JP2000244018A - Optical functional unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical functional unit in which a plurality of optical elements can be arranged integrally in a compact state by taking the structural advantage of a reflection-type LED for efficiently utilizing the space produced when a reflecting mirror is utilized as the optical system of the LED for, for example, the miniaturization of a camera. SOLUTION: A lens 1 on which such a thin film is formed that reflects light (for example, visible light) having a first wavelength and transmits light (for example, infrared light) having a second wavelength which is different from the first wavelength is provided in an optical system. A first optical functional element 11 is arranged at focal point or its vicinity of the reflecting surface of the thin film reflecting the light having the first wavelength in the lens 1 and a second optical functional element 12 is arranged at the focal point of the lens 1 or its vicinity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical system applied to an optical function element incorporated in an optical apparatus.

[0002]

2. Description of the Related Art Recent technologies relating to light emitting diodes (hereinafter abbreviated as LEDs) include, for example, Japanese Patent Application Laid-Open No. 9-298.
No. 315, the LED of this example is disclosed.
Has a long life and good optical characteristics without deterioration such as yellowing of the radiation surface.

[0003] Also, LED utilization technology, for example, LE
As an application of D, there is a non-uniform high-brightness reflective LED as taught in JP-A-9-36433, which can also be used as a light source for color adjustment that requires a color image. . Such a technique is an example of a basic technique showing the structure of a reflection type LED, and as an optical system of the LED,
This is a reflection-type LED using a parabolic reflector formed of resin without using a resin lens conventionally used. By using the reflecting mirror in this way, the light extraction efficiency can be improved as compared with the conventional case, and the dimension in the optical axis direction can be shorter than that of the conventional resin lens.

[0004]

As described above, by forming the condensing optical system of the LED with a reflecting mirror, it is possible to improve the efficiency and make the optical system thinner. Thus, the recent reflection type LED has succeeded in making the optical system thinner than the one using the conventional resin lens.

[0005] However, there is no description of a method of effectively utilizing the space created by reducing the thickness of the LED. In addition, in order to make a camera as an optical device smaller, for example, an optical functional element (that is, a photometric sensor, an active A
F elements or remote control receiving elements) are required to be efficiently incorporated into the limited space. However, this necessity has led to the thin LED, which is one of the optical functional elements described above.
It is conceivable to make effective use of this at this time.

Accordingly, an object of the present invention is to utilize the space created by using a reflector as an optical system of an LED efficiently, for example, to reduce the size of a camera. It is an object of the present invention to provide an optical function unit in which a plurality of optical elements can be compactly and integrally arranged while making the best use of them.

[0007]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention takes the following measures. That is, according to the present invention, an optical system having a lens formed with a thin film that reflects light of a first wavelength and transmits a second wavelength different from the first wavelength, A first optical functional element disposed at or near the focal position of the reflecting surface of the thin film that reflects light of the first wavelength, and a second light disposed at or near the focal position of this lens An optical function unit having a functional element is proposed.

An optical function unit is proposed in which one of the first and second wavelengths is infrared light and the other is visible light. Also, the present invention proposes an optical function unit, wherein the first and second optical function elements are arranged on or near the same optical axis.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention will be described below in detail with reference to embodiments. (First Embodiment) FIGS. 1A and 1B show one optical system of the optical function unit of the present invention, and FIG. 1A shows the optical system of this unit in a front view. FIG. 1B shows this optical system in a side view. In a finder unit 10 as an optical function unit, a first element 11 and a second element 12 are arranged apart from each other on an optical axis. One of the first elements 11 is fixedly inserted into the lens 1 together with the lead frame 7b facing the slit slightly apart while maintaining the connection relationship with the lead frame 7a. One surface (1a) of the lens 1 is flat, and the other surface (1b) is a plano-convex lens formed in a convex shape. The convex lens surface 1b is coated with a special thin film so as to function as a reflection surface.

