System for entering a code into a tactile keyboard suitable for visually impaired persons
Patent Information
- Application Number
- EP2024702814
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-01-05
- Filing Date
- 2024-01-02
- Publication Date
- 2025-11-12
AI Technical Summary
Existing touch keyboards are not ergonomically accessible for visually impaired individuals, as the visual representations of keys are difficult to access, leading to incorrect code entries due to the nature of touch-based key activation, which does not allow for preliminary key location without triggering character entry.
A touch keyboard system with a processing unit that operates in a visually impaired mode, where characters are selected by two successive tactile contacts on the same key, allowing users to slide and locate keys without immediate activation, and an approach sensor to switch modes, ensuring accurate character entry without unintended selections.
The system enhances accessibility and reduces errors by allowing visually impaired users to mentally retain the keyboard layout, improving the ergonomic experience and accuracy of code entry.
Smart Images

Figure 1.1
Abstract
Description
[0001] DESCRIPTION
[0002] TITLE: Code entry system on a touchscreen keyboard adapted for visually impaired people
[0003] [Technical field]
[0004] The invention relates to an input system for entering a code on a touch keyboard.
[0005] It relates more specifically to an entry system for entering a code for visually impaired or blind people.
[0006] The invention finds a preferred, and non-limiting, application for a secure access control reader requiring the entry of a code to authorize access to a secure space, but can also find an application in other sectors such as electronic payment terminals and self-service distribution terminals (for example, ATM, food dispenser, beverage dispenser, etc.).
[0007] [State of the art]
[0008] As is known, devices requiring the entry of a code comprising a series of characters, and in particular numbers, have a keyboard comprising several keys assigned to respective characters including numbers, and possibly also alphabetic characters and / or special characters, such as for example the characters “*” and “#”, and / or functional characters, such as for example a validation key for validating the code once entered, or a backspace or correction key when entering the code, or even a key for canceling the complete entry.
[0009] Each key has a visual representation of a symbol informing the user about the character assigned to the key: indication of the number to which a number key relates for entering the number code; indication of the alphabetic character; indication of the special character; indication of the functional character (or function of the key), for example by a color, such as a green key for validating the code; a red key for canceling the entry; etc.
[0010] Typically, such a keyboard can be a mechanical keyboard or a touch keyboard. The technologies differ between the two keyboard models, but the principle remains common, namely that the keyboard includes a plurality of discrete keys, and the user presses the keys to enter the associated characters. In a mechanical keyboard, the keys are mechanical keys that the user must push or press to trigger input; in a touch keyboard, the keys are formed by tactile sensors based on touch (or contact) detection technology, such as capacitive technology, inductive technology or infrared technology, so that the user only needs to touch the key to trigger input, without needing to apply any particular pressure. In practice, the keys of a touch keyboard are domed, hollow or raised, to allow the keys to be distinguished.
[0011] However, the visual representations of the keys are difficult to access for people with visual impairments, and are completely inaccessible to blind people.
[0012] Solutions have been designed to make keyboards accessible to the visually impaired.
[0013] In accordance with European standard EN 13332-3 06-1999, for keyboards, the "5" key on mechanical and tactile keyboards is provided with a tactile marking relief so that by moving their finger over the keyboard, the visually impaired person can identify this key and use it as a reference point to locate the other keys; the "2" key is located above the "5" key, the "4" key to the left, the "6" key to the right, etc. Similarly, for electronic payment terminals, embossings in the shape of an "O" and an "X" respectively are used so that the visually impaired person can locate the validation and cancellation keys.
[0014] In the case of a mechanical keyboard, this solution with a tactile marking relief is sufficient, because the visually impaired person can search for and touch the mechanical keys to identify the tactile marking relief, without pressing them, so that there is no risk of triggering an erroneous entry of a character during this preliminary phase of searching for the marking relief.
[0015] On the other hand, this solution with a tactile marking relief is not satisfactory in the context of a tactile keyboard, because the visually impaired person must search for and touch the tactile keys to identify the tactile marking relief (generally by sliding their finger), then to search for the other keys once the tactile marking relief has been identified, so that it will inevitably trigger erroneous character entries during this preliminary phase of searching for the marking relief and when searching for the keys (because the simple contact on a tactile key of a tactile keyboard triggers the entry of the character concerned, there is no need to press the key as in a mechanical keyboard). Consequently, this preliminary phase on a tactile keyboard leads to the entry of an incorrect code, thus making this solution not very ergonomic for visually impaired people.
[0016] Input systems intended for use by both sighted and visually impaired or blind people are proposed in the literature.
[0017] Document US7737955 discloses an ATM equipped, for visually impaired and blind people, with a jack socket for connecting headphones. Once connected, the user hears voice prompts through their headphones to guide and assist them in using the ATM. This solution is not very accessible for visually impaired and blind people because they ultimately have to use the ATM like a sighted person, but also impractical because they have to carry their own headphones.
[0018] Documents EP2390606 and US2020 / 402423 disclose electronic payment terminal (EPT) solutions, each comprising at least one touchscreen displaying a virtual keyboard and offering, for entering the PIN code of a bank card, an input mode intended for sighted people (sighted mode or main mode) and an input mode intended for visually impaired or blind people (visually impaired mode or secondary mode). The touchscreen is provided with a pin to locate the "5" key (also called the central key) and each key is provided with a relief to feel its location on the touchscreen by contact. For both solutions, it is provided that the user presses the central key at least once to locate it and mentally represent the virtual keyboard and then, if he wishes to reach another key, slides his finger on the touchscreen from the central key to this other key.
[0019] In EP2390606, the secondary mode is designed such that the validation of a key is based on a keypress time exceeding a given time delay. However, this key validation by keypress time can be problematic and impractical for users, such as the elderly, for whom a mental representation of the virtual keyboard may be less obvious. In fact, the time taken by these users to browse the touchscreen, identify the reliefs of the keys, etc. can be longer. Potentially, these users can leave their finger pressed longer on a key, causing the keypress time to exceed the set time delay and then leading to an involuntary validation of the key.
[0020] In US2020 / 402423, the secondary mode is designed such that the validation of a key (corresponding for example to a number) is based on a first press on it, followed by a double-tap anywhere on the surface of the touch screen. The disadvantage of such validation is that the visually impaired or blind person, after having double-tapped anywhere on the surface of the touch screen, may lose all mental reference point / reference in relation to it and the arrangement of its keys; forcing them then, if they have to enter a new number, to move their finger back on it until they find the nub of the central key "5", to be able to once again "center" their mental representation of the touch screen, hence a loss of time in entering their bank card code.
