Flexible or portable closure – partition – or panel – With mounting – fastening – or supporting means – Automobile windshield weather protector or sunshield
Patent
1999-08-30
2000-10-24
Johnson, Blair M.
Flexible or portable closure, partition, or panel
With mounting, fastening, or supporting means
Automobile windshield weather protector or sunshield
160265, 160242, 160295, B60J 300
Patent
active
06135192&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a blind device adapted to be mounted on a rear window of an automobile or a window of a building for shielding light, and in particular to a blind device which shields light by paying out a screen wound on a roll.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,836,263 discloses an automotive screen device for shielding light in which spring means applies a biasing force to a roll having a light shielding screen wound thereon in a direction to wind up the roll, and an electric actuator or a hydraulic actuator applies an extending force to the light shielding screen via rotatable arms.
In this case, because the rotative force applied to the roll and the tension applied to the light shielding screen are not properly coordinated with each other, if either one of them is lost, the light shielding screen may be subjected to an excessive tension or may produce a slack. Furthermore, if the rotational angles of the rotary arms do not synchronize with each other, uneven tension may be applied to the screen and the screen may be creased or the smooth movement of the screen may become impossible. Therefore, mechanical means is required for synchronizing the rotary motions of the two arms, and this tends to complicate the structure.
In the case of a drive unit using an electric motor, the stop control of the motor is carried out by monitoring the electric current of the electric motor when the driven member has reached an end of the stroke of its movement. As this involves the detection of an over-current as a signal for stopping the electric motor, circuits for comparing and computing electric current levels are required, and the control device tends to be undesirably expensive. Furthermore, an over-current condition is necessarily produced immediately before stopping the electric motor, and this may reduce the durability of the electric motor.
In view of such problems of the prior art, a primary object of the present invention is to provide a blind device which can be stop controlled independently from the load of the electric motor, and which can prevent any excessive tension from being applied to the screen or any creases from being produced in the screen with a simple structure.
BRIEF SUMMARY OF THE INVENTION
Such an object can be accomplished by providing a blind device as set forth in claim 1, or a blind device, comprising a fixed frame, at least a pair of arms each having an end pivotally attached to the fixed frame, a moveable frame which is adapted to move toward and away from the fixed frame in a parallel relationship by rotational movements of the two arms, and a light-shielding screen having one end fixedly attached to and wound around a roll which is pivotally supported by the fixed frame, and another end fixedly attached to the moveable frame, characterized by that; a pivot shaft for pivotally supporting each arm on the fixed frame is incorporated with spring means which resiliently urges the corresponding arm toward its upright position, and the blind device further comprises an electric actuator having reverse drive preventing means for applying a rotative force to the roll so as to wind the screen thereon against a spring force of the spring means.
Thus, the resilient force of the spring means applies a moment to the arms to urge it toward their upright positions, and the torque of the electric actuator winds the screen onto the roll. Because the electric actuator would not be reverse driven, once the electric actuator is stopped, the screen is kept stationary with a desired length thereof pulled out. Furthermore, because the resilient force of the spring means is always applied to the arms, the screen would not slack at any extended position. Also, by controlling the rotational speed of the electric motor, the speed of paying out and winding the screen can be controlled in a stable fashion.
If the blind device further comprises a male thread shaft which is rotatable jointly with a rotary shaft of the electric actuator, an axially moveable member ha
REFERENCES:
patent: 4836263 (1989-06-01), Ament
patent: 5615729 (1997-04-01), Matsumoto et al.
patent: 5653278 (1997-08-01), Cheng
patent: 5752560 (1998-05-01), Cherng
patent: 5791721 (1998-08-01), Lin
patent: 5896910 (1999-04-01), Chen
Patent Abstracts of Japan; Publication No. 06221072, Aug. 9, 1994; Appln. No. 05029753 filed Jan. 26, 1993; "Electric Blind Position Adjusting Device"; Nichibei Co., Ltd.; Yukinori et al.
Patent Abstracts of Japan; Publication No. 08246767, Sep. 24, 1996; Appln. No. 07087809 filed Mar. 7, 1995; "Automatic Lifting Gear of Blind"; Hirata Yoshio.
Inoue Masaru
Sasuga Ichiro
Suzuki Ken
Johnson Blair M.
NHK Spring Co. Ltd.
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