JP6635111B2 - Lighting optical unit and lighting device - Google Patents

Description

  The present invention relates to an illumination optical unit for irradiating an object to be illuminated with light emitted from a plurality of light sources, and an illumination device incorporating the illumination optical unit.

  2. Description of the Related Art In recent years, an LED lighting device using a light-emitting diode (LED) that is energy-saving and has a long life as a light source has attracted attention and has been actually used in response to an increasing energy problem. In general, since LEDs have strong directivity, when they are used for, for example, signboard lighting or liquid crystal backlights, lenses, diffusers, and the like are used for the purpose of expanding the irradiation range. When it is desired to irradiate a stronger and wider area, a method using a substrate on which a plurality of LED chips are arranged and a lens for condensing, collimating, or diffusing light emitted from each LED has been adopted. When using such a light source, by turning off a specific LED chip among a plurality of LED chips, light is not illuminated in a specific direction, or characters or shapes are formed by turning on a specific LED chip. You can also imitate light. Here, in general, when light emitted from a light source is condensed or collimated by optical means, the light intensity distribution on the irradiation surface is projected as an image in the form of the light source as it is. In other words, when using multiple light sources, it is difficult to completely eliminate the gap between the light sources due to physical restrictions, even if they are arranged at high density. For example, rectangular light sources are arranged at high density. In this case, the light intensity distribution on the irradiation surface has grid-like intensities. Such a phenomenon is a problem to be avoided as a lighting device.

  Patent Literature 1 discloses an illumination device that illuminates illumination light emitted from a plurality of light sources arranged at high density in a planar shape (array) onto a planar-shaped illuminated object using an optical unit. . In Patent Document 1, the light source is set not at the best focus position of the optical means but at a position slightly deviated from the best focus position (defocused), and the image of the light source is deliberately defocused, so that the intensity distribution of the adjacent light source is adjusted. Are superimposed to make the irradiation intensity distribution uniform.

  However, since the technique based on defocusing as in Patent Literature 1 is to reduce the intensity of light emitted from each light source on the irradiation surface to expand the irradiation range, a plurality of light sources are overlapped on the irradiation surface. By the combination, a certain irradiation intensity can be obtained. However, when an illumination method that does not illuminate a specific area or imitates (or simulates) a character or shape is realized on the premise of a defocus method, such a method may blur the boundary between light and dark. There is. Further, the defocusing method has high sensitivity to disturbances due to assembly errors between the light source and the optical means, vibrations, and the like, and easily deteriorates optical characteristics (hereinafter, defocus characteristics) when there is a shift in the optical axis direction. There is a risk that it will. Further, when a plastic lens or the like is used as the optical unit, optical specifications such as a focal length change due to a temperature change due to heat generation of the light source, and as a result, the uniformity of the irradiation intensity distribution may be lost. In particular, in a field where LEDs are arranged in a high-density array and a high light amount is required (for example, a vehicle-mounted lighting device, etc.), this problem becomes very remarkable.

JP 2002-268001 A

  The present invention has been made in view of the above background art, and is capable of projecting radiated light from a plurality of light sources arranged at high density onto an irradiation surface with uniform and high intensity and having excellent defocusing characteristics. It is an object to provide an optical unit for use.

  Another object of the present invention is to provide a lighting device incorporating the above-mentioned lighting optical unit.

In order to achieve the above object, an illumination optical unit according to the present invention has a plurality of lenses arranged in an optical axis direction, and illuminates incident light from a plurality of light sources arranged in a direction perpendicular to the optical axis. An illumination optical system that converts the light into emission light for illumination, and a lens barrel that holds the illumination optical system. The illumination optical system has a lens when parallel light passes from the emission side toward the light source side. The light condensing positions α (mm), β (mm), and γ (mm) of the light passing through the central region, the intermediate region, and the peripheral region of the opening satisfy the following conditional expressions.
| Γ-α |> 0.5 (1)
| (Α + γ) / 2−β | <| (γ−α) / 3 | (2)
However, the central region of the lens opening is a region of 10% or less in the radial direction from the optical axis, the intermediate region is a region of 45% or more and 55% or less in the radial direction from the optical axis, and the peripheral region is light. This area is 90% or more in the radial direction from the axis. Here, converting incident light from a light source into outgoing light for illumination means changing the traveling direction of light, for example, condensing, collimating, or diverging light. The lens opening is an opening on the emission side of the lens barrel, and corresponds to the effective diameter of the lens on the most emission side of the illumination optical system. The central region, the intermediate region, and the peripheral region have, for example, a shape in which the outer shape of the lens opening is approximated by a circle. When the outer shape of the lens opening is not circular, the shape of each region may be a circumscribed circle of the outer shape. In addition, these regions are defined by considering height positions in the direction perpendicular to the optical axis, and the light condensing positions α, β, and γ are averaged according to the area ratio of each region. Become.

