JP2002098821A - Display device, display method and optical disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk cartridge which does not require processing accuracy of a diffraction grating when a pattern such as characters, figures or the like is to be displayed by diffracted light by a diffraction grating formed in the shell of an optical disk. SOLUTION: The optical disk cartridge has an optical disk (14) having guide grooves for tracking control formed into a spiral or concentric form and a shell (11) having a transmission type diffraction grating (16). The pattern to be displayed is visualized by forming the transmission type diffraction grating (16) corresponding to the pattern in such a manner that when natural light transmitted and diffracted through the transmission type diffraction grating (16) is reflected and diffracted on the optical disk (14) and the reflected light (-first order diffracted light) entering the back face of the transmission type diffraction grating (16) exits perpendicular to the shell 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for displaying an arbitrary pattern such as a character or a figure by combining a transmission type diffraction grating and a reflection type diffraction grating.

[0002]

2. Description of the Related Art A disk-shaped recording medium such as an optical disk or a magneto-optical disk is housed in a case composed of two upper and lower shells and is treated as an optical disk cartridge. Conventionally, in order to display characters, symbols, figures, diagrams, etc. (for example, logos) on the surface of an optical disk cartridge, characters, symbols, etc. are printed directly on the surface of the shell, or the surface of the shell is made uneven. The light is scattered or diffracted by processing.

[0003]

However, printing on the surface of the shell requires a printing cost. In addition, in order to change some colors of characters, symbols, and the like, it is necessary to increase the number of ink colors, which further increases the printing cost.

Further, when the surface of the shell is processed into an uneven shape to scatter or diffract light to visualize characters, symbols, etc., the color of the display portion cannot be changed. If a diffraction grating is formed on the shell, the color of the display portion can be changed, but in this case, it is necessary to form a reflective film for reflecting light on the back surface of the shell, which increases the manufacturing cost. become.

When the number of times of diffraction of incident light is one, it is necessary to narrow the interval between the diffraction gratings in order to obtain a predetermined diffraction angle, which requires a correspondingly high processing accuracy.

Accordingly, an object of the present invention is to provide an optical disk cartridge which does not require processing accuracy of a diffraction grating when displaying a pattern such as a character or a figure by diffracted light from a diffraction grating formed on a shell of the optical disk. And

Another object of the present invention is to provide a display device and a display method for displaying an arbitrary pattern such as a character or a figure by combining a transmission type diffraction grating and a reflection type diffraction grating.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a transmission type diffraction grating and a reflection type diffraction grating are prepared, and natural light transmitted and diffracted by the transmission type diffraction grating is used in the reflection type diffraction grating. By forming the transmission diffraction grating corresponding to the pattern to be displayed, so that the reflected light is reflected and diffracted, and the reflected light incident on the back surface of the transmission diffraction grating is emitted in one direction,
Visualize the pattern. The diffraction order of the reflection type diffraction grating is preferably + 1st order or -1st order.

[0009] The direction of emission of reflected light for visualizing a pattern out of the reflected light that is transmitted and diffracted by the transmission type diffraction grating and reflected and diffracted by the reflection type diffraction grating is reflected by the reflection type diffraction grating without passing through the transmission type diffraction grating. It is preferable to form a transmission type diffraction grating so as not to coincide with the emission direction of the natural light reflected and diffracted by the above. With this configuration, the pattern can be displayed relatively bright.

An optical disk cartridge according to the present invention includes an optical disk having a spirally or substantially concentrically formed groove, and a shell having a transmission type diffraction grating. A transmission diffraction grating corresponding to the pattern to be displayed is formed so that the natural light transmitted and diffracted by the transmission diffraction grating is reflected and diffracted on the optical disk, and the reflected light incident on the back surface of the transmission diffraction grating is emitted in one direction. To visualize the pattern.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an optical disk cartridge. The optical disk cartridge 10 has a configuration in which a magneto-optical disk 14 is housed by two upper and lower shells 11 and 12. The shells 11 and 12 are molded from a transparent member such as polycarbonate or ABS resin, and are configured to transmit natural light. Therefore, the shell 11,
The magneto-optical disk 14 housed inside 12 can be seen through from the outside. The shell 11 is provided with a shutter 13 for the playback device to access the optical disc. The shutter 13 has a structure that opens when an optical disk is inserted into the playback device and closes when the optical disk is removed from the playback device.

A diffraction grating is formed on the surface of the shell 11 so as to correspond to the shape of a logo to be displayed on the optical disk cartridge 10. Natural light entering the shell 11 is emitted in one direction (for example, perpendicularly) to the shell 11. by doing,
The logo 15 is visualized and displayed. By appropriately setting the grating pitch of the diffraction grating, the inclination of the grating, the depth of the grating, and the like, the display color and brightness can be adjusted.

