GB2231702A - Reading etc. aids for the blind - Google Patents

Abstract

The shape of a letter or symbol printed or written on a document 1 is transferred to an electronic signal by a photo- electronic sensor 3 with a scanning system 4-5, and sorted in a memory. Then the image of the letter/symbol is displayed on an opto-electronic dot-matrix board 9 (e.g. a LED array). This is sensed by a sensor fitted to a blind person's finger 7, the sensor 8 consisting of photo-electric sensor 12 (eg a photo diode) linked to an electro-mechanical transducer 13 (eg an electro-magnet) with its finger-contacting piece 14. The apparatus may include an electronic letter-size controller 11, a circuit to improve the resolution of the images of small letters, a circuit to select a single letter at a time from letters displayed and a circuit producing a warning if the setting of the system is not correct. In an alternative arrangement, the sensor may include a light source and may be moved directly over printed or written matter itself. <IMAGE>

Description

ELECTRONIC READING AID FOR THE BLIND This invention relates to an electronic reading aid for the blind.

It is known that some blind people can identify the shape of letters by touching them with the finger, providing that the letters are in a touchable form and they are trained to do so, even they have never seen printed letters. This invention relates to an apparatus to convert ordinary letters printed or written on a document or book instantaneously into such a tqpshable form. In this method, letter recognition is carried out by the user's own brain, and the apparatus does not contain a letter recognition system. This makes the apparatus simpler, smaller and less expensive than other methods (e.g. a reading aid with a letter recognition system and a voice output) so that the apparatus can be personalized. This also makes wider a range of readable letter styles which is restricted by a letter recognition system in other methods.

According to the present invention, an apparatus is provided which consists of a photo-electronic sensor to detect a letter on a document, an electronic memory to store the signal from the sensor, an opto-electronic dot-matrix display board (eg a LED-array) to display the shape of a letter (or letters) through the memory, and a 'finger-top sensor' which is placed on the top of a finger and converts the letter on the display board into a mechanical stimulation on the finger, so that a blind person can detect the shape of the letter by searching on the surface of the display board.The apparatus also contains facilities:- a circuit to keep the size of a letter on the display board almost constant when the size of the original letter on a document is arbitrary; a circuit to improve the resolution of the image of small letters; a circuit to adjust a position of the letter-irnge sensor on a document; a circuit to isolate a single letter for clearer reading; and a circuit to warn of an incorrect setting of the apparatus.

The invention also contains a simplified apparatus to train a blind person's sense of identifying letters by using the 'finger-top sensor'.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: The top drawing of Figure 1 shows the top view of the whole apparatus, and the middle and bottom drawings show the sectional-view and top-view of the 'finger-top sensor' with the display board respectively; Figure 2 shows an arrangement of the inside of the 'sensor-guide box'; Figure 3 shows the inside of the 'letter-image sensor unit'; Figure 4 shows the block diagram of the main circuit; Figure 5 shows the block diagram of the circuit to adjust the letter size appropriately without an optical zoom lens; Figure 6 shows the timing diagram of the circuit shown in Figure 5; Figure 7 illustrates the effect of the circuit shown in Figure 5; Figure 8 shows the circuit which improves resolution of the image of a small letter obtained by a simple lens;; Figure 9 shows the effect of the circuit shown in Figure 8; Figure 10 shows an example of the positions of letters on the display board:- an arbitrary position (the upper drawing) and an adjusted position (the lower drawing); Figure 11 shows the circuit to adjust the letter position automatically; Figure 12 shows the timing diagram of the circuit shown in Figure 11; Figure 13 shows the circuit by which a blind person feels the first letter only on the display board, and its effect; Figure 14 shows the circuit which gives warning to a user of the apparatus, if his adjustment is not appropriate.

Figure 15 shows the simple apparatus to train a blind person's sense of identifying letters with the 'finger-top sensor Figure 16 shows the general-view (left drawing) and sectional-view (right drawing) of a small projection on the bottom of the 'finger-top sensor' and a frame of the display board.

Referring to the top drawing of Figure 1, a document 1 is set on a board 2 which has a photo-electric 'image-sensor unit' 3. The sensor unit 3 can be located on any position on the document 1 by using a 'sensor-guide box' 4 (for a horizontal movement) and a 'guide rail' 5 (for a vertical movement).