  The illumination optical unit intentionally generates spherical aberration by having an illumination optical system that satisfies the conditional expressions (1) and (2). Thereby, a quasi-focus range in which the intensity distribution can be made uniform while suppressing the unnecessary divergence of the illumination light and ensuring the irradiation intensity (the balance between the maintenance of the illumination intensity and the suppression of the dark line described below is just a good range. (Including the best focus). Therefore, the light source and the illumination optical unit or the like, which is an optical unit, are more resistant to assembly errors and the influence of disturbance such as temperature. In addition, since the intensity of the radiated light from each light source on the irradiation surface can be secured, when not illuminating a specific area, or when simulating a character or a shape, it corresponds to the gap between the light sources in the bright area The boundary between light and dark can be clarified at the outer edge of the light area while preventing the occurrence of dark lines.

  A lighting device according to the present invention includes the above-described lighting optical unit and an array light source having a plurality of light sources.

  By incorporating the above-mentioned illumination optical unit in the above-described illumination device, the quasi-focus range in which the intensity distribution can be made uniform while the illumination intensity is secured is widened. Therefore, the light source and the illumination optical unit or the like, which is an optical unit, are more resistant to assembly errors and the influence of disturbance such as temperature. In addition, since the intensity of the radiated light from each light source on the irradiation surface can be ensured, when a specific area is not illuminated, or when simulating a character or a shape, a dark line is prevented from occurring in a bright area. The boundary between light and dark can be defined at the outer edge of the light area.

FIG. 1A is a conceptual diagram illustrating an illumination device and the like including the illumination optical unit according to the first embodiment, and FIG. 1B is a plan view of an array light source in the illumination device. 2A and 2B are diagrams illustrating conditional expressions satisfied by the illumination optical array. 3A is a cross-sectional view illustrating an illumination optical unit and the like in the illumination device according to the first embodiment, and FIGS. 3B and 3C are diagrams illustrating spherical aberration and astigmatism of the illumination optical unit in FIG. 3A. 4A is a cross-sectional view illustrating an illumination optical unit and the like in the illumination device according to the second embodiment, and FIGS. 4B and 4C are diagrams illustrating spherical aberration and astigmatism of the illumination optical unit in FIG. 4A. 5A is a cross-sectional view illustrating an illumination optical unit and the like in the illumination device according to the third embodiment, and FIGS. 5B and 5C are diagrams illustrating spherical aberration and astigmatism of the illumination optical unit in FIG. 5A. 6A is a cross-sectional view illustrating an illumination optical unit and the like in the illumination device of Comparative Example 1, and FIGS. 6B and 6C are diagrams illustrating spherical aberration and astigmatism of the illumination optical unit of FIG. 6A. 7A and 7B are diagrams illustrating simulation results of the lighting device according to the example. 8A and 8B are diagrams illustrating simulation results of the lighting device of the comparative example. It is a top view explaining an array light source among the lighting devices of a 2nd embodiment. FIG. 10A is a diagram illustrating a simulation result of the lighting device of the example in the second embodiment, and FIGS. 10B to 10D are diagrams illustrating a simulation result of the lighting device of the comparative example.

[First Embodiment]
Hereinafter, an illumination optical unit and an illumination device according to a first embodiment of the present invention will be described with reference to FIG. 1A and the like. Note that the illumination optical unit 10 illustrated in FIG. 1A has the same configuration as an illumination optical unit 10A according to a first embodiment described later.

  As shown in FIGS. 1A and 1B, the illumination device 100 irradiates light emitted from a plurality of light sources arranged in an array to an illuminated object SB by using an illumination optical unit 10 described later. . The illumination device 100 includes an illumination optical unit 10, an array light source 20, and a control device 30. The application of the illumination device 100 includes, for example, a video device, a microscope illumination device, and the like. Here, the image device means an indoor lighting device, a building lighting device, an in-vehicle lighting device, a magnifying projection device, or the like, which enables illumination and projection.

The illumination optical unit 10 includes an illumination optical system 11 and a lens barrel 12. The illumination optical unit 10 satisfies the following conditional expression (4) as a premise regarding brightness.
Fno <1.0 (4)
Here, Fno is the F number of the illumination optical system 11. Thereby, the amount of light taken in by the illumination optical unit 10 increases, and the light use efficiency increases.