FIG. 2 is a sectional view of the optical disk cartridge. As shown in the figure, a diffraction grating 16 is formed in a predetermined area of the shell 11 corresponding to the shape of the logo to be displayed. The diffraction grating 16 shown in the figure is a blazed diffraction grating and has a sawtooth-shaped cross section. It is known that a diffraction grating of this type can obtain a very high diffraction efficiency when the angle of reflection or refraction of incident light on a slope matches the angle of diffraction. The diffraction grating 16 functions as a transmission type diffraction grating for transmitting incident light.

On the other hand, the magneto-optical disk 14 includes an acrylic substrate 17 in which grooves serving as guide grooves for tracking control are formed in a spiral shape along the track, and a recording layer 18 on which a TeOxGe thin film is vacuum-deposited on the acrylic substrate 17. ing. The track pitch formed on the acrylic substrate 17 is 1.61 μm, and the height of the land is 0.07 μm.
Therefore, the magneto-optical disk 14 functions as a reflection type diffraction grating.

In FIG. 1, an optical path indicated by a solid line is an optical path of natural light transmitted through the reflection type diffraction grating 16, and an optical path indicated by a dotted line is a portion where the reflection type diffraction grating 16 is not formed (for example, a reflection type diffraction grating). Shell 1 around the grid 16)
1 is an optical path of natural light transmitted through the light source 1. Both are shown in the same drawing for convenience of explanation.

In the above configuration, natural light incident on the diffraction grating 16 is diffracted and transmitted through the diffraction grating 16 and is incident on the magneto-optical disk 14 as indicated by the optical path indicated by the solid line. Since the magneto-optical disk 14 functions as a reflection-type diffraction grating, natural light incident on the magneto-optical disk 14 is diffracted and reflected by the optical disk 14 and is incident on the diffraction grating 16 again. Natural light incident on the back surface of the diffraction grating 16 from the optical disk 14 is diffracted again and exits the optical disk cartridge 10.

In FIG. 1, the + 1st order diffracted light, the 0th order diffracted light, and the −
Although the first-order diffracted light is illustrated, the diffraction grating 16 has a grating pitch, a grating inclination, and a grating depth such that only the −1st-order diffracted light is emitted perpendicular to the shell 11. Are formed based on values calculated in advance. When the line of sight of the observer who views the optical disk cartridge 10 is set perpendicular to the optical disk cartridge 10, the logo 15 is visualized by the -1st-order diffracted light that is diffracted and transmitted through the diffraction grating 16 and reflected and diffracted by the optical disk 14. . In this example, the emission direction of the −1st-order diffracted light is set to one direction, so that the −1st-order diffracted light is used as the diffracted light for visualizing the logo 15. By setting the emission direction to one direction, the + 1st-order or 0th-order diffracted light may be used as the diffracted light for displaying the logo 15.

On the other hand, natural light that has entered the portion of the shell 11 where the diffraction grating 16 is not formed passes through the shell 11 and enters the magneto-optical disk 14 as shown by the optical path indicated by the dotted line. Natural light that has entered the magneto-optical disk 14 is diffracted and reflected, enters the back surface of the shell 11 and
Inject outside. In the figure, the + 1st-order diffracted light, the 0th-order diffracted light, and the -1st-order diffracted light are illustrated as the diffracted lights emitted from the shell 11, and these diffracted lights (the diffraction indicated by the dotted line) are illustrated. It is preferable to form the diffraction grating 16 so that the emission direction of the light is different from the emission direction of the diffracted light for visualizing the logo 15 (-1st-order diffracted light indicated by the solid line).

As described above, the diffraction grating 16 is adjusted so that the emission direction of the diffracted light that is diffracted and reflected on the optical disk 14 without passing through the diffraction grating 16 does not coincide with the emission direction of the diffracted light for visualizing the logo 15. By forming, the intensity of light emitted from the periphery of the logo 15 viewed from an observer who has set the viewing direction perpendicular to the optical disc cartridge 10 can be relatively weakened, and the logo 15 can be displayed more brightly. can do. The direction of emission of the diffracted light for visualizing the logo 15 is not limited to the above. For example, between the 0th-order diffracted light and the + 1st-order diffracted light that are diffracted and reflected on the optical disk 14 without passing through the diffraction grating 16, It is set so as to be between the next diffraction light and the -1st diffraction light, between the + 1st diffraction light and the + 2nd diffraction light, and between the -1st diffraction light and the -2nd diffraction light. Is also good.