[0021] [Summary of the invention]
[0022] The invention aims to address the problem posed by providing a solution for entering a code on a touchscreen keyboard that is more accessible and ergonomic for visually impaired people. The solution can also be used by a sighted person.
[0023] Thus, the invention relates to an input system for entering a code comprising a sequence of characters, this input system comprising:
[0024] - a touch keyboard provided with discrete touch keys assigned to respective characters including at least numbers, each touch key comprising a touch sensing surface and the touch sensing surface of at least one of the touch keys is provided with a marking relief, said touch keyboard being configured to generate key signals in response to tactile contacts exerted by a finger on the touch sensing surfaces of the touch keys, each of the key signals being associated with the touch key on which the tactile contact is exerted; and
[0025] - a processing unit connected to the touch keyboard to acquire the key signals generated by the touch keyboard, and configured to analyze said key signals to select characters according to said key signals; wherein the processing unit is configured to operate at least in an input mode adapted to the visually impaired, called visually impaired mode, in which the processing unit is configured to select each of the characters as follows: acquisition of a key signal, called first key signal, associated with a touch key assigned to a character, followed by an acquisition of a second key signal associated with the same touch key after a period without acquisition of a key signal between the acquisitions of the first key signal and the second key signal, such that a character is selected only by a first tactile contact of a finger on the touch key assigned to said character,followed by a removal of said finger, then followed by a second tactile contact of the finger on the same tactile key assigned to said character. In other words, the input system relies, when in visually impaired mode, on an acquisition of two successive tactile contacts on the same tactile key to select the character assigned to the tactile key; thus an unfortunate tactile contact on a tactile key (for example when the finger passes over it while sliding), which would not be followed by a removal of the finger then a new tactile contact on this same key, will not lead to the selection of the character assigned to the key.,
[0026] Thus, thanks to this implementation of the visually impaired mode, the visually impaired person simply has to slide their finger on the touch keyboard to detect the relief marking (by sliding, the finger passes over touch keys but no character selection takes place), then they slide their finger from the relief marking to reach the target touch key (and thus the processing unit acquires a first key signal associated with this target touch key), lift their finger (and thus the processing unit no longer detects a key signal, and therefore detects the removal of the finger), and finally puts their finger back on the target touch key (and thus the processing unit acquires a second key signal associated with this target touch key), so that the processing unit selects the character assigned to this target touch key.With the finger placed on the validated key, the visually impaired person mentally retains their representation of the layout of the keys on the touch keyboard (without having to go back to find the relief marker), so that the operation can be repeated easily, by sliding the finger from this validated key to the new target touch key, then lifting the finger and placing the finger again on this new target touch key. In other words, a character is selected by a double contact on the same key; the first contact can be at the end of a slide of the finger after entering a previous character, and the second contact can be the beginning of a slide of the finger to enter a next character.
[0027] It should be noted, for the purposes of this description, that the selection of a character by the processing unit means that the processing unit transmits this character as an input for the validation of the code. Each character selected by the processing unit forms a sequence of characters which is compared to the stored code, for example to authorize access, validate a payment, etc. This comparison of the sequence of characters selected by the processing unit can be done within the processing unit, or within a host system which receives the selected characters from the processing unit and then compares them with the stored code. According to one possibility, the visually impaired mode is a default input mode, or even the only input mode implemented by the processing unit.
[0028] Advantageously, in the visually impaired mode, the processing unit is configured to select each of the characters on the condition that the period between the acquisitions of the first key signal and the second key signal is less than a maximum time threshold, such that a character is selected by the first tactile contact of the finger on the touch key assigned to said character, followed by a removal of said finger, then followed by the second tactile contact of the finger on the same touch key assigned to said character, within a time less than the maximum time threshold between the first tactile contact and the second tactile contact.
[0029] In other words, for two successive contacts on the same touch key to be taken into account to select the character assigned to the touch key, the delay (also called period) between the two contacts must be less than this maximum time threshold; in other words, the two contacts must be close together in time. This maximum time threshold can, for example, be of the order of 1 to 2 seconds, and it can be configurable.
[0030] In a particular embodiment, the processing unit is configured to operate in another input mode suitable for sighted people, and called sighted mode, in which the processing unit is configured to select each of the characters by operating as follows: acquisition of a key signal followed by automatic assignment of the character which is assigned to the touch key associated with said key signal, so that a character is automatically selected by a tactile contact of a finger on the touch key assigned to said character.
[0031] This sighted mode corresponds to a classic mode where it is sufficient to touch a touch key to select a character. The process of selecting a character therefore varies depending on whether the processing unit is in sighted mode or in visually impaired mode. In sighted mode, each time a touch key is touched, this results in the selection of the affected character; while in visually impaired mode, it is not sufficient to touch a touch key to select the affected character; an additional validation condition associated with this touch key must also be met, namely to lift the finger and then touch the same touch key again.
[0032] In an optional embodiment, the input system comprises at least one approach sensor configured to detect an approach action performed by a user and in response to deliver an approach signal, said at least one approach sensor being distinct from the touch keys of the touch keyboard, and the processing unit is connected to the at least one approach sensor and is configured to switch from sighted mode to visually impaired mode upon receipt of at least one approach signal from the at least one approach sensor.
[0033] In other words, in this embodiment, the input system is based on the principle of allowing a visually impaired person to switch to the visually impaired mode that is more suitable for them, instead of the sighted mode that uses sight, in an easy manner, by performing a predefined approach action, such as for example by bringing their hand or a badge closer to the touch keypad or by coming into contact with the touch keypad; this approach or this contact of the hand or badge being detected by the approach sensor (or one of the approach sensors). Since the approach sensor is separate from the touch keys of the touch keypad, a user cannot switch to the visually impaired mode by pressing one of the touch keys; in other words, the processing unit is not configured to switch to the visually impaired mode upon receipt of a key signal, and it switches to the visually impaired mode only upon receipt of an approach signal that is different from the key signals.
