FR2642895A1 - CONFIDENTIAL KEYBOARD WITH TOUCH EFFECT AND USE OF KEYBOARD - Google Patents

Abstract

Confidential keyboard with tactile effect comprising a set of sensitive conductive capsules 4 with click, with omega-shaped section, forming a switch with the conductive tracks 10, 11, 12 of a printed circuit, characterized in that a washer 6 of material of given rigidity, diameter and thickness is placed on each capsule and covered with an element of translucent material forming, using microvutlets 50, a directional filter and supporting the screen printing.

Description

264289S

  CONFIDENTIAL KEYBOARD WITH TOUCH EFFECT AND USE OF

KEYBOARD.

  The present invention relates to a confidential keyboard to

tactile effect and its use.

  Known keyboards having a flat surface and operating either on an electrostatic principle with capabilities, as for example in the patent application FR 2499352, corresponding to GB 2090979, or on an electromechanical principle with contacts, as in

The patent application FR 2586117.

  The latter type of keyboard is generally made of a membrane having a contact which, under the pressure of the oigt, comes to touch a fixed contact surface and establish an electrical connection between two lines - inverters supported by a printed circuit. This type of keyboard generally comprises a means producing a tactile effect, that is to say a feeling of resistance followed by a feeling of depression, as soon as one goes beyond a

  certain pressure exerted by the finger.

  In some applications, these inexpensive keyboard production may also require measures that allow to keep confidential the information that is introduced by pressing the various keys

of the keyboard.

  A first object of the invention is therefore to provide a keyboard for keeping confidential the information that is introduced by preventing the observation by a third party, while maintaining this tactile effect that avoids a double introduction of the

same data.

  This goal is achieved by the fact that the touch sensitive keypad has a set of capsules

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  omega-shaped switch-shaped sensitive sensing switches formed in a printed circuit, a washer of stiffness material of given diameter and thickness is placed on each capsule and covered with a material element translucent forming a directional filter with microvolts and supporting screen printing. According to another feature of the invention, the diameter of the washer is between one third of the diameter of the capsule and half the diameter of the capsule, the thickness is greater than or equal to half the thickness of the element forming the filter and supporting

silkscreen.

  According to another feature, the element is formed of a single sheet having on the back, on the turned side

to rondelie, screen printing.

  According to another feature, the element consists of a first sheet of translucent material supporting the screen printing, and a second translucent sheet with microscreens. According to another embodiment of the invention, the washer is made of material having a minimum hardness of 40 to 45 shores. Another object of the invention is to improve visual perception for the user while maintaining confidentiality. This object is achieved by the fact that the first sheet comprises a screen printing consisting of a light background and characters

dark alphanumeric.

  According to another particularity, the serigraphic printing comprises a dark circle surrounding a clear zone in

  which alphanumeric characters are inscribed.

-3-

  A last goal is to propose a use of the keyboard.

  This object is achieved by the fact that the keyboard is used in a bank machine whose chassis includes a cedar of dimensions adapted to the dimensions of the plate that printed circuit, characterized in that the frame has a shoulder height corresponding to the thickness two leaves, and of greater size than the lateral dimensions of the two leaves so as to

to spare a free space.

  other features and advantages of the present invention will become more clearly apparent on reading the

  description hereinafter made with reference to the drawings

  annexes, in which: - Figure 1 shows a sectional view of the device of the invention; - Figure 2 shows a top view of the contact capsule and the washer; - Figure 3 shows a side view in section of the capsule and the washer; - The fiieure 4 represents a vuw from above the serigraphy. The touch-sensitive electromechanical contact keyboard structure is constituted by a multilayer printed circuit board (1, 2), a first layer (1) of which has on one of its faces the conducting track (12) bringing the current to

  a contact (13) which is itself connected to the capsule (4).

  This capsule (4), whose section shown in Figure 1 and Figure 3 has substantially the shape of an omega, is made of conductive material and has a shape such that in a first time it resists crushing until to reach a certain force of -4 pressure and beyond this pressure force, the curved portion (40) crushes to come to touch the fixed contact (10) which is integral with the insulating layer of printed circuit (1) . This sudden crash produces a sensation to the touch of the observer that is called effect

  Touch. This contact (10) communicates with a second -

  conductive track (11). The tracks (11, 12) of each contact are connected to the pad of a connector in a known manner. The collar (41) forming the foot of the capsule whose section has substantially the shape of an omega is wedged between the first layer (1) and the second layer (2) to the printed circuit. On the layer (2) of the printed circuit, in a conventional constitution keyboard, rests a flexible sheet (3) in mylar which

includes a silkscreen.