FIG. 4 shows a pattern of the diffraction grating 16 formed so that only the −1st-order diffracted light transmitted through the diffraction grating 16 is emitted perpendicular to the shell 11. In the figure, the solid line (thin line) indicates the track pattern of the magneto-optical disk 14, and the dotted line indicates the pattern of the diffraction grating 16 calculated so that only the −1st-order diffracted light is emitted perpendicular to the shell 11. ing. The solid line (thick line) indicates the pattern of the diffraction grating 16 in which the calculated pattern is actually formed on the shell 11 corresponding to the shape of the logo to be displayed on the optical disk cartridge 10. Similarly, diffraction grating 1
FIGS. 5 and 6 show the patterns of the diffraction grating 16 formed so that only the +1 order and 0 order diffracted lights that have passed through 6 are emitted perpendicular to the shell 11, respectively. When the zero-order diffracted light is used, there is no wavelength separation due to diffraction, so that it is difficult to perform wavelength separation at the diffraction grating 16. Therefore, the use of ± 1st-order diffracted light makes it easier to design the diffraction grating 16.

Next, the diffraction grating 15 shown in FIGS.
The procedure for calculating the pattern is described. As shown in FIG.
The plane including the optical disk cartridge 10 is defined as an XY plane.
Then, the axis perpendicular to this is set as the Z axis. And the incident light
The wave vector of (natural light) is k (k_x, K_y), Shell 1
The grating vector of the diffraction grating 16 formed in
K_s(K_sx, K_sy), The grayness of the magneto-optical disk 14
K_d(K _dx, K_dy). Greaty
Vector K_sCan be expressed as 2π / Δ
Yes, and the direction is the direction of the gradient. Where Δ is the diffraction grating
This is the lattice pitch of the child 16. The gray of the magneto-optical disk 14
The running vector K_dCan be similarly considered.

The natural light incident on the shell 11 is
6, the natural light diffracted and transmitted by the magneto-optical disk 14, reflected and diffracted by the magneto-optical disk 14, and further transmitted by the diffraction grating 16 is emitted perpendicularly to the shell 11, as shown in FIG. resulting vector obtained by adding the grating vector K _d for the grating vector K _s and the magneto-optical disk 14 of the diffraction grating 16 to k may if zero. Natural light for transmitting the diffraction grating 16 twice, the grating vector K _s of the diffraction grating 16 will be added twice. Therefore, it suffices to satisfy the following expression. Here _{k x + qK dx + 2K sx} = 0 k y + qK dy + 2K sy = 0, q is the diffraction order, for example, when calculating the -1-order diffracted light takes a value of -1, + 1-order diffraction When calculating for light, a value of +1 is taken. Now, as incident light, consider only light that comes to the front as viewed from the observer.
The direction of the observer's line of sight is taken on the Y axis, and the direction perpendicular to this is X
Take on the axis. X of the wave vector of incident light coming from the line of sight
Since the component is 0, k _x = 0. Therefore, the above equation can be expressed as the following equation. _{K sx = -qK dx / 2 K} sy = - (k y + qK dy) / from K _sx and K _sy determined by 2 above equation the coordinates (i, j) the height h (i, j) in determining the Can be. h
(I, j) can be obtained by the following equation.

(Equation 1) Here, K _sx (i, 0) is the X component of the grating vector at coordinates (i, 0), and K _sy (i, j) is the Y component of the grating vector at coordinates (i, j). Dx and dy are sampling intervals of each coordinate (i, j). When h (i, j) obtained by the above equation is drawn on a graph, it is as shown in FIG. 9A. Even if the shell 11 is processed into the shape shown in FIG.
By slicing the graph at a height d at which the phase difference between the natural light passing through the shell 11 and the natural light passing through the air is 2π, the graph shown in FIG. Here, the height d can be expressed as d = λ / (n−1), where λ is the wavelength of natural light of the color to be displayed and n is the refractive index of the shell 11. By quantizing this graph into 256 levels as shown in FIG. 10, 8-bit height data is obtained. That is, the maximum height is set to 255 levels (white) and the minimum height is set to 0 level (black), thereby quantizing the image into 256 grayscale monochrome colors.

Next, a procedure for forming the shell 11 having the diffraction grating 16 will be described with reference to FIG. The basic procedure is the same as the processing procedure of the optical disk stamper.
The laser light 22 emitted from the laser device 21 is reflected by a mirror 23
After the optical path is corrected so as to guide the light to the acousto-optic modulator 24, the intensity is modulated by the acousto-optic modulator 24. The transmissivity of the acousto-optic modulator 24 changes according to the input control signal, and can modulate the intensity of transmitted light. As the acousto-optic modulator 24, for example, a device utilizing the photoelastic effect of an acousto-optic element can be used.

