KR101875381B1 - Aspheric mirror for head-up display - Google Patents

Abstract

The present invention relates to an aspherical mirror for use in a head-up display device for a vehicle, wherein the surface of the aspherical mirror is divided into a plurality of regions having different refractive powers, and a coating layer is laminated on the surface of the aspherical mirror.

Description

[0001] ASPHERIC MIRROR FOR HEAD-UP DISPLAY [0002]

Field of the Invention [0002] The present invention relates to an aspherical mirror for head-up display, and more particularly to an aspherical mirror for head-up display comprising a plurality of sections having different refractive powers.

The head-up display for a vehicle includes various types of vehicle information such as arrow information for guiding the route change in the visible area (eye box) of the driver, text information for expressing the speed, etc. in cooperation with the navigation system on the windshield or in the form of an augmented reality Which is mounted on a vehicle which has recently been released.

When the head-up display is used, the driver does not need to move his or her eyes to the direction of the terminal providing the information in order to check the vehicle information. Since the head-up display image can be viewed while looking ahead, It is helpful.

A head-up display for a vehicle generates an image using a micro display device, and expands the magnification and image of the generated image through a projection optical system to provide the driver with a vehicle information image.

At this time, it is essential to have a function of adjusting the height of the eye box according to the change of the driver's eye level, and the information projected from the PGU (Picture Graphic Unit) is reflected through the aspheric mirror and displayed on the windshield.

In addition, the display height of the information displayed on the windshield is adjusted as a result by adjusting the angle of reflection of the aspheric mirror by rotating the motor connected to the aspherical mirror.

Since the windshield is shaped as an aspheric surface, the actual head-up display device for a vehicle reflects the aspheric surface mirror for a vehicle head-up display corresponding to the aspherical shape (i.e., curved surface) of the windshield of the vehicle type to display information on the windshield . However, when the display height of the information displayed on the windshield is changed as described above, screen distortion of up to 30% occurs due to the aspheric characteristics of the windshield.

In addition, a motor, a motor driver, a position sensor, a motor mechanism, and the like are required for driving the mirror, and a vibration of the image due to driving of the motor may occur.

Especially, it is required to develop a head-up display that can provide information to the driver regardless of the amount of light or background color outside the vehicle, while preventing the front view from being disturbed during operation by reducing the light loss of the aspherical mirror .

Korean Patent Publication No. 10-2016-0116139 Korean Patent Publication No. 10-2016-0090519

SUMMARY OF THE INVENTION It is an object of the present invention to provide a windshield display device capable of reducing screen distortion caused by aspheric characteristics of a windshield, And it is an object of the present invention to provide an aspherical mirror that can be applied to a head-up display that can be provided.

According to an aspect of the present invention, there is provided an aspheric mirror for a head-up display, which is used in a head-up display device for a vehicle, wherein a surface of the aspheric mirror is divided into a plurality of regions having different refractive powers, And a coating layer formed of a coating liquid containing a nickel paste, a resin and a solvent is laminated.

The plurality of regions may include one central mirror region and two or more outer mirror regions, and the refractive power of one outer mirror region may be greater than the refractive power of the central mirror region.

In addition, the resin may be composed of an acrylate monomer and a urethane acrylate oligomer, and the solvent may be a mixed solvent of methyl ethyl ketone and toluene.

The aspherical mirror according to the present invention is excellent in reflectance, optical characteristics and durability, so that the screen displayed on the windshield can be prevented from being distorted due to the aspheric characteristics of the windshield, To a head-up display capable of providing a head-up display.

Hereinafter, the present invention will be described in more detail. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

The aspherical mirror for head-up display according to the present invention is used in a head-up display device for a vehicle, wherein the surface of the aspheric mirror is divided into a plurality of regions having different refractive powers, and a coating layer is laminated on the surface of the aspherical mirror .

When the aspherical mirror reflects an image incident from the image output device in the head-up display, the surface of the windshield is not flat when projected onto the windshield, so that screen distortion due to aspheric characteristics may occur. The driver may not be able to recognize the entire information of the windshield clearly according to the amount of light. In particular, when the sharpness of the windshield is deteriorated at the outskirts of the windshield, there is a case where the driver can not properly identify the information displayed in real time.

For this reason, in the present invention, the aspherical mirror is divided into a plurality of regions, and the refracting power of the regions is made different, thereby improving the sharpness of the image projected onto the windshield.

That is, it is preferable that the plurality of regions constituting the aspherical mirror include one central mirror region and two or more outer mirror regions, and the refractive power of the outer mirror region is larger than the refractive index of the central mirror region.

