DE1274836C2 - Arrangement for converting an optical image into thermal stimuli perceptible on the human body - Google Patents

Description

GERMAN 4VN ^ PATENT OFFICE

German class: 42 η-2/02

PATENT LETTERING

Number: 1274 836

File number: P 12 74 836.6-51 (P 36462) J 274 836 Filing date: April 6, 965

Opening day: August 8, 1968
Issue date: March 27, 1969
The patent specification corresponds to the interpretation specification

The invention relates to an arrangement for converting an optical image into a human Thermal stimuli that can be perceived by the body, which is particularly suitable for providing an image to blind people to convey to their environment.

Various arrangements and methods have been proposed to help blind people to convey an image of their environment through their sense of touch, hearing or their sense of warmth.

In a known arrangement, which is said to be particularly suitable for reading, the letters are scanned in the reading direction by a row of selenium cells perpendicular to the reading direction. The height and the width correspond to each row of the shadow effect of the vertical and horizontal stroke width of the letters, and each cell must have a remarkable i acting particularly on the feeler members of the reader recognition device. This z. B. Detection devices formed by keys have various high constant temperatures, which are partly achieved by appropriate heating by means of a heating current, partly by cooling, in order to produce greater irritation when the detection devices act on the tactile organs of the reader.

However, this known arrangement is relatively sluggish and unsuitable for the blind person to have many pixels at the same time, that is, to convey an overall picture through thermal stimuli.

The purpose of the invention is to create an arrangement which the blind person can use as possible provides an accurate and detailed image of its moving environment, which is simply structured and works safely.

The invention is therefore based on the object of an arrangement for converting an optical Image in thermal stimuli perceptible on the human body with the properties mentioned above to accomplish.

According to the invention, this object is achieved by a system of η photoelectric components on which the optical image to be converted is mapped and broken down into η pixels, and a system of π Peltier elements connected to the system of photoelectric components that is sensitive to thermal stimuli Place of the body can be placed, each Peltier element being controlled by a photoelectric component assigned to it so that the temperature of the part of the Pcltier element to be placed on the body corresponds to the illuminance on the photoelectric component.

Arrangement for converting an optical
S image in on the human body
perceptible thermal stimuli

Patented for:

Philips Patentverwaltung G. mb H.,
2000 Hamburg 1, Mönckebergstr. 7th

Named as inventor:
Dipl.-Phys. Dr. rer. nat. Joachim Schnell,
so 5101 hairs

Each Peltier element of the photoelectric component assigned to it is preferably so controlled that. the temperature of the part of the Peltier element resting on the body changes between positive and negative values related to body temperature.

The invention is explained in more detail below using an exemplary embodiment. The associated The drawing shows a schematic representation of the exemplary embodiment.

The arrangement shown in the drawing consists in principle of an optical system 8, a system of η photoelectric elements and a system of Peltier elements connected to it via bridge circuits 3. The photoelectric elements 1 are arranged in a plane in the form of a grid. They resolve an image projected onto them into individual pixels. The η bridge circuits 3 are fed by a common current source 5. One of the bridge resistors of this bridge circuit 3 is formed by the respective associated photoelectric element 1. Each bridge circuit 3 feeds a Pclticr element 2. Each of the η Peltier elements 2 consists of at least two semiconductor legs 7 of different conduction types. The surface 4 of each Pelticr element formed by the connecting bridge of the two half-liter legs lies in an outer surface of the

909 613/2233

Claims (6)

