JPH0415618A - Variable aperture device - Google Patents

Abstract

PURPOSE:To make grooves for the formation of aperture elements deep to the inside of a transparent substrate, to make the capacity between the aperture elements, and to prevent the generation of crosstalk by adhering an electrooptic medium which constitutes a variable aperture element and the transparent substrate in one body with an optical adhesive. CONSTITUTION:The electrooptic medium 103 which constitutes the variable aperture element 1' and the transparent substrate 102 are adhered together in one body by using the optical adhesive 104. When the grooves 105 and 107 - 109 are formed in the electrooptic medium 103 to partition the electrooptic medium 103 into plural aperture elements 101, the grooves 105 and 107 - 109 can be made deep to the inside of the transparent substrate 102. Consequently, the capacity between adjacent aperture elements can be made small and the variable aperture device equipped with the variable aperture element 1' having such structure that no crosstalk is generated and the capacitor capacity is small can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable aperture device used in a recording optical system of an optical recording device such as a laser printer or a digital copying machine.

[Conventional technology]

In recent years, laser printers, digital copying machines, digital facsimiles, etc. scan an image forming means such as a photoreceptor with a laser beam modulated by digital information, develop the image formed on the image forming means, and then print it on paper. Optical recording devices have been developed that record information by transferring the information to, for example, a recording medium.

In such an optical recording device, in order to improve the accuracy of recorded information, it is also required to realize multi-gradation recording, and a means for changing the dot size corresponding to one pixel is required.

One possible means of changing this dot size is to use a variable aperture element (spatial light modulation element), but as this variable aperture element, for example,
It is known to form interdigital electrodes on the surface of a PLZT electro-optic crystal and independently control each bit to turn on and off the light to control the amount of light transmission.
125 x 6.5 ml 1 liter, 100 at 270 μm pitch
There are things in which bits are arranged (for example, 1 document "P L
Z T 5patial light modulato
r for a 1-D hologram mea+
ory”: Applied0ptics Vol, 19
．． No. 1 (1980)).

[Problem to be solved by the invention]

By the way, the drawbacks of the technology described in the above literature are as follows:
The response speed of the element is 30μsec for rising and 8μsec for falling.
It is at the slow point c.

The reason for this is that the bit size is large at 0.125 x 6.5 mm and the lead electrode for extraction is also long, resulting in a large capacitance of the capacitor. Also, because it has a planar electrode configuration.

The driving voltage is high, and crosstalk occurs due to the capacitance i between adjacent electrodes.

The present invention has been made in order to solve the above-mentioned technical problems9, and its first objective is to realize a variable aperture device equipped with a variable aperture element having a fast response speed. This is the realization of a variable aperture device equipped with a variable aperture element having a structure that reduces the capacitance of the capacitor. The second goal is to realize a variable aperture device with low driving voltage, and the third goal is to realize a variable aperture device without crosstalk.

[Means to solve the problem]

In order to achieve the above object, a variable aperture device according to the present invention is constructed by bonding an electro-optic medium and a transparent substrate with an optical adhesive and forming a groove in the electro-optic medium, and a plurality of light beams partitioned by the groove. A variable aperture element whose transmission region functions as an aperture element, an electrode formed on each aperture element of the variable aperture element, a recording integrated circuit for driving each aperture element of the variable aperture element, and the integrated circuit. and a circuit for connecting each aperture element are mounted on a substrate.

[For production]

In the variable aperture device according to the present invention, since the electro-optic medium constituting the variable aperture element and the transparent substrate are bonded together with an optical adhesive, grooves are formed in the electro-optic medium and the electro-optic medium is partitioned by the grooves. When forming multiple aperture elements, the grooves can be deepened into the transparent substrate, which can reduce the capacitance between adjacent aperture elements, resulting in a variable capacitor with a structure that reduces the capacitance. A variable aperture device with an aperture element is realized.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1(a) and 1(b) are schematic configuration diagrams showing one embodiment of a variable aperture device according to the present invention, and FIG. 1(a) is a side view seen from a direction perpendicular to the optical axis; (b) is a plan view seen from the optical axis direction.

In FIGS. 1(a) and 1(b), variable aperture device 1
The aperture element 1' is fixed with an adhesive, an alloy, etc. to a ceramic substrate 2 having an opening in the laser beam r transmission area, and a wiring pattern is printed on the ceramic substrate 2, and a driving integrated circuit 6 is attached.゜7 has been implemented. The electrode lead terminal of each aperture element (described later) of the variable aperture element 1' is connected to the wiring pattern on the ceramic substrate 2 by a bonding wire 5, and each aperture element is is turned ON-OFF.

Note that, as shown in FIG. 1, a polarizer 3 and an analyzer 4 are arranged at right angles before and after the variable aperture device 1.

Next, variable aperture element 1' of variable aperture device 1
The configuration will be explained in more detail.

