Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1986-05-23
1988-05-03
Coles, Sr., Edward L.
Facsimile and static presentation processing
Facsimile
Recording apparatus
358249, 358254, H04N 565
Patent
active
047423986
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
Apparatus for viewing an image on a cathode ray tube.
PRIOR ART
Video display terminals (VDT's) at present usually comprise video display unts (VDU's), which may be set up on a desk and coupled to a keyboard which may be placed in front of the unit. Such VDU's generally take up large space and they must be viewed at a suitable reading distance for the information thereon to be apprehended. This often results in that operators who have to wear spectacles often need to use spectacles especially suited solely to reading the VDU. However, it often happens that the operator views the VDU at very close range instead of using spectacles, which is not to be recommended from the ophthalmic as well as the ergonomic aspect. Operators who do not wear spectacles often have sight problems also, which primarily depends on the fact that the human eye is poorly suited to focusing objects which emit light.
It is also known that VDU's generate pulsing longwave electro magnetic radiation and that they are surrounded by magnetic fields. It cannot be ignored that these factors can detrimentally affect the operator's health. An industrial medicine evaluation of the risks in question is still lacking today, and is difficult to carry out, since it is difficult to identify study conditions and long-term tests. The risks have been particularly pointed out with regard to pregnant women and women of childbearing age. It has been further pointed out that unease and uncertainty with regard to the risks can be a health risk in itself. This uncertainty, in combination with the implementation of the workplace can generally result in that the operator chooses a greater viewing distance than that required by the size of the symbols. The urge to distinguish details results in that the accommodation of the eye will be greater than the corresponding converging angle. This is, of course, tiresome for the eyes andcan give rise to discomfort and a state of tension.
A VDU is generally placed where it is well visible at the workplace in question, resulting in that unauthorized viewing is difficult to prevent. This means that information can leak out to unauthorized persons, which is extremely unsatisfactory from the aspect of industrial espionage, for example. Even if the display surface itself is screened off, this measure will not be particularly effective, since there are always oblique angles from which the display surface can be viewed. Furthermore, a VDT can be easily electronically searched by unauthorized persons, since it sends revealing signals. This is very unsatisfactory from the security aspect.
It may be pointed out that in this connection, that image transmission using mirroring from a VDU mounted under the operator's desk surface is known from the Finnish published specification No. 67,270. A simple raisable mirror is used to make the content on the VDU screen visible to the operator.
SUMMARY OF THE INVENTION
The present invention relates to a solution which can effectively prevent injurious radiation as well as revealing signals, and which furthermore has viewing conditions such that substantially only the operator can base the content on the display surface. An apparatus in accordance with the invention is based on the transfer of images from the VDU to the operator via an optical image transfer system for viewing in a transverse direction in relation to the VDU. What is essentially novel according to the invention is that the optical image transfer system includes mirroring means mounted in a screening casing centrally over the image screen of the VDU, the mirroring means co-acting with light refractive means and/or are formed for light refraction adjusted to the operator. This means that the VDU as well as the screening casing can be implemented so that the latter screens both incident light as well as injurious electromagnetic radiation .
The invention will now be described in details in connection with an embodiment illustrated on the accompanying drawing, where
FIG. 1 is a perspective view of an a
REFERENCES:
patent: 4360836 (1982-11-01), Breck et al.
patent: 4444465 (1984-04-01), Giulie et al.
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