[0010] More specifically, the lens 1 is made of a transparent material such as an epoxy resin to be substantially transparent. In the case of this example, the refractive index of the resin is about 1.55. The lens 1 has an outer diameter of, for example, 10 (mm), a thickness of, for example, 6 (mm), and a plano-convex lens in which the lens surface 1b is formed into a spherical surface with a radius of, for example, 10 (mm). The thin film coated on the lens surface 1b is a film that reflects light of a specific wavelength and has a property of transmitting a specific light. This is done with a coating technique based on:

The focal point of the lens surface 1b and the reflecting mirror (mirror) formed by the thin film is the lens surface 1b in the paraxial region.
It exists at a position of, for example, 4 (mm) from the vertex of b. The first element 11 is arranged at this position. The first element 11 is held in the resin by the lead frames 7a and 7b and is electrically connected. The focal point of the lens 1 is, for example, at a position of 18 (mm) from the vertex of the lens surface 1b in the paraxial region. Therefore, the second element 12 is disposed at a position on the optical axis at a distance of 18 (mm) from this vertex.

That is, on one surface of the lens 1, a so-called "wavelength selection mirror" for selectively reflecting light of a predetermined wavelength component from light of a plurality of wavelength components is formed as a thin film, and a light having a first wavelength is formed. A first element 11 that functions with a light component (for example, visible light) is disposed on the focal plane of the mirror, and a second element 12 that functions with a light component of a second wavelength (for example, infrared light) is focused on Placed on the surface.

With this arrangement, the light component emitted from the first element 11 is reflected by the curved mirror on which the thin film is formed, becomes parallel rays along the optical axis, and travels toward the subject. You can see that.

The thin film shown in this embodiment is shown in FIG.
(A) and (b) function as so-called "hot mirrors" and "cold mirrors" having the characteristics shown in the graphs, respectively. A hot mirror is a mirror surface with a thin film formed on the lens surface to transmit visible light and reflects infrared light. A cold mirror is a thin film on the lens surface that reflects visible light and transmits infrared light. This is a mirror surface formed with. The wavelength range of the transmitted light and the wavelength range of the reflected light can be appropriately adjusted depending on how the thin films forming the mirror are stacked.

Assuming that a thin film as a hot mirror having the characteristics shown in FIG. 2A is coated on the convex surface of the lens 1, in this case, an LED that emits infrared light can be disposed as the first element 11. . For example, in an active automatic focusing (AF) used for a camera,
An LED that emits such infrared rays is required. On the other hand, as the second element 12, for example, a silicon photodiode (hereinafter abbreviated as SPD) can be arranged. As described above, in a camera, such an element called SPD is required to measure the luminance of a subject.

As in this example, one optical system of the finder unit 10 for a camera can be formed by the combination of the infrared light emitting diode (LED) as the first element 11 and the SPD as the second element 12. I understand.

As the elements that can be used as the first element 11 and the second element 12, various elements other than the infrared light emitting diode and the SPD can be applied. Accordingly, in Table 1 shown in FIG. 5, available elements and combinations thereof are listed and illustrated. That is, what can be used as the first element 11 may be any electronic element used for infrared light. Also, what can be used as the second element 12 is
Any electronic device that acts on visible light can be used. According to Table 1 specifically, the first optical functional element (11) and the second optical functional element (12) are, for example, one of them having an active AF (automatic focus adjustment) infrared light emitting diode and a remote control. For example, a silicon photodiode for measuring subject brightness, an LED for reducing red-eye, a bulb for reducing red-eye, a CdS for measuring subject brightness, a line sensor for measuring subject distance, or a passive AF Any combination of the auxiliary light LED and the xenon (Xe) tube for a strobe can be used as a unit that functions effectively.

As described above, the combination of the first element 11 and the second element 12 exemplified in FIG. 5 (Table 1) is obtained when the thin film having the graph characteristic shown in FIG. What is available. In addition, when a thin film as a cold mirror having the graph characteristic of FIG. 2B is coated, the combination of the first element 11 and the second element 12 in Table 1 can be used as it is. You can see that.

