JPS62297822A - Method for controlling automatic glare-proof mirror - Google Patents

Abstract

PURPOSE:To attain automatic glare shield free from a sensor of incompatibility by positioning a sensor on the back of a liquid crystal cell for controlling light transmissivity and generating a control signal. CONSTITUTION:A transmissive part 1a of a small area having no aluminum deposition and exerting no influence upon reflection on a mirror surface is formed on the center part of the mirror surface 1. When the photosensor 2 such as a pohtodiode 2 is arranged on the transmissive part 1a on the back position of the liquid crystal cell 3 for controlling the light transmissivity, the transmissivity of the cell 3 is detected. When the transmissivity of the cell 3 is controlled by using the output of the sensor 2 as a control signal, automatic and excellent glare shield free from a sensor of incompatibility can be practically attained by the sensor 2 arranged on a position where light is made incident upon a driver.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rear view mirror that is provided in the interior of a vehicle such as an automobile, and is used for a driver to monitor the rear view while driving. In particular, it relates to a method of controlling an automatic dimming device provided to the rearview mirror.

[Prior Art] A conventional method for controlling this type of auto-dimming mirror is, for example, as shown in FIG. A sensor 13, which is a light-receiving element such as a PD (photodiode), is placed at an appropriate position near the rear view mirror 11, facing the rear window of the automobile, and at night, the sensor 13 is set at a certain value or more/below a certain value. The output sets the liquid crystal cell 12 to 0N10F.
It was a binary control system with F.

[Problems to be Solved by the Invention] However, in the conventional method described above, since a sensor is provided at a position different from the rearview mirror, the amount of light that reaches the driver via the rearview mirror is This inevitably causes a difference in the passage of light rays received by the sensor, leading to problems such as the anti-glare device sometimes not operating even though the driver feels dazzled. Naturally, problems also arise in the reverse case.

[Means for Solving the Problems] The present invention provides a concrete means for solving the problems of the conventional auto-dimming mirror described above, which includes a mirror surface, a liquid crystal cell covering the mirror surface, and a liquid crystal cell that covers the mirror surface. In an auto-dimming mirror comprising a control circuit for controlling transmittance and a sensor for emitting a control signal from the control circuit, the sensor is located on the back side of the liquid crystal cell.Ii! The above-mentioned conventional problems are solved by providing an auto-dimming mirror characterized in that the auto-dimming mirror is configured such that the control signal is sent to the control circuit.

[Example] Next, the present invention will be described in detail based on an example shown in the drawings.

The reference numeral 1 in FIG. 1 is a mirror surface formed by vapor-depositing aluminum or silver, and a sensor 2 such as a PD is arranged approximately at the center of the mirror surface 1, as shown in FIG. In order to
A is provided.

The sensor 2 is arranged on the back side of the light-transmitting part 1a, and if we explain here that the light-transmitting part 1a is provided on a part of the mirror surface 1, the sensor 2 is extremely small. Therefore, the light transmitting portion 1a may also be small, and this does not cause any inconvenience such as obstructing the view due to the mirror surface 1. A liquid crystal cell 3 is provided closely on the front side of the mirror surface 1.
For example, it can be a TN (twisted nematic) liquid crystal cell (or a GH (guest host) liquid crystal, or even a single layer or a double layer. In short, the liquid crystal cell 3 described above can be 0N10FFt, etc. Sometimes differences in transmittance occur,
In addition, it is important that it does not disturb the reflected image.
They may be arbitrarily selected and employed depending on the intended transmittance, color tone, and other conditions.

By arranging the sensor 2 in this way, the sensor 2 is naturally covered with the liquid crystal cell 3, and is affected by the change in transmittance due to 0N10FF of the liquid crystal cell 3. 3 is turned on, the amount of light reaching the sensor 2 decreases, and it is determined that the state is dark, that is, there is no need to perform anti-glare, and the liquid crystal cell 3 is turned on.
Although there is a possibility that malfunctions such as FF may occur, as a result of the study by the inventor of the present invention, the 0N1 of the liquid crystal cell 3
The effect of 0FF does not extend to the infrared region, and it is known that even if the liquid crystal cell 3 is set to 0N10FFk, the transmittance in the infrared region does not change at all. By using an external PD, a binary control anti-glare mirror can be implemented without any problems.

If it is inconvenient to use an infrared sensor for the sensor 2, the sensor 3 may be sensitive to visible light, and the sensor 3 may be sensitive to visible light. Malfunctions can be eliminated by providing a difference of 1 as hysteresis to the operating point of the liquid crystal cell.

Furthermore, when a G)l liquid crystal cell is adopted as the liquid crystal cell 3, the transmittance of the GH liquid crystal cell can be continuously changed by the driving voltage, so that, for example, the output of the sensor 2 can be changed. With a simple configuration that just amplifies it appropriately and applies it to the liquid crystal cell 3, if a large amount of light hits the sensor 2, the output automatically causes the liquid crystal cell 3 to reduce its transmittance. A mirror surface with a servo function is obtained in which the position of the sensor 2, that is, the brightness of the mirror surface 1 is always constant.

[Effects of the Invention] As explained in detail above, according to the present invention, the sensor of the auto-dimming mirror is arranged so as to be located on the back side of the liquid crystal cell to emit a control signal to the control circuit. in,
By measuring the amount of incident light at a position equivalent to the driver's field of vision, it is possible to perform a natural anti-glare operation, which has an excellent effect on improving the practicality of this type of auto-dimming mirror.
Furthermore, it is also possible to provide a completely new auto-dimming mirror with an auto-servo function that always maintains a constant mirror surface reflectance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of an embodiment of an auto-dimming mirror according to the present invention, FIG. 2 is an explanatory view showing a light-transmitting part provided on the mirror surface, and FIG. 3 is a perspective view showing a conventional example. . 1...Mirror surface 1a...Transparent part 2...
...Sensor 3...Liquid crystal cell patent applicant Honda Motor Co., Ltd. Stanley Electric Co., Ltd. Figure 1 Figure 2 Figure 311

Claims (1)

[Claims] In an auto-dimming mirror comprising a mirror surface, a liquid crystal cell covering the mirror surface, a control circuit for controlling transmittance of the liquid crystal cell, and a sensor for emitting a control signal for the control circuit, the sensor is located on the back surface of the liquid crystal cell. It is arranged so that it is located on the side,
A method for controlling an auto-dimming mirror, characterized in that the control signal is sent to the control circuit.