The electronic signal from the sensor unit 3 is fed into an electronic system 6, and its output is displayed on a dot-matrix opto-electronic display board 9 teg a LED array), letter 'S' being an example. This is detected by a blind person's finger 7 with a 'finger-top sensor' 8. The size of a letter on the display board 9 is adjusted by a letter-size controller 11 so that the size is almost constant independently of the size of the original letter on the document 1. The system 6 also contains other facilities for the operation which are controlled by controllers 10. The middle drawing of Figure 1 show a sectional view of the 'finger-top sensor' 8 and the display board 9, together with a blind person's finger 7. The bottom drawing of Figure 1 shows their top views.The body of the 'fingertop sensor' is made of a flexible material (eg rubber) for fitting on the top of a finger. This contains a photo-electronic sensor 12 (eg a photodiode) and an electro-mechanical transducer 13 (eg an electro-magnet) with a contact piece 14 which stimulates the finger top only when it is electrically activated. Both the sensor 12 and the transducer 13 are linked with the system 6 through a flexible cable 15. The blind parson can detect, therefore, the shape of a letter on the display board 9 by searching its surface.

Referring to Figure 2, this shows the inside of the sensor-guide box 4. A photo-electronic image-sensor unit 3 which can slide in two directions along a window 16 on the bottom of the box 4 is driven by an electric motor 17 through a pulley 18, a string 19 and guide rollers 20. The movement of the sensor unit 3 is limited by electronic position sensors 21 (eg magnet diodes) which are linked with the motor-driving circuit. The motor 17 is automatically controlled from the electronic system 6 (in Figure 1), so that the ima-sensor unit 3 scans letters on the document 1.

Referring to Figure 3, this shows the inside of the sensor unit 3. The surface of the document is illuminated through a window 22 by a lamp 23 through an optical guide 24 (eg a transparent plate). The reflected light from the document enters a photo-electronic image sensor 25 (eg a onedimensional CCD) through a mirror 26 and a lens 27. The CCD vertically scans a letter on the document, while the movement of the whole unit 3 scans the document horizontally, so that the image of a letter is converted into an electronic signal.

Referring to Figure 4, this shows a block diagram of the electronic circuit (essential part only). A letter ('S' as an example, although a series of letters in practice) on the document 1 is converted into an electronic signal by using a photo-electronic image sensor 25 with a lens 27. This is fed into a memory 28, after the signal has been binarized by a binarization circuit 29, and controlled by the letter-sensor- & memory control circuit 30.The memorized signal is displayed on the display board 9, by using the neniory- & display-board control circuit 31. the letter on the display board 9 is sensed by a blind person's finger with the 'finger-top sensor' 8, since the photo-electri sensor 12 closes a circuit consisting of electromechanical transducer 13 and an AC or DC source 32 so that the contact piece 14 is activated and this stimulates the finger top only when the sensor : is on the letter on the display board 9.

Referring to Figure 5, this shows the block diagram of a circuit which controls the letter size with a single fixed-focus-length lens (without an optical zoom lens). A fixed-focus lens 27 is set so that the largest letter (within a specified range) on a document 1 makes the maximum image on a'photo-electric image sensor 25. This circuit works in such a way that a letter having an arbitrary size (within a certain range) on the document 1 appears in an almost constant size on the display board 9, by operating the controller 11. The photo-electronic image-sensor 25, the binarization circuit 29, the memory 28, the display board 9, the fast clock 33 (frequency Pv ad the slow clock 34 (frequency Q) are parts of the main circuit already shown in Figure 4.The rest of the blocks (inside the dotted-line frame) are the additional circuit for controlling the letter size. The additional circuit consists of a divided-by-n-counter 35, a divided-by-m-counter 36, a divided-by-K-counter 37, a flipflop (FF) 38, an AND-gate 39 and a controller 11 which sets values of n and m of the counters 35 and 36 respectively. The fast clock 33 scans the pixels of the image sensor 25 (in the vertical direction of a letter, if a onedimensional image sensor is used). The slow clock is related to the horizontal scanning of letters. sine the image-sensor unit 3 (in Figures 1 and 2) scans letters horizontally at a constant speed.The divided-by-Kcounter 37 divides the output pulses of the divided-by-n-counter 35, where K is the number of segments tor dots) of a vertical column of the display board 9, K being constant te Y, = 16). The output of the divided-by-Kcounter sets the (FF) 38. and the output of the divided-by-m-counter 36 resets the FF 38. The output of the FF 38 and the output of the divided-byn-counter 35 are fed into the AND gate 39. The output of this gate drives the chip-enable terminal (CE) of the memory 28 and the memory-address-code generator 40 which is fed into the address terminal (AD) of the memory 28.

