JPS625222A - Optical deflector - Google Patents

Abstract

PURPOSE:To reduce the size of a device and to obtain substantial durability by providing an aspherical convex lens, optical shutter means and solid-state optical deflecting element, etc. CONSTITUTION:The laser beam emitted from a monochromatic light source 30 passes a substrate 28 and is then converged by a condenser lens 32 to a light converging point 34. The light is thereafter diffused again and is made incident on the front face of the lens type optical deflecting element 14. The point 34 is positioned between the point spaced by as much as the focal point from the aspherical convex lens in the optical axis direction and the point spaced by as much as twice the focal point. A light source device is constituted by the light source 30 and the lens 32. On the other hand, the light past either one of the partial convex lens parts is condensed onto an image plane 36 when any of the partial convex lens parts is selectively opened by an optical shutter in the element 14. Various optical elements are properly used as necessary between the light source 30 as well as the element 14 and the image plane 36. The device is thus made smaller is size and the durability is maintained.

Description

TECHNICAL FIELD The present invention relates to improvements in optical deflection devices for deflecting light.

BACKGROUND OF THE INVENTION Devices such as laser beam printers and bar code leagues use optical deflection devices to deflect light to a desired angle. Polygon mirrors, hologram scanners, etc. are known as such optical deflection devices, but all of them are equipped with mechanically movable parts such as a rotation mechanism and its drive device, making the devices complicated and large. ,Also,
Sufficient durability was not always achieved.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is (1) division with a plane parallel to the plane containing the optical axis as the border; an aspherical convex lens consisting of a plurality of partially convex lens portions, the focal points of the partially convex lens portions being sequentially shifted in one direction perpendicular to the optical axis;
(2) a light source device that causes light to enter the aspherical convex lens; (3) a light shutter means that selectively allows light to pass through a partially convex lens portion of the aspherical convex lens; and (4) light that enters the aspherical convex lens. The object of the present invention is to include a solid-state optical deflection element that changes the deflection angle of the light to be deflected in advance by an acousto-optic effect or an electro-optic effect.

In this way, the focus of the partially convex lens portion through which light is selectively passed by the light shutter means is sequentially shifted in one direction parallel to the plane containing the optical axis, The light transmitted through the convex lens portion is focused at different positions corresponding to the partially convex lens portion. This focal point corresponds to the shift dimension of the partially convex lens section, and by selecting the partially convex lens section through which light is transmitted by the optical shutter means, it is as if the convex lens were moved in a direction perpendicular to its optical axis. As the lens moves, the light that passes through one point and is irradiated onto the aspherical convex lens is deflected to a desired angle. .

Furthermore, when the light incident on the aspherical convex lens is deflected in advance by the solid-state optical deflection element, the focal point can be changed over a wider range depending on the deflection angle of the incident light on the aspherical convex lens. Therefore, mechanically movable parts such as a rotation mechanism for deflecting light and its drive device are not required, so that the device can be made smaller and have sufficient durability.

The aspherical convex lens is preferably formed into a plano-convex lens shape with a flat negative surface, and the optical shutter means is provided on one of the planar surfaces of the aspherical convex lens. The optical shutter means may be a liquid crystal cell, or may be a solid state optical shutter element made of a material having an electro-optic effect.

The aspherical convex lens is preferably made by polishing a material prepared by laminating temporary glass pieces in advance into a convex lens shape, and then sequentially shifting the plate glass pieces in one direction perpendicular to the optical axis. They are constructed by being fixed to each other. Alternatively, the aspherical convex lens can be made by polishing - pieces of glass material into a convex lens shape, and then dividing it along a plane parallel to the plane containing the optical axis of the convex lens, to obtain plate glass pieces corresponding to the partially convex lens part. It can also be constructed by creating a plurality of glass plates, sequentially shifting the glass pieces in a direction perpendicular to the optical axis, and fixing them to each other.

Further, the light source device preferably includes a monochromatic light source including a semiconductor laser element that outputs laser light, and condenses the laser light output from the semiconductor laser element to one point, and then sends the laser light to the aspherical convex lens. The one point through which the light emitted from the light source toward the aspherical convex lens passes is preferably separated from the aspherical convex lens by its focal length in the optical axis direction. It is located between the point and a point separated by twice the focal length.

This has the advantage that the distance between the convergence points of the light that has passed through the partially convex lenses is increased by more than the amount of shift between the partially convex lenses.