[0034] In use, a visually impaired person therefore performs the approach action necessary to switch to the visually impaired mode, without having to touch the touch keys because the approach sensor is separate from the touch keys, and then touches the keys to search for the marking relief and then to touch the touch keys by sliding their finger on the touch screen in order to enter the code, respecting the additional validation condition which is, as a reminder, a detachment of the finger followed by a new contact on the same touch key. Indeed, when the processing unit is in the visually impaired mode, this mode is well suited to visually impaired people because an accidental contact on a touch key does not automatically trigger the selection of the assigned character, it is still necessary to perform an additional action to meet the additional validation condition.Thus, this visually impaired mode is intended to avoid unwanted character selections when the visually impaired person fumbles with the screen keys, particularly when looking for the relief marker or a key.
[0035] A sighted person, on the other hand, performs direct tactile input by touching or pressing the tactile keys that they are viewing, because the tactile keyboard operates in the sighted mode adapted to sighted people, that is to say with classic input by simple tactile contacts on the tactile keys, in other words each tactile contact on a tactile key automatically triggers the selection of the assigned character.It should be noted that, according to the invention, the keyboard is a touch keyboard, with touch keys which are discrete keys each allocated to a specific character; it being conceivable that the characters may comprise only numbers, namely the numbers "0" to "9", or comprise both these numbers and other characters, such as alphabetic characters and / or special characters, such as for example the characters "*" and "#", and / or functional characters, such as for example "validation", "correction or backspace", "cancellation". For the purposes of the invention, this touch keyboard is not a mechanical keyboard with mechanical keys which must be pressed or pushed.
[0036] According to one possibility, the processing unit is configured to be by default in the seeing mode, in the absence of reception of the approach signal from the at least one approach sensor.
[0037] Alternatively, the processing unit, when in visually impaired mode, is configured to automatically switch from visually impaired mode to sighted mode once the characters forming the code have been entered, for example after a predefined time delay.
[0038] In other words, when the visually impaired person has correctly entered the code in the visually impaired mode, then the processing unit automatically returns to the sighted mode.
[0039] According to one feature, the processing unit, when in low vision mode, is configured to automatically switch from low vision mode to sighted mode if no key signal is generated by the touch keyboard after a predefined period of time.
[0040] So, if the visually impaired mode is activated and no touch button is touched during this time, then the processing unit automatically returns to sighted mode.
[0041] In an advantageous embodiment, the at least one approach sensor comprises at least one lateral approach sensor shaped to detect the approach action in the form of an approach or contact of a hand of the user on at least one side of the touch keyboard.
[0042] Thus, the approach action that the visually impaired person must perform takes the form of an approach or contact with one hand on one side of the tactile keyboard, to the right, to the left, above or below the front face of the tactile keyboard where the tactile keys are located.
[0043] In other words, the input system is based on the principle of allowing a visually impaired person to switch to visually impaired mode by bringing their hand closer to the touch keyboard from the side or by coming into contact with the touch keyboard; this approach or contact of the hand or the badge being detected by the lateral approach sensor (or one of the lateral approach sensors).
[0044] Since the lateral approach sensor is separate from the touch keys (in other words, separate from the means implemented by the touch keyboard for entering characters), a conventional approach of the hand by a sighted person to the touch keyboard (in other words, to the front face where the touch keys are arranged) will not be detected by this lateral approach sensor and will therefore not be confused with an approach to the side used to switch to visually impaired mode. On the other hand, when a visually impaired person approaches their hand to the keyboard, they naturally search for the keyboard using a scanning gesture, which leads to an approach or contact on one side of the keyboard, and therefore to detection by the lateral approach sensor.
[0045] It should be noted that the side of the touch keypad means, within the meaning of the description, a lateral part extending next to the front face of the touch keypad; in other words, this front face of the touch keypad is clearly excluded from the definition of the side of the touch keypad. Furthermore, when the touch keypad is embedded in a locker and / or is integrated into a secure access control reader, then the side of the touch keypad may correspond to the side of this locker and / or to the side of this reader.
[0046] In a particular embodiment, the at least one lateral approach sensor comprises at least one side sensor which is positioned on the at least one side of the touchpad.
[0047] By placing this sensor sideways on one side of the touch keyboard, it is easy to detect a hand approaching that side (or coming into contact with that side), as long as that hand approaches that sensor sideways.
[0048] As explained previously, this side sensor can be placed directly on the side of the touch keyboard, and can also be placed on the side of the locker and / or the reader.
[0049] According to one possibility, the at least one side sensor is selected from a capacitive sensor, an inductive sensor, a radar sensor, an ultrasonic sensor, an accelerometer, a camera and a mechanical sensor.
[0050] Such capacitive, inductive, radar, ultrasonic, or optical sensors (in the form of a camera) are advantageous for reliably detecting the approach of the hand to the side of the touch keyboard; an accelerometer is advantageous for detecting contact (in the form of a shock) of the hand to the side of the touch keyboard; a mechanical sensor (switch type) is also advantageous for detecting contact (in the form of a force on the mechanical sensor) of the hand to the side of the touch keyboard.
[0051] In an advantageous embodiment, the at least one side sensor comprises several side sensors arranged on several sides of the touch keyboard, or a peripheral sensor extending on several sides of the touch keyboard.
[0052] This way, the hand can approach the touch keyboard from several sides, or even any side, to activate the visually impaired mode.
[0053] In another embodiment, the at least one lateral approach sensor comprises at least one front sensor which is positioned on a front face of the touch keyboard on which the touch keys are arranged, such a front sensor having a detection field making it possible to detect the approach or contact of the user's hand on at least one side of the touch keyboard.
[0054] Thus, in this variant, the lateral approach sensor is not positioned on the side of the touch keyboard (as is the case with the side sensor), but is positioned on the front face of the touch keyboard, while being able to detect the approach or contact of the user's hand on the side of the touch keyboard thanks to a wide detection field.
[0055] Alternatively, the at least one facade sensor is selected from a radar sensor, an ultrasonic sensor, and a camera.
[0056] So, the front sensor can be a wide-angle camera capable of seeing to the sides while being placed on the front side of the touch keyboard, and for example in the center of the keyboard.
[0057] According to one possibility, the processing unit is configured to switch from sighted mode to visually impaired mode upon receipt of two consecutive approach signals from the at least one lateral approach sensor, the two consecutive approach signals being spaced apart by a time interval less than a given threshold.
[0058] This option is advantageous because it ensures that a single approach of the hand to the side cannot activate the low vision mode; only a double approach or double contact, sometimes called a "tap-tap", will allow switching to the low vision mode.