FIG. 3 shows an example in which an optical system having a finder unit 10 as an optical function unit is incorporated in a camera. In this example, the finder unit 1
Reference numeral 0 designates a lens 1, a lens 2, and a lens 5 arranged on the front surface. The lens 1 is arranged on the strobe lens 30 as shown in FIG.

The finder unit 10 has a function of measuring the brightness of the subject (brightness measuring function) and a function of measuring the distance to the subject (distance measurement) in addition to the function as a finder optical system for observing the subject. Function). That is, as shown in FIG. 1, for example, when a light beam (infrared light) emitted toward a subject via the lens 1 is reflected by the subject, the light is reflected by a sensor inside the lens 5 via the lens 5. The light is detected, and the distance to the subject can be calculated based on the calculation method of the related art. Further, the reflected light having a predetermined wavelength related to the luminance passes straight through the thin film of the lens 1 and can be detected by the second element 12, so that the luminance of the subject can be measured.

More specifically, the combination of the elements in the finder unit 10 and the function thereof will be described.
FIG. 4 is a sectional view of the finder unit 10 taken along the line AA. The lenses 1 arranged on the optical axis 1z are characteristic optical system elements exemplified in FIGS. 1A and 1B. In this example, the first element 11 emits infrared light. LED is adopted. The infrared light of this LED is reflected on the reflection surface of the lens 1 and is irradiated on the subject. After being reflected by the subject, the infrared light forms an image on the third element 13 through the lens 5. The third element 13 functions as a position detection sensor (hereinafter abbreviated as PSD). Therefore, by detecting the image formation position of the infrared light from the object on the PSD, the distance to the object (object distance) can be calculated based on the image formation position and the base line length of the lens 1 and the lens 5. It can be seen that the configuration is as follows.

That is, the lenses 5 arranged on the optical axis 3z
Is provided at a predetermined distance (base line length) from the optical axis 1z, and the third
It is designed to detect incident light by the element 13. On the other hand, the second element 12 is an SPD, and is configured to measure the brightness of the subject based on the output. The lenses 2, 3, and 4 arranged on the optical axis 2z
Is an optical system forming a finder optical system arranged at the center of the camera, and is used exclusively for observing a subject.

(Operation and Effect 1) In order to effectively utilize the space generated by using the reflection type LED, the reflection type LE is used.
The reflecting mirror, which is the optical system of D, has a "frequency selection function". That is, the coating of the reflecting mirror acts as a reflective film with respect to the emission wavelength of the LED, while forming a light component other than the emission wavelength so as to be transmitted. The light component having a wavelength different from that of the LED acts as a “refractive type” optical system.

By making the reflection film forming the reflection mirror of the reflection type LED transmit at a wavelength other than the required wavelength, one optical system can be used as a reflection optical system and a refraction optical system. As a result, two types of optical functional elements can be arranged compactly. As described above, by utilizing the structural advantage of such a reflection type LED using a reflection mirror as the optical system of the LED, an empty space is generated as compared with the related art and the unit can be downsized. . Therefore, by arranging a plurality of optical elements integrally as illustrated, for example, a small optical function unit for realizing a compact camera body can be provided.

(Modification 1) The above-described first embodiment may be modified as follows, and equivalent or more effects can be expected. For example, the positions of the first and second elements need not necessarily be the focal positions of the optical system. Further, for example, when an infrared LED is disposed at the focal position as the first element 11, the infrared light emitted by the infrared LED becomes a parallel ray along the optical axis and is irradiated. However, at a specific distance, if it is desired to collect the infrared light of the LED, it is necessary to arrange the LED at a position slightly shifted from the focal position. That is, the element to be adopted may be disposed at an appropriate position near the focal position of the optical system according to the method of use.