The solid-state light deflection element is preferably provided between the monochromatic light source and the condenser lens of the light source device.

Embodiment FIG. 1 shows an optical deflection device used in a laser printer or the like, in which a lens-type optical deflection element 14 consisting of an aspherical convex lens 16 and an optical shutter 20 is mounted on a fixed base 10. It is fixed. As shown in FIGS. 2 and 3, the aspherical convex lens 16 has a plurality of convex lenses with a plane that includes the optical axis and is parallel to the moving direction of the movable table 12, that is, a horizontal plane in FIG. The optical shutter 20 is composed of a plurality of segmented convex lens parts 18a, 18b, 18c, etc.
It consists of shutter segments 22a, 22b, 22c, etc. arranged corresponding to shutter segments 8b, 18c, etc. The aspheric convex lens 16 is, for example, a plano-convex lens made of a glass material with a polished spherical surface, as shown in FIG. Partially convex lens parts 18a, 18 obtained by dividing
b, 18c, etc. are fixed to each other in a state in which they are sequentially shifted toward one direction that is the plane direction of the dividing plane and perpendicular to the optical axis. Further, the aspheric convex lens 16 is prepared by laminating a large number of temporary glass pieces 24 in the state shown in FIG. 6, and is polished into a plano-convex lens shape.
It can also be obtained by fixing the partially convex lens portions 18a, 18b, 18c, etc. obtained in this manner to each other as shown in FIG. 2 in the state shown in the figure.

Shutter segments 22a, 22 of the optical shutter 20
b, 22c, etc. are partially convex lens portions 18a.

They are each fixed to one flat surface such as 18b and 18c. Those shutter segments 22a, 22b, 22
The elements c and the like are each made of an electro-optical material that exhibits different optical anisotropy depending on the electric field, and are provided with a pair of transparent electrodes (not shown) that sandwich the material in a direction parallel to the optical axis. By changing the optical anisotropy of the electro-optic material in accordance with the voltage applied to the pair of transparent electrodes, an optical shatter effect can be obtained.゛Although the optical shutter 20 of this embodiment is composed of a large number of shutter segments 22a, 22b, 22c, etc. as described above, one substrate made of a substance having an electro-optic effect is transparent on the entire surface thereof. While the electrodes are provided, a large number of striped transparent electrodes corresponding to the partially convex lens portions 18a, 18b, 18c, etc. may be provided on the other surface.
Instead, a liquid crystal cell in which liquid crystal is sealed to a predetermined thickness and electrodes similar to those described above are formed on the inside of glass plates sandwiching the liquid crystal may be used as the optical shutter.

Returning to FIG. 1, a laser beam emitted from a fixed monochromatic light source 30 made of a semiconductor laser element or the like passes through a group vi 28 constituting a solid-state optical deflection element, and then is passed through a condensing lens 32 at a condensing point 34. After that, the light is diffused again and is incident on the front surface of the lens-type light deflection element 14. The condensing point 34 is located between a point separated from the aspherical convex lens 16 by the focal point and a point separated by twice the focal point in the optical axis direction. 3o and the condenser lens 32 constitute a light source device.

In the lens type optical deflection element 1.4, the optical shutter 20
Therefore, when any one of the partially convex lens parts 18a, 18b, and 13c is selectively opened, the partially convex lens part 18
The light passing through any one of aSl 8 b, 18 c, etc. is focused on a screen 36 consisting of a master drum of a laser printer or the like.

Although not shown, various optical elements are appropriately used between the monochromatic light source 30 and the lens-type light deflection element 14, and between the lens-type light deflection element 14 and the screen 36, as necessary.

The substrate 28 constituting the solid-state optical deflection element is, for example, L
It is made of a material having translucency and piezoelectric effect, such as a tNbOs crystal, and has a thickness of about 0.5 mm, and a leading waveguide is provided on its -plane.

This leading waveguide has a larger refractive index than other parts of the substrate 28 and has a characteristic of confining light in the thickness direction, so that light can be guided appropriately. By diffusing the
It is formed into a relatively thin layer of about 300 m. As shown in FIG. 7, the laser beam 40 incident from the end surface 38 on the incident side of the substrate 28 is converged into parallel light at the light converging section 42 while being guided through the optical waveguide, and is converged into parallel light at the light deflecting section 42. 44, it is deflected by the acousto-optic effect and is emitted from the other end face.

That is, in the light converging section 42, a diffusing material such as Ti is diffused such that the diffusion concentration increases as it approaches the optical axis L0 of the laser beam 40 in the plane direction of the substrate 28 and in the direction perpendicular to the optical axis L0 of the laser beam 40. As a result, the refractive index of the leading waveguide increases as it approaches the optical axis L0, thereby providing a convex lens function. The optical deflection section 44 uses a surface acoustic wave (ultrasonic wave) 50 excited by a pair of comb-shaped electrodes 46. A periodic refractive index change is formed, and the laser beam 40 passing through this is diffracted along the optical axis by Bragg diffraction. That is, assuming that the wavelength of light is λ, the refractive index of the optical waveguide is n, and the wavelength of 500 surface acoustic waves is 8, the diffraction angle 2θ due to Bragg diffraction can be obtained according to the following equation (1).

2 sin θ, wλ/nA −・・(1)
As the frequency of the voltage supplied to the comb-shaped electrodes 46 and 48 is changed, the frequency of the surface acoustic wave 50 changes by Δ
When f is changed, the laser beam 40 is deflected at a deflection angle Δθ according to the following equation (2).

Only that can be changed. Note that although the surface acoustic waves 50 cannot actually be seen with the naked eye, they are shown for ease of understanding. In this embodiment, since the substrate 28 is made of L i N b Ox having a function as a piezoelectric element, surface acoustic waves 50 are generated by applying a voltage between the comb-shaped electrodes 46 and 48. An ultrasonic transducer or the like may be attached to the side of the substrate 28.

2Δθ, -λ・Δf/v...J・(2) However, ■ is the propagation speed of the surface acoustic wave.

The effects of this embodiment will be explained below.

In the lens-type light deflection element 14, as described above, the laser beam 40 from the monochromatic light source 30, which has passed through the substrate 28 and the condensing lens 32, is directed onto the screen 36 through one partially convex lens portion whose transmission is allowed by the optical shutter 20. As shown in FIG. 8, the partially convex lens portion at this time is, for example, 18f, and the condensing point on the screen 36 is St. Next, when the other Φ partially convex lens portion, for example 18g, is opened by the optical shutter 20, the laser beam that has passed through the partially convex lens portion 18g is focused on point S1 on the screen 36. do. 2 like this
The two condensing points St and Sg are located at the partially convex lens portion 18f indicated by the solid line in FIG.
The result is the same as when the laser beam is moved in a direction perpendicular to the optical axis to the position g, and the laser beam is deflected. In particular, the focal point 3
4 is a point F! corresponding to twice the focal length of the aspherical convex lens 6 in the optical axis direction thereof. Since the distance between the condensing points Sf and S is larger than the amount of deviation between the partially convex lens parts 18f and 18g, the moving distance of the condensing point is greatly amplified.

In the above state, when the frequency of the voltage supplied to the comb-shaped electrode 46.4 is changed, for example, in about 20 steps, the voltage before it enters the front surface of the aspherical convex lens 16 changes depending on the step of the frequency change. The laser beam 40 of
Since the beam 40 is deflected in accordance with the equation (2) above, the focal point of the beam 40 is changed on the screen 36. For example, the comb-shaped electrode 18f may be connected to the optical shutter 2.
0, the focal point of the beam 32 is positioned within the interval between the focal points Sf to S9, depending on the frequency of the voltage supplied to the comb electrodes 46,48. . By controlling the frequency change of the voltage supplied to the comb-shaped electrodes 46, 48 and the voltage applied to the shutter segments 22a, 122b, 22c, etc., the laser beam is placed at any position within the area indicated by the broken line on the screen 36. While the beam is condensed, desired characters, etc. can be drawn by controlling the screen 36 to be sent up and down.

As described above, according to this embodiment, the lens-type optical deflection element 1
4 is composed of an aspherical convex lens 16 consisting of partially convex lens parts 18a, 18b, 18c, etc., which are sequentially shifted in one direction perpendicular to the optical axis, and an optical shutter 20 that selectively opens the partially convex lens parts 18as 18118c, etc. In addition, since the solid-state optical deflection element for predetermining the incident light of the aspherical convex lens 16 is composed of the substrate 28 provided with the comb-shaped electrodes 46 and 48, the movable part is fixed with respect to the deflection of the laser beam 40. This makes it possible to achieve an extremely high level of reliability as well as a smaller size. That is, compared to the conventional case using a polygon mirror or a hologram scanner, there is no need for a rotation mechanism, a driving device, etc., and the device becomes smaller and simpler, and its durability is improved.