The aspheric mirror is divided into a plurality of regions along the horizontal direction from the inside close to the windshield and the outside far from the windshield.

The aspheric shape is similar to a loose normal distribution curve, and its shape is not spherical or planar. Thus, the aspheric surface is a flattened shape in which the curvature decreases from the central portion to the peripheral portion, or the central portion is flat and the curvature increases toward the peripheral portion . That is, the curvature of the aspherical mirror changes from the central portion to the peripheral portion, and the refractive power also changes.

Therefore, the aspheric mirror is formed such that the refracting power of the mirror regions gradually increases from the inner side toward the outer side so that the refracting power at the boundaries of the mirror regions is the same. Thus, all the reflected images are displayed clearly on the aspheric windshield And distortion and astigmatism of the image can be minimized.

Further, since the refractive powers are the same at the boundaries of the respective mirror regions, it is possible to prevent the occurrence of the jump phenomenon at the boundaries of the mirror regions.

In one embodiment, the aspherical mirror may be divided into three regions, and two outer mirror regions may be defined around one central mirror region. The two outer mirror regions may be divided into a first outer mirror region near the windshield and a second outer mirror region farther from the windshield.

In this case, the ratio of angular widths along the X-axis direction of the first outside mirror region, the center mirror region, and the second outside mirror region may be 5: 3: 2 or 4: 3: 3 in the horizontal direction. That is, the first outer mirror region has the largest width, the widths of the central mirror region and the second outer mirror region are equal to each other, or the width of the second outer mirror region is minimized.

The area of the first outside mirror area must be the widest. This design may be advantageous to overcome the distortion of the reflected image and the inaccurate distance feeling.

In addition, the first outside mirror region is configured such that the refracting power is increased along the X-axis direction that is the horizontal direction from the outermost edge to the border with the center mirror region, and the refractive power at the boundary with the central mirror region can be designed to be the same. That is, the refractive power gradually increases along the X-axis direction in the first outside mirror region, thereby preventing occurrence of jump at the boundary between the inside mirror region and the center mirror region. Therefore, in the aspheric mirror according to the present embodiment, the refractive power of the first outside mirror region is formed to be larger than the refractive power of the central mirror region.

Further, the refractive power of the central mirror region increases along the X-axis direction from the boundary with the first outside mirror region to the boundary with the second outside mirror region, so that the refractive power at the boundary with the second outside mirror region may be the same. Further, the refractive power in the central mirror region can be gradually increased. As a result, it is possible to prevent the jump phenomenon from occurring at the boundary between the central mirror region and the second outside mirror region. Further, the refractive power of the second outside mirror region may increase along the X-axis direction from the boundary with the central mirror region to the outside edge. In the outer mirror region, the refractive power may gradually increase.

As a result, the aspheric mirror can project the incident image on the windshield in a clear and uniform resolution without distortion.

In addition, the aspheric mirror of the present invention forms a coating layer on the surface, which is applied to increase the brightness of the aspheric mirror and to improve the surface durability.

The coating layer may be formed of a coating liquid containing a nickel paste, a resin, and a solvent.

The nickel paste is formed by mixing a nickel powder having an average particle size of 1 to 50 탆, preferably 5 to 10 탆, with a resin, and the nickel paste is preferably contained in an amount of 2 to 10 parts by weight. When the average particle size of the nickel powder is smaller than 1 占 퐉 or larger than 50 占 퐉, the metallic luster of the mirror feeling can not be expressed. When the content of the aluminum paste is less than 2 parts by weight, the hiding power of the resin or solvent mixed in the coating solution is lowered. When the amount of the aluminum paste is more than 10 parts by weight, the brightness is significantly reduced.

Further, the resin is preferably composed of an acrylate monomer and a urethane acrylate oligomer. The acrylate monomer may be, for example, hydroxy ethyl acrylate (HEA), hydroxy ethyl methacrylate (HEMA), hydroxy propyl acrylate (HPA) ) And trimethylolpropane triacrylate (TMPTA) may be used, and it is preferable to blend such that the content ranges from 5 to 15 parts by weight. If the amount is less than 5 parts by weight, the strength of the coating film is weakened, and if it is more than 15 parts by weight, cracks may occur in the coating film.

The urethane acrylate oligomer may be exemplified by aliphatic urethane acrylate. The content of the urethane acrylate oligomer is preferably 5 to 25 parts by weight, more preferably 5 to 25 parts by weight, If it exceeds the weight part, drying of the coating liquid is slowed and the smoothness is adversely affected, so that it is preferably used within the above range.

