JPH0443808Y2 - - Google Patents

Description

[Detailed explanation of the idea]

TECHNICAL FIELD The present invention relates to a road surface condition display device that determines and displays a road surface condition, and more particularly to a road surface condition display device that optically determines and displays a road surface condition. BACKGROUND ART The principle of such a device for determining road surface conditions is shown in, for example, Japanese Patent Laid-Open No. 55-156841, and a typical prior art based on this principle is the
As shown in the figure. The road surface 1 is irradiated with light from the light emitting diode 2 via the condensing lens 3 as shown by the optical axis 4. It has an angle θb. The reflected light from the road surface 1 is divided by an image splitting lens 7 having an optical axis 6, and the horizontally polarized light component passing through the horizontal polarizer 8 is received by the light receiving element A. Further, the vertically polarized light component from the image splitting lens 7 via the vertical polarizer 9 is received by the light receiving element B. The outputs from the light-receiving elements A and B are applied to band pass filters 11a and 11b, where only the modulated light is waved, and detected by detectors 12a and 12b. In this way, a signal representing the level ρh of the horizontal polarization component is derived on line 13a, and line 1
3b, a signal representing the level ρv of the vertical polarization component is derived. Signals from lines 13a and 13b are applied to a sum calculation circuit 14 and a difference calculation circuit 15, and calculations ρh+ρv and ρh−ρv are calculated.
The outputs from these circuits 14 and 15 are given to a ratio calculation circuit 16 to determine the degree of polarization γ. γ=ρh−ρv/ρh+ρv…(1) The road surface condition corresponding to this degree of polarization γ is shown on the display 1.
Displayed by 7. Problems to be Solved by the Invention This prior art requires a summation circuit 14, a difference calculation circuit 15, and a ratio calculation circuit 16 in order to perform the calculation of the first equation, and has a complicated configuration and is expensive. There is a problem with becoming. An object of the present invention is to provide a road surface condition display device with a simplified configuration. Means for Solving the Problems The present invention irradiates light onto the road surface and determines the road surface condition based on the light reception outputs of the light receiving elements that respectively receive the horizontally polarized light component and the vertically polarized light component of the reflected light. A road surface condition display device for displaying a road surface includes a plurality of comparator circuits in which a received light output representing a vertically polarized light component is commonly given to one input terminal, and a received light output representing a horizontally polarized light component is divided into a plurality of voltages, and each divided voltage output is This is a road surface condition display device characterized by comprising voltage dividing circuits that respectively apply to the other input terminals of the comparison circuits, and means for displaying the road surface condition in response to the output from each comparison circuit. Effect According to the present invention, a received light output representing a vertically polarized light component is given to one input terminal of the comparator circuit,
The other input terminals each receive a received light output representing a horizontally polarized light component voltage-divided by a voltage-dividing circuit. In this way, the road surface condition is determined based on the polarization ratio K, which is the ratio between the level ρh of the horizontal polarization component and the level ρv of the vertical polarization component. The polarization ratio K and the road surface condition correspond as shown in Fig. 3, which will be described later.
It is desired that the value be determined with high accuracy in the range of 1 to 10. In Figure 4, which will be described later, the polarization ratio K and polarization degree γ
Indicates the relationship between According to FIG. 4, when the polarization ratio is in the range of 1 to 10, the rate of change in the degree of polarization γ is smaller than the amount of change in the polarization ratio K. Therefore, by using the polarization ratio K, It is possible to identify road surface conditions with high accuracy. Embodiment FIG. 1 is an electrical circuit diagram of an embodiment of the present invention. The road surface 21 is irradiated with light from a light emitting diode 23 via a condensing lens 24 as shown by an optical axis 25 . The reflected light from the road surface 21 is applied from the image splitting lens 26 to the first light receiving element A via the horizontal polarizer 27, and is also applied to the second light receiving element B via the vertical polarizer 28. The optical axis of the image splitting lens 26 is indicated by reference numeral 29. The optical axes 25, 29 have approximately a Brieuster angle θb with respect to the normal 30 to the road surface 21. This Brieuster angle θb is, for example, approximately 50°. The light emitting diode 23 is driven by the drive circuit 31 at, for example, 5kHz.
The light is pulsed. The outputs from the first and second light receiving elements A and B are:
The light is amplified by amplifier circuits 32a and 32b, and applied to band pass filters 33a and 33b to form modulated light, which is applied to detectors 34a and 34b and detected. A signal representing the level ρh of the horizontally polarized light component derived from the detector 34a to the line 35 is connected to the resistor R1.
~Rn is divided by a voltage dividing circuit 36. At the subsequent stage of the voltage dividing circuit 36, a plurality of comparison circuits C1
~Cn is provided. The non-inverting input terminal of comparator circuit C1 is connected to line 35. A divided voltage from the voltage dividing circuit 36 is applied to each non-inverting input terminal of the remaining comparison circuits C2 to Cn. Comparison circuit C
The inverting input terminals 1 to Cn are supplied with a signal representing the level ρv of the vertically polarized light component via the line 37 from the detector 34b. These comparison circuits C1~
Cn derives a high-level signal when the voltage at the non-inverting input terminal exceeds the voltage at the inverting input terminal, and derives a low-level signal when the voltage is lower than that. The display means 38 includes light emitting diodes D1 to Dn.
will be provided. The outputs of the comparison circuits C1 to Cn are given to the anodes of the light emitting diodes D1 to Dn,
The cathode is grounded. In the voltage dividing circuit 36, the resistors R1 to Rn are set to have the same resistance value. Therefore, the voltage at the connection point 39 between the resistors R1 and R2 in the voltage dividing circuit 36 is n-1/nρh, if the voltage on the line 35 is expressed with the same reference symbol as the level ρh of the horizontal polarization component, and the voltage at the connection point 39 between the resistors R1 and R2 is n-1/nρh. The partial pressure value at the connection point 40 between R2 and R3 is n-2/nρh. Further, the divided voltage value at the connection point 41 of the resistor Rn is 1/nρh. In this way, the lighting conditions for the light emitting diodes D1 to Dn corresponding to the comparison circuits C1 to Cn are as shown in Table 1.

【table】

Claims (1)

[Claims for Utility Model Registration] Road surface condition that determines and displays the road surface condition based on each light reception output of a light receiving element that irradiates light onto the road surface and receives horizontally polarized light components and vertically polarized light components of the reflected light. In a display device, a plurality of comparison circuits are provided, in which a received light output representing a vertically polarized light component is commonly given to one input terminal, and a received light output representing a horizontally polarized light component is divided into a plurality of voltages, and each divided voltage output is applied to the other input terminal of the comparing circuit. What is claimed is: 1. A road surface condition display device comprising: voltage dividing circuits respectively applied to input terminals of the comparator circuits; and means for displaying road surface conditions in response to outputs from the respective comparison circuits.