  The illumination optical system 11 converts incident light from the array light source 20 into emission light for illumination, and includes a plurality of lenses L1 to Ln (n is a natural number) arranged in the direction of the optical axis OA. . Here, converting incident light from the array light source 20 (light source) into outgoing light for illumination means changing the traveling direction of light, for example, condensing, collimating, or diverging light. It is preferable that the illumination optical system 11 includes three to five lenses. At least one lens of the illumination optical system 11 has a negative refractive power. The lens on the most exit side (first lens L1 in FIG. 1A) and the lens on the light source side (fifth lens L5 in FIG. 1A) each have a positive refractive power. Thus, the illumination optical unit 10 can have a small and bright F-number while suppressing chromatic aberration, so that color unevenness is small and high light use efficiency can be realized. It is preferable that the lens closest to the light source (the fifth lens L5 in FIG. 1A) has a surface with a relatively large curvature on the exit side. Thereby, the light from the array light source 20 can be secured as much as possible. The illumination optical system 11 includes at least one plastic or resin aspheric lens. Thereby, cost reduction and weight reduction of the illumination optical unit 10 can be achieved. As the plastic, for example, a material having high heat resistance such as acrylic or polycarbonate is preferable.

It is preferable that the illumination optical system 11 has only one lens having a negative refractive power among a plurality of lenses. In this case, the illumination optical system 11 satisfies the following conditional expression (3) from the viewpoint of achieving a small and bright F-number while suppressing chromatic aberration.
Pr> Pf (3)
Here, Pr is the combined refractive power of the lens disposed on the emission side of the negative lens (the third lens L3 in FIG. 1A), and Pf is the combined refractive power of the lens disposed on the light source side of the negative lens.

When passing parallel light (light parallel to the optical axis OA) from the emission side to the light source 22 side, the illumination optical system 11 transmits the central area AR1, the intermediate area AR2, and the peripheral area AR3 of the lens opening 13a. The light condensing positions α (mm), β (mm), and γ (mm) of the light passing through each satisfy the following conditional expressions (1) and (2).
| Γ-α |> 0.5 (1)
| (Α + γ) / 2−β | <| (γ−α) / 3 | (2)
However, as shown in FIGS. 2A and 2B, the central area AR1 of the lens opening 13a is an area that is 10% or less in the radial direction from the optical axis OA, and the intermediate area AR2 is the radial direction from the optical axis OA. The peripheral area AR3 is an area that is 90% or more in the radial direction from the optical axis OA. These light condensing positions α, β, and γ use an arbitrary position on the optical axis OA as a common reference point. The lens opening 13a is an opening on the emission side of the lens barrel 12, and corresponds to the effective diameter of the lens (first lens L1) on the most emission side of the illumination optical system 11. The central area AR1, the intermediate area AR2, and the peripheral area AR3 have, for example, a circular outline when the outer shape of the lens opening 13a is a circle, and a circular outer shape when the outer shape of the lens opening 13a is not a polygon or any other circle. Has a shape similar to Further, the size of these areas AR1, AR2, AR3 is defined by considering the value of the radius giving a circular contour, that is, the height position perpendicular to the optical axis, and the range of the effective diameter of the first lens L1. Within the range, the area is 100% or less. Furthermore, the light condensing positions α, β, and γ are obtained by averaging the areas AR1, AR2, and AR3 in accordance with the area ratio of the annular zones.

  The illumination optical system 11 intentionally generates spherical aberration by satisfying the conditional expressions (1) and (2). Thereby, a quasi-focus range in which the intensity distribution can be made uniform while suppressing the unnecessary divergence of the illumination light and ensuring the irradiation intensity (the balance between the maintenance of the illumination intensity and the suppression of the dark line described below is just a good range. (Including the best focus). For this reason, the light source 22 and the illumination optical unit 10 or the like, which are optical means, are more susceptible to assembly errors and disturbances such as temperature. In addition, since the intensity of the radiated light from the individual light sources 22 on the irradiation surface (specifically, the illuminated object SB) can be secured, when not illuminating a specific area or when imitating a character or shape, The boundary between light and dark can be clarified while preventing the occurrence of dark lines.

  The lens barrel 12 stores and holds the illumination optical system 11. The lens barrel 12 has a lens opening 13a through which a light beam from the light source 22 is incident, and a lens opening 13b through which the light beam that has passed through the illumination optical system 11 is emitted.