[0059] Furthermore, the processing unit is configured to remain in LED mode if the time interval is greater than the given threshold.
[0060] In one variant, the at least one approach sensor comprises a radio identification sensor for detecting the approach action in the form of an approach or contact of a radio identification badge containing switching information.
[0061] Thus, the approach action that the visually impaired person must perform takes the form of an approach or contact with a radio identification badge worn by the person and which contains switching information that the processing unit will retrieve to switch to the visually impaired mode. It should be noted that this radio identification sensor can be considered alone, or in combination with the lateral approach sensor(s) described above. The radio identification badge can be a card, a token, or be integrated into a mobile terminal such as a telephone.
[0062] In this case, with a radio identification sensor to switch to visually impaired mode, this radio identification sensor can very well be placed on the side of the touch keyboard or on the front, behind the touch keyboard.
[0063] This RFID sensor can operate in Bluetooth®, LoRa®, WiFi®, UWB, NFC, or other wireless technologies.
[0064] Advantageously, the processing unit is connected to at least one alert transmitter, which is audible or vibratory, and the processing unit is configured to control the at least one alert transmitter in order to produce an alert signal, which is audible or vibratory, when said processing unit switches from sighted mode to visually impaired mode.
[0065] In this way, the visually impaired person is notified that the visually impaired mode is now activated.
[0066] According to one feature, the processing unit is connected to at least one return transmitter, which is sound or vibration, and the processing unit is configured to, at least in the visually impaired mode, drive the at least one return transmitter in order to produce a sound or vibration return signal, when the processing unit selects a character.
[0067] Advantageously, the feedback (whether audible and / or vibratory) that the visually impaired user will hear or feel when their finger is placed on a touch key on the touch keyboard will alert them that they have selected a number. It is possible to provide such feedback in sighted mode as well.
[0068] The invention also relates to a secure access control reader comprising an input system as previously described.
[0069] The invention also relates to an input method for entering a code comprising a sequence of characters, this input method operating on an input system as previously described, and comprising:
[0070] - generating key signals in response to tactile contacts made by a finger on the touch-sensing surfaces of the touch keys, each of the key signals being associated with the touch key on which the tactile contact is made;
[0071] - acquire by the processing unit the key signals generated by the touch keyboard;
[0072] - analyzing said key signals by the processing unit to select characters according to said key signals.
[0073] This input method comprises at least one input mode adapted to the visually impaired, called visually impaired mode, in which the processing unit carries out the following steps to select each of the characters: acquisition of a key signal, called the first key signal, associated with a touch key assigned to a character, followed by an acquisition of a second key signal associated with the same touch key after a period without acquisition of a key signal between the acquisitions of the first key signal and the second key signal, so that a character is selected only by a first tactile contact of a finger on the touch key assigned to said character, followed by a removal of said finger, then followed by a second tactile contact of the finger on the same touch key assigned to said character.
[0074] Advantageously, in the visually impaired mode, a comparison is implemented between a maximum time threshold and the period between the acquisitions of the first key signal and the second key signal to select each of the characters on the condition that the period between the acquisitions of the first key signal and the second key signal is less than the maximum time threshold, so that a character is selected by the first tactile contact of the finger on the tactile key assigned to said character, followed by a removal of said finger then followed by the second tactile contact of the finger on the same tactile key assigned to said character, within a time less than the maximum time threshold between the first tactile contact and the second tactile contact.
[0075] This input method may also include a mode adapted to LEDs, called LED mode, in which the processing unit performs the following steps to select each of the characters: acquisition of a key signal followed by automatic assignment of the character which is assigned to the touch key associated with said key signal, so that a character is automatically selected by a tactile contact of a finger on the touch key assigned to said character.
[0076] This input method may alternatively comprise a step of switching from sighted mode to visually impaired mode upon receipt of at least one approach signal from the at least one approach sensor configured to detect an approach action performed by a user, said at least one approach sensor being distinct from the touch keys of the touch keyboard.
[0077] Of course, all the features previously mentioned for the input system also apply to the input process.
[0078] [Brief description of the figures]
[0079] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:
[0080] [Fig 1] is a schematic view of an input system provided with a touch keyboard, a processing unit which is in the sighted mode adapted to sighted people, and an approach sensor which is here a side sensor;
[0081] [Fig 2] is a schematic view equivalent to that of Figure 1, where a simple touch contact on the touch key “2” is illustrated allowing the selection of the number “2” in the indicator mode by the processing unit;
[0082] [Fig 3] is a schematic view of the input system of Figure 1, illustrating a detection by the side sensor of an approach action of a user, in the form of an approach or contact of a hand on one side of the touch keyboard, so that the processing unit switches to the low vision mode adapted for the visually impaired;
[0083] [Fig 4] is a schematic view equivalent to that of Figure 3, where the start of a tactile search phase for the location relief by a visually impaired person is illustrated in the visually impaired mode, who places his finger on a starting location which is here the tactile key “7” without the number “7” being selected in the visually impaired mode;
[0084] [Fig 5] is a schematic view equivalent to that of Figure 4, where the visually impaired person's finger is illustrated in the visually impaired mode, sliding from the starting location until reaching the marking relief placed here on the touch key "5", without the number "5" being selected in the visually impaired mode;
[0085] [Fig 6] is a schematic view equivalent to that of Figure 5, where the visually impaired person's finger is illustrated in the visually impaired mode sliding from the relief of the marker until reaching a target touch key, which is here the touch key "3", without the number "3" being selected in the visually impaired mode;
[0086] [Fig 7] is a schematic view equivalent to that of Figure 6, where the removal of the finger (in other words the detachment of the finger) from the target touch key, here the touch key “3”, is illustrated in the visually impaired mode, in order to achieve the additional validation condition to be able to select the number “3” in the visually impaired mode;
[0087] [Fig 8] is a schematic view equivalent to that of Figure 7, where the return of the finger to contact with the target touch key, here the touch key “3”, is illustrated in the visually impaired mode, in order to finalize the additional validation condition allowing the selection of the number “3” in the visually impaired mode by the processing unit;
[0088] [Fig 9] is a schematic view of a variant of the input system of Figure 1, comprising a radio identification sensor in place of the side sensor to form the approach sensor, and illustrating a detection by the radio identification sensor of an approach action of a user, in the form of an approach of a radio identification badge, so that the processing unit switches to the visually impaired mode adapted for the visually impaired;
[0089] [Fig 10] is a schematic view of another variation of the capture system of Figure 1, including a camera-type front sensor in place of the side sensor to form the approach sensor;
[0090] [Fig 11] is a schematic view of a secure access control reader integrating the entry system, with a user entering a code.
