DEVICE FOR AUTOMATICALLY SWITCHING ON LIGHTS FOR REFRIGERATORS AND COLD ROOMS WITHOUT MECHANICAL CONTACT

Description

MINISTRY OF ECONOMIC DEVELOPMENT GENERAL DIRECTORATE FOR THE FIGHT AGAINST COUNTERFEITING ITALIAN PATENT AND TRADEMARK OFFICE Section Class Subclass Group Subgroup F 21 S Section Class Subclass Group Subgroup F 25 D APPLICATION NUMBER 101999900753747 Filing Date 04 / 21 / 1999 Publication Date 10 / 21 / 2000 Title DEVICE FOR AUTOMATICALLY SWITCHING ON LIGHTS FOR REFRIGERATORS AND COLD ROOMS WITHOUT MECHANICAL CONTACT PD99A000080 STELLA Giorgio - NERVESA DELLA BATTAGLIA (TV), via X° Armata 13 TITLE DEVICE FOR AUTOMATIC LIGHT SWITCHING ON FOR REFRIGERATORS AND COLD ROOMS WITHOUT MECHANICAL CONTACT DESCRIPTION This patent relates to the sector of cold storage rooms and refrigerators and in particular concerns devices for switching on internal lighting lamps 10 in refrigerators and cold storage rooms in general. Both refrigerators and cold rooms and other similar cabinets are equipped with one or more internal lights that turn on automatically when the door is opened. Currently, the automatic switching on of these lamps occurs by means of a mechanical switch placed at the edge and where the internal edge of the door is equipped with a relief or tooth or other device that acts on said switch (or vice versa). Due to repeated activations and the particular nature of the working environment, these mechanical switches often have an inconsistent and imprecise operation to the point of stopping their functioning. Various measures and precautions to protect the 25 switches do not completely eliminate the problem. the To overcome all the above-mentioned drawbacks, a new type of device has been designed and developed for the automatic switching on of internal artificial light for refrigerators and cold rooms without mechanical contact. The new device consists of a lighting lamp and a multi-stage open door detection circuit. All these parts of the new device are contained in a watertight casing that can be fixed anywhere in the compartment to be illuminated and not necessarily in correspondence with the door. The new device bases its operating principle on the detection of light entering through the opened door. When the door is opened, the device detects an increase in the amount of light and turns on the lamp. The device periodically turns off the lamp and re-detects the amount of light in the compartment: if the door is open, there is light, and the device turns the lamp back on; if the door is closed, there is no light in the compartment, the device does not turn the lamp back on. This way there is no wear of mechanical parts and the lamp is guaranteed to turn on. Furthermore, in the case of large cold storage rooms, if the door closes and a person is still inside the cell, there is a period of time during which the light remains on and allows the person to reach the exit. The light detection and lamp control circuit consists of several stages, mainly a detector stage, a trigger stage, a timer off stage, a power stage, a power supply stage, a feedback stage. The detector stage features the light-sensitive element, typically a phototransistor (for example, in a Darlington configuration with a BC237). At the slightest presence of light, its potential increases, while it is grounded in total darkness. At the slightest presence of light, it enables the trigger stage. The trigger stage consists of an NE555 in astable configuration that triggers the lamp's ignition control timer. This block ensures that the timer is triggered whenever light is present. The off timer stage consists of a NE555 in a monostable configuration and determines the lamp's on time. This time can be adjusted from approximately 30 seconds to about 10 minutes. The power stage features an optotriac isolation stage for maximum safety. The optotriac directly drives the triac that powers the lamp. This ensures complete isolation between the detection circuit and the lamp power supply. The power stage consists of a circuit that regulates and stabilizes the power supply of the entire detection circuit. The feedback stage is a circuit that delays the next ignition of the lamp to avoid unwanted oscillations. It is possible to provide that the open door detection circuit is equipped with an acoustic signal and an additional adjustable timer connected to the lamp switch-on control timer. When the lamp is turned on, the additional timer starts counting and is reset as soon as the door is closed. When the door is open and the additional timer reaches the set time, the buzzer is activated so that the user is warned that the door has been left open. The attached tables show, by way of example and not as a limitation, a practical embodiment of the invention. Table 1 shows a possible electronic diagram for the detector stage (S1) in which the phototransistor (Q5) for light detection can be recognized. Table 2 shows a possible electronic diagram for the ignition stage (S2), the switch-off timer stage (S3) and the feedback stage (S4). 1 three stages (S2, S3, S4) are connected to each other in order to obtain the best functioning of the circuit. Table 3 shows a possible electronic diagram for the construction of the power stage (S5) and the supply stage (S6). It is evident that during the manufacturing phase the device and / or its elements may be made with different dimensions and shapes, meaning that they will still remain protected by this patent.

Claims

1. Device for the automatic switching on of lights for refrigerators and cold rooms, characterised by the fact that it consists of an open door detection circuit composed of several stages, and where the detection circuit controls the switching on of a lamp when it detects light entering from the open door of the cold room and controls the switching off of the same lamp when it detects the absence of light from the closed door of the cold room.

2. Device for automatically turning on the light for refrigerators and cold rooms as per claim 1, characterized in that it consists of a light and a multi-stage open door detection circuit, where the detection circuit switches the light on when it detects light entering from the open door of the cold room and switches the light off when it detects the absence of light from the closed door of the cold room. Device for automatically turning on the light for refrigerators and cold rooms as per claim 1 or 2, characterized in that when the light is on, the detection circuit periodically switches it off to check whether there is light entering from outside, or whether the door is open or closed.

4. Device for automatically switching on a light for refrigerators and cold rooms as per claim 3, characterised in that the detection circuit is made up of a detector stage which has a light-sensitive element (typically a phototransistor), a trigger stage which starts the switch-on control timer, a switch-off timer stage which determines the (adjustable) lamp-on time, a power stage which has an insulating stage to separate the detection circuit from the lamp power supply, a power supply stage which regulates and stabilises the power supply of the entire detection circuit, a feedback stage which delays the next switch-on of the lamp to avoid unwanted oscillations.

5. Device for the automatic switching on of lights for refrigerators and cold rooms as per claims 3, 4, characterised in that it is equipped with an additional adjustable timer connected to the timer for controlling the switching on of the lamp and with an acoustic warning device, and where the acoustic warning device is activated by the additional timer when the time set in said additional timer has elapsed and the detection circuit does not detect that the door has been closed.