  The array light source 20 has a substrate 21 and a plurality of light sources 22. The substrate 21 supports the plurality of light sources 22 and has wiring and the like for supplying power to the light sources 22. The light source 22 is arranged in a direction perpendicular to the optical axis OA. That is, the light sources 22 are arranged in an array on the surface of the substrate 21. Examples of the plurality of light sources 22 include a plurality of LED chips and other solid-state light sources. As shown in FIG. 1B, the plurality of light sources 22 are linearly arranged. Each light source 22 has a substantially square outline and is the same size. Therefore, a thin linear gap GA is formed between adjacent light sources 22. As a whole, the elongated rectangular area is a light emitting area corresponding to a bright area on the irradiation surface (specifically, the illumination target SB). The illumination optical system 11 projects the images of the plurality of light sources 22 arranged linearly. In this case, it is possible to perform linear illumination in which the boundary between light and dark is clarified at the outer edge of the light area while preventing generation of a dark line corresponding to the gap GA. The distance Ld between the gaps between the adjacent light sources 22 is 50 μm or less, and the improvement of the defocus characteristic and the like due to the spherical aberration is more reliable. The array light source 20 may be composed of, for example, LED chips of the same color or of different colors.

  The control device 30 drives the array light source 20. The control device 30 controls the lighting state of each light source 22 constituting the array light source 20. For example, the control device 30 is connected to the LED chip as the light source 22 or each of the attached circuits by wiring, and the LED chip lights up intermittently or continuously. A desired lighting pattern can be formed by selectively lighting only a specific light source 22. The control device 30 may operate by an operation of an operator or may operate by a program.

  Hereinafter, an example of a use state of the lighting device 100 will be described. First, the control device 30 is operated by an operator or a program, and the light source 22 to be turned on among the array light sources 20 is selected. Next, the control device 30 is operated to turn on the selected light source 22. The light emitted from the light source 22 enters the illumination optical unit 10 and is converted into illumination emission light. The light beam that has passed through the illumination optical unit 10 is illuminated on the illuminated object SB in a quasi-focus state in which the contours or dark lines of the individual light sources 22 are inconspicuous. An image corresponding to the brightness of the array light source 20 is projected on the irradiation surface of the illuminated object SB with a high illumination intensity. At this time, the boundary between light and dark can be made clear at the outer edge of the light area corresponding to the group of light sources 22 turned on while making the outline of each light source 22 inconspicuous.

  The illumination optical unit 10 and the illumination device 100 described above can intentionally generate spherical aberration, thereby increasing the quasi-focus range in which the intensity distribution can be made uniform while maintaining the illumination intensity, and the defocus characteristic can be improved. It will be excellent. In other words, even if the whole or a part of the illumination optical unit 10 is slightly displaced in the direction of the optical axis OA, it is possible to project the radiated light from the plurality of light sources 22 arranged at high density onto the irradiation surface with uniform and high intensity. . As a result, an influence of an assembly error between the light source and the illumination optical unit 10 or the like as the optical means, a disturbance such as a temperature, or the like becomes strong. In addition, since the intensity of the radiated light from each light source 22 on the irradiation surface can be ensured, the boundary between the light sources is suppressed from being ambiguous, and a specific area is not illuminated or characters or shapes are imitated. It is suitable for such an illumination method.

  On the other hand, in the illumination system using the conventional method of defocusing due to defocus, the quasi-focus range in which the intensity distribution can be uniformized while securing the illumination intensity is extremely narrow, and the desired characteristics are obtained by the above-described disturbance. Is more likely not to be available.

〔Example〕
Hereinafter, examples of an optical unit for illumination and the like according to the present invention will be described. The symbols used in each example are as follows.
Fno: F number R: Paraxial radius of curvature D: Axis upper surface distance n: Refractive index for d-line of lens material
eff.rad .: Effective radius of the lens In addition, the symbol Surf.N means the surface number, the symbol INF means infinity or ∞, the symbol PS means the emission side or the irradiation surface side, and the symbol. LS means the light source side, and the symbol STOP means the aperture stop S.

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ ：曲率半径
Ｋ ：円錐定数 In each embodiment, the surface indicated by “*” after each surface number is a surface having an aspherical surface shape. The aspherical surface shape has the origin at the vertex of the surface and the Z axis in the optical axis direction. , And the height in the direction perpendicular to the optical axis is represented by h, and is represented by the following “Equation 1”.