The output of the FF 38 also resets the divided-by-K-counter.

Referrin to Figure 6. this is a timing diagram of the additional circuit shown in Figure 5, the horizontal axis of all the diagrams being the time axis in a common scale and the line numbers 41 to 47 being signals shown in Figure 5. The fast clock 41 (frequency P) is divided by n (eg n = 3) as shown in line 42. This is again divided by K (eg K = 16) as shown in line 4.3. The slow clock 44 (frequency Q) is divided by m (eg m = 2) as shown in line 45. Line 46 shows the output of the FF 38, and the line 47 shows the output of the AND gate 39 respectively. Note, line 47 has a frequency of nP and a duration of m/Q.When the output 47 of the AND gate 39 is fed into the memory 28 and the memory-address-core generator 40, the original letter on the document 1 appears on a display board 9, in such a way that the full effective vertical dimension of the display board 9 corresponds to 1/n of the full effective vertical dimension of the image sensor 25, and the full effective horizontal dimension of the display board 9 corresponds to l/m of the horizontal scanning distance of the image-sensor unit 3 (in Figures 1 and 2) cn the document 1.

Referring to Figure 7 the left drawing shows an example of a letter size seen by the image sensor 25, the vertical axis being its full scale (eg the number of pixels C = 128); and the right drawing shows the letter size seen on the display board 9. the vertical scale being its full scale (eg the number of segments K = 16).

Referring to Figure 8, this shows the block diagram of another additional circuit (inside the dotted-line frame) to the circuit shown in Figure 5.

This circuit improves the resolution of an image produced by a simple lens.

The circuit consists of a divided-by-s-counter 48, a flipflop (FF) 49, and an AND gate 50. The fast clock 33 is divided by s (eg s = 16) by the counter 48, and its output sets the FF 49. The slow clock 34 resets both the counter 48 and the FF 49. The output of the AND gate 50 is fed into the divided-by-n-counter 35 (shown in Figure 5). The value of s is controlled by the controller 11 (Figure 1).

Referring to Figure 9, this is a timing diagram relating to the circuit shown in Figure 8, the horizontal axes being the time axes. 51 shows a typical output waveform of the image sensor 25 when its full effective range 52 is used. The resolution of an image produced by a simple lens is usually best around its centre 53 and degrades towards its edges. The circuit works in such a way that pixels in a narrow range near the centre 53 are used for a small letter as shown in 54, and almost all the pixels are used for a large letter as shown in 55; ie the state of the effective range is controlled by selecting the value of S in the counter 48.

Referring to Figure 10, the top drawing shows letters displayed on the display board 9 in an arbitrary position; and the bottom drawing shows that the left-hand edge of one of the letters 'i' is shifted to the left-hand edge of the display board 9. If a letter always appears on the left-hand edge of the display board 9, this helps the blind person who is searching a single letter on the display board.

Referring to Figure 11, this shows the block diagram of a circuit to realize the operation shown in Figure 10. When clock-pulses (CP) 56, the memory-data output 57 which is synchronized with the CP, and a manually operated control signal 58 are fed into the circuit, these produce an output signal 59 which shifts a letter on the display board 9 as shown in Figure 10. The circuit consists of an 8-stage binary counter 60, a 2-stage binary counter 61, a 16-stage shift register 62, five flipflops (FF) and other gates. The input terminals of each FF are indicated by 'R' and 'S', the former being 'terminal to set FF' and the latter 'terminal to reset FF'. Peripheral componants are omitted from the diagram. The memory-data output 57 is a series of binary pulses corresponding to segments of the display board 9.The number of the pulses corresponding to a single vertical column of the display board 9 is K (eg K = 16). A high-state of a pulse indicates an activated segment (or a part of a letter) of the display board 9, and a low-state a non-activated segment (or the background of letters). It is assumed that a 'space' between a set of adjacent letters is represented by a vertical column (or columns) which contains no high-state pulse.

Referring to Figure 12, this shows the timing diagram of the circuit shown in Figure 11, the vertical axis being binary signal (high or low), and the horizontal axis being time by using the clock pulse (CP which has a period of T) as units. The reference numbers for diagrams are common throughout Figures 11 and 12.

Referring to the top diagram in Figure 12, this illustrate the generation of a signal 66 indicating a 'space'. Several cases where the memory-output data contains high-state pulses in different timing (sections 'a' to 'd'), and a case where there is no high-state signal (section 'e') are shown.