Furthermore, since the light convergence position can be changed by the light deflection action of the two deflection elements arranged in series, it is possible to move the light convergence point over a wider range.

Note that the solid-state optical deflection element may be constructed from a substrate 64 shown in FIGS. 9 and 10. That is, the substrate 64 is made of a material having an electro-optic effect, and the laser beam emitted from the semiconductor laser element 66 fixed at the end face is converted into a parallel beam at the light collecting section 68, and then The light is deflected by the light deflecting section 70 and is emitted from the other end face. The light collecting section 68 is similar to the light collecting section 42, and has a refractive index distribution having a convex lens function due to diffusion. The optical deflection unit 70 includes a pair of electrodes 72.74 located on both sides of the optical axis L2, and the electrodes 72.74.
In between, the electrode 76 obliquely intersects the optical axis L2, and its deflection effect utilizes the effect of the material constituting the leading waveguide 78 changing its refractive index in accordance with the electric field. When a voltage is applied between the electrodes 72 and 74 and the electrode 76, the electric field E and the refractive index change Δn in the leading waveguide 78 on the A-A, B-B, and C-C lines of the optical deflection section 70 are respectively The process is completed as shown in FIGS. 11, 12, and 13. Therefore, the laser beam traveling along the optical axis L2 experiences a different refractive index in each part of the light beam, and is deflected according to the magnitude of the refractive index change Δn.
By temporally changing the voltage applied between the electrodes 72, 74 and 76, the deflection angle of the laser beam can be changed. Note that 80 is a thin film of SiO□ or the like, and is a buffer layer provided so that light propagates efficiently within the optical waveguide peak 78.

Further, as shown in FIGS. 14 and 15, the aspherical convex lens 16 may be integrally formed by polishing a glass material. Further, as shown in FIG. 16, the lens-type optical deflection element 14 may be composed of an aspherical convex lens 82. As described above, this aspherical convex lens 82 is arranged one after another in one direction orthogonal to the optical axis. It consists of shifted partially convex lens parts 84a, 84b, 84c, etc., but the partially convex lens parts 84a, 84b, 84c, etc. themselves are made of a material having an electro-optic effect, and transparent electrodes (not shown) are individually provided on both surfaces thereof. The partially convex lens portions 84a, 84b, 84c, etc. themselves also serve as shutter segments.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating an optical deflection device according to an embodiment of the present invention. FIG. 2 is a front view of an aspherical convex lens that constitutes a part of the lens-type optical deflection element provided in the apparatus of FIG. 1. FIG. 3 is a side view of the lens-type optical deflection element shown in FIG. 1. FIG. 4, FIG. 5, and FIG. 6 are diagrams each explaining the manufacturing process of the aspherical convex lens of FIG. 2. FIG. 7 is a diagram illustrating a solid-state optical deflection element provided in the apparatus of FIG. 1. FIG. 8 is a diagram illustrating the light deflection effect of the lens-type light deflection element shown in FIG. 1. Figures 9 and 10
The figures are a plan view and a side view showing a solid-state optical deflection element in another embodiment of the present invention. 11, 12, and 13 are diagrams showing the electric field and refractive index changes on the lines AA, BB, and CC of the optical deflection section in FIG. 9, respectively. FIGS. 14 and 15 are views corresponding to FIGS. 2 and 3 showing a lens-type optical deflection element in another embodiment of the present invention. FIG. 16 is a side view showing a lens-type optical deflection element in another embodiment of the present invention. 16.82: Aspherical convex lens 20; Optical shank (shutter means) 28.64: Substrate (solid light deflection means) Applicant Brother Industries, Ltd. Figure 2 Figure 3rIA ゝ°''', 5□ No. 681 No. 7 @ No. Figure 8

Claims (1)

[Claims] A non-convex lens consisting of a plurality of partially convex lens sections divided along a plane parallel to a plane containing the optical axis, the focal point of the partially convex lens sections being sequentially shifted in one direction parallel to the plane. a spherical convex lens; a light source device that causes light to enter the aspherical convex lens; a light shutter means that selectively allows light to pass through a partially convex lens portion of the aspherical convex lens; and a deflection angle of the light that is incident on the aspherical convex lens. 1. An optical deflection device comprising: a solid-state optical deflection element that changes in advance by an acousto-optic effect or an electro-optic effect.