FIGS. 2(a), (b), and (c) show variable aperture element 1.
Figures (a) and (c) are side views when viewed from two directions perpendicular to the optical axis, and (b) is a diagram when viewed from the optical axis direction. be.

In FIGS. 2(a), (b), and (c), the variable aperture element 1' is bonded to an electro-optic medium 103 and a transparent substrate 102 with an optical adhesive 104, and the electro-optic medium 10
Grooves 105, 107, 108, and 109 are formed in 3.

A plurality of light transmitting regions partitioned by each groove 105, 107, 108, 109 are an aperture element 101.
It is configured to function as

More specifically, first, PL is used as the electro-optic medium 103.
Using ZT electro-optic crystal, PLZT electro-optic crystal 103
and a transparent substrate 102 are integrated with a transparent optical adhesive 104. Here, glass is used as the transparent substrate 102, but in order to efficiently dissipate the heat generated during operation,
A transparent substrate with better thermal conductivity is used, and in this case, for example, a sapphire substrate is used.

Next, grooves are cut in the PLZTt pneumatic crystal 103 to form a plurality of prismatic protrusions (light transmitting regions) to form the aperture element 101.
The size is approximately μm×50 μm×100 μm, and electrodes 106 are formed on the side walls of the prism.

Each of these prismatic projections is cut into a plurality of pieces by grooves 108 and grooves 109 formed by a dicing saw (diamond cutter). Note that the groove 108 remains within the electro-optic crystal 103, and the groove 109 remains within the electro-optic crystal 1.
03 and reaches inside the transparent substrate 102.

Next, the manufacturing process of this variable aperture element will be explained in more detail.

First, 300 μm thick PLZT with optical polishing on both sides.
The electro-optic crystal 103 and the transparent substrate 102 are bonded together with an ultraviolet curable transparent adhesive, and grooves 105 and 107 with a depth of about 200 μm are formed on the other surface of the electro-optic crystal 103 using a dicing saw. Then, a light transmitting area is left between the grooves 105 and 107, protruding in the shape of a line with a width of 50 μm. In addition, the width of grooves 105 and 107 should be 1 mm or more, or
Alternatively, it may cover the entire surface of the crystal, leaving a light transmitting region.

In this state, the aluminum electrode film 106 extends from the side wall of the light transmitting region protruding like a line to the groove 105, 107.
is formed by sputtering or the like. After forming the electrode film 106, a depth of 250 mm is formed in the direction perpendicular to the grooves 105 and 107.
Dig multiple grooves 108 with a groove width of 50 μm at a pitch of 100 μm, 1! In addition to separating the poles, a plurality of prismatic protrusions are formed as described above, and the aperture element 10
Form 1. Then, a further groove @20 μm groove 109
Dig into the transparent substrate with a 100 μm pinch to a depth of 50 μm. This groove 109 is for preventing crosstalk between the aperture elements 101.

Now, as described above, an aperture element 1' having a plurality of aperture elements 101, which are light ON/OFF regions, arranged in a row is formed.

Next, the operation of the variable aperture device 1 according to the present invention including the variable aperture element 1' will be described.

FIG. 3 shows the operating principle of the variable aperture device 1 having the configuration shown in FIG. 1, in which the polarizer 3. The analyzers 4 are orthogonal to each other and set at an angle of 45° with respect to the direction of the electric field applied to the variable aperture element 1'. Further, FIG. 3 shows an example of an output pattern when a parallel laser beam is input as incident light. In this example, the three central aperture elements 101 are in a light transmitting state, and the remaining four aperture elements 101 are in a light blocking state.

Now, set the input light intensity to 11 and the output light intensity to 11. When considered within one aperture element, the following relationship holds true.

Io=I+sin”(r/2)”
(1) However, r=(i/λ)・t−n03・R1・E
2λ: wavelength, t thickness of near aperture element no: refractive index, E: electric field strength R6: second-order electro-optic constant Here, equation (1) is expressed when the phase difference r is mπ (m is an odd number). is the maximum. That is, when the aperture is in a light transmitting state and m'π (m' is an even number), I.

becomes the minimum, and the aperture is in a light-blocking state.

Therefore, according to this operating principle, it is possible to control the opening and closing of any aperture element by independently applying a voltage to each aperture element 101, and it is possible to control the light transmitted through the variable aperture element 1'.

Next, FIG. 4 is a side view showing another embodiment of the variable aperture element, and corresponds to FIG. 2(a).

The difference between this embodiment and the embodiment shown in FIG.
The reason is that processing was performed using a dicing saw until reaching 02. That is, by processing the grooves 205 and 207 in this manner, it is possible to reduce the area in which the electro-optic crystal having a large dielectric constant and the electrode come into contact, and therefore, the inter-electrode capacitance can be further reduced.