However,
Ai: i-th order aspherical coefficient R: radius of curvature K: conic constant

[Example 1]
The optical parameters of the illumination optical system according to the first embodiment are shown below.
Fno: 0.55

Table 1 below shows data on the lens surface and the like of the illumination optical system according to the first embodiment.
[Table 1]
Surf.NR (mm) D (mm) n eff.rad. (Mm)
PS INF INF
1 * 59.193 12.084 1.488 28.836
2 * -50.631 0.500 27.884
3 * 75.748 12.810 1.488 25.000
4 * -49.801 1.852 24.829
5 * -29.598 5.000 1.579 23.641
6 * 18.284 18.317 18.650
7 (STOP) INF 0.100 16.102
8 * 17.869 12.764 1.488 15.813
9 * -72.208 0.500 15.648
10 13.247 11.000 1.593 12.000
11 42.708 6.032 9.677
LS INF 0.000

Table 2 below shows the aspheric coefficients of the illumination optical system of the first embodiment. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is represented by E (for example, 2.5E-02).
[Table 2]
First side
R = 59.193, K = -6.460, A4 = 4.878E-06, A6 = -2.015E-08,
A8 = 1.194E-11, A10 = 0.000E + 00
Second side
R = -50.631, K = -20.000, A4 = 3.977E-08, A6 = -8.508E-09,
A8 = 9.648E-12, A10 = 0.000E + 00
Third side
R = 75.748, K = 0.543, A4 = -2.033E-06, A6 = 8.642E-09,
A8 = -7.758E-12, A10 = -2.094E-14
Fourth side
R = -49.801, K = 1.352, A4 = 1.280E-05, A6 = -3.272E-08,
A8 = 2.937E-11, A10 = 0.000E + 00
Fifth surface
R = -29.598, K = -10.464, A4 = -1.565E-06, A6 = -1.398E-08,
A8 = 3.831E-11, A10 = 0.000E + 00
Side 6
R = 18.284, K = -2.668, A4 = 4.055E-06, A6 = -2.219E-08,
A8 = 8.537E-11, A10 = -2.019E-13
Side 8
R = 17.869, K = 0.000, A4 = -3.915E-05, A6 = -1.312E-07,
A8 = 1.266E-09, A10 = -4.896E-12
9th page
R = -72.208, K = 0.000, A4 = -6.859E-09, A6 = 2.274E-07,
A8 = -1.630E-09, A10 = 2.492E-12

  FIG. 3A is a cross-sectional view of the illumination optical unit 10A and the like according to the first embodiment. The illumination optical unit 10A includes five lenses, and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. When the illumination optical unit 10A includes five lenses as in the illumination optical unit 10A, the illumination optical unit has a high performance. The first lens L1 side is the emission side or the irradiation surface side, and the fifth lens L5 side is the light source side. An aperture stop S is provided between the third lens L3 and the fourth lens L4. In addition, the code | symbol I shows the surface (or light emitting surface) of the array light source 20 (the same also in the following Examples).

  3B and 3C show the spherical aberration and the astigmatism of the illumination optical unit 10A according to the first embodiment shown in FIG. 3A. The spherical aberration is shown at wavelengths of 486, 588 and 656 nm.

(Example 2)
The optical specifications of the illumination optical system of the second embodiment are shown below.
Fno: 0.88

Table 3 below shows data on the lens surface and the like of the illumination optical system according to the second embodiment.
[Table 3]
Surf.NR (mm) D (mm) n eff.rad. (Mm)
PS INF INF
1 * 32.966 17.889 1.488 23.979
2 * -35.128 3.279 26.000
3 * -18.264 5.000 1.579 20.963
4 * 100.000 5.408 15.841
5 (STOP) INF 0.100 15.478
6 * 31.018 13.686 1.488 16.000
7 * -37.128 7.480 15.917
8 18.401 11.000 1.593 14.000
9 26.911 8.923 11.964
LS INF 0.000

Table 4 below shows the aspheric coefficients of the illumination optical system of the second embodiment.
[Table 4]
First side
R = 32.966, K = -0.867, A4 = 1.552E-06, A6 = 4.346E-09,
A8 = -3.161E-11, A10 = 0.000E + 00
Second side
R = -35.128, K = -0.192, A4 = 1.609E-05, A6 = -2.542E-08,
A8 = 2.629E-11, A10 = 0.000E + 00
Third side
R = -18.264, K = -3.523, A4 = 1.278E-05, A6 = -1.840E-08,
A8 = 4.954E-11, A10 = 0.000E + 00
Fourth side
R = 100.000, K = -1.226, A4 = 4.674E-05, A6 = -1.639E-07,
A8 = 5.504E-10, A10 = -3.865E-13
Side 6
R = 31.018, K = 0.000, A4 = 2.398E-06, A6 = -4.605E-08,
A8 = 7.552E-11, A10 = 1.322E-13
Surface 7
R = -37.128, K = 0.000, A4 = 2.005E-05, A6 = -4.399E-08,
A8 = -1.022E-10, A10 = 4.603E-13

