JP2974593B2 - Image processing device for tire tread - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for measuring a contact surface pressure of a tire, a wear state of a tire surface, and the like. The present invention relates to a tire ground contact surface image processing apparatus capable of performing image processing of a tire ground contact state in a short time and performing measurement in a dynamic state in which a tire is rotated.

[0002]

2. Description of the Related Art A tire contact surface image processing apparatus disclosed in Japanese Utility Model Application No. 5-29529 has been proposed to measure the contact shape and contact pressure distribution of a tire. In this technique, a right-angle prism is provided below a glass plate on which a tire is mounted and supported, and a light source that emits pin spot light is provided as a light source below the right-angle prism, and a photomultiplier is used as a light receiving device. A tube is provided, and the light of the light source is received by the photomultiplier tube via a condenser lens or a mirror.

That is, the light from the light source is made into a spot-like light having a diameter of 0.1 to 1 mm, applied to a tire contact surface formed on a glass plate through a prism, and reflected light from the tire is received by a photomultiplier tube. An A / D converter, a central processing unit, and an image display device are sequentially connected to the photomultiplier tube, and the contact pressure of the tire is measured by measuring the amount of light absorption on the tire contact surface. The principle of this measurement is that "When the surface of a rubber similar to a tread rubber of a tire is polished or worn to a uniform roughness, when the rubber is pressed against the total reflection surface of the prism, 50% of true contact is made.
And the absorptance of light on the total reflection surface is proportional to about 0.9 power of the contact pressure. "
By measuring the presence or absence of light absorption, the tire contact shape and the contact area can also be measured.

[0004] The thickness of the reflected light that can be received by the photomultiplier tube is as fine as 0.1 to 1 mm in diameter as described above.
In order to perform the measurement over the entire area of the tire tread, the following means is required. That is, a light source and a photomultiplier tube are mounted on a plane parallel to the glass plate, and XY
A moving table that moves two-dimensionally in the axial direction is provided, and a moving mechanism that drives the moving table by a pulse motor (or a stepping motor) is required.

[0005]

When the above-described apparatus is used to measure the contact state of the tire, the light source must be located at hundreds to thousands of measurement points in order to measure the entire area of the planar tire contact surface. In addition, the photomultiplier tube must be moved, and it takes several tens of minutes to measure the entire area of the tire contact surface.

During this measurement, the tire to be tested must be kept stationary at the measurement position on the glass plate for several tens of minutes, and measurement in a dynamic state in which the tire is rotated is impossible. In addition, there is a problem that it is not possible to measure a tire contact state such as a contact area and a contact pressure distribution of the tire which are similar to a tire use state.

Accordingly, a first object of the present invention is to provide an image processing apparatus for a tire contact surface which can measure the state of the tire contact surface in a short time. A second object of the present invention is to provide an image processing apparatus for a tire contact surface, which can measure the condition of the tire contact surface in a dynamic state in accordance with the use of rotating the tire.

[0008]

According to the present invention, which has achieved the above two objects, a prism is provided at a lower portion of a tire, light is applied to the tire ground plane through the prism, and the reflected light is applied to a central processing unit. A light source that emits light is formed in a planar shape, is totally reflected on a tire contact surface , and the tire
A television camera that receives planar light partially absorbed by the tread surface through the prism is disposed, and the image of the television camera is processed to obtain a pressure at the tire tread surface.
A central processing unit capable of displaying a force distribution is connected to the television camera.

In the present invention, the cross section of the prism is formed in a triangular shape, and a tire is mounted above a portion corresponding to the bottom surface of the prism via a glass plate, and the tire is opposed to two inclined surfaces of the prism. Preferably, a light source or a television camera is arranged.

Further, according to the present invention, the cross section of the prism on which the tire is mounted is formed in a trapezoidal shape, the upper side corresponding to the tire mounting surface side, and the planar light source or the television is opposed to the two inclined surfaces of the prism. Preferably, a camera is located.

On the other hand, it is recommended to connect an image memory to the central processing unit.

