CHAIR SAFETY SYSTEM AGAINST ACCIDENTAL PRESSING

A chair safety system against accidental pressing has a central processing unit, multiple sensors, multiple linear pushrods, a power device, and a controller. The multiple sensors, the multiple linear pushrods, the power device, and the controller are electrically connected to the central processing unit, respectively. The multiple sensors include a first sensor and at least one second sensor that are respectively mounted to the linear pushrods, a linkage of a height adjustable chair, or a seat of the height adjustable chair. The first sensor is a human touch sensor or a Hall Effect sensor. The at least one second sensor is a pyroelectric sensor, a microwave sensor, or an ultrasonic sensor. By different sorts of the sensors working simultaneously, the linear pushrods will be stopped if any obstacles exist below the seat; thus damage to the obstacles and the seat may be prevented.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a safety system for a chair, and more particularly to a chair safety system that may detect an area below a descending seat of a chair to prevent accidental pressing on obstacles in the area of the chair.

2. Description of Related Art

Aging population all over the world has raised demands for elder-friendly apparatus, for example, height adjustable chairs. It is difficult for seniors with powerless legs to squat down gradually to sit on a chair, and a height adjustable chair is for solving this problem.

A conventional height adjustable chair has a seat, a backrest, a leg rest, and a linkage connected to the seat, the backrest, and the leg rest. With a remote control, a user may drive the linkage to function so as to adjust either a height of the seat, a tilt of the backrest, or a height of the leg rest. Thus, the user may raise the seat to approach his hips, and then the user may easily sit on the seat. After seated on the conventional height adjustable chair, the user may once again adjust the seat, the backrest, and the leg rest to a comfortable position.

However, the conventional height adjustable chair has the following shortcomings.

1. Below the seat, there is a blind area. If children or pets run into the blind area during a descending process of the seat, the children or the pets will probably be squeezed or pressed by the seat or the linkage.

2. Obstacles under the descending seat may also be broken, or cause damage to the conventional height adjustable chair.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a chair safety system. With multiple sensors, accidental pressing on obstacles under a descending seat of a chair is preventable.

The chair safety system is applied to control a height adjustable chair that comprises a seat, a backrest, and a leg rest.

The chair safety system has a central processing unit, multiple sensors, multiple linear pushrods, a power device, and a controller. The multiple sensors are electrically connected to the central processing unit, and comprise a first sensor and at least one second sensor. The first sensor is electrically connected to the central processing unit, and is used to detect if any obstacles exist below the seat. The at least one second sensor is a different sort of sensor from the first sensor, is electrically connected to the central processing unit, and is used to detect if any obstacles exist below the seat. The multiple linear pushrods are connected to the seat, the backrest, and the leg rest, and drive the seat, the backrest, and the leg rest to move respectively. The power device is electrically connected to the central processing unit. The controller is electrically connected to the central processing unit. When the first sensor detects an obstacle, the first sensor will send a first actuation signal to the central processing unit to stop movements of the multiple linear pushrods; when the at least one second sensor detects an obstacle, the at least one second sensor will send a second actuation signal to the central processing unit to stop movements of the multiple linear pushrods.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference toFIGS. 1 and 2, a first embodiment of a chair safety system against accidental pressing is applied with a height adjustable chair80. The height adjustable chair80comprises a seat81, a backrest82, a leg rest83, and a linkage84at a bottom of the height adjustable chair80. The linkage84is made of an electrically conductive material, and is connected to the seat81, the backrest82, and the leg rest83. The height adjustable chair80is conventional, and the features and the structures of the height adjustable chair80are not described in detail.

The chair safety system against accidental pressing in accordance with the present invention comprises a central processing unit10, multiple sensors20, multiple linear pushrods30, a power device40, and a controller50. The sensors20, the linear pushrods30, the power device40, and the controller50are electrically connected to the central processing unit10.

In the first embodiment of the present invention, the central processing unit10is a microcomputer used to receive signals from the multiple sensors20and the controller50, and to drive the multiple linear pushrods30.

With reference toFIG. 1, the multiple sensors20comprise a first sensor21and at least one second sensor22. With reference toFIG. 3, a first sensor21and two second sensors22are used for detailed description in the first embodiment in accordance with the present invention. The first sensor21is a human touch sensor. Each one of the two second sensors22is a pyroelectric sensor or a microwave sensor.

The first sensor21is mounted on the linkage84and is located below the seat81. The first sensor21applies a voltage on the linkage84, so an electric field will be generated on the linkage84. Also, the first sensor21measures a value of capacitance of the linkage84. Once a person or a creature touches the linkage84, capacitance will be changed, and then the first sensor21will send a signal to the central processing unit10. In the first embodiment of the present invention, the linkage84is made of metal, and is coated with electrically conductive paint. The two second sensors22are mounted on a bottom side of the seat81at a spaced interval, and are used to detect if any obstacles are located below the seat81.

With reference toFIGS. 3 and 4, the multiple linear pushrods30are connected to the linkage84. Powered by electricity, each one of the multiple linear pushrods30may extend out and retract back in order to adjust the seat81, the backrest82, and the leg rest83. In the first embodiment of the present invention, the multiple linear pushrods30comprise a first linear pushrod31and a second linear pushrod32, for different functions. For instance, the first linear pushrod31may be used to control the linkage84to incline the backrest82for a comfortable lying position or a sit-up position depending on a user, while the second linear pushrod32may be used to control the ascending and descending of the seat81and the leg rest83, for an appropriate height for the user.

To supply electric power, the power device40comprises a plug41and a transformer42. The plug41is connected to a socket for electricity supply. The transformer42is connected to the plug41. To supply electrical power for other components of the chair safety system, the transformer42converts the electricity from the plug41into direct current (DC) power.

The controller50is a remote control having buttons for ascending and descending of the seat81and the leg rest83, inclining of the backrest82, and cancelling of a locked mode. The controller50may be a wired remote control51or a wireless remote control52, wherein the wired remote control51is wired to the central processing unit10, and the wireless remote control52is connected with the central processing unit10wirelessly.

Besides, the central processing unit10may have a wireless transmission circuit such as a Bluetooth circuit. Then a communication device60may control the chair safety system via wireless signals to the central processing unit10. The communication device60is able to cancel the locked mode as well, and the communication device60may be a mobile phone.

With reference toFIGS. 2 to 4, the user may send commands to the central processing unit10with the controller50or the communication device60so as to adjust the height adjustable chair80. During the adjusting process, if a child or a pet accidentally touches the linkage84, the first sensor21will measure a variance of the capacitance and send a first actuation signal to the central processing unit10. Then the central processing unit10will turn into the locked mode to stop the motions of the multiple linear pushrods30instantly from pressing the height adjustable chair80on the child or the pet.

Moreover, as a pyroelectric sensor or a microwave sensor, each one of the two second sensors22is able to detect presence of creatures. When the second sensor22detects the child or the pet entering an area below the seat81of the height adjustable chair80, a second actuation signal will be sent to the central processing unit10, and the central processing unit10will turn into the locked mode. In addition, the second sensor22may be applied with a modulating unit, which is used to adjust a range of detection of the second sensor22. The amount of the second sensor22may be more than two to make the height adjustable chair80safer.

Once the central processing unit10has turned into the locked mode due to a child, a pet or any other kinds of obstacles entering the area below the seat81, the multiple linear pushrods30are stopped from further extending or retracting. To drive the multiple linear pushrods30to work anew, the user has to remove the child, the pet, or the other obstacles away from the height adjustable seat80, and press the corresponding button of the controller50or the communication device60for cancelling the locked mode. As the locked mode is cancelled, the multiple linear pushrods30may continue to lower down the seat81.

A second embodiment of a chair safety system in accordance with the present invention differs from the first embodiment in that the second sensor22is an ultrasonic sensor. The ultrasonic sensor continuously emits ultrasonic waves toward the area below the seat81, receives reflected waves, and records time taken by the ultrasonic waves to travel from emission to receipt. Therefore, if an obstacle appears in the area below the seat81, changes in the time taken by the ultrasonic waves will be detected, and then the two second sensors22will send a second actuation signal to the central processing unit10to stop the multiple linear pushrods30.

A third embodiment of a chair safety system in accordance with the present invention differs from the first embodiment in that the first sensor21is a Hall Effect sensor. The first sensor21is mounted on one of the multiple linear pushrods30, and is electrically connected to the central processing unit10and the power device40. The first sensor21is used to detect values of currents in ascending and descending processes of the seat81. In order to completely lower down the seat81, a larger current is required by the multiple linear pushrods30when the seat81descends and presses on an obstacle. If the current goes beyond a threshold value, the first sensor21will send a first actuation signal to the central processing unit10to stop the multiple linear pushrods30.

In a fourth embodiment of a chair safety system in accordance with the present invention, the first sensor21is a Hall Effect sensor, and the first sensor21works as described in the third embodiment; the second sensor22is an ultrasonic sensor, and the second sensor22works as described in the second embodiment.

With the aforementioned technical features, the chair safety system against accidental pressing in accordance with the present invention has the following advantages.

1. Two different kinds of sensors, the first sensor21and the second sensor22, are applied simultaneously. Even if one of the first sensor21and the second sensor22malfunctions, accidental pressing may still be avoided by the remaining one of the sensors21,22.

2. The locked mode should be cancelled manually by the user, so the seat81will not descend anew unless the user confirms that the child, the pet, or the other obstacles below the seat81have been removed.

3. It is convenient for the user that the chair safety system may also be manually operated by the communication device60such as a mobile phone.