  FIG. 4A is a cross-sectional view of the illumination optical unit 10B and the like according to the second embodiment. The illumination optical unit 10B includes four lenses, and has a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. When the optical unit is composed of four lenses as in the illumination optical unit 10B, the illumination optical unit balances cost, size, and performance. The first lens L1 side is the emission side, and the fourth lens L4 side is the light source side. An aperture stop S is provided between the second lens L2 and the third lens L3.

  4B and 4C show the spherical aberration and the astigmatism of the illumination optical unit 10B according to the second embodiment shown in FIG. 4A.

(Example 3)
The optical parameters of the illumination optical system of the third embodiment are shown below.
Fno: 0.89

Table 5 below shows data on the lens surface and the like of the illumination optical system according to the third embodiment.
[Table 5]
Surf.NR (mm) D (mm) n eff.rad. (Mm)
PS INF INF
1 * (STOP) 22.553 15.047 1.492 18.000
2 * -40.189 5.774 17.435
3 * -6.073 5.496 1.584 16.846
4 * -32.050 1.000 14.938
5 * 7.606 24.901 1.492 15.000
6 * 141.114 6.000 12.909
LS INF 0.000

Table 6 below shows the aspheric coefficients of the illumination optical system of the third embodiment.
[Table 6]
First side
R = 22.553, K = -0.882, A4 = -1.233E-06, A6 = 7.158E-08,
A8 = -1.894E-10, A10 = 0.000E + 00
Second side
R = -40.189, K = -11.897, A4 = 3.168E-05, A6 = -1.812E-07,
A8 = 2.828E-10, A10 = 0.000E + 00
Third side
R = -6.073, K = -3.727, A4 = 3.864E-05, A6 = -1.365E-07,
A8 = 3.001E-10, A10 = 0.000E + 00
Fourth side
R = -32.050, K = -1.330, A4 = 8.238E-05, A6 = -1.504E-07,
A8 = 2.983E-10, A10 = 0.000E + 00
Fifth surface
R = 7.606, K = -3.622, A4 = 5.643E-05, A6 = -1.054E-07,
A8 = 1.017E-10, A10 = 0.000E + 00
Side 6
R = 141.114, K = 12.761, A4 = -5.889E-05, A6 = 4.635E-07,
A8 = -1.698E-09, A10 = 0.000E + 00

  FIG. 5A is a cross-sectional view of the illumination optical unit 10C and the like according to the third embodiment. The illumination optical unit 10C includes three lenses, and has a first lens L1, a second lens L2, and a third lens L3. When the illumination optical unit 10C is configured by three lenses as in the illumination optical unit 10C, the number of lenses is relatively small, so that the illumination optical unit is low-cost and small. The first lens L1 side is the emission side, and the third lens L3 side is the light source side. An aperture stop S is provided on the emission side of the first lens L1.

  5B and 5C show the spherical aberration and the astigmatism of the illumination optical unit 10C according to the third embodiment shown in FIG. 5A.

(Comparative Example 1)
The optical parameters of the illumination optical system of Comparative Example 1 are shown below.
Fno: 0.55

Table 7 below shows data on the lens surface and the like of the illumination optical system of Comparative Example 1.
[Table 7]
Surf.NR (mm) D (mm) n eff.rad. (Mm)
PS INF INF
1 * 65.827 12.348 1.488 28.874
2 * -47.072 0.500 27.575
3 * 66.806 13.000 1.488 24.000
4 * -49.680 1.824 23.608
5 * -30.391 5.565 1.579 22.342
6 * 15.597 15.082 17.531
7 (STOP) INF 0.100 16.141
8 * 17.800 13.257 1.488 15.906
9 * -57.459 0.500 15.593
10 13.279 11.000 1.593 12.000
11 45.093 5.951 9.716
LS INF 0.000

