X-ray or gamma ray systems or devices – Electronic circuit – With switching means
Reexamination Certificate
1999-11-17
2001-09-25
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
With switching means
C378S098800, C378S189000
Reexamination Certificate
active
06295337
ABSTRACT:
DESCRIPTION
1. Technical field
The present invention relates to a digital radiography device with protection against electrical risks.
This device can advantageously be used in the field of digital dental radiography.
2. Prior art
The present invention is situated in the medical field and relates to any device which combines a diagnostic or treatment device with an acquisition, control and/or treatment system, using the mains for its electrical supply or supplies of another type whose voltage exceeds safety low voltages.
Such a connection of one of the elements of the equipment to the mains must cause no risk to the patient, operator and/or third parties. Various standards oblige the manufacturer to review all the risks which may be presented by his equipment vis-à-vis such people and to afford a remedy for them preventatively, as from the design and manufacture, by taking appropriate steps of such a nature as to mitigate the risks identified.
The digital medical radiography devices which currently exist on the market take into account the electrical risks in a conventional fashion. Usually, a “relay box” is placed on the sensor/computer path, whose essential function is to establish an isolation barrier on the sensor/computer path, as well as vis-à-vis the mains supplying the energy. This relay box has a double-insulation mains supply, which satisfies current standards, and supplies power to local electronics and to the remote sensor. These local electronics transform the analogue signal coming from the sensor into digital signals, so that any exchange with the computer relates only to the digital signals passing through optical couplings (optocouplers) isolating the sensor from the computer on an electrical level. Thus the sensor is isolated from the mains at the relay box by a supply including a double-insulated transformer and, at the computer, by the presence of an optical barrier on the data path.
Such a technique significantly increases the cost incurred for protection against electrical risks and introduces a second risk element, namely an independent power supply, without eliminating the computer, from which it is also necessary to be protected.
The object of the invention is a device for guarding against any electrical risks which may be feared, when one of the elements constituting it is supplied with power from the mains, or any other source if voltages are higher than safety low voltage.
SUMMARY OF THE INVENTION
The invention proposes a digital radiography device with protection against electrical risks, having:
a radiation source, for example X-rays;
a sensor connected to an electronic card of a computer,
characterised in that it comprises first and second assemblies isolated from each other from the galvanic point of view, the first assembly comprising electronic means connected to the sensor, the second assembly comprising means for supplying a voltage for supplying the sensor during the presence of radiation and a voltage for supplying the sensor part of the card, and means for providing management of the sensor, recovery of the data and processing thereof, the two assemblies exchanging information by optical means, and in that the two assemblies cohabit within the electronic card.
Advantageously, the two assemblies are surrounded by a belt of air.
Advantageously, the first assembly comprises electronics located on the electronic card and disposed in a galvanic isolation enclosure situated on the said card, the sensor and a connecting cable connecting the sensor and the said electronics.
Advantageously, the electronics of the sensor assembly are protected by an isolating belt, the connection between isolating enclosure and connecting cable being effected by a movable plug passing through the metallic enclosure of the computer, this plug having insulation reinforced by superimposed moulding, the fixed base of the connector which receives the plug being situated recessed in the isolation enclosure. The analogue data issuing from the sensor are digitised in the sensor electronics within the isolation enclosure.
Advantageously, the power necessary to the isolation assembly is taken off in the computer assembly downstream from the safety power supply, on low voltage supplies, and transmitted by means of DC/DC converters situated on the electronic card.
The device of the invention can notably be used in the field of dental radiography.
The device of the invention protects the patient and operator against potential but uncertain electrical risks. This device provides an isolation barrier ensuring compliance with electrical standards between a sensor, or any other element, in contact with a patient at one end and, at the other end, control and/or processing electronics, supplied with power from the mains.
The device of the invention is advantageous because of its simplicity, and therefore its cost, since it uses electrical protection, processing of the data issuing from a sensor within a single electronic card and display of these data without sacrificing any of the elementary requirements of diagnostic equipment.
The invention can be applied to any passive or active sensor in contact with a patient so long as:
it receives, for its functioning, energy, possibly electrical stimuli, coming from equipment connected to the mains, or provided with a self-contained power supply, so long as its voltage exceeds the safety low voltage level (50 volts);
it supplies, possibly, in return, measuring signals or parameters, so long as these signals are sent to processing electronics supplied from voltage sources whose voltage exceeds safety low voltages, all the more so when it is a case of the 220 volts 50 or 60 Hz mains.
REFERENCES:
patent: 5434418 (1995-07-01), Schick
patent: 5454022 (1995-09-01), Lee et al.
patent: 5912942 (1999-06-01), Schick et al.
patent: 6044131 (2000-03-01), McEvoy et al.
patent: 0 544 974 A1 (1991-11-01), None
patent: 0 666 483 A2 (1995-01-01), None
Glasser Francis
Thevenin Bernard
Commissariat A l'Energie Atomique
Kim Robert H.
Pearne & Gordon LLP
Song Hoon Koo
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