Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Patent
1991-03-27
1993-02-23
Howell, Janice A.
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
369111, 365122, G11B 1100
Patent
active
051896583
DESCRIPTION:
BRIEF SUMMARY
The invention pertains to a device for recording information in rows and columns on a data carrier with a film the optical properties of which can be influenced by temperature variation. Starting from an initial temperature (for example, room temperature) and an initial optical state (e.g., opaque), the film can be changed to a second optical state (e.g., transparent) by heating the film to a second temperature. This change can be made permanent by cooling the film back to the first temperature. The change in state can later be reversed by heating the film, which is now in its second state, from the first temperature to a third temperature and then cooling it again. In this process, the second temperature is greater than the first temperature, and the third temperature is greater than the second temperature.
BACKGROUND OF THE INVENTION
A data carrier of this type is already known. European Patents 0 000 868 and 0 014 826 describe a material with reversible fixed and temperature-variable light extinction, which is designed as an erasable data carrier consisting of a pair of substances, which has a decreasing light extinction with increasing heating temperature, for example, on heating from the state of maximum light extinction to a temperature of transparency below a transition temperature, and then cooling to below a low temperature value.
The recording and erasing process can be repeated as often as desired. The recording can be made by finely beamed infrared or luminous radiation or by contact heat. The known data carrier is thus suitable for the erasable recording of numbers, letters, pictures, patterns, etc. The recordings can be made either in transparent form on an opaque field or in opaque form on a transparent field.
The goal of the invention was to develop a suitable device for recording optical information on a data carrier of this type.
SUMMARY OF THE INVENTION
This goal is achieved by the following devices: an erasing device, a cooling device, a preheating device (if necessary) and a recording device. The erasing device heats the film to the third temperature or the second temperature, and the cooling device cools the film to the first temperature. The preheating device heats the film to a fourth temperature between the first temperature and the second or third temperature. The recording device heats the appropriate points on the film to the third or the second temperature, according to the information to be recorded. The sheetlike data carrier passes successively through these individual devices in the order described above. Each of the devices is arranged over the full width of the data carrier. The preheating device is located very close to the recording device or may actually be a part of the recording device. The recording energy is controlled by signals from thermal and/or optical sensing devices. The optical sensors check the information recorded on the data carrier by the recording device.
The erasing device ensures that the data carrier is converted to a well-defined state, independently of its current state. The cooling device cools the data carrier to room temperature. It is possible to dispense with such a cooling device if the temperature around the data carrier is kept suitably low after the erasing process, and the data carrier quickly cools by itself. The purpose of the preheating device is to accelerate the recording process by raising the data carrier to a certain temperature before or during the recording process and maintaining that temperature. However, this temperature may not fall within a temperature range in which the state established by the erasing process is changed. The information to be recorded is then recorded on the data carrier by the recording device. At the end of the recording process, we will have either a nontransparent data carrier, in which the recorded information is visible in transparent form, or a transparent data carrier, in which the recorded information is nontransparent. Since the data carrier is sheetlike, the device of the invention can b
REFERENCES:
patent: 4773060 (1988-09-01), Shimada et al.
patent: 4922462 (1990-05-01), Ikegawa et al.
Howell Janice A.
Nguyen Kiet T.
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