[0012]

In the present invention, light emitted from a planar light source passes through a prism, abuts the bottom surface (corresponding to the long side) of the prism on the tire contact surface (sometimes via a glass plate or the like). The reflected light reflected from the tire contact surface is received by a television camera typified by a CCD television camera through a prism, and the entire tire contact surface is captured as one image for measurement. In the television camera, the amount of reflected light (measuring the difference in the amount of light absorbed on the tire contact surface) is output as a digital signal at each pixel arranged vertically and horizontally, and this signal is processed by a central processing unit. , And a fine pressure distribution on the tire contact surface is calculated, and the result can be displayed on a display device such as a television screen or a printing device.

As described above, the difference in the light absorptivity over the entire area of the tire contact surface is instantaneously received as a difference in the amount of light by a television camera having a large number of pixels. There is no need to move the part in the two-dimensional direction, and measurement can be performed in a very short time of several tenths of a second.

The tire is brought to a measurement position by moving the glass plate with respect to the tire which is freely rotatable and having a fixed axis, or by rotating the tire and guiding it on the glass plate with a prism. be able to. In addition, since the above TV camera can process many screens in a short time, measurement can be performed within a short time when the tire passes over the glass plate, and the contact surface state of the tire is measured in a dynamic state similar to the use state You can do it.

On the other hand, the prism on which the tire is mounted is formed in an inverted triangle, and the bottom surface corresponding to the long side is adhered under the glass plate supporting the load, and is located at a lower position facing the slope of the prism. The structure is such that a planar light source and a television camera are provided respectively. As a result, a television camera or the like is provided below the tire contact surface, and a part of the measuring device does not protrude above the glass plate.

Alternatively, the prism is formed in a trapezoidal cross section, and a portion corresponding to the upper side (the upper surface having a smaller area than the bottom surface) is used as a tire mounting surface. If a surface light source and a television camera are installed at the position facing the two slopes (side position of the prism) and the measuring device is installed at the same height position as the prism installation position, it can be dug underground. Without the need for a measuring device.

An image memory is connected to the central processing unit so that data output from the television camera can be reserved and arithmetic processing can be performed, and the instantaneous contact state can be accurately measured. The light emitted from the planar light source is preferably of a single wavelength, and the television camera serving as the light receiving unit can measure an accurate value without disturbing the measurement of the difference in light amount.

[0018]

FIG. 1 is an explanatory sectional view showing a typical embodiment of the present invention. The tire T is placed on the upper part of the glass plate 1,
An inverted triangular prism 3 is joined to a lower portion of the glass plate 1 via a buffer material 2 so that a bottom surface 3 a of the prism 3 is in contact with a lower surface of the glass plate 1. The cushioning material 2 is made of a material (for example, silicon rubber) having a refractive index close to that of the glass plate 1 and the prism 3, and serves to bond the glass plate 1 and the prism 3 and absorb distortion caused by the load of the glass plate 1. Fulfill.

A planar light source 4 is disposed so as to face one inclined surface 3b of the prism 3. The planar light source 4 may be, for example, a planar one formed by arranging fluorescent tubes in parallel, or a planar light source such as a light bulb, which is expanded in a planar manner by a scattering filter or a scattering reflector. The planar light source preferably emits a single wavelength of visible light, and for example, various gas tubes and fluorescent tubes such as a sodium lamp are used.

Further, another inclined surface 3 of the prism 3
The CCD television camera 5 is arranged to face c. An image memory 6, a central processing unit 7 and an image display device 8 are connected to the CCD television camera 5 in this order. Accordingly, the amount of light received by each pixel (each CCD pixel arranged in a plane) constituting the CCD television camera 5 is stored in the image memory 6 as a digital signal, and is processed by the central processing unit 7. Are processed into output measurement values (contact area, contact pressure distribution, wear amount, etc.) and displayed on the image display device. This image display device uses a television screen, a printer, or the like.

In the CCD television camera 5, since the amount of light can be output as a digital signal at each of the pixels arranged in a large number of rows and columns, the amount of light (reflected light from the tire ground surface) within an instantaneous time is stored in an image memory. 6 and can be processed and output.

The method of dynamically measuring the contact state of the tire T will be described in detail. In a device (not shown) capable of rolling the tire T for a certain distance while applying a load,
The glass plate 1 and the prism 3
Is arranged, the contact state of the tire T can be measured.

