JPH10149085A - Holographic display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and easily correct the distortion of a display virtual image without minutely regulating the correction and deformation by means of try-and- error while confirming the display image by showing the deformation of a display body by a function when the display form of the display body is preliminarily deformed in order to correct the distortion of the display virtual image by hologram. SOLUTION: When a display image obtained when a rectangular body is displayed on a display body is curved upward, this deformation (x, y) → (x', y') is shown as x'=fx (x, y), y'=fy (x, y) by functions fx , fy of x, y. When the horizontal and vertical average magnification of hologram are m1 , m2 , respectively, the deformation (x, y) → (x1 , y1 ) of the display body for correction is deformed as x1 =hx (x, y), y1 =hy (x, y) by functions hx , hy . Thus, the display image of the rectangular form having no distortion which is enlarged horizontally m1 times and vertically m2 times can be provided by correcting every point of the display of the display body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic display device for projecting information necessary for an observer, and more particularly to a holographic display device for a vehicle for displaying driving information to a driver or the like.

[0002]

2. Description of the Related Art In recent years, as a method of displaying information to a driver of a vehicle such as an automobile, a display device such as a head-up display (hereinafter, referred to as HUD) has been used. In this method, optical information projected from an information projection means such as a liquid crystal display device is projected on a combiner having a half mirror or a hologram incorporated in a windshield or the like of an automobile, so that a driver can almost see from a driving state. The information can be read without moving.

In particular, a hologram using a combiner has a function of diffracting optical information toward a driver and a lens function, so that the optical information can be diffracted in the direction of the driver's field of view. Alternatively, it is possible to form an image at an arbitrary position without using an optical system such as a lens, and because the half width of the diffraction spectrum is narrow, high brightness without impairing the foreground brightness. It has a feature that a display image can be obtained, and is effective as a combiner of a display device.

FIG. 4 shows an example of a vehicle HUD. A transmission type liquid crystal display element 5 emitted from a light source 6 through a lens system 4
The light 3 including the information to be displayed that has passed through the hologram is irradiated on the hologram 2 provided on the windshield 7 of the vehicle body, diffracted, and visually recognized by the driver at the observation position 1. The lens system 4 has a function as a collimator. By giving the hologram 2 a magnification, the display images of the speed display 8 and the warning display 9 are formed as virtual images in the distance.

However, such a conventional HUD is very large because it is directly mounted on a vehicle. In addition, the information display source is assembled in the dashboard of the vehicle, whereas the combiner is provided on the windshield, so that mutual alignment and adjustment are difficult, and mounting on the vehicle is not easy. Further, there is a problem that the cost is high because the system is large-scale.

Therefore, it has been considered that the magnification of the hologram is further increased to reduce the size of the display system and the optical path length and the size of the entire system. However, in general, when the magnification of an optical element such as a hologram is increased, image distortion occurs. If the display image is distorted, the visibility is poor, and attempts have been made to reduce the image distortion as much as possible. For example, the hologram may be improved by optimizing the exposure. In the case where the image distortion cannot be completely improved only by the hologram, a method of providing a correction optical system such as a relay lens system is known. However, the method of providing a correction optical system has a large effect of improving image distortion, but requires a large-scale lens system, which eventually results in a large-scale system, which does not meet the purpose of reducing the size and cost of the system. .

Therefore, instead of providing a correction optical system,
Japanese Unexamined Patent Publication No.
257225.

[0008]

However, the conventional method of deforming the display is a method based on a trial and error. In other words, there has been a method of gradually changing the shape of the display body while observing the degree of deformation of the display image. For example, a method has been adopted in which a large number of masks imitating a display body are manufactured, and a mask capable of obtaining an optimum display image is selected.
Such a conventional method has a problem that it takes much time and cost. Further, even if it can cope with simple image distortion, it cannot cope with complicated deformation such as asymmetric distortion. Further, even in the case of simple image distortion, there is a problem that correction of a simple figure is possible but correction of a complicated display pattern such as a character cannot be performed.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a holographic display device which has not been known so far.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a light source and a display for displaying information to be displayed, and generates information to be displayed as light. In a holographic display device having an information display source and a combiner provided with a hologram for diffracting the light toward an observer and displaying the hologram as a virtual image, the display body is provided with a hologram in advance to correct the deformation of the display virtual image by the hologram. The display shape is deformed, the coordinates of the display on the display body surface are (x, y), the coordinates of the virtual image on the virtual image plane are (x ′, y ′), and the deformation of the virtual image displayed by the hologram (x, y). → (x ', y') represents a function f _x, f _y by _{x '= f x (x,} y), y' = f y (x, y) , the
Assuming that the average magnification in the horizontal direction of the hologram is m ₁ and the average magnification in the vertical direction of the hologram is m ₂ , the deformation (x, y) → (x ₁ , y ₁ ) of the display body is represented by the functions h _x , h _The present invention provides a holographic display device characterized in that y is represented by x ₁ = h _x (x, y) and y ₁ = _hy (x, y).