Note a 'space signal' 66 is produced only in section 'e' which has no highstate in 57.

Referring to the bottom diagram in Figure 12, this illustrates a further processing of the 'space signal' 66 to obtain the final output 50. Note, only a single pulse 70 is produced ignoring the second pulse in 69 in this example. When a signal 58 is activated manually, a series of pulses 78 (three pulses in this example) is generated, and this is fed into the shift register 62 (in Figure 11, 16 stage in this example), and this is taken out from the register 62 after one cycle (256 T in this example) of its circulation. as a series of three pulses 50. These three pulse shifts the first letter ('i' in this example) on the display board in the horizontal direction by three columns as shown in Figure 10.

Referring to Figure 13, the left-hand drawing shows an example in which more than one letter is displayed on the display board 9, and the first letter 'S' is shifted to the left edge of the board by the circuit shown in Figure 11. It is effective if a blind person senses the fist letter only with the 'finger-top sensor' 8, while it is convenient for a sighted person (eg a tutor) to see all the letters on the board. The circuit shown in the right-hand drawing of Figure 13 satisfies these requirements. When the photo sensor 12 senses the letters on the display board 9, its output is fed into the output circuit 79 for the electro-mechanical transducer 13 through an AND-gate 80 to which signal 70 (see Figures 11 and 12) is also fed. Note, the pulse width of signal 70 corresponds to the period of the horizontal scanning of the first letter only.Therefore, a blind person feels the first letter only, even if he accidentally exceeds his searching area toward the second letter.

Referring to Figure 14. this circuit gives warnings to a blind person by using a sounder, if he sets the image-sensor unit 3 (Figure 1) in an inappropriate height compared with a line of words on a document 1, or if he sets the letter-size controller 11 incorrectly. The circuit has six input terminals, an electronic sounder 81, several gates with diodes and capacitors. Only when the memory-data output 57 coincides with signal 63, is gate 82 activated, and its output signal is stored in capacitor 83 through diode 84, so that a high-frequency AC signal (HF) 87 goes through further. Note, signal 63 corresponds to the highest segments of the display board 9 (see Figure 12) indicating that a letter is touching the top of the letter-scanning area.Similarly, only when the memory-data output 57 coincides with signal 85, is gate 86 activated, and a low-frequency AC signal (LF) 88 goes through its channel. Note, signal 85 corresponds to the lowest segment of the display board 9 (see Figure 12) indicating that a letter is touching the bottom of the letter-scanning area. A very-low frequency switching signal < 'VLF) 89 switches the two channels alternately giving warnings;- the position of the sensor-guide box 4 (in Figure 1) is too high (high-frequency sound, too low (low-frequency sound), or the letter-size controller is not in an appropriate range (alternately highand low-frequency sounds).

Referring to Figure 15. the top drawing shows a general view of the apparatus to train a bind person's sense of identifying letters with the 'finger-top sensor'. This apparatus is far simpler and smaller (therefore inexpensive) than the full apparatus, and is suitable for training blind people at their school with a tutor. The differences between this apparatus and the full apparatus are:- the size of letters is fixed; each letter is printed separately on a standard card; and the 'finger-top sensor (L)' 90 has a built-in light-source 91 in addition to a photo-electric sensor 12 and a electro-mechanical transducer 13. A letter is printed on a card 92 (eg made of paper) which has the same dimensions as the display board 9 of the full apparatus (see Figure 1).A set of cards on which alpha-numerical letters are printed is prepared for training purposes, a single letter being on each card. A card 92 can be slid (one card at a time) into a pair of rails 9 (or a similar facility) fixed on a small box 94 which contains the electronic components and batteries. together with its controls 95 and a switch 9t^, on the side of the box. The bottom diagram of Figure 15 shows the circuit of the training apparatus. The light from the light source 91 reflected by the card surface enters the photo-electric sensor 12, and its output signal is fed into a voltage comparator 97 which has the thresholdvoltage controller 95. The output of the comparator 97 drives the electromechanical transducer 13 with the contact piece 14 which contacts with the blind person's finger.If necessary, a low-frequency modulator 98 for the output signal can be added as shown in the diagram.