Alternatively, the glass plate 1 is formed to be elongated,
By mounting this on a rail (not shown), the glass plate 1 can be moved along the rail, and the prism 3 is bonded to a fixed portion of the lower surface of the glass plate 1, while the tire T is made of glass. It is configured to be rotatably fixed on the plate 1. Then, the tire T is rotated by moving the glass plate 1, and when the prism 3 reaches directly below the tire T, the contact state of the tire T can be dynamically measured by an auto switch.

An example of measuring the contact area and contact pressure distribution of a tire using the image processing apparatus of FIG. 1 will be described in detail below. (Example of Measuring Contact Area of Tire in Static State) First, light from a planar light source is applied to the tire contact surface through the inclined surface 3b of the prism 3, and the reflected light is received by the CCD television camera 5 through the prism inclined surface 3c. At this time, the light is totally reflected on the non-contact surface of the tire, and a part of the light is absorbed by the tire T in a portion where the tire is in contact. Therefore, if the central processing unit 7 processes the portion where the amount of reflected light is reduced, the contact area of the tire in a stationary state can be output to the image display device. If the portion where the amount of reflected light is reduced is graphically displayed, the shape of the ground contact surface can be viewed on an image display device.

(Example of Measurement of Contact Pressure Distribution of Tire at Rest) On the contact surface of the tire, the amount of light reflected by the CCD television camera 5 is measured at each pixel, and the central processing is performed by applying the principle described above. In the device 7, the percentage of the amount of received light at each measurement point corresponding to the percentage of the total reflected light amount is divided.
%, 75-80%, etc., and calculate the difference distribution. The distribution unit can be arbitrarily selected, such as 1% or 10%. Then, if the measured value for the reference pressure is input to the central processing unit 7, the pressure distribution on the tire contact surface can be color-coded and displayed on the image display device.

FIG. 2 is an explanatory sectional view showing another embodiment of the present invention. The cross-sectional shape of the prism 3 is formed in a trapezoidal shape, and the bottom surface 3e is configured so that light is totally reflected (mirror finishing).
The upper surface 3d corresponding to the upper side is used as a tire mounting surface. A planar light source 4 is arranged to face one slope 3f of the prism 3, and a CCD television camera 5 is arranged to face another slope 3g. A central processing unit 7 and the like are connected to the CCD television camera 5 as in FIG. As a result, the planar light source 4 and the CCD television camera 5 can be arranged above the ground G, so that it is not necessary to dig underground, and the apparatus itself can be easily arranged on the ground.

[0027]

Since the present invention is configured as described above, the tire contact surface can be grasped in a planar manner and its state can be measured instantaneously, and the measurement time is drastically reduced as compared with the conventional product. Now you can. In addition, since instantaneous measurement becomes possible, dynamic measurement by rotating the tire becomes possible, and the state of the ground contact surface of the tire can be measured in a dynamic state that approximates the usage state of the tire.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a typical embodiment of the present invention.

FIG. 2 is an explanatory sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 glass plate 2 cushioning material 3 prism 4 planar light source 5 CCD television camera 6 image memory 7 central processing unit 8 image display device L ray T tire

Claims (4)

(57) [Claims] 1. An apparatus for measuring a tire contact state, wherein a prism is provided at a lower portion of the tire, light is applied to the tire contact surface through the prism, and the reflected light is processed by a central processing unit. The light source that emits light is formed in a planar shape, and is totally reflected at the tire tread and partially at the tire tread.
A television camera that receives the planar light to be absorbed through the prism is disposed, and the image of the television camera is processed to ground the tire.
A central processing unit capable of displaying a pressure distribution on a surface is connected to the television camera. 2. A prism having a triangular cross section, a tire mounted above a portion corresponding to the bottom of the prism via a glass plate, and a planar light source or a television facing two slopes of the prism. The image processing device for a tire tread according to claim 1, wherein a camera is arranged. 3. A cross section of a prism on which a tire is mounted is formed in a trapezoidal shape, and a portion corresponding to an upper side thereof is a tire mounting surface side,
2. The image processing device for a tire contact surface according to claim 1, wherein a planar light source or a television camera is arranged to face the two inclined surfaces of the prism. 4. The image processing device for a tire contact surface according to claim 1, wherein an image memory is connected to the central processing unit.