The optical system illustrated in FIGS. 1 (a) and 1 (b)
One surface of the plano-convex lens is coated with a thin film, and this optical system is the most basic of the present invention. However, a desired performance may not be obtained with such an optical system. For example, since the lens surface 1b is spherical, "spherical aberration" occurs at the focal point of the reflecting mirror. If the desired optical characteristics cannot be obtained due to the spherical aberration, the manufacturing method becomes difficult, but the shape of the lens surface 1b may be parabolic.

Also, spherical aberration occurs on the focal plane of the lens 1. In order to reduce this spherical aberration, the lens 1 and the second
A desired lens element may be inserted between the elements 12.
The lens surface 1a is a flat surface, but may be formed into any appropriate curved surface in order to reduce spherical aberration. Regarding aberrations other than the above-mentioned spherical aberration, the degree of the aberration may be corrected by making some modifications to the optical system as needed.

The optical system shown in FIGS. 1A and 1B can be used for equipment other than a camera. This is useful in a small device using a plurality of optical elements operating at different wavelengths.

(Modification 2) Further modifications may be made as follows, and an effect equivalent to that of the first embodiment can be expected.
For example, the thin films shown in the graphs of FIGS.
Although the filter has a high-pass characteristic and a low-pass characteristic having a cutoff point near a wavelength of 700 (nm), a thin film having band-pass characteristics may be used depending on the characteristics of the element.

(Modification 3) In FIGS. 1 (a) and 1 (b), the first and second elements are arranged on the optical axis of the optical system. May be arranged at different positions. For example, they may be arranged as shown in FIG. In recent years, in auto focus, a distance measurement operation is often performed at a plurality of points on a shooting screen. In this case, an infrared LED is used.
Are required. In the example shown in FIG.
Three infrared LEDs 1a, 11b and 11c are arranged assuming three distance measuring points. Specifically, element 1
1b corresponds to the distance measuring point at the center, and element 1
Reference numerals 1a and 11c are arranged outside the optical axis on both sides in accordance with each distance measuring point. Also, lead frames 7a, 7b, 7
c is added to power each element 11a, 11b, 11c. In this example, the second element 1
2 is one, but when it is necessary to measure the luminance at a plurality of points on the photographing screen, similar elements may be arranged outside the optical axis. As a result, an effect equal to or greater than that of the first embodiment can be expected.

(Other Modifications) In addition, various modifications can be made without departing from the gist of the present invention.

Although the embodiments have been described above, the present invention includes the following inventions. For example, (1) having a lens made of a transparent resin having a thin film formed so that light of a first wavelength is reflected and light of a second wavelength different from the first wavelength is transmitted. A light comprising: an optical system; and a second optical functional element provided outside the lens and functioning with light of the second wavelength disposed at or near a focal position of the lens. Functional units can be provided.

(2) The optical function unit according to (1), wherein the thin film has a characteristic of reflecting infrared light and transmitting visible light. (3) The optical function unit according to (1), wherein the thin film has a property of reflecting visible light and transmitting infrared light. (4) The optical function unit according to any one of (1) to (3), wherein the first optical function element and the second optical function element are arranged on the same optical axis. Can be provided.

(5) One of the first optical function element and the second optical function element is either an infrared light emitting diode for active AF (that is, automatic focusing) or an infrared light receiving diode for remote control, and the other. Is, for example, a silicon photodiode for measuring the luminance of a subject, and
ED, red-eye reduction bulb, CdS for measuring subject brightness, line sensor for measuring subject distance, auxiliary light L for passive AF
The optical function unit according to any one of (1) to (4), which is one of an ED and a xenon (Xe) tube for a strobe, can be provided.

(6) The optical function unit according to (1) to (5), wherein the lens is a plano-convex lens. (7) The optical function unit according to (6), wherein the thin film is formed on the spherical surface side of the plano-convex lens. (8) The light of the second wavelength is visible light when the light of the first wavelength is infrared light, or the light of the second wavelength is light when the light of the first wavelength is visible light. The optical function unit according to (1), wherein the light having the second wavelength is infrared light.

