the same members as those of FIG. Third
The difference from the figure is that the heating resistors (4a, 4b) are
b) Two light beams that are symmetric with respect to the incident light beam 18 that is incident perpendicularly to the plane are arranged at intervals, and an aperture plate 17 for limiting the light beam incident range is provided on the element surface. It is provided. In this element, the heating resistors 4a and 4b are caused to generate heat at the same time to generate the refractive index distributions 10a and 10b which are equal to each other inside the medium 2. At this time, by appropriately controlling the distance between the heating resistors 4a and 4b, the amount of heat generation, and the size of the opening 17, as shown in the figure, the periphery of the light flux through which the refractive index change passes through a part of the medium. It is possible to create a state in which the portion is larger, that is, the peripheral portion has a lower refractive index. In such a state, the refractive index distribution acts as a convex lens on the incident light flux, so that the light flux incident in a parallel state as shown in the figure reciprocates inside the medium 2 and then converges at one point 19. That is, the aperture plate 17 receives the incident light beam 18
Are arranged so that they are incident only on the lower half of the refractive index distribution 10a and the upper half of the refractive index distribution 10b.The light flux that is refracted by the lower half of the refractive index distribution 10a and the upper half of the refractive index distribution 10b The light beam that undergoes the refraction action converges on one point 19. Therefore, one lens is formed by the two refractive index distributions (10a, 10b).

The heating resistors 4a and 4b are both 40 μm wide and 400 μm long,
When a stripe shape having a resistance value of about 127 Ω was set, and a space between the heating resistors was set to 180 μm and a voltage of about 12 V was applied, a cylindrical convex lens effect of f≈2.5 mm and NA≈0036 was confirmed. If you lower the voltage below 12V,
As shown in FIG. 6, it was observed that the focal length became longer as the power consumption of the heater decreased. The thermal effect medium used in the above example is ethyl alcohol.

7 and 8 are views for explaining the second embodiment of the present invention. FIG. 7 is a plan view of the device and FIG. 8 is a sectional view taken along the line AA of FIG. Since the basic structure of the element shown in the figure is the same as that of the embodiment shown in FIG. 5, the description of the members having the same part numbers is omitted. Unlike the first embodiment, the present embodiment is a light transmission type element. In this element, the electrode 5 and the heating resistors (20a, 20b ...) Are formed of a member which is opaque to the incident light flux, and also serve as an opening for limiting the incident range of the light flux. The heating resistors (20a, 20b ...) Have a ring shape, and the inside thereof transmits an incident light beam. Further, the heating resistors (20a, 20b ...) Are arranged in series by the electrode 5 and simultaneously generate heat when energized. With such a configuration, the present element can generate and eliminate a convex lens action inside the heating resistor depending on the presence or absence of energization, and can also have a function as a minute lens array. In addition, the focal length can be arbitrarily changed by controlling the amount of heat generated by the low fever antibody.

FIG. 9 is a diagram for explaining an example in which the element shown in FIGS. 7 and 8 is applied to a reading optical system. This device has a structure in which two sets of the devices shown in FIG. 8 are opposed to each other with a diaphragm 21 interposed therebetween. Heating resistors (20a, 20b ...) and (20a ', 20b'
...) are simultaneously energized to generate heat by a predetermined amount, the refractive index distribution generated in the medium 2 causes a convex lens action, and an object existing on the object surface 22 is converted into an image surface by the pair of opposed convex lenses. An erecting equal-magnification image is formed at 23. The diaphragm 21 is a field diaphragm that blocks stray light other than a predetermined field of view. Such an element can be easily thinned, reduced in size and weight, which is advantageous as a reading optical system for copying machines, facsimiles, and the like, and can be applied in various ways by taking advantage of the fact that a lens function is generated by energizing only when necessary. .

