Automatic sunshade curtain with sustained state at transition

Details Automatic sunshade curtain with sustained state at transition Automatic sunshade curtain with sustained state at transition

2001-09-04

2004-07-06

Luu, Thanh X. (Department: 2878)

Radiant energy

Photocells; circuits and apparatus

Photocell controlled circuit

C359S601000, C296S097100

Reexamination Certificate

active

06759643

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a control device, and more particular to a light-responsive control device for automatically controlling a headlamp and/or a sunshade curtain of a vehicle.
BACKGROUND OF THE INVENTION
Intense sunlight often bothers the driving operation of a driver, and makes the passengers seated in the vehicle uncomfortable. Therefore, various sunshade curtains are developed to solve this problem. Most of the sunshade curtains are manually attached to and detached from the side windows and/or rear windscreen to avoid direct radiation of sunlight. In some luxurious cars, a semi-automatic sunshade curtain is equipped for blocking sun from the rear windshield. That is, it requires the driver to push a button manually, and the sunshade curtain automatically ascends or descends.
On the contrary to the situation of intense sunlight, a situation of weak light in daytime should also be taken into consideration. In general, the headlamp of a vehicle will not be switched on in daytime. When sunlight suddenly becomes weak for example owing to a tunnel, clouds or rains, and the driver forgets to activate the headlamp, it may results in danger for driving. A conventional automatic headlamp activating system includes a photo-responsive sensor disposed on the dashboard and oriented upwards for detecting the intensity of sunlight. Once the sunlight becomes weak, the headlamp is automatically activated immediately. This conventional automatic headlamp activating system, however, has a disadvantage that the headlamp is possibly required to be activated and deactivated within an extremely short period. For example, when the vehicle with the automatic headlamp activating system is traversing under a viaduct, the upward photo-sensor will inform the control circuit of low light intensity so as to automatically activate the headlamp. When the photo-sensor is out of the viaduct range, the control circuit will deactivate the headlamp. However, the period for driving across a viaduct is generally very short. It means that the headlamp will be deactivated soon after it is activated. This operational mode is harmful to the lifespan of the headlamp. Thus, another conventional automatic headlamp activating system has the photo-sensor mounted on the interior rearview mirror and oriented forwards to solve this problem. For the prior art, the headlamp, once activated, has only one option in its intensity. Therefore, the energy consumption is not properly controlled.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a light-responsive control device for automatically controlling the activation of a vehicular headlamp, which performs a confirmation function to avoid mis-operation.
Another object of the present invention is to provide a light-responsive control device for automatically controlling the activation of a vehicular headlamp, which performs 4-level or above headlight control for dynamically compensating the insufficient illumination.
A further object of the present invention is to provide a light-responsive control device for automatically controlling a vehicular sunshade curtain.
A still further object of the present invention is to provide a light-responsive control device, which uses a single photo-sensor to perform the automatic control of a vehicular headlamp and a vehicular sunshade curtain.
A first aspect of the present invention relates to a light-responsive control device for automatically controlling a headlamp of a vehicle. The control device includes a photo-sensor mounted on the vehicle for generating a sensing signal in response to the intensity of an environmental light; a discriminating circuit electrically connected to the photo-sensor for optionally generating a first triggering signal according to a comparing result of the sensing signal with a first reference signal; a hold circuit electrically connected to the discriminating circuit for outputting a first confirming signal in response to the first triggering signal uninterrupted for a predetermined period; and a drive circuit electrically connected to the hold circuit and the headlamp of the vehicle for providing a drive current in response to the first triggering signal for the headlamp to emit a certain level of light.
Preferably, the photo-sensor is disposed at an interior rearview mirror of the vehicle, and oriented to receive a forward light as the environmental light.
Preferably, the discriminating circuit includes at least a first comparing unit for comparing the sensing signal with the first reference signal. For example, the discriminating circuit further includes a second, a third and a fourth comparing units for comparing the sensing signal with a second, a third and a fourth reference signals, respectively, and optionally generating a second, a third and/or a fourth triggering signals according to respective comparing results.
In an embodiment that the discriminating circuit includes four comparing units as mentioned above, the drive circuit includes a constant voltage source; a load resistor having a first end thereof electrically connected to the constant voltage source in series; a first, a second, a third resistors having first ends thereof electrically connected to a second end of the load resistor; a first controlled switch electrically connected to the discriminating circuit, a second end of the first resistor, and ground for serially connecting the first resistor to ground in response to the first triggering signal; a second controlled switch electrically connected to the discriminating circuit, a second end of the second resistor, and ground for serially connecting the second resistor to ground in response to the second triggering signal; a third controlled switch electrically connected to the discriminating circuit, a second end of the third resistor, and ground for serially connecting the third resistor to ground in response to the third triggering signal; and a fourth controlled switch electrically connected to the discriminating circuit, the second end of the load resistor, and ground for serially connecting the load resistor to ground in response to the fourth triggering signal; wherein a common node of the second end of the load resistor and the first ends of the first, second and third resistors serves as a voltage output end for outputting a drive voltage signal of one of a first, a second, a third and a fourth levels according to a conduction combination of the first, second, third and fourth controlled switches.
Preferably, the drive circuit further includes a field effect transistor electrically connected to the voltage output end for providing the drive current of one of a first, a second, a third and a fourth levels for the headlamp in response to the drive voltage signal.
A second aspect of the present invention relates to a method for automatically controlling an activation state of a headlamp of a vehicle. The method includes steps of: generating a sensing signal in response to the intensity of an environmental light; comparing the sensing signal with a reference signal to optionally generate a triggering signal; and providing a drive current for the headlamp if the triggering signal is generated and uninterrupted for a predetermined period.
Preferably, the predetermined period is no less than 0.1 second, and more preferably, about 0.5 second.
A third aspect of the present invention relates to a light-responsive control device for automatically switching illumination levels of a headlamp of a vehicle. The control device includes a photo-sensor mounted on the vehicle for generating a sensing signal in response to the intensity of an environmental light; a plurality of comparing units electrically connected to the photo-sensor for comparing the sensing signal with a corresponding number of reference signals to optionally generate respective triggering signals; and a drive circuit electrically connected to the plurality of comparing units and the headlamp of the vehicle for providing a drive current for the headlamp to em

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