(9) A light projecting lens that transmits and projects light of a plurality of wavelength components, and is formed on one surface of the light projecting lens, and selectively emits light of a predetermined wavelength component from the light of the plurality of wavelength components. A first element functioning at a first wavelength, and a second element functioning at a second wavelength, wherein the first element is disposed on a focal plane of the wavelength selection mirror. In addition, an optical function unit can be provided, wherein the second element is arranged on a focal plane of the light projecting lens.

(10) The optical function unit according to (9), wherein the first element functions as a light receiving function element and the second element functions as a light emitting function element. (11) The optical function unit according to (9), wherein the first element functions as a light emitting function element, and the second element functions as a light receiving function element.

(12) Including a lens made of a transparent resin, one surface of the lens reflects light of the first wavelength,
An optical system having a thin film formed thereon for transmitting light of a second wavelength, a first optical functional element disposed at or near a focal position of a reflection surface formed by the thin film in the lens, and the lens And a second optical functional element disposed at or near the outer focal position.

(13) The optical function unit according to (12), wherein the thin film reflects infrared light and transmits visible light, or transmits infrared light and reflects visible light. Can be provided. (14) The optical functional unit according to (12), wherein the thin film is disposed on the same optical axis between the first optical functional element and the second optical functional element. .

[0040]

As described above, according to the present invention, the space generated by using a reflecting mirror as the optical system of the LED can be efficiently used for miniaturizing the optical equipment. It is possible to provide an optical function unit in which a plurality of optical elements can be arranged compactly and integrally while taking advantage of the above advantages.

[Brief description of the drawings]

1 (a) and 1 (b) show an optical system of an optical function unit according to the present invention. FIG. 1 (a) is a front view of the optical system, and FIG. 1 (b) is an optical system. Side view.

2 (a) and 2 (b) show characteristics of a thin film of the present invention, FIG. 2 (a) is a characteristic graph of a thin film as a hot mirror, and FIG. 2 (b) is a graph of a thin film as a cold mirror; Characteristic graph of the thin film.

FIG. 3 is a perspective view of a camera incorporating the optical function unit having the optical system of FIG. 1;

FIG. 4 is a cross-sectional view of the entire optical system of the optical function unit in FIG. 3;

FIG. 5 is a list showing an application example of a first element and a second element according to the present invention.

FIG. 6 is a perspective view showing a modified example of the optical function unit according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... lens, 1a ... lens surface, 1b ... lens surface (reflection surface), 2 ... lens (finder optical system), 3 ... lens (finder optical system), 4 ... lens (finder optical system), 5 ... lens, 7a .. Lead frame a, 7b Lead frame b, 10 Finder unit, 11 first element, 12 second element, 13 third element, 20 photographing lens barrel, 30 strobe lens, 40 shutter Button.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA02 KA14 LA11 LA21 PA01 PA02 PA17 PB01 PB02 QA01 QA02 QA07 QA13 QA17 QA21 QA33 QA42 RA42 RA44 RA45 5F041 AA37 AA47 DA17 DA43 DA55 EE11 EE23 BF16 BC03 BCBC BC24 CA20 DA05 EA04 9A001 KK16 KK42

Claims (3)

[Claims] 1. The method of claim 1, wherein light of a first wavelength is reflected, and
An optical system having a lens formed with a thin film that transmits a second wavelength different from the first wavelength, and a reflection surface of the thin film provided in the lens and reflecting light of the first wavelength An optical function unit comprising: a first optical function element disposed at or near the focal position of the lens; and a second optical function element disposed at or near the focal position of the lens. 2. The optical function according to claim 1, wherein one of the first wavelength light and the second wavelength light is infrared light, and the other is visible light. unit. 3. The device according to claim 1, wherein the first optical function element and the second optical function element are arranged on or near the same optical axis. The optical function unit as described.