The functions h _x and h _y are x ′ = m ₁ × x =
f _x (x ₁ , y ₁ ), y ′ = m ₂ · y = _fy (x ₁ , y
₁ ) Meet.

[0012]

The present invention models the deformation of a display image due to a hologram and provides a general basic principle for correction. For this purpose, first, an orthogonal coordinate system is provided on the display body surface and the display image surface. That is, an x, y rectangular coordinate system having the origin at the center of the display body plane and an x ', y' rectangular coordinate system having the origin at a point on the display image plane which intersects with the optical axis connecting the viewpoint center and the hologram center. is there. If the display surface is curved, a virtual plane including the origin is considered and a display image projected on the plane is considered.

Hereinafter, the principle of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating the principle of the present invention. It is assumed that a display image obtained when a rectangular display is performed on the display body is distorted upward. This transformation (x, y) →
(X ', y') in the present invention represents x, the function f _x of y, x by _{f y '= f x (x} , y), y' = f y (x, y) and. When the average magnification of the hologram is m ₁ and m _{2 in the} horizontal direction and the vertical direction, respectively, the deformation (x, y) → (x ₁ , y ₁ ) of the display body for correction is calculated by the functions h _x and h _y. It is a feature of the present invention that the deformation is performed as x ₁ = h _x (x, y) and y ₁ = _hy (x, y). Where the function h
_x, h _y is _{x '= m 1 · x =} f x (x 1, y 1), y'
= M ₂ · y = f _y (x ₁ , y ₁ ).

By correcting (moving) each point of the display on the display in accordance with the principle of the present invention, for example, FIG.
As a result, a rectangular display image having no distortion and magnified by m ₁ times in width and m ₂ times in height can be obtained. Here, (x ₁ ,
y ₁ ) is an uncorrected point (x, y) in the x, y rectangular coordinate system.
It represents a point obtained by correcting (moving) y) by the functions h _x and h _y , and does not represent a coordinate system different from the x, y orthogonal coordinate system.

Specific examples of the functions f _x , f _y , h _x , and h _y will be described. As an example, consider a horizontal line of a distorted display image. x ',
In the y 'orthogonal coordinate system, the horizontal line is a curve, and y' of a point on the line can be generally approximated by a polynomial of x '. Naturally, the higher the order, the more strict approximation is obtained. However, in the case of a holographic display device, a quadratic expression is sufficient for practical use. Therefore, in the transformation (x, y) → (x ′, y ′), y ′
May be represented by a quadratic expression of x. That is, y ′ = a · x ²
+ B.x + c (*).

However, as can be seen from FIG. 1, the way the horizontal line bends is different between the upper and lower sides. That is, the coefficients a, b, and c in the above equation are also functions of y. Therefore, a, b and c are also y
Of the form of the quadratic expression ^{A · y 2 + B · y} + C, to organize coefficients is substituted into the above equation (*) deployment. If the higher-order x ² y ² term is ignored, then y ′ = f _y (x, y) = k ₁ × ² +
_{k 2 · x + k 3 ·} x 2 y + k 4 · xy 2 + k 5 · y 2 +
k ₆ · y + k ₇ is obtained. Here, k _{1 to} k ₇ are coefficients obtained by developing and arranging the above two equations, and a, b, c, A,
It is represented by a polynomial such as B or C. Other f _x , h _x , h
_y is represented by the same formula.