10 and 11 are views for explaining an embodiment in which the device according to the present invention is used for an optical shutter, FIG. 10 is a plan view of an element, and FIG. 11 is a cross section taken along the line BB of FIG. The cross-sectional view in FIG. In the device shown in the figure, low fever antibody
The electrodes (24a, 24b ...) Are configured to be capable of independently heating and energizing via the electrodes (25a, 25b ...). Reference numeral 26 represents a common electrode. (27a, 27b ...) are optical stoppers formed on the rear part of the base 6. Now assume that the light flux enters from the left side of FIG. 11, and the heating resistors 24a and 24c generate heat as shown in the figure.
24b is not heating up. In such a state,
The incident light beams 30 and 32 are focused on the optical stoppers 27a and 27c, respectively, by the convex lens action generated in the medium 2, and are not emitted rearward. On the other hand, the incident light flux 31 goes straight as it is without being affected by the convex lens, passes through the periphery of the optical stopper 27b, and is emitted to the rear of the element. Therefore, the element of this embodiment has a function as a light shutter or a light valve that blocks or passes light depending on whether or not the heating resistor is energized. A further advantage of the present embodiment is that not only the light is turned on and off, but also the amount of transmitted light can be continuously changed. As described above, the element of the present invention has a condensing function as a convex lens, and its focal length is variable, so that the heat generation amount of the heat generating resistor is controlled so that the convergence position of the light flux is set to the front and rear of the optical stopper. By changing the amount, the amount of light emitted rearward from the periphery of the optical stopper can be changed. Contrary to FIG. 11, if the portions corresponding to the optical stopper portions (27a, 27b, 27c) are made to be openings and the other portions are made to be light-shielding portions, the amount of transmitted light at the opening portions corresponding to the conducting portions of the heating resistor is It is also possible to increase the number of modulations, which has a relationship of negative and positive inversion with FIG. Also in this case, the amount of emitted light can be continuously changed by controlling the amount of heat generation, as in the embodiment shown in FIG. Since the conventionally proposed lens action by heat has only the action of a concave lens, it was necessary to combine it with another convex lens in order to efficiently perform the above-mentioned light modulation, but in the present embodiment, Since the element itself has a function of a convex lens, another lens is unnecessary, and a thin, lightweight, low-cost optical modulator can be achieved.

FIG. 12 is a schematic diagram for explaining an example in which the element of the embodiment shown in FIGS. 10 and 11 is applied to a printer. 4 in the figure
0 is a light source such as a halogen lamp, 41 is the 10th and 11th
The light modulation element array 42 according to the present invention described in the drawing represents an electrophotographic photosensitive member. Each heating resistor (not shown) in the optical modulation element array 41 can independently apply voltages Va, Vb ... In response to a signal input by a signal input means (not shown). Light can be transmitted or blocked only in the portion corresponding to each heating resistor, and an electrostatic latent image is formed on the photoconductor 42 accordingly.

A visible image can be printed by a known electrophotographic process (not shown). By using the element of the present invention in such a printer, the element and further the light source can be integrated to achieve size reduction and weight reduction.

FIG. 13 is a diagram for explaining an example in which the element of the present invention is applied to a reading optical system such as a copying machine or a facsimile machine. In the figure, 43 is the subject to be read, and 44 is FIGS.
The optical modulator array of the embodiment described with reference to FIG. 1, 45 denotes an optical fiber tube whose one end is expanded in the array direction of the optical modulator array 44, and 46 denotes an optical sensor. Voltages V _a , V _b , V _c, ... Are sequentially applied to individual heating resistors (not shown) in the optical modulator array 44 by the voltage applying means, and only the corresponding portions of the heating resistors are applied by the applied voltage. Transmits light. The transmitted light is converted into an electric signal by the optical sensor 46 through the optical fiber tube 45, and is transmitted to a memory, a signal transmission mechanism or the like (not shown) according to the application. As in the example of FIG. 12, by using the element of the present invention, it is possible to achieve a reduction in size and weight of the reading optical system.

As described above, by using the present invention, it is possible to obtain a convex lens and a concave lens with one heat effect medium, and thus it is possible to obtain a positive lens and a negative lens with an optimum heat effect medium. Further, when such a lens device is widely applied as a reading device, a writing device, and a shutter array device, it greatly contributes to making the device thinner, smaller and lighter.

[Brief description of drawings]

1 (A), (B), FIG. 2, FIG. 3 and FIG. 4 are diagrams for explaining the principle of the optical element used in the present invention, and FIGS. 5 and 6 are the present invention. FIG. 7 is a view showing an embodiment of the lens forming apparatus according to the present invention, FIGS. 7 and 8 are views showing another embodiment of the lens forming apparatus according to the present invention, and FIG. 9 is a reading application of the present invention. FIG. 10 is a diagram showing an embodiment of an apparatus, FIG. 10 and FIG. 11 are diagrams showing an embodiment of an optical shutter array to which the present invention is applied, and FIG. 12 is an embodiment of an optical printer to which the present invention is applied. FIG. 13 is a diagram showing another embodiment of the reading device to which the present invention is applied. 1 ... Transparent protective plate 2 ... Thermal effect medium 3 ... Insulating layer 4a, 4b ... Heating resistor 5 ... Electrode 6 ... Transparent substrate 10a, 10b ... Refractive index distribution 13 ... Light reflection layer 17 ... … Aperture plate 18 …… Incident light flux 19 …… Focus point

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Ken Baba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Atsushi Someya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Masayuki Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP 59-191001 (JP, A) JP 59-154427 (JP) , A) JP-A-59-181324 (JP, A)

Claims (1)

[Claims] 1. A liquid medium whose refractive index changes depending on temperature, an insulating layer, and an intermediate region which simultaneously generates refractive index distributions at a plurality of locations of the liquid medium and straddles a plurality of refractive index distributions. And a plurality of heating resistors for heating a plurality of portions of the liquid medium via the insulating layer so as to form a lens on the lens forming apparatus.