[0091] [Detailed description of one or more embodiments of the invention]
[0092] With reference to Figures 1 to 9, an input system 1 according to an exemplary embodiment of the invention comprises a touch keyboard 2 provided with discrete touch keys 21 assigned to respective characters including at least numbers. In the example illustrated, the touch keys 21 are twelve in number and comprise ten touch keys assigned to the numbers “0” to “9”, and two touch keys assigned to the special characters “#” and “*”. Of course, other characters are conceivable. In the remainder of the description, a touch key 21 assigned to a character “X” (for example the number “5”), will be called the touch key “X” (for example touch key “5”).
[0093] These tactile keys 21 are arranged on a front face 22 (also called front panel) of the tactile keyboard 2. The tactile keyboard 2 also has sides 23 (or lateral edges) which border the front face 22 at the periphery. In the example illustrated, the tactile keyboard 2 has a generally square or rectangular shape, so that it has four sides 23, which are a right side, a left side, a top side, and a bottom side. These tactile keys 21 may be of a domed shape, for example hollow in the form of a crater or raised in the form of a dome, in order to be identifiable by touch.
[0094] Each touch key 21 comprising a touch detection surface 24, shown diagrammatically by hatching on the touch keys “6” and “#” in Figure 1. The touch detection surface 24 of at least one of the touch keys 21 is provided with a marking relief 25; in the example illustrated, only the touch key “5” is provided with such a marking relief 25, this touch key “5” being substantially in the center of the touch keys 21, as can be seen in a conventional keyboard.
[0095] The touch keyboard 2 is configured to generate key signals 20 in response to tactile contacts exerted by a finger 10 on the tactile detection surfaces 24 of the tactile keys 21, each of the key signals 20 being associated with the tactile key 21 on which the tactile contact is exerted. This tactile contact is sometimes called pressing, however it is sufficient to touch the tactile detection surface 24 to generate the associated key signal 20, without necessarily exerting pressure on the tactile detection surface 24, for example by sliding one's finger 10 over it.Thus, a tactile contact on the tactile detection surface 24 of the tactile key “0” generates the key signal 20 associated with the character “0” (also called the key signal “0”), a tactile contact on the tactile detection surface 24 of the tactile key “1” generates the key signal 20 associated with the character “1” (also called the key signal “1”), a tactile contact on the tactile detection surface 24 of the tactile key “2” generates the key signal 20 associated with the character “2” (also called the key signal “2”), etc. and this for each tactile key 21.
[0096] This input system 1 further comprises a processing unit 3 which is connected to the touch keyboard 2 to acquire the key signals 20 generated by the touch keyboard 2, and configured to analyze these key signals 20 to select characters according to the key signals 20. This processing unit 3 can be a processor, a controller, an electronic card or a computer terminal.
[0097] The processing unit 3 is configured to operate in two distinct modes, which are a sighted mode P suitable for sighted people and a visually impaired mode S suitable for visually impaired people; these two modes P, S are distinguished in the way of processing / analyzing the key signals 20 to select the characters, and therefore in the way for the user U to act on the touch keys 21 to enter a character.
[0098] Thus, the input system 1 makes it possible to enter a code comprising a sequence of characters, and the processing unit 3 is configured to select the characters by means of tactile contacts on the dedicated tactile keys 21. With reference to Figure 11, this input system 1 can be integrated into a secure access control reader 9 for entering an access code authorizing access to a secure area, for example for opening a door 90 or an access barrier.
[0099] In the indicator mode P, the processing unit 3 is configured to select each of the characters by operating as follows: acquisition of a key signal 20 followed by automatic assignment of the character which is assigned to the touch key 21 associated with said key signal 20. Thus, a character is automatically selected by a tactile contact of a finger 10 on the touch key 21 assigned to said character. For the user, it is therefore sufficient to touch one of the touch keys 21 with his finger 10 for the character assigned to this touch key 21 to be selected.
[0100] In the example of Figure 2, the user makes a tactile contact on the touch key “2”, and thus the touch keyboard 2 generates the key signal 20 associated with the character “2” (or key signal “2”), and the processing unit 3 selects the number “2”. If the user lifts the finger 10 and places the finger 10 again on this same touch key “2”, the processing unit 3 will again select the number “2”. If the user slides the finger 10 on the front face 22 and his finger 10 passes over the touch key “2”, the processing unit 3 will also select the number “2”.
[0101] It is therefore obvious that this seeing mode P is suitable for sighted people, because it is necessary to aim at the touch keys 21 to enter / select the characters; because any contact with a touch key 21 triggers the entry of the associated character. In other words, this seeing mode P is unsuitable for visually impaired people who must slide their finger 10 on the front face 22 to search by touch for the marking relief 25 and then the touch keys 21; in fact this sliding of the finger 10 on the front face 22 would automatically trigger erroneous entries or selections of characters.
[0102] To switch to the visually impaired mode S, the input system 1 comprises at least one approach sensor, which is a side sensor 4 in the example of Figures 1 to 8, a radio identification sensor 5 in the example of Figure 9 or a facade sensor 6 in the example of Figure 10, in which this approach sensor 4, 5, 6 is distinct from the touch keys 21 of the touch keyboard 2 and is shaped to detect an approach action carried out by a user, and in response to deliver an approach signal 40, 50, 60.
[0103] In the example of Figures 1 to 8, the approach sensor is a side sensor 4 positioned on at least one side 23 of the touch keyboard 2 to detect the approach action in the form of an approach or contact of a hand 11 of the user on this side 23 of the touch keyboard 2, as illustrated in Figure 3; this side sensor 4 thus forming a lateral approach sensor, such as for example a proximity sensor, or a presence or contact detection sensor. In this example, a side sensor 4 is provided positioned on only one side 23 of the touch keyboard 2, here the left side.
[0104] Alternatively, the input system 1 may comprise several side sensors 4 positioned on several sides 23 of the touch keyboard 2, or even on all sides 23 of the keyboard 2. Alternatively, the input system 1 may comprise at least one side sensor 4 extending over several sides 23 of the touch keyboard 2, in which case it is referred to as a peripheral sensor. In these variants, the approach action is in the form of an approach or contact of a hand 11 of the user on one of the several sides 23 of the touch keyboard 2 equipped with a side sensor 4.