The solvent used for the coating solution is preferably a mixed solvent of methyl ethyl ketone and toluene. Methyl ethyl ketone is an organic solvent required for improving the adhesion between the coating liquid and the surface of the mirror. Since the evaporation rate is high, Thereby increasing the mirroring effect. It is preferable that the methyl ethyl ketone contains 5 to 20 parts by weight. When the amount is less than 5 parts by weight, the adhesion of the paint becomes poor. When the amount exceeds 20 parts by weight, the surface of the coating film becomes rough. Therefore, desirable.

In addition, the toluene improves the adhesion of the coating liquid because of the slow evaporation rate, and serves to improve the spreadability of the coating liquid, and it is preferable to use 3 to 10 parts by weight. When the amount is less than 3 parts by weight, the adhesive strength of the coating solution deteriorates. When the amount exceeds 10 parts by weight, the substrate may be eroded.

Various additives may be added to the coating solution. To improve the brightness, a brightness improving agent may be added, and a spreadability improver and a slipping agent may be included. The brightness enhancer improves the brightness while preventing the occurrence of streaking on the coating film. For example, Lactimon can be used. Further, the spreadability improver may be a polyacrylate solution as an additive for improving thermal stability and re-stretchability. Further, the slip agent can be applied as a slip agent of silicone as an additive which improves the water-solubility of the paint material and maximizes the slip property of the paint. The additive is preferably added in an amount of 1 to 8 parts by weight.

When the above-mentioned coating liquid is applied to the surface of the aspherical mirror, the abrasion resistance, impact resistance, and temperature resistance of the mirror are improved.

In order to evaluate this, the pencil hardness, the adhesion test, the X-cut test, the heat shock test, and the humidity resistance test were performed on the aspheric mirror formed with the coating layer of the present invention.

The pencil hardness test was carried out two times in the direction of the pencil center by placing the tip of the pencil on the test surface at a load of 1 kgf at a 45 ° inclination after the surface of the tip of the pencil was flattened and the paint coated on the specimen was peeled or scratched .

The X-cut test was performed by using a blade to draw a line at each of the 11 locations at intervals of 1 mm in width and length, adhering the tape to the surface of the specimen so that no air bubbles would be generated, and then pulling it rapidly at an angle of 15 ° three times , It was judged that the case where the cubic-shaped deviation was within 5% of the total area based on the tape, and the surface was not peeled off.

The abrasion resistance test was carried out with an RCA tester at a load of 275 g and 80 cycles. When the base material of the test piece was exposed or there was no color contrast, it was judged to be acceptable.

In addition, in the thermal impact test, the specimen was allowed to stand at room temperature for 2 hours under the conditions of -40 ° C and 85 ° C for 45 minutes for 48 hours (32 cycles), and then X-cut was performed. And there was no change compared with that of the test.

Also, in the humidity resistance test, the specimen was allowed to stand at 60 ° C and 95% RH for 48 hours, then left at room temperature for 2 hours, and then subjected to X-cut once to show no change compared to the initial state of the specimen The case was judged as passing.

As a result of the above test, the aspherical mirror having the coating layer of the present invention was judged to be acceptable under all the test conditions.

However, the aspheric mirror without the coating layer was judged to have failed in the pencil hardness, abrasion resistance and adhesion test. When the aluminum paste was used instead of the nickel paste, the aspheric mirror was rejected in the heat shock test and the humidity resistance test, The characteristics of the coating layer of the aspheric mirror were influenced by the type of the aspherical mirror.

It is to be understood that the present invention is not limited to the above-described embodiments, but is defined by the claims, and those skilled in the art can make various changes and modifications within the scope of the claims It is self-evident.

Claims (5)

An aspherical mirror used in a head-up display device for a vehicle,
The surface of the aspheric mirror is divided into three regions having different refractive powers,
A coating layer is laminated on the surface of the aspheric mirror,
The three zones are composed of a first outside mirror zone near the windshield, a windshield and a second outside mirror zone far from the center, with one central mirror zone as the center,
The first outer mirror region, the central mirror region, and the second outer mirror region have a ratio of angular widths along the X axis direction of 5: 3: 2 or 4: 3: 3 in the horizontal direction,
Wherein the coating layer comprises a coating liquid containing a resin consisting of 5 to 15 parts by weight of nickel paste, acrylate monomer and 5 to 25 parts by weight of aliphatic urethane acrylate, 5 to 20 parts by weight of methyl ethyl ketone and 3 to 10 parts by weight of a mixed solvent of toluene And the aspherical mirror for head-up display. delete delete delete delete