In the present invention, modeling of image distortion and modeling of correction deformation of a display body are performed using an x, y orthogonal coordinate system.
Needless to say, modeling is possible in other coordinate systems such as a polar coordinate system. However, they are mathematically equivalent to the present invention and are not essentially different from the present invention. In view of the fact that generally used displays are rectangular, the present invention employs an x, y orthogonal coordinate system. This is the most preferable coordinate system in view of the shape of the display.

In the present invention, modeling is started from a quadratic expression as a specific function form. As a matter of course, a higher-precision approximation can be obtained by using a higher-order polynomial. Therefore, the shape of the equation may be derived in the above manner as necessary. However, in general, considering the resolution of the display body and the discriminating ability of the observer, the quadratic expression shown in the present invention can be said to be practically sufficient.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the present invention, the values of a point (x, y) on a display element and a corresponding point (x ', y') on a virtual image plane are calculated for some combinations. You have to know. For example, it is the coordinates of a rectangular grid point on the display element shown in the upper left of FIG. 1 and a rectangular grid point convexly curved on the display image shown in the upper right.

There are several ways to do this. For example, there is a method of calculating coordinates of a point on a display element and a corresponding point on a virtual image plane by simulation based on a ray tracing method. According to this method, if the conditions such as the exposure arrangement of the hologram and the arrangement of the optical components at the time of reproduction can be determined, the shape of the display image obtained with respect to the shape of the display element can be freely calculated. is there. There is also a method based on actual measurement. A method of actually measuring the position of a point on the display element and then measuring the position of a corresponding point on the virtual image plane by providing a screen on the virtual image plane is conceivable.

Regarding the display element, in the case of the dot matrix display element, the position of the dot may be checked and converted from the dot interval to the position instead of the actual measurement. Alternatively, a lattice-like evaluation pattern may be used. On the other hand, regarding virtual images,
A method is also conceivable in which a virtual image is input not by a screen but by a two-dimensional light receiving device such as a CCD camera or an image pickup tube and converted into a position by image processing. In any method, in order to calculate a coefficient of a deformation function described below, it is necessary to find as many sets of points on the virtual image plane as possible corresponding to points on the display element. The coefficients cannot be determined with high precision unless there is at least a set of data equal to or more than the number of coefficients (7).

Next, the modified polynomial functions f _x , f _y ,
It is necessary to determine sets of coefficients k _{1 to} k ₇ for h _x and h _y , respectively. As the method, fitting by the least square method or the like can be preferably applied. That is, for example, f _y
In the case of, the point (x, y) on the display element obtained by the above method and the corresponding point (x ',
and the value 'y _{of)' y, y'calc = k 1} · x 2 + k 2 · x +
^{_{k 3 · x 2 y + k}} 4 · xy 2 + k 5 · y 2 + k 6 · y +
sum of squares of the difference from the calculated value y′calc obtained at k ₇ Σ (y′−
y′calc) A set of k ₁ to k ₇ that minimizes ² may be determined.

Also, the display deformation h for correcting the distortion of the virtual image.
_{As for x} and h _y , as described above, x ′ = m ₁ × x = f
_{x (x 1, y 1)} , y '= m 2 · y = f y (x 1,
x ₁ = h _x (x, y), y ₁ that satisfies y ₁ )
= H _y (x, y) may be determined by the least square method or the like.

There are mainly two ways to use the thus obtained deformation function. One is a case where a fixed display such as a so-called 8-segment or mask pattern is displayed. The pattern shape of the display element may be deformed in advance by the obtained deformation equation. Another is T
This is a case where a dot matrix type display element such as an FT liquid crystal display element is used. In this case, the positions of the dots to be displayed on the display element may be individually corrected according to the equation of the deformation. These may be calculated in real time, or there is a method using a conversion table. In addition, a deformed pattern may be stored in a memory and displayed.

It should be noted in the case of the dot matrix type display. The fixed pattern may correct the contour of the opening or the light emitting portion, but in the dot matrix, not only the contour of the figure but also the inside must be filled with dots.
Since the dot interval is finite, a gap may occur due to correction. In such a case, it is preferable to complement so as to fill the generated gap in order to obtain a good display image.

The hologram constituting the combiner in the holographic display device of the present invention is usually several tens mm.
From several μm to several tens of μm
Those having a thickness of about m are exemplified. This hologram is preferable in that a volume / phase hologram such as a Lippmann type can obtain a high diffraction efficiency, but a hologram such as an emboss type or a rainbow type can be widely used. The type of the hologram is not particularly limited, such as a transmission type and a reflection type.