Table 8 below shows the aspheric coefficient of the illumination optical system of Comparative Example 1.
[Table 8]
First side
R = 65.827, K = -8.461, A4 = 6.802E-06, A6 = -2.515E-08,
A8 = 1.647E-11, A10 = 0.000E + 00
Second side
R = -47.072, K = -19.999, A4 = -2.891E-07, A6 = -8.284E-09,
A8 = 1.053E-11, A10 = 0.000E + 00
Third side
R = 66.806, K = 1.616, A4 = -1.169E-06, A6 = 8.712E-09,
A8 = -1.050E-11, A10 = -2.912E-14
Fourth side
R = -49.680, K = 1.266, A4 = 1.184E-05, A6 = -3.256E-08,
A8 = 3.145E-11, A10 = 0.000E + 00
Fifth surface
R = -30.391, K = -9.513, A4 = -1.217E-06, A6 = -1.260E-08,
A8 = 4.087E-11, A10 = 0.000E + 00
Side 6
R = 15.597, K = -2.137, A4 = 6.258E-06, A6 = -2.375E-08,
A8 = 6.587E-11, A10 = -2.737E-13
Side 8
R = 17.800, K = 0.000, A4 = -2.836E-05, A6 = -1.497E-07,
A8 = 1.222E-09, A10 = -4.658E-12
9th page
R = -57.459, K = 0.000, A4 = 5.041E-06, A6 = 2.362E-07,
A8 = -1.642E-09, A10 = 2.524E-12

  FIG. 6A is a cross-sectional view of the illumination optical unit 10U and the like of Comparative Example 1. The illumination optical unit 10U includes five lenses, and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. The first lens L1 side is an emission side, and the fifth lens L5 side is a light source side. An aperture stop S is provided between the third lens L3 and the fourth lens L4.

  6B and 6C show the spherical aberration and astigmatism of the illumination optical unit 10U of Comparative Example 1 shown in FIG. 6A.

(Simulation of the embodiment)
7A and 7B show simulation results for the first embodiment. In this simulation, the illumination optical unit is assumed to have an illumination optical system including five lenses and an F number of 0.55. Each light source was a square having a side of 0.4 mm, and the distance or width of the gap between the light sources was 0.01 mm.

  FIG. 7A is a lighting example of a single light source when assuming the illumination optical unit 10A of the first embodiment. In this case, even at the time of the best focus, the outline is blurred, but the illumination intensity is high. Here, the ideal intensity ratio is 0.85 or more. The quasi-focus range where the illumination intensity is high is wider than a design in which spherical aberration, which will be described later, does not appear. FIG. 7B is a lighting example of five light sources when assuming the illumination optical unit 10A of the first embodiment. That is, the example of FIG. 7B corresponds to a case where the light sources are arranged in a straight line on the premise of the illumination optical unit 10A of the first embodiment shown in FIG. 7A. In this case, the balance between the illumination intensity maintenance and the dark line suppression (to make the dark lines inconspicuous) within the range of -0.10 mm to +0.15 mm at the time of the best focus is just right, and the position shift and the mounting error due to the disturbance can be prevented. It can be said that it is strong. Although a specific description is omitted, the simulation results regarding the second and third embodiments are the same as the simulation results regarding the first embodiment.

(Simulation for comparative example)
8A and 8B show simulation results for Comparative Example 1. FIG. The conditions of this simulation are the same as those of the simulation according to the first embodiment.

  FIG. 8A is a lighting example of a single light source when assuming the illumination optical unit 10U of Comparative Example 1. In this case, the intensity is strong and the outline is clear at the time of the best focus, but the intensity decreases with defocus and the outline becomes blurred.

  FIG. 8B is a lighting example of five light sources when assuming the illumination optical unit 10U of Comparative Example 1. That is, the example of FIG. 8B corresponds to a case where the light sources are arranged in a straight line, based on the illumination optical unit 10U of Comparative Example 1 shown in FIG. 8A. In this case, in the range of ± 0.05 mm at the time of the best focus, the dark line in the gap between the light sources is clearly visible. On the other hand, in the range of ± 0.1 to ± 0.15 mm, the balance between the maintenance of the illumination intensity and the suppression of the dark line is just right, but the state is weak against a positional shift due to a disturbance, an installation error and the like.

表９からわかるように、実施例において、準フォーカス範囲が広くなっているのがわかる。Hereinafter, Table 9 shows the results obtained by summarizing the present example and the comparative example. The shaded portion in Table 9 is a quasi-focus range in which the balance between the maintenance of the illumination intensity and the suppression of dark lines is just right.
[Table 9]

As can be seen from Table 9, in the example, the quasi-focus range is widened.