The intensity-modulated laser 22 is guided by a mirror 26 to a movable optical bench 27. The movable optical bench 27 includes a mirror 28 and an objective lens 29, and guides the laser 22 to the objective lens 29 by the mirror 28. The laser 22 condensed by the objective lens 29 forms a laser spot on the photoresist 32 applied on the glass master 30 and exposes the photoresist 32. Glass master 3
Numeral 0 is chucked to the turntable 31 and is rotationally driven by a spindle motor. The exposure position is adjusted by controlling the number of rotations of the turntable 31 and the movement of the movable optical bench 27 in the horizontal direction.

Incidentally, the movable optical table 27 is a glass master 3
Since the photoresist 32 is exposed while moving from the inner circumference to the outer circumference of 0, that is, moving in the radial direction, the trajectory of the laser spot becomes spiral. Therefore, the exposure of the photoresist 32 must be performed based on the rθ coordinate system. On the other hand, since the generation of the height data of the diffraction grating 16 needs to be based on the XY coordinate system as described above, the coordinate conversion from the rθ coordinate system to the XY coordinate system is required.

The coordinate system of the drawing pattern of the shell 11 will now be described with reference to FIG. In the figure,
Reference numeral 40 denotes a rotation center of the glass master 30, and reference numeral 41 denotes a pattern drawing area of the shell 11. As the rθ coordinate system, arcs are set at 0.9 μm intervals around the rotation center 40. From the rotation center 40 m th arc of radius r _m
When a _{r m + 1 -r m = 0.9μm} . Furthermore, 193,200 present Draw straight line passing through the center of rotation 40, n th straight line predetermined reference line (e.g., below Y axis) and angle theta _n formed between and an equal angle, each of the adjacent straight eggplant, θ _{n + 1} -θ _n = 2π / 193200 (ra
d). In the figure, a grid indicated by a dotted line is an XY coordinate system, and coordinate points are defined at a pitch of 0.9 μm in both the X and Y directions. In the present embodiment, the area of the drawing area 41 is X
5000 × 5000 points were set in the Y coordinate system. In the figure, the hatched portions indicate the portions to be irradiated with the laser spot, and the darker the hatching, the higher the exposure power.

While performing the exposure processing, the signal generator 25
Represents the coordinates of the exposure position of the laser spot as X from the rθ coordinate system.
The data is converted into a Y coordinate system, and height data of the diffraction grating 16 at the exposure position is calculated in real time. The calculation procedure of the height data is as described above. The height data is converted into an analog signal by a D / A converter, and
Control signal. The acousto-optic modulator 24 is a laser beam 22
Is modulated to the exposure power corresponding to the height data.

After the completion of the exposure process, the photoresist 32 is developed, a conductive thin film is formed on the surface, and this is electroformed to form a mold. When the resin is molded using this mold, the shell 11 having the diffraction grating 16 formed on the surface can be molded. The molding of the shell 11 can use an injection molding method, a 2P method (photo polymarization method), or the like.

As described above, by adopting a configuration in which the height data of the diffraction grating 16 is calculated in real time while performing the exposure processing, the storage capacity is reduced as compared with the case where the height data is stored in an external storage device in advance. Need less. Therefore,
Exposure processing can be performed regardless of the capacity of the external storage device.

In the above description, a blazed diffraction grating is given as an example of the diffraction grating 16 formed on the surface of the shell 11, but a binary diffraction grating as shown in FIG. 3 may be used. It is known that a binary diffraction grating has a step-like cross-sectional shape and exhibits high diffraction efficiency like a blazed diffraction grating. Although the binary diffraction grating shown in FIG. 1 has two levels, the number of levels is not particularly limited. In a binary diffraction grating, the diffraction efficiency increases as the number of levels increases. When the number of levels is binary, it is about 40% as compared with a blazed diffraction grating, and when the number of levels is eight, it is eight.
It will be about 30% efficient. Further, in the above description, a magneto-optical disk is given as an example of the optical disk, but the present invention is not limited to this, and the present invention is also applicable to an optical disk housed in a shell such as an MO or a DVD-RAM.

According to the present invention, since the diffraction grating formed on the shell is used as a transmission diffraction grating and the optical disk is used as a reflection diffraction grating, natural light incident on the shell is diffracted a plurality of times. As a result, the light can be emitted out of the shell, and a predetermined diffraction angle can be obtained even when the processing accuracy of the transmission type diffraction grating is low. Also, the shell can be molded by a conventional molding process.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical disk cartridge.