The hologram in the present invention is laminated on a base material, and the base material is appropriately selected according to the use and the use condition. It goes without saying that the incident side of the reproduction light and the exit side of the diffracted light with respect to the hologram are transparent substrates, but this may be one that partially transmits light. For example, a non-colored transparent glass plate or a glass plate colored with bronze or green can be used as the base material. As a material of the base material, besides glass, a resin substrate such as acryl, polycarbonate, polyvinyl chloride, polyolefin, or the like, or a transparent crystal may be used. The thickness of the substrate may be a plate having a thickness of several mm, a film having a thickness of 1 mm or less, or a block having a thickness of several cm.

The display virtual image distortion correction method described in the present invention comprises:
The holographic display device is suitable for use in general holographic display devices in which light from an information display source that emits light containing information is diffracted toward an observer by a hologram and the observer visually recognizes a display image. In particular, a HUD in which a high-magnification hologram is sealed in a windshield, a HUD in which the hologram and the observer are arranged at an angle, or a combiner is pivotally supported by a main body provided with an information display source. It is preferably used as a combiner of a small so-called separately-installed HUD (see FIG. 2) having a short optical path length and placed on a dashboard to allow a driver or the like to visually recognize driving information. That is, the present invention can be preferably applied to the correction of the deformation of the virtual image due to the high magnification and the deformation of the image caused by the asymmetric arrangement.

FIG. 2 shows a separately placed HUD which is an example of the holographic display device of the present invention. A combiner 50 provided with a hologram on a transparent substrate is rotatably supported by a main body 51 of the HUD via a holding member 54. A leg 53 is provided on the bottom surface of the main body 51, and the leg 53 is held at an installation location of the HUD (for example, on a dashboard of a vehicle). An information display source including a light source 57 and a display body 56 is provided in the main body 51, and irradiates light containing information toward the combiner at an incident angle θ _i . The light is reflected and diffracted by the diffraction angle theta _d by the hologram,
The driving information is visually recognized by an observer (for example, a driver).

An information display source in a holographic display device typified by this separately mounted HUD has a function of emitting light for display, and heat is applied to a display body composed of a so-called light receiving type display element such as a liquid crystal display element. Cathode tube (HCT),
It irradiates light emitted from a light source such as a cold cathode tube, a fluorescent display tube (VF), a halogen lamp, a light emitting diode, and a semiconductor laser, or may have a combination of these functions.

When the holographic display device of the present invention performs color display, the liquid crystal display element includes
A color filter and a transmission type twisted nematic liquid crystal element, or a color liquid crystal display element including a super twisted nematic liquid crystal display element and the like can be preferably used, and a light ray emitted from one light source is irradiated as a light ray of a desired color. be able to. The display body has a shape deformed in advance so as to correct the distortion of the display virtual image as described above.

In this manner, light beams of a plurality of colors can be emitted from the same information display source. When these light beams of a plurality of colors are displayed at the same time, the display images are superimposed and displayed. In order to prevent the display images from overlapping, if necessary, a combination of a color filter and a light source or a color liquid crystal display element may be controlled so that light beams of a plurality of colors are not simultaneously irradiated.

Alternatively, the light source itself may be patterned and arranged to generate specific information as light without using a light receiving type display element. In the case where the above-mentioned light source is used in combination with the light receiving type display element, appropriate light collimating means such as a lens system and a curved reflecting mirror, and appropriate light guiding means such as a light guide plate are provided between the light receiving type display element and the light source. It may be arranged. Further, in the optical path before the light is projected on the hologram, if necessary, a light polarizing means or KN
A nonlinear optical element such as O ₃ may be provided.

When the holographic display device of the present invention is used for color display, if the distance from the combiner to the display image is the same for each color, color display can be performed on the same plane. It is possible to obtain a three-dimensional image in which the display image is observed at different distances depending on the color.