[Second embodiment]
Hereinafter, the illumination optical unit and the illumination device according to the second embodiment will be described. The illumination optical unit and the like according to the second embodiment are partially modified from the illumination optical unit and the like according to the first embodiment, and items not particularly described are the same as those of the illumination optical unit and the like according to the first embodiment. It is.

  As shown in FIG. 9, in the illumination device 100 of the present embodiment, the plurality of light sources 22 constituting the array light source 20 are two-dimensionally arranged in a matrix, and the illumination optical system 11 not shown The image of the light source 22 is projected. In this case, it is possible to imitate a character or shape with a clear boundary between light and dark while preventing the occurrence of dark lines.

  10A to 10D show simulation results of the present embodiment. The simulation conditions are the same as those in Example 1 of the first embodiment. 10A to 10D are examples when two Chinese characters are projected. FIG. 10A is a lighting example of a two-dimensional array light source in a design that produces spherical aberration as an example. As shown in FIG. 10A, in the embodiment, the intensity maintenance and the dark line suppression can be balanced in the reference state. 10B to 10D are lighting examples of a two-dimensional array light source in a design with no spherical aberration as a comparative example. As shown in FIG. 10B, in the comparative example in which the defocus is small, the dark line is clearly visible in the reference state. Further, as shown in FIG. 10D, in the comparative example in which the defocus is large, the intensity ratio is weak, and although the dark line is not visible, the outline of the character is not clear. As shown in FIG. 10C, in the intermediate comparative example, the outline of the character is clear although some dark lines remain in the defocused state. From the above, it is understood that the balance between maintaining the illumination intensity and suppressing the dark line is important.

  The illumination optical unit and the illumination device according to the embodiment have been described above, but the illumination optical unit and the like according to the present invention are not limited to the above-described examples. For example, in the above embodiment, a bending mirror may be provided on the emission side of the illumination optical unit 10.

Claims (14)

An illumination optical system that has a plurality of lenses arranged in the optical axis direction and converts incident light from a plurality of light sources arranged in a direction perpendicular to the optical axis into emission light for illumination,
A lens barrel that holds the illumination optical system,
With
The illumination optical system is configured such that, when parallel light passes from the emission side toward the light source side, a light condensing position α (mm) of light passing through a central area, an intermediate area, and a peripheral area of the lens opening. , Β (mm) and γ (mm) satisfy the following conditional expressions:
| Γ-α |> 0.5 (1)
| (Α + γ) / 2−β | <| (γ−α) / 3 | (2)
However, the central region of the lens opening is a region of 10% or less in the radial direction from the optical axis, and the intermediate region is a region of 45% or more and 55% or less in the radial direction from the optical axis; The peripheral region is a region that is 90% or more in the radial direction from the optical axis.   The illumination optical unit according to claim 1, wherein the illumination optical system includes three lenses.   The illumination optical unit according to claim 1, wherein the illumination optical system includes four lenses.   The illumination optical unit according to claim 1, wherein the illumination optical system includes five lenses.   The lens according to any one of claims 2 to 4, wherein at least one lens of the illumination optical system has a negative refractive power, and the lens on the most exit side and the lens on the light source side have a positive refractive power. The optical unit for illumination according to claim 1. The lens having negative refractive power is composed of only one lens,
The illumination optical unit according to claim 5, wherein the following conditional expression is satisfied.
Pr> Pf (3)
However,
Pr: combined refractive power of a lens arranged on the emission side from the negative lens Pf: combined refractive power of a lens arranged on the light source side of the negative lens The illumination optical unit according to any one of claims 1 to 6, which satisfies the following conditional expressions.
Fno <1.0 (4)
However,
Fno: F number of the illumination optical system   The illumination optical unit according to any one of claims 1 to 7, wherein the illumination optical system includes at least one plastic aspheric lens.   The illumination optical unit according to any one of claims 1 to 8, which is used in any of a video device and a microscope illumination device. An illumination optical unit according to any one of claims 1 to 9,
An array light source having the plurality of light sources,
A lighting device comprising:   The illumination device according to claim 10, wherein the illumination optical system projects images of the plurality of light sources arranged in a straight line.   The illumination device according to claim 10, wherein the illumination optical system projects the plurality of light sources arranged two-dimensionally.   The lighting device according to any one of claims 10 to 12, wherein the light source is an LED chip.   The lighting device according to claim 10, wherein the plurality of light sources are arranged substantially along a predetermined plane, and a gap between adjacent light sources is 50 μm or less.

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