[0105] The or each side sensor 4 may be selected from a capacitive sensor, an inductive sensor, a radar sensor, an ultrasonic sensor, an optical sensor (or camera), an accelerometer, and a mechanical sensor.
[0106] In the example of Figure 9, the approach sensor is a radio identification sensor 5 positioned on the touch keyboard 2, and for example provided with an antenna positioned at the rear of the front face 22, to detect the approach action in the form of an approach (within the range of the antenna) of a radio identification badge 51 containing (or storing) switching information.
[0107] In the example of Figure 10, the approach sensor is a front sensor 6 which is positioned on the front face 22 of the touch keyboard 2 (on which the touch keys 21 are arranged, as a reminder), in which this front sensor 6 has a detection field making it possible to detect the approach or contact of the user's hand 11 on at least one side 23 of the touch keyboard 2; this front sensor
[0108] 6 thus forming a lateral approach sensor like the side sensor described above. In the illustrated example, this front sensor 6 is a camera 6, and in particular a wide-angle camera for viewing the sides of the touch keyboard 2.
[0109] The processing unit 3 is connected to the approach sensor 4, 5, 6 and is configured to switch from the sighted mode P to the sighted mode S upon receipt of the approach signal 40, 50, 60 from the approach sensor 4, 5, 6.
[0110] The input system 1 may also comprise at least one alert transmitter 7, 8 connected to the processing unit 3, such as for example a vibration alert transmitter 7 and / or an audible alert transmitter 8 as illustrated in Figure 3; so that the processing unit 3 is configured to control this vibration alert transmitter.
[0111] 7 and / or this sound alert transmitter 8 in order to produce an alert signal, which is audible or vibratory, when the processing unit 3 switches from the seeing mode P to the visually impaired mode S.
[0112] The processing unit 3 is configured to be in the P indicator mode by default, in the absence of reception of the approach signal 40, 50 from the approach sensor 4, 5, 6.
[0113] Furthermore, when the processing unit 3 is in the visually impaired mode S, it is configured to automatically switch from the visually impaired mode S to the sighted mode P once the characters forming the code have been entered, for example after a predefined time delay. In other words, when a visually impaired person has switched the processing unit into the visually impaired mode S and then correctly entered the code on the touchscreen keyboard 2, then the processing unit 3 automatically returns to the sighted mode P.
[0114] In addition, when the processing unit 3 is in the visually impaired mode S, it is configured to automatically switch from the visually impaired mode S to the seeing mode P if no key signal 20 is generated by the touch keyboard 2 after a predefined period of time. In other words, when a visually impaired person has switched the processing unit into the visually impaired mode S and then has not touched any touch keys 21 or has interrupted touching the touch keys 21, then the processing unit 3 automatically returns to the seeing mode P.
[0115] The processing unit 3 can be configured to control the vibratory alert transmitter 7 and / or the audible alert transmitter 8 in order to produce an alert signal, which is audible or vibratory, when the processing unit 3 switches back from the visually impaired mode S to the seeing mode P.
[0116] As explained previously, the visually impaired mode S differs from the sighted mode P in the way of entering characters on the touch keyboard 2. More precisely, in the visually impaired mode S, the processing unit 3 is configured to select each of the characters as follows: acquisition of a key signal 20 (called the first key signal) followed by a verification of an additional validation condition by analysis of the key signals 20 (namely the first key signal and possibly also a second key signal which follows the first key signal), and allocation of the character which is assigned to the touch key associated with said first key signal only if the additional validation condition is met. Thus, a character is selected by a tactile contact of a finger 10 on the touch key 21 assigned to said character followed by compliance with the associated additional validation condition.For the user, it is therefore necessary to touch one of the touch keys 21 with his finger 10, and it is then necessary to fulfill the additional associated validation condition, so that the character assigned to this touch key 21 is selected.
[0117] In the example illustrated in Figures 4 to 8, the processing unit 3 is configured so that, in the visually impaired mode S, following the acquisition of a key signal 20, called the first key signal, associated with a touch key 21 assigned to a character, the additional validation condition comprises the acquisition of a second key signal 20 associated with the same touch key 21 after a period without acquisition of a key signal between the acquisitions of the first key signal and the second key signal. Thus, a character is selected by a first tactile contact of a finger 10 on the touch key 21 assigned to this character, followed by a withdrawal of the finger 10 (which then no longer touches a touch key 21), then followed by a second tactile contact of the finger 10 on the same touch key 21 assigned to this character; this is then referred to as an additional validation condition called double contact.
[0118] In other words, the visually impaired person simply needs to slide his finger 10 onto the target touch key 21 (the one associated with the character he wants to enter), which triggers the acquisition of the first key signal 20 associated with this target touch key 21, then lift the finger 10 and then place the finger 10 back on this same target touch key 21, which triggers the acquisition of the second key signal 20 associated with this target touch key 21; and then the processing unit 3 selects the character assigned to this target touch key 21. The visually impaired person can then slide his finger 10 towards another target touch key 21 and repeat the operation.
[0119] According to one possibility, the additional validation condition also comprises a comparison between a maximum time threshold and the period between the acquisitions of the first key signal 20 and the second key signal 20, so that a character is selected following the first tactile contact of the finger on the tactile key 21 assigned to said character, followed by a removal of said finger, and finally followed by the second tactile contact of the finger on the same tactile key 21 assigned to said character, within a time less than the maximum time threshold between the first tactile contact and the second tactile contact.
[0120] In other words, if the duration is too long (i.e. it exceeds the maximum time threshold) between the two successive tactile contacts on the same tactile key 21, then the processing unit 3 will not select the character assigned to this tactile key 21.
[0121] With reference to Figure 4, at the start of typing, the visually impaired person places his finger 10 at a starting location on the front face 22 of the touch keyboard 2, with the aim of finding the marking relief 25 by sliding his finger 10 on the front face 22. In Figure 4, the finger 10 is placed on the touch key “7” which is therefore the starting location here. Thus, the processing unit 3 receives the key signal “7”.
[0122] With reference to Figure 5, the visually impaired person slides his finger 10 from the starting location until it reaches the marking relief 25; the sliding movement of the finger 10 being here shown diagrammatically by the arrow 15. Also, in the example illustrated, the finger 10 slides from the touch key “7” to the marking relief 25 placed on the touch key “5”. Thus, the processing unit 3 receives the key signal “5”.