Next, FIGS. 5(a) and 5(b) are schematic configuration diagrams of an optical system showing an embodiment in which the variable aperture device according to the present invention is applied to a recording optical system of a laser printer. FIG. 3A is a diagram showing the arrangement of the optical system on a plane superimposed on the deflection scanning plane of the rotating polygon mirror 12 and including the optical axis, and FIG.

In FIGS. 5(a) and 5(b), the semiconductor laser LD
The emitted light is made into parallel light by the coupling lens 10, and then the plane of polarization is rotated by the λ/2 plate 11 so that the polarization direction of the light beam is 458 times the sub-scanning direction. The beam emitted from the λ/2 plate 11 is transmitted through the cylinder lens C.
The light is focused onto the variable aperture device 1 by the LI. Here, the variable aperture device II is arranged so that the individual aperture elements of the aperture element section are lined up in the sub-scanning direction.

This variable aperture device! The output beam controlled by 1 is converted into a beam by a lens Ll and a cylinder lens CL2, is deflected and scanned by a rotating polygon mirror 12, and is focused and imaged on a scanned surface 14 by a toroidal fθ lens 13.

Here, what is important in the recording optical system is that the variable aperture device 1 and the surface to be scanned 14 are in a conjugate relationship in terms of image formation. In other words, the element surface of the variable aperture device 11 is imaged on the scanned surface.

Next, a specific example of variable dot diameter in the recording optical system having the above configuration will be described.

FIG. 6 shows the dot diameter in the sub-scanning direction changed by the variable aperture device H1. That is, the semiconductor laser LD is controlled by the image signal, and at the same time, each of the seven virtual elements of the variable aperture device is controlled according to the density of the image signal, thereby realizing multilevel gradation recording.

FIG. 7 shows an example in which the dot diameter in the sub-scanning direction is varied by a variable aperture device, and the dot diameter is varied in the main-scanning direction by pulse width modulation driving of a semiconductor laser.

Incidentally, by combining the example shown in FIG. 6 with multilevel modulation (power modulation) of a semiconductor laser, variable dot diameter recording is also possible. It is also possible to realize multilevel gradation recording by combining dot diameter variation using a variable aperture device, dot diameter variation using pulse width modulation, and dot diameter variation using multilevel modulation (power variation: [).

(Effects of the Invention) As explained above, in the variable aperture device according to the present invention, the electro-optic medium constituting the variable aperture element and the transparent substrate are bonded together with an optical adhesive, so grooves are formed in the electro-optic medium. When forming a plurality of 7-vertical elements by partitioning the electro-optic medium with this groove, the groove can be made deep into the transparent substrate, thereby reducing the capacitance between adjacent aperture elements. Therefore, it is possible to realize a variable aperture device including a variable aperture element that has a structure that reduces the capacitance of the capacitor and can prevent the occurrence of crosstalk.

Furthermore, in the variable aperture device according to the present invention, since the length of the electrode lead that contacts the electro-optic crystal that constitutes the aperture element can be shortened, the capacitance of each aperture element is small, and therefore, driving with high response speed is possible. .

In addition, in the variable aperture device according to the present invention, since the driving electrode is formed on the side wall of the prismatic projection constituting the aperture element, the optical length is lengthened and at the same time an electric field is effectively applied, so low voltage driving is possible. It becomes possible.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are schematic configuration diagrams showing one embodiment of a variable aperture device according to the present invention, and FIG. 1(a) is a side view seen from a direction perpendicular to the optical axis; (b) is a plan view seen from the optical axis direction, and FIG. 2 (a). (b) and (C) are diagrams showing the structure of the variable aperture element, in which (a) and (c) are side views when viewed from two directions perpendicular to the optical axis, and (b) is a diagram showing the structure of the variable aperture element. 3 is an explanatory diagram of the operating principle of the variable aperture device configured as shown in FIG. 1; FIG. 4 is a side view showing another embodiment of the variable aperture element; FIG. Figures (a) and (b) are schematic configuration diagrams of an optical system showing an embodiment in which the variable aperture device according to the present invention is applied to a recording optical system of a laser printer, and (a) is a rotating polygon mirror. Figure 12 shows the optical system arrangement on a plane perpendicular to the deflection scanning plane and including the optical axis; FIG. 6(b) shows the optical system arrangement on the deflection scanning plane; FIGS. 6 is an explanatory diagram showing a specific example of variable dot diameter in the recording optical system shown in FIG. 5. FIG.

Claims (1)

[Claims] A variable aperture element, which is formed by bonding an electro-optic medium and a transparent substrate with an optical adhesive and forming grooves in the electro-optic medium, and in which a plurality of light transmission areas partitioned by the grooves function as an aperture element; An electrode formed on each aperture element of the aperture element, a driving integrated circuit for driving each aperture element of the variable aperture element, and a circuit connecting the integrated circuit and each aperture element are mounted on a substrate. A variable aperture device characterized by: