Patent Application
20110031901
The invention relates to a portable electric lamp supplied by a DC power source and comprising a casing containing:
The different functions of a LED lamp controlled by an electronic circuit are conventionally adjustment of the power, of the focusing angle of the beam, of the colour by selecting the LEDs, and of the lighting mode—permanent or blinking. These functions enable the user to adjust his lighting to his environment managing the consumption of electric power supplied by the batteries. Access to one of these functions systematically requires action from the user who has to actuate the manual control means either by pulses (pushbutton), or by pivoting (lever), or by translation (slider).
When the power selected by the user is maximum, sudden movement of the light beam onto a close-by object causes intense lighting which the user's eyes have to get accustomed to. Reciprocally, when the power selected by the user is minimum, sudden movement of the light beam onto a far-away object generates insufficient lighting. Depending on whether the lamp is oriented for close or far vision, this results in a certain visual discomfort, except if the user modifies the state of the manual control means at each movement.
In the document JP9048280, an automatic switch for the interior of a vehicle causes the lamp to light as soon as a hand approaches. According to the document JP7111193, an ambient light sensor actuates lighting of the lamp. Control is performed by servo-controlling the ambient light. In both cases, the sensor does not regulate the light source it senses.
The document JP 63046726 describes a lighting system to regulate illumination of a surface. A sensor is positioned close to the surface, outside the lighting source.
The document WO 2005/024898 relates to a fixed ceiling light with an integrated optic sensor arranged next to the LEDs. The sensor measures the power of the LEDs to control the emitted light according to a setpoint fixed by remote control. Servo-controlling is performed exclusively according to the emitted light. The same is the case for the document US 2008/0074872 which mentions a lighting unit designed to equalize the lighting coming from several lighting modules.
The document US 2007/0133199 relates to a torch light whose lighting is servo-controlled according to various parameters (battery voltage, light emitted).
The object of the invention consists in remedying these shortcomings and in providing a portable lamp with regulated lighting enabling the lighting performances to be increased, visual comfort to be procured for the user, and electric power to be saved according to the environment.
The portable lamp according to the invention is characterized in that an optic sensor is housed in the casing near the light-emitting diode LED to deliver a signal representative of the light reflected by the surface of the illuminated object, and to transmit said signal to a second input of the control circuit to automatically regulate the power of the LED according to a predefined threshold.
The optic sensor detects the reflected light and not the emitted light as in the prior art. The light beam emitted by the lamp is thus automatically regulated without any manual action to adjust the lighting to the environment, while at the same time managing the power consumption.
According to a preferred embodiment, the optic sensor is chosen to correspond to the response profile and to the sensitivity of the human eye (passband in the visible comprised between 450 nm and 700 nm), and comprises an optic axis parallel to the longitudinal axis of the lamp. Regulation of the illumination enables the visual comfort to be increased by a sensation of illumination in the longitudinal axis independently from the abrupt change of orientation of the lamp.
Another advantage is to prevent any risk of glare for a group of users each equipped with a lamp according to the invention.
According to a first embodiment, the analog circuit control comprises a comparator circuit having a first input receiving a setpoint corresponding to said threshold, and a second input receiving said signal from the optic sensor. The output of the comparator circuit controls a switch to make resistors in series with the LED vary.
According to a second embodiment, the control circuit comprises a servo-control circuit to adjust the power of the LED by means of a power converter to perform servo-controlling the power of the LED to the first manual setpoint, and to an automatic setpoint coming from the optic sensor and from the current intensity absorbed by the LED. For this purpose, the power converter has a modulation input controlled by:
According to a third embodiment, the digital control circuit comprises a microcontroller operating according to the following steps:
According to a fourth embodiment, the lighting module is composed of two light-emitting diodes supplying a narrow beam and a broad beam. The total power is distributed between the two diodes by a microcontroller associated with three optic sensors, one of which is provided with an optic system only sensing the light emanating from the longitudinal axis of the lamp, the other two sensors sensing the light reflected by the obstacles situated on both sides.
Other advantages and features will become more clearly apparent from the following description of particular embodiments of the invention given for non-restrictive example purposes only and represented in the appended drawings, in which:
In
A user control means 13 is electrically connected to a first input E1 of control circuit P for switching on or off, and emission of a manual setpoint or input of parameters for choice of the functions of lamp 10.
An optic sensor 14 is housed with lighting module 11 in casing BT of lamp 10. Sensor 14 performs control of the sensed lighting after reflection on object 16 of the light beam emitted by the LED. Sensor 14 is connected via an amplifier 15 to a second input E2 of control circuit P.
Optic sensor 14 is formed by a photosensitive receiver, for example of photodiode, phototransistor, CCD or other type, which is situated close to the LED of lighting module 11. It can be noted in
The optic axes of the LED and sensor 14 are preferably substantially parallel so that the image of illumination of object 16 detected by sensor 14 is the most representative. The type of optic sensor 14 is chosen to correspond to the response profile and to the sensitivity of the human eye (passband in the visible comprised between 450-700 nm). This results in optimum visual comfort by a sensation of lighting in the axis independent from the visualization movement of the lighted object between two instants (for example map-reading then looking for a waymark located at a distance).
This results in optic sensor 14 detecting the light from the LED of lighting module 11 which it regulates. Light beam 17 emitted by lamp 10 is thus automatically regulated without manual action to adjust the lighting to the environment while at the same time managing the power consumption.
Control circuit P can be achieved in different manners, in particular in the form of an analog or digital electronic circuit, which will be described for exemplary purposes hereafter.
According to a first embodiment illustrated in
Depending on whether the value of signal S from sensor 14 is above or below the threshold of comparator circuit 19, switch 18 is open or closed so as to modify the value of the resistance in series with diode LED. This results in a variation of the lighting power of the LED, in particular a maximum power and a reduced power.
In both cases, we obtain two power levels of the LED automatically regulated by optic sensor 14, which can be suitable for long-distance lighting and short-distance lighting.
Electronic control circuit P can comprise several stages of analog comparator circuits 19 with different thresholds to obtain several power levels of the LED.
The second embodiment of
According to a third embodiment represented in
In a too bright lighting state, the acquisition value from optic sensor 14 is higher than second setpoint C2. If at the same time the power of the LED is greater than Pmin, microcontroller 27 will command a decrease of x% of the power of the LED.
In an insufficient lighting state, the acquisition value from optic sensor 14 is lower than second setpoint C2. If at the same time the power of the LED is lower than Pmax, microcontroller 27 will command an increase of x% of the power of the LED.
The presence of optic sensor 14 enables a constant lighting to be maintained independently from the distance from the lighted object and from the movement necessary for the change of direction. The user's eye does not have to get accustomed as it is the lamp that takes care of this.
According to a fourth embodiment of
Lamp 100 is equipped with three optic sensors 140, 141, 142, one of which is provided with an optic system only sensing light emanating from the longitudinal axis of the lamp. The other two sensors 141, 142 sense the light reflected by the obstacles situated on both sides. The information delivered by sensors 140, 141, 142 modulates the power distribution between the two leds LED1, LED2 so as to preserve a constant ratio between the light received in the axis and the light received on the two sides, left and right.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0802233 | Apr 2008 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR2009/000447 | 4/16/2009 | WO | 00 | 10/8/2010 |