  In the invention, this mylar sheet (3) is spaced from the capsule by a washer (6) made of material, such as for example neoprene, having a rigidity of at least 40 to 45 shore A. This washer ( 6) must have a minimum thickness (e) and a diameter that is related to the diameter (D) of the capsule. Above the mylar sheet (3) is placed a sheet (5) of translucent material (51) having, at regular intervals and perpendicular to the surface of the sheet, microvolets (50). This sheet (5) with microvolets (50) spaced at regular intervals forms a directional microvolt filter which allows the eye (d) of an observer in the angle (B) to observe what is in the behind this sheet (5) and in particular to look at the silkscreen of the mylar sheet. On the other hand, an observer (9) who is outside the angle (B) will not be able to see the

  silkscreen, and therefore the inscriptions.

  In order to obtain a touch-sensitive keyboard allowing a certain degree of confidentiality to the information inputted to the keyboard, one would have thought that it was sufficient to superimpose the sheet (5) on the classical constitution of the keyboard. In doing so, we realized that the keyboard

  lost its tactile characteristic.

  The washer (6) whose diameter (d) must satisfy the relation: 0.3 D <d <0.5 D and whose thickness (e) must satisfy the relation e> 0.5 E; E being the total thickness of the

sheet (5) and the sheet (3).

  Surprisingly, by the addition of this washer (b), the tactile effect reappears, while retaining for the device a certain confidentiality to the observation of a third party. This tactile effect reappears under certain conditions of values this diameter, thickness, nature and hardness of the material I the washer (6) which must be defined according to the diameters, depth and driving force of the capsule (4), as well as thickness

  of the element consisting of the two sheets (5) and (3).

  Being aware that microvolets are opaque and that the sheet (6) li.ite the passage of light, to improve the visual perception of screen printing in the case of an unlit keyboard, it is advantageous to use black numbers (31). ) arranged on a white background. Finally, to facilitate the use, and in particular the orientation of the user's fingers on the keyboard, it will materialize on the mylar layer (3) a circle (-30) surrounding each alphanumeric screen element, for the purpose of materialize the target to which the finger should move. This arrangement is preferable to a provision materializing a grid on the surface of the keyboard, because with such a grid the confidential appearance created by the microvolette sheet would disappear. Indeed, 6 - an observer could, thanks to the presence of the grid on the surface of the keyboard, memorize the position of the depressed contacts without knowing their alphanumeric meaning. To allow normal operation of this confidential and tactile keyboard, it is necessary to provide in the frame (7) surrounding this keyboard a recess (71) which allows the sheets (5) and (3) to move in this recess, in order to absorb dimensional variations

  of the sheet caused by pressing the keys.

  This recess (71) has a height (H) corresponding substantially to that of the sheets (3) and (5) and the washer (6). Thus, the printed circuit in known manner is held tight against the shoulder (70) of the frame, while the sheets (5) and (3) can move and slide relative to the edges of the frame (7) forming the notch (71). The frame (7) can do

  part of the chassis of a bank machine.

  Other modifications within the reach of the skilled person

  are also part of the spirit of the invention.

  Alternatively, the sheets (3) and (5) can be replaced by a single translucent microvolt element, the back of which is the side facing the washer (6). this case of screen printing. - 7 -

Claims (7)

  1. A touch-sensitive confidential keyboard comprising a set of omega-shaped sensing click-sensitive conductive capsules (4) forming a switch with the conductive tracks (10, 11, 12) of a printed circuit, characterized in that a washer (6) of material of rigidity, diameter and thickness dornés is placed on each capsule and covered with a translucent material element forming, with mi = rovolets (50), a directional filter and supporting the s4rigraphie.   2. Keyboard according to claim 1, characterized in that 1 diameter (d) is the roncelie () is between one third of the diameter (D) of the capsule and half the diameter of this capsule, the thickness (e) of the washer is greater than or equal to half the thickness (E) of   the element forming the filter and supporting the screen printing.   3. Keyboard according to claim 1 or 2, characterized in that the element is formed of a sheet having on the back, on the side facing the washer, the screen printing. 4. Keyboard according to claim 1 or 2, characterized in that the element consists of a first sheet (3) of translucent material supporting the screen printing placed under a second sheet (5) of microvolts translucent material. 5. Keyboard according to claim 3 or 4, characterized in that the washer (6) is made of material whose minimum hardness is 40 to 45 shore A. -8 -   6. Keyboard according to one of claims 3 to 5, characterized   in that the first sheet (3) comprises a silk-screen printing consisting of a light background (32) and   alphanumeric characters (31) dark.   7. Keyboard according to claim 6, characterized in that the screen printing comprises a black circle (30) surrounding a white area (32) in which the   Alphanumeric characters (31) are entered.   : Use of the keypad according to one of the claims   Drecedents in a bank machine whose chassis includes a frame of dimensions adapted to the dimensions of a printed circuit board, characterized in that the frame comprises a shoulder (71) of height corresponding to the thickness of the two sheets (3, 5) and depth   greater than the lateral dimensions of the two leaves.