When the holographic display device of the present invention is used for a vehicle, the information to be displayed is appropriately selected depending on the display purpose, and may be a speedometer, a tachometer, a shift lever display of a vehicle, and various other information. Warning lamps, navigation information, information on ancillary equipment such as air conditioners and audio equipment, and the like.
Further, it is of course possible to display information from outside the vehicle such as road information and parking lot availability information. For aircraft and ships, various information related to vehicle operation and duties, such as position and orientation information such as latitude, longitude, altitude, direction of travel, weather information, radar obstacle information, fish finder information, etc. can be considered. . The observer is mainly a driver of a vehicle such as a vehicle, but may include a passenger seat and other passengers, and all of these persons.

The hologram laminate and holographic display device of the present invention can be used for various purposes other than the example applied to the above-mentioned HUD for automobiles. For example, a virtual image corner marker indicating a corner of a vehicle, or
It can be widely applied to all display devices using a hologram, such as a prompter and a game.

[0037]

Embodiments of the present invention will be described below. In the example of FIG. 2, the combiner 50 is set so that θ _w = 65 ° with respect to the horizontal, the incident angle θ _i from the light source center to the hologram center is 65 °, the diffraction angle θ _d is 35 °, and the display body The distance from the center of 56 to the center of the hologram was 60 mm. Therefore, when the main body 80 is installed horizontally, the direction to the viewer's eyes is 10 ° from the horizontal.

In this embodiment, a hologram having a thickness of 20
A photosensitive material composed of a μm acrylic photopolymer was used, and a volume phase reflection hologram was used. The exposure of the hologram was performed using a dye laser 5 using rhodamine 6G.
The measurement was performed using light in which 74.5 nm light and 647.1 nm light of a Kr laser were coaxially superposed. As an optical system for expanding the laser light, two cylindrical lenses were used. The positions of the divergence points in the horizontal and vertical directions are substantially changed by the cylindrical lens. The distance from the exposure point to the hologram is set to 90 mm and 360 mm on the light source side (reference light side), and on the image side (object light side). The distance from the exposure point to the hologram was 360 mm and 1080 mm, respectively. The exposure angle is 63 ° on the light source side and 34 ° on the light source side with respect to the center of the optical axis. After the laser exposure, ultraviolet irradiation and heat treatment were performed to produce a hologram.

The hologram thus obtained had diffraction peaks at around 545 nm and 613 nm for 65 ° incidence, and the diffraction efficiencies were 70% and 50%, respectively. The full width at half maximum of wavelength was about 10 nm. When the display element 56 was arranged at a distance of 60 mm from the hologram, a display image enlarged about twice was obtained. The display image had a shape curved upwardly convex. It should be noted that a vivid two-color display was obtained in which the color tone of the display image was divided into a green region in a portion passing through a green transmission filter and a red region in a portion passing through a red transmission filter. If green and red diffracted lights are mixed without using a filter, a yellow display image can be obtained with the hologram of this embodiment. In addition, by appropriately adjusting the relationship between the intensity of the emission line of the light source corresponding to green and red, the transmittance of the filter, and the diffraction efficiency of the hologram, display images of various colors such as green, yellow green, yellow, orange, and red can be obtained. Obtainable.

An example of distortion correction of a display image will be described with reference to FIG. A display image when a rectangle having a width of 28 mm and a length of 14 mm was displayed on the display body as shown in the upper left was calculated by simulation. The positions of 5 points in each of the vertical and horizontal directions, a total of 25 points, were calculated. The display image curves upward and convex as shown in the upper right, and reproduces the deformation of the actual display image. When a function of the deformation was calculated by the least square method, k ₁ ~k ₇ = about f _x (- 7.
7 × 10 ^-8 , 2.00, -2.7 × 10 ^-8 , -1.4 ×
10 ⁻⁸ , −0.01, −3.2 × 10 ⁻⁷ , 4.5 × 10
^-6 , 2.1 × 10 ^-5 ), and for f _y , k ₁ to k
₇ = (− 0.02, −4.7 × 10 ⁻⁵ , −3.9 × 10
^-9 , -1.1 × 10 ^-6 , -2.4 × 10 ^-5 , -1.9 ×
10 ⁻⁶ , 1.5, 4.9 × 10 ⁻⁵ ).