[0123] It should be noted that, in the visually impaired mode S, the processing unit 3 does not select the number “7”, even though it has acquired the key signal “7” at the start of the input. Indeed, to the extent that the visually impaired person, after placing his finger 10 on the touch key “7”, has not carried out an action of removing the finger 10 and then placing the finger 10 back on this same touch key “7”, then the additional validation condition has not been met and therefore the processing unit 3 does not select the number “7”.
[0124] With reference to Figure 6, once the visually impaired person has his finger 10 on the locating relief 25, he mentally visualizes the tactile key “5” under his finger 10 as well as the other tactile keys 21 of the tactile keyboard 2, and he can therefore go and find the tactile keys 21 by sliding his finger 10 to successively enter the characters forming the code. In the illustrated example, the first character to be entered is the number “3”, so the visually impaired person slides his finger 10 from the locating relief 25 (or from the tactile key “5”) to the target tactile key 21 which is here the tactile key “3”; the sliding movement of the finger 10 being here shown diagrammatically by the arrow 16. Thus, the processing unit 3 receives the key signal “3”, called the first key signal “3”.
[0125] It should be noted that, in the visually impaired mode S, the processing unit 3 does not select the number “5”, even though it has acquired the key signal “5” when the finger 10 came into contact with the marking relief 25 placed on the touch key “5”. Indeed, to the extent that the visually impaired person, after sliding his finger 10 onto the touch key “5”, has not carried out an action of withdrawing the finger 10 and then placing the finger 10 back onto this same touch key “5” (in fact, the finger 10 has slid again to go to the touch key “3”, without detaching the finger 10), then the additional validation condition has not been met and therefore the processing unit 3 does not select the number “5”. With reference to Figure 7, once the visually impaired person has their finger 10 on the target touch key 21 which is here the touch key “3”, they remove (or unstick) their finger 10.
[0126] With reference to Figure 8, the visually impaired person, after having removed (or detached) his finger 10, again places his finger 10 in contact with the target touch key 21 which is here the touch key “3”, so that the touch keyboard 2 generates a second key signal “3”. The processing unit 3 then receives this second key signal “3”, and deduces therefrom that the additional validation condition is fulfilled to operate a selection of the number “3”; also on the condition that the finger 10 has been removed for a duration less than or equal to the maximum time threshold, or else on the condition that the period (or duration) between the acquisition of the first key signal “3” and the second key signal “3” is less than or equal to the maximum time threshold.
[0127] A key signal 20, as presented previously, may be in the form of a one-time feedback signal (in other words a pulse) generated by the touch keyboard 2 as soon as a finger touches a touch key 21, and transmitted to the processing unit 3 for analysis. This key signal 20 of course contains information identifying the touch key 21 which is touched. Also, holding the finger 10 on a touch key 21 and then removing it has no impact on the operation of the touch keyboard 2 which only reacts to contacts and not to withdrawals. Thus, for the touch keyboard 2 to be able to generate a first key signal and then a second key signal for the same touch key 21, it is necessary for the finger 10 to be removed (or detached) between two touch contacts on this same touch key 21.
[0128] If the visually impaired person then has to enter a new character (here a character distinct from the number “3”) associated with a new target tactile key 21, then the visually impaired person can repeat the operation by sliding his finger 10 towards this new target tactile key 21, either directly if his mental visualization of the tactile keyboard 2 allows him to do so, or by going back through the relief marking 25 and therefore through the tactile key “5”.
[0129] In a first variant, if the visually impaired person has to enter the same character again (here the number "3"), then the visually impaired person can remove finger 10, and then repeat the operation of placing finger 10 on the touch key "3", then removing finger 10 for a duration less than or equal to the maximum time threshold, and finally placing finger 10 back on the same touch key "3". In other words, in this first variant, to enter "33" (in other words to enter the character "3" twice in a row), a first double contact must be made to enter the first "3", then a second double contact must be made to enter the second "3".In other words, four touch contacts must be made in a row, with a first and second touch contacts to enter the first "3", and then a third and fourth touch contacts to enter the second "3" (the third touch contact and the fourth touch contact being considered a first touch contact and a second touch contact for the second "3").
[0130] In a second variant, if the visually impaired person has to enter the same character again (here the number "3"), then the visually impaired person can remove finger 10, for a duration less than or equal to the maximum time threshold, and then place finger 10 again on the same touch key "3". In other words, in this second variant, to enter "33" (in other words to enter the character "3" twice in a row), a triple contact must be made to enter the two "3"s in a row. In other words, three tactile contacts must be made in a row, with a first and a second tactile contact to enter the first "3", and then a third tactile contact to enter the second "3" (the second tactile contact and the third tactile contact being assimilated to a first tactile contact and a second tactile contact for the second "3").
[0131] The input system 1 may also comprise at least one feedback transmitter connected to the processing unit 3, such as for example a vibratory feedback transmitter and / or an audible feedback transmitter. In the example of Figure 3, the vibratory feedback transmitter corresponds to the alert vibratory transmitter 7, and the audible feedback transmitter corresponds to the audible alert transmitter 8; such that the processing unit 3 is configured to drive this vibratory feedback transmitter 7 and / or this audible feedback transmitter 8 in order to produce a feedback signal, which is audible or vibratory, when the processing unit 3 selects a character in the visually impaired mode S.
[0132] Thus, in the example where the additional validation condition corresponds to a double contact on the same touch key 21, the visually impaired person is directly informed by the return signal that his second touch contact on the same touch key 21 has indeed resulted in the selection of the character associated with this touch key 21; and he can then calmly initiate a slide to go and find another touch key 21.