FIG. 2 is a sectional view of an optical disk cartridge.

FIG. 3 is a sectional view of an optical disk cartridge.

FIG. 4 is an explanatory diagram of a diffraction grating pattern using -1st-order diffracted light.

FIG. 5 is an explanatory diagram of a diffraction grating pattern using + 1st-order diffracted light.

FIG. 6 is an explanatory diagram of a diffraction grating pattern using zero-order diffracted light.

FIG. 7 is an explanatory diagram of a coordinate system for obtaining the height of a diffraction grating.

FIG. 8 is an explanatory diagram of a vector sum.

FIG. 9 is a graph of h (i, j).

FIG. 10 is an explanatory diagram when quantizing a graph of h (i, j).

FIG. 11 is a configuration diagram of an exposure apparatus.

FIG. 12 is an explanatory diagram of a coordinate system of a laser drawing area.

[Explanation of symbols]

10 optical disk cartridge, 11 shell, 12
Shell, 13 ... Shutter, 14 ... Optical disk, 15 ...
Logo, 16: diffraction grating, 17: acrylic substrate, 18: recording layer, 21: laser device, 22: laser beam, 23: mirror, 24: acousto-optic modulator, 25: signal generator, 26
... mirror, 27 ... moving optical table, 28 ... mirror, 29 ... objective lens, 30 ... glass master, 31 ... turntable,
32: photoresist, 40: rotation center, 41: drawing area

Claims (11)

[Claims] 1. A transmission type diffraction grating comprising a transmission type diffraction grating and a reflection type diffraction grating, wherein natural light transmitted and diffracted by the transmission type diffraction grating is reflected and diffracted by the reflection type diffraction grating, and reflected light incident on the back surface of the transmission type diffraction grating. A display device that visualizes the pattern by forming the transmission diffraction grating corresponding to a pattern to be displayed such that the light is emitted in one direction. 2. The diffraction order of the reflection type diffraction grating is +1.
The display device according to claim 1, wherein the display device is of the first order or the first order. 3. The transmission direction of the reflected light for visualizing the pattern, out of the reflected light that is transmitted and diffracted by the transmission type diffraction grating and reflected and diffracted by the reflection type diffraction grating, is transmitted through the transmission type diffraction grating. 3. The display device according to claim 1, wherein the transmission diffraction grating is formed so as not to coincide with an emission direction of natural light reflected and diffracted by the reflection diffraction grating. 4. A transmission type diffraction grating and a reflection type diffraction grating are prepared, and natural light transmitted and diffracted through the transmission type diffraction grating is reflected and diffracted by the reflection type diffraction grating, and is reflected on the rear surface of the transmission type diffraction grating. A display method for visualizing the pattern by forming the transmission diffraction grating corresponding to a pattern to be displayed so that light is emitted in one direction. 5. The diffraction order of the reflection type diffraction grating is +1.
The display method according to claim 4, wherein the display method is of the first order or the first order. 6. The transmission direction of the reflected light for visualizing the pattern out of the reflected light that is transmitted and diffracted by the transmission type diffraction grating and reflected and diffracted by the reflection type diffraction grating is transmitted through the transmission type diffraction grating. The display method according to claim 4, wherein the transmission diffraction grating is formed so as not to coincide with an emission direction of natural light reflected and diffracted by the reflection diffraction grating. 7. An optical disk having a spirally or substantially concentrically formed groove, and a shell having a transmission type diffraction grating, wherein natural light transmitted and diffracted by the transmission type diffraction grating is reflected and diffracted on the optical disk, and An optical disc cartridge for visualizing a transmission type diffraction grating by forming the transmission type diffraction grating corresponding to a pattern to be displayed so that reflected light incident on the back surface of the transmission type diffraction grating is emitted in one direction. 8. The optical disk cartridge according to claim 7, wherein a diffraction order of the optical disk is +1 order or −1 order. 9. An optical disc that transmits and diffracts the transmission diffraction grating, and that the reflected light for visualizing the pattern of the reflected light reflected and diffracted by the optical disc does not pass through the transmission diffraction grating. 9. The optical disc cartridge according to claim 7, wherein the transmission type diffraction grating is formed so as not to coincide with an emission direction of natural light reflected and diffracted by the optical disc. 10. The optical disk cartridge according to claim 7, wherein the optical disk is a disk in which a guide groove for tracking control is formed in a spiral shape or a substantially concentric shape. 11. The optical disk cartridge according to claim 7, wherein the shell is formed of a transparent resin.