Therefore, the display body was corrected and deformed in advance as shown in the lower left corner so that the display image became a rectangle as shown in the lower right corner. The function of this correction deformation was calculated by the least square method, and for h _x , k ₁ to k ₇ = (− 2.8 × 10
^-7 , 1.01, 1.3 × 10 ^-7 , 2.7 × 10 ^-5 , 5.
2 × 10 ⁻³ , 1.5 × 10 ⁻⁶ , −1.7 × 10 ⁻⁵ , −
2.5 × 10 ^-5 ), and for h _y , k ₁ to k ₇ =
(−0.014, 2.3 × 10 ⁻⁵ , 1.4 × 10 ⁻⁴ ,
2.0 × 10 ⁻⁷ , 1.3 × 10 ⁻⁵ , 1.1 × 10 ⁻⁴ ,
1.0, 4.3 × 10 ⁻⁴ ).

When the display of the display body was actually deformed and displayed in advance by the correction deformation function obtained as described above, a good display image without distortion could be obtained. As in the prior art, the correction deformation can be corrected quickly and easily without performing fine adjustment while checking the display image by trial and error, and the effectiveness of the present invention can be confirmed.

[0043]

According to the present invention, when the display shape of the display is deformed in advance in order to correct the distortion of the display virtual image due to the hologram, the deformation of the display (x, y) →
(X ₁ , y ₁ ) is converted to x ₁ = h by the functions h _x and h _{y.
x (x, y), y} 1 = h y (x, y) is represented by (In this _{case, x '= m 1 · x} = f x (x 1, y 1),
y ′ = m ₂ · y = _fy (x ₁ , y ₁ ), and x ′ = f
_x (x, y), y ′ = _fy (x, y); m ₁ : average magnification in the horizontal direction of the hologram; m ₂ : average magnification in the vertical direction of the hologram) Correction can be performed quickly and easily without fine adjustment while checking the display image.

In particular, since the above-mentioned deformation technique can be applied to the deformation of the display virtual image of various holograms, any holographic display device can quickly and easily realize the distortion correction of the display image.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the principle of distortion correction of a holographic display device of the present invention.

FIG. 2 is a sectional view showing an example of the holographic display device of the present invention.

FIG. 3 is a conceptual diagram showing an example of a distortion correction method for a holographic display device according to the present invention.

FIG. 4 is a conceptual diagram illustrating an example of a holographic display device.

[Explanation of symbols]

 1: Observer 2: Hologram combiner 3: Light containing information 4: Lens system 5: Display body 6: Light source 7: Windshield 8: Speed display image 9: Warning display image 50: Hologram combiner 51: Main body 53: Leg Part 54: holding member 56: display body 57: light source

Claims (5)

[Claims] 1. An information display source having a light source and a display body for displaying information to be displayed, the information display source generating information to be displayed as light, and a hologram for diffracting the light toward an observer and displaying it as a virtual image. In a holographic display device having a combiner provided with a hologram, the display body is previously deformed in display shape in order to correct deformation of a display virtual image by a hologram, and coordinates of display on the display body surface are represented by (x,
y), the coordinates of the virtual image on the virtual image plane are (x ′, y ′), and the deformation of the virtual image displayed by the hologram is (x, y) → (x ′,
y ') of the function f _x, f _y by _{x' = f x (x,} y),
When y '= f _y (x, y) and the average magnification in the horizontal direction of the hologram is m ₁ and the average magnification in the vertical direction of the hologram is m ₂ , the deformation of the display body is (x, y) → ( x ₁ ,
y ₁₎ is the function h _x, h _y by _{x 1} = h x (x,
a holographic display device represented by y), y ₁ = _hy (x, y). However, the function h _x, h _y is _{x '= m 1 · x =} f x (x 1, y
₁ ), y ′ = m ₂ · y = f _y (x ₁ , y ₁ ). 2. A function f _x , f _y , h _x , h _{y of the} transformation is a polynomial k ₁ · x ² + k ₂ · x + k ₃ · x ² y +
^{_{k 4 · xy 2 + k 5}} · y 2 + k 6 · y + be expressed in the form of k _7, wherein the holographic display device of claim 1. _{However, k 1, k 3, k} 4, k 5, k 6, k 7 is a coefficient. 3. The holographic display device according to claim 1, wherein the display of the display is a fixed pattern. 4. The holographic display device according to claim 1, wherein said display is a dot matrix type display. 5. The holographic display device according to claim 4, wherein when a gap is formed between the dots of the corrected dot matrix type display, the gap is corrected so as to fill the gap.