Claims
CLAIMS 1. Input system (1) for inputting a code comprising a sequence of characters, said input system (1) comprising: - a touch keyboard (2) provided with discrete touch keys (21) assigned to respective characters including at least numbers, each touch key (21) comprising a touch detection surface (24) and the touch detection surface (24) of at least one of the touch keys (21) is provided with a marking relief (25), said touch keyboard (2) being configured to generate key signals (20) in response to tactile contacts exerted by a finger (10) on the touch detection surfaces of the touch keys (21), each of the key signals (20) being associated with the touch key (21) on which the tactile contact is exerted; and - a processing unit (3) connected to the touch keyboard (2) for acquiring the key signals (20) generated by the touch keyboard (2), and configured to analyze said key signals (20) to select characters according to said key signals (20);wherein the processing unit (3) is configured to operate in at least one input mode suitable for the visually impaired, called the visually impaired mode (S), wherein the processing unit (3) is configured to select each of the characters as follows: acquisition of a key signal (20), called the first key signal (20), associated with a touch key (21) assigned to a character, followed by an acquisition of a second key signal (20) associated with the same touch key (21) after a period without acquisition of a key signal (20) between the acquisitions of the first key signal (20) and the second key signal (20), such that a character is selected only by a first touch contact of a finger (10) on the touch key (21) assigned to said character, followed by a removal of said finger (10), then followed by a second touch contact of the finger (10) on the same touch key (21) assigned to said character.; 2. Input system (1) according to claim 1, wherein, in the visually impaired mode (S), the processing unit (3) is configured to select each of the characters under the condition that the period between the acquisitions of the first key signal (20) and the second key signal (20) is less than a maximum time threshold, so that a character is selected by the first tactile contact of the finger (10) on the touch key (21) assigned to said character, followed by a removal of said finger (10) then followed by the second tactile contact of the finger (10) on the same touch key (21) assigned to said character, within a time less than the maximum time threshold between the first tactile contact and the second tactile contact.
3. Input system (1) according to claim 1 or 2, wherein the processing unit (3) is configured to operate in another input mode adapted to LEDs, called LED mode (P), in which the processing unit (3) is configured to select each of the characters by operating as follows: acquisition of a key signal (20) followed by automatic assignment of the character which is assigned to the touch key (21) associated with said key signal (20), so that a character is automatically selected by a tactile contact of a finger (10) on the touch key (21) assigned to said character.
4. Input system (1) according to claim 3, wherein the processing unit (3), when in visually impaired mode (S), is configured to automatically switch from visually impaired mode (S) to sighted mode (P) once the input of the characters forming the code has been completed, for example after a predefined time delay.
5. Input system (1) according to claim 3 or 4, wherein the processing unit (3), when in visually impaired mode (S), is configured to automatically switch from visually impaired mode (S) to sighted mode (P) if no key signal (20) is generated by the touch keyboard (2) after a predefined period of time.
6. Input system (1) according to any one of claims 3 to 5, comprising at least one approach sensor (4; 5; 6) shaped to detect an approach action performed by a user and in response to deliver an approach signal (40; 50; 60), said at least one approach sensor (4; 5; 6) being distinct from the touch keys (21) of the touch keyboard (2), and in which the processing unit (3) is connected to the at least one approach sensor (4; 5; 6) and is configured to switch from sighted mode (P) to visually impaired mode (S) upon receipt of at least one approach signal (40; 50; 60) from the at least one approach sensor (4; 5; 6).
7. Input system (1) according to claim 6, wherein the processing unit (3) is configured to be by default in the indicator mode (P), in the absence of reception of the approach signal (40; 50; 60) coming from the at least one approach sensor (4; 5; 6).
8. A capture system (1) according to claim 6 or 7, wherein the at least one approach sensor (4; 5; 6) comprises at least one lateral approach sensor (4; 6) shaped to detect the approach action in the form of a approach or contact of a hand (11) of the user on at least one side (23) of the touch keyboard (2).
9. Input system (1) according to claim 8, wherein the at least one lateral approach sensor (4; 6) comprises at least one side sensor (4) which is positioned on the at least one side (23) of the touch keyboard (2).
10. Input system (1) according to claim 9, wherein the at least one side sensor (4) is selected from a capacitive sensor, an inductive sensor, a radar sensor, an ultrasonic sensor, an accelerometer, a camera and a mechanical sensor.
11. Input system (1) according to claim 9 or 10, wherein the at least one side sensor (4) comprises several side sensors arranged on several sides (23) of the touch keyboard (2), or a peripheral sensor extending on several sides (23) of the touch keyboard (2).
12. Input system (1) according to claim 8, wherein the at least one lateral approach sensor (4; 6) comprises at least one front sensor (6) which is positioned on a front face (22) of the touch keyboard (2) on which the touch keys (21) are arranged, said front sensor (6) having a detection field for detecting the approach or contact of the user's hand (11) on the at least one side (23) of the touch keyboard (2).
13. Input system (1) according to claim 12, wherein the at least one facade sensor (6) is chosen from a radar sensor, an ultrasonic sensor and a camera.
14. Input system (1) according to any one of claims 6 to 13, wherein the at least one approach sensor (4; 5; 6) comprises a radio identification sensor (5) for detecting the approach action in the form of an approach or contact of a radio identification badge (6) containing tilting information.
15. Secure access control reader (9) comprising an input system (1) according to any one of the preceding claims.
16. Input method for entering a code comprising a sequence of characters, said input method operating on an input system (1) conforming to any one of claims 1 to 14, and comprising: - generating touch signals (20) in response to tactile contacts exerted by a finger (10) on the touch detection surfaces of the touch keys (21), each of the touch signals (20) being associated with the touch key (21) on which the tactile contact is exerted; - acquiring by the processing unit (3) the key signals (20) generated by the touch keyboard (2); - analyzing by the processing unit (3) said key signals (20) to select characters according to said key signals (20);said input method comprising at least one input mode adapted to the visually impaired, and called visually impaired mode (S), in which the processing unit (3) carries out the following steps to select each of the characters: acquisition of a key signal (20), called first key signal (20), associated with a touch key (21) assigned to a character, followed by an acquisition of a second key signal (20) associated with the same touch key (21) after a period without acquisition of a key signal (20) between the acquisitions of the first key signal (20) and the second key signal (20), so that a character is selected only by a first tactile contact of a finger (10) on the touch key (21) assigned to said character, followed by a removal of said finger (10), then followed by a second tactile contact of the finger (10) on the same touch key (21) assigned to said character.; 17. Input method according to claim 16, wherein, in the visually impaired mode, a comparison is implemented between a maximum time threshold and the period between the acquisitions of the first key signal (20) and the second key signal (20) to select each of the characters under the condition that the period between the acquisitions of the first key signal (20) and the second key signal (20) is less than the maximum time threshold, so that a character is selected by the first tactile contact of the finger (10) on the tactile key (21) assigned to said character, followed by a removal of said finger (10) then followed by the second tactile contact of the finger (10) on the same tactile key (21) assigned to said character, within a time less than the maximum time threshold between the first tactile contact and the second tactile contact.