Referring to to Figure 1, the whole set of the board 2, the 'image-sensor unit' 3, the 'sensor guide box' 4, and the guide rail 5 can be replaced by a 'free-position image-sensor unit' which consists of a two-dimensional image sensor ceg a tow-dimensional CCD) with a fixed-focal length lens, and a light source is necessary. with a minor modification of the circuit in the electronic system 6, and with the same 'finger-top sensor' 8 and the display board 9. The 'free-position image-sensor unit' can be put on a letter (or letters) on an object which cannot be used with the board 2, eg a letter on a large box, or a letter on a computer-output display screen.

Referring to Figure 16, the left drawing shows the general view of a small projection 100 on the bottom of the 'finger-top sensor' (8 in Figure 1 or 90 in Figure 15) and a square frame 99 surrounding the display board 9; and the right drawing shows their sectional-view, together with the finger of a blind person. The inner edge of the frame 99 is higher than the surface of the display board 9, but lower than the height of the projection 100 so that the movement of the finger is limited within the frame. This helps the sense of position of the finger when the blind person searches a letter on the display board 9.

Claims (10)

1. An electronic reading aid for the blind comprising: an electronic dot-matrix display board on which a letter (hereafter this word represents 'letters', 'a symbol', or 'symbols') is displayed by being transferred from a printed or written document through an electronic image-sensor; and a 'finger-top sensor' consisting of an electronic photo-sensor, an electro-mechanical transducer with a piece to contact a finger, and their container which can be put on the top of the finger, the transducer being activated only when the photo-sensor is activated by a light from the display board; so that when a blind person puts the 'finger-top sensor on the top of his (or her) finger, and when he searches the surface of the display board, he can detect the shape of the letter and identify it.

2. An electronic reading aid for the blind as claimed in Claim 1 wherein an electronic circuit including a divided-by-n-counter (or counters) and a flipflop, by which the image of a letter is compressed vertically and/or horizontally, is provided to adjust an arbitrary size of letters on a document into an almost constant size on the display board with a fixedfocus-length lens so that a use of a zoom lens having a variable focuslength is avoided.

3. An electronic reading aid for the blind as claimed in Claims 1 and 2, wherein an electronic circuit is provided to improve the resolution of an image of a small letter sensed by an electronic image-sensor with a simple lens (where the image resolution is better near its centre than its edge) by shifting the position of the image towards the centre of the lens.

4. An electronic reading aid for the blind as claimed in Claim 1, wherein an electronic circuit is provided to find a space between two adjacent letters and to shift a letter towards one of the vertical edges of the display board, so that the identity of a single letter by using the 'finger-top sensor' becomes easier to a blind person.

5. An electronic reading aid for the blind as claimed in Claims 1, 2, 3 and 4, wherein an electronic circuit is provided to make only one letter on the display board palpable at a time to the 'finger-top sensor', despite the fact that more than one letter is visible on the display board to a sighted person.

6. An electronic reading aid for the blind as claimed in Claims 1, 2, 3 4, and 5, wherein an electronic circuit to warn a blind person if the position of a letter on the display board is not correctly set (eg too high or too low), or if the letter-size controller is not correctly set (eg a too narrow range), by using a part of the electronic signal contained in the circuit described in Claim 4.

7. An electronic reading aid for the blind comprising: a 'finger-top sensor (L)' consisting of an electronic photo-sensor, an electro-mechanical transducer with a piece to contact a finger, a light source, and their container which can be put on the top of the finger; a simple electronic circuit by which the transducer is activated only when the photo-sensor is activated by a light which is emitted from the light source and reflected from an external object; a board on which a card can be fixed temporarily; and a set of cards on each of which a letter is printed or written; so that when a blind person puts the 'finger-top sensor (L)' on the top of his finger, and searches the surface of a card on the board, he can trace the shape of the letter and identify it, mainly for the training of sense of identifying letters with the 'finger-top sensor' claimed in Claim 1, and partly for a practical use.

8. An electronic reading aid for the blind as climed in Clines 1, 2, 3, 4 and 5. but the 'image-sensor unit' with its scanning board (Figure 1) is replaced by a 'free-position image-sensor' (containing a two-dimensional image-sensor) so that the apparatus can be applied to a letter on an object which cannot be put on the scanning board.

9. An electronic reading aid for the blind claimed in Claims 1 and 7 wherein a small projection on the bottom of the 'finger-top sensor' and a square frame surrounding the display board which limit the movement of the finger of a blind person to help his sense of position of his finger within the frame.

10. An electronic reading aid for the blind as described herein with reference to Figures l-16 of the accompanying drawing.