1 system formed by all η Peltier elements 2. In order to keep the drawing clear, only three connections between photoelectric element 1, bridge circuit 3 and Peltier element 2 are shown. The semiconductor legs 7 of the η Peltier elements 2 are made of a poorly thermally conductive material 9, for. B. a polyurethane foam, embedded so that only the surfaces 4 on which the current-dependent temperature changes occur are exposed. The metallic, e.g. made of copper, metal legs 6 connected to the semiconductor legs 7 are, after prior electrical insulation, in a highly thermally conductive material 10, e.g. B. a metal or a metal alloy embedded. The Peltier elements2 are thus each connected thermally in parallel on one side. This side must be cooled in order to dissipate the excess heat (Joule heat in the Peltier elements), e.g. by protruding copper lugs that give off the heat to the ambient air. The arrangement works in principle as follows: The image to be conveyed is mapped onto the system of photoelectric components 1 via the imaging system 8. The components can be photocells, photodiodes, photoresistors or similar elements, but they can also be controlled by scanning methods, as are customary in television recording technology. The image is broken down into η light points by the grid formed from the photoelectric components 1. Each of the photoelectric components controls the intensity and direction of the current through the Peltier FJement 2 connected to this bridge circuit according to the illuminance on its active surface via the associated bridge circuit 3 Current through the Peltier element and thus the illuminance on the associated photoelectric component 1 corresponds. A thermal image is thus produced over all surfaces 4 of the Peltier elements 2 which corresponds exactly to the optical image projected onto the photoelectric components 1. The system of Peltier elements 2 rests with its curses 4 on a skin area that is as smooth as possible and cmpiindliehen, such as the forehead, hand, arm, chest, etc. of the person to whom the optical image is to be conveyed by thermal stimuli. Since the number of thermoreceptors on these sensitive areas of the skin is relatively large (around four heat-sensitive and twelve cold-sensitive thermoreceptors per square centimeter of skin), a fairly finely rastered image can be thermally perceived. The dimensions of the surfaces 4 are approximately 2 ″ 2 mm, so that approximately 15 to 20 Peltier elements can easily be arranged on a 1 cm * surface. The size of the systems formed in each case from the photoelectric components 1 and the Peltier elements 2 can be approximately 1010 cm. About 1000 to 2000 elements are then arranged over this area. The energy requirement required to control this number of Peltier elements as a function of the illuminance of the associated photoelectric components when using bridge circuits should be around 10 to 20 watts. 836 Because the surfaces 4 of the Peltier elements can both heat up and cool down as a result of the change and reversal of the current compared to the ambient temperature, a temperature origin of at least 40 ° C. can easily be achieved. This makes the mediated thermal stimulus very intense. The surfaces 4 of the Peltier elements also have a very low heat capacity, so that a cooling or heating rate of about 10 0 C / sec. is possible. This high rate of change or low thermal inertia is sufficient to convey fast moving images through the thermal stimuli from the Peltier elements. The position of one at medium distance at a speed of around 50 miles per hour. Passing cars should be able to be conveyed to the person carrying the arrangement with an accuracy of ± 1 m. The bridge circuit 3, via which the Peltier elements 2 are controlled by the photoelectric components, can be replaced by other suitable circuits, in particular those which allow lossless control. So it is F. It is conceivable to use photocells as photoelectric components, which control the current through the Peltier elements via transistors. A fatigue of the addressed sensory cells, i. H. the thermoreceptors in the skin, which may occur under certain circumstances, can, for. B. be countered by an intermittent operation of the Peltier elements. The thermal image on the Peltier element system is deleted after each work interval. This can be done, for example, in that a thermal image is generated which corresponds to the thermal image to be deleted in relation to the mean temperature, i.e. H. body temperature, is complementary. Patent claims: 1. An arrangement for converting an optical image into perceptible thermal stimuli on the human body, characterized by a system of η photoelectric components (1) on which the optical image to be converted is mapped and broken down into η pixels, and a system of photoelectric components connected system of η Peltier elements (2), which can be placed on a point of the body sensitive to thermal stimuli, each Peltier element (2) being controlled by a photoelectric component (3) assigned to it so that the temperature of the the part (4) of the Peltier element (2) to be placed on the body corresponds to the illuminance on the photoelectric component (1). 2. Arrangement according to claim 1, characterized in that each Peltier element (2) of the associated photoelectric component (1) is controlled so that the temperature of the part resting on the body (4) of the Peltier element (2) changes between positive and negative values with respect to the body temperatures. 3. Arrangement according to claim 1 or 2, characterized in that each Peltier element (2) is controlled via a bridge circuit (3), in one branch of which the photoelectric component (1) assigned to it is located. 4. Arrangement according to at least one of the preceding claims, characterized in that that it is operated intermittently. 5. Arrangement according to claim 4, characterized in that after each working interval the thermal image on the Peltier element system (2) is deleted. 6. Arrangement according to claim 5, characterized in that the deletion by generating a thermal image which is complementary to the existing thermal image in relation to the body temperature is brought about. 1 sheet of drawings