ITPD990080A1 - DEVICE FOR THE AUTOMATIC SWITCHING ON OF LIGHT FOR REFRIGERATORS AND REFRIGERATED CELLS WITHOUT MECHANICAL CONTACT - Google Patents

Description

TITLE

DEVICE FOR AUTOMATIC IGNITION OF

LIGHT FOR REFRIGERATORS AND COLD ROOMS

WITHOUT MECHANICAL CONTACT

DESCRIPTION

This patent relates to the cold room and refrigerator sector and in particular concerns the devices for switching on the internal lighting lamps in refrigerators and cold rooms in general.

Both refrigerators and cold rooms and other similar cabinets are equipped with one or more internal lighting lamps which are switched on automatically when the door is opened.

Currently, the automatic switching on of said lamps takes place by means of a mechanical switch placed at the edge and where the inner edge of the door is equipped with a relief or tooth or other that acts on said switch (or vice versa).

Due to repeated activations and given the particular nature of the work environment, said mechanical switches often have an inconsistent and imprecise operation until their operation is interrupted.

Various switch protection measures and precautions do not completely eliminate the problem.

To obviate all the aforementioned drawbacks, a new type of device has been studied and implemented for the automatic switching on of the internal artificial light for refrigerators and cold rooms without mechanical contact.

The new device consists in its main parts of a lighting lamp and an open door detection circuit composed of various stages.

All these parts of the new device are contained in a watertight casing which can be fixed in any point of 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 from the door that is opened.

When the door is opened, the device detects an increase in the amount of light and activates the ignition of the lamp.

Periodically the device turns off the lamp and detects again the amount of light present in the compartment: if the door is open there is light and then the device turns the lamp back on; if the door has been closed in the compartment there is no light the device does not turn the lamp back on.

In this way there is no wear of mechanical parts and you can be sure that the lamp is switched on.

Furthermore, in the case of large cold rooms, if the door closes and a person is still inside the cell, there is a period of time in which the lamp remains on and allows the person to reach the exit.

The light detection and lamp control circuit consists of various stages, mainly a detector stage, a trigger stage, an off timer stage, a power stage, a power stage, a feedback stage.

The detector stage has the light-sensitive element, typically a phototransistor (for example in a darlington configuration with a BC237). At the slightest presence of light there is an increase in potential while it is grounded if it is in total darkness. At the slightest presence of light it enables the trigger stage.

The trigger stage is formed by a NE555 in astable configuration which triggers the lamp ignition control timer. This block gives us the certainty of triggering the timer at every light presence.

The sleep timer stage is formed with a NE555 in a monostable configuration and determines the lighting time of the lamp. This time can be adjusted from approximately 30 seconds to approximately 10 minutes. The power stage features an optotriac isolating stage for maximum safety. The optotriac directly drives the triac that powers the lamp. In this way there is complete isolation between the detection circuit and the lamp power supply.

The power supply stage is formed by a circuit that regulates and stabilizes the power supply of the entire detection circuit.

The feedback stage is a circuit that delays the subsequent 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 timer that can be set connected with the lamp control timer.

When the lamp is switched 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 of the door left open. In the attached tables, a practical embodiment of the invention is presented by way of non-limiting example.

Table 1 shows a possible electronic scheme of realization of the detector stage (S1) in which the phototransistor (Q5) for detecting light is recognizable.

Table 2 shows a possible electronic scheme for the construction of the ignition stage (S2), the shutdown timer stage (S3) and the feedback stage (S4).

The three stages (S2, S3, S4) are connected to each other in order to obtain the best operation of the circuit.

Table 3 shows a possible electronic scheme of realization of the power stage (S5) and of the power supply stage (S6).

It is evident that in the manufacturing phase the device and / or its elements can be made with different dimensions and shapes, meaning that they remain in any case protected by the present patent.

Claims (1)

CLAIMS 1st Device for automatic switching on of light for refrigerators and cold rooms characterized by the fact that it consists of an open door detection circuit composed of various stages, and where the detection circuit commands the switching on of a lamp when it detects the incoming light from the open compartment door and controls the switching off of the same lamp when it detects the absence of light from the closed compartment door. Z Device for automatic switching on of light for refrigerators and cold rooms as per claim 1, characterized in that it consists of a lighting lamp and an open door detection circuit composed of various stages, and where the detection circuit controls the lighting of the lamp when it detects the light entering from the open compartment door and commands the lamp to switch off when it detects the absence of light from the closed compartment door. Z Device for automatic switching on of light for refrigerators and cold rooms as per claim 1 or 2, characterized by the fact that when the lamp is on the detection circuit switches it off periodically to check if there is light entering from the outside, or if the door is open or closed. Device for automatic switching on of light for refrigerators and cold rooms as per claim 3, characterized in that the detection circuit consists of a detector stage which has a light-sensitive element (typically a phototransistor), an ignition stage which starts the on control timer, an off timer stage which determines the (adjustable) time the lamp is switched on, a power stage which has an insulating stage to separate the detection circuit from the lamp supply, a stage power supply that regulates and stabilizes the power supply of the entire detection circuit, a feedback stage that delays the subsequent ignition of the lamp to avoid unwanted oscillations. ^ Device for automatic switching on of light for refrigerators and cold rooms as per claims 3, 4, characterized in that it is equipped with an additional settable timer connected to the lamp switch-on control timer and an acoustic alarm, and where the acoustic alarm 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.