GB2388904A

GB2388904A - Touch-sensitive illuminated control element

Info

Publication number: GB2388904A
Application number: GB0201859A
Authority: GB
Inventors: Ian William Jennings
Original assignee: AUDIX BROADCAST Ltd
Current assignee: AUDIX BROADCAST Ltd
Priority date: 2002-01-26
Filing date: 2002-01-26
Publication date: 2003-11-26
Also published as: GB2388904A9; GB0201859D0

Abstract

A touch-sensitive illuminated control element (10) comprising illumination means (14, 16, 18) to provide illumination of the control element is provided, wherein the illumination means has first and second on states and is responsive to a touch on the control element to change from the first on state to the second on state so as to alter a characteristic of the illumination of the control element, and the illumination means is preferably comprised within or forms an integral component of the control element. The illumination means preferably includes one or more sets of tricolour light-emitting diode integrated circuits, and the control element may advantageously further comprise diffusion means (24, 22) so as to give the control element the appearance of uniform illumination.

Description

1 23889G4

Title: Touch-Sensitive Illuminated Control Element Field of the Invention

This invention relates to a touch-sensitive control element having illumination means operable to change between first and second on states in response to a touch on the control element so as to alter a characteristic of the illumination, and in particular to a touch-

sensitive illuminated fader knob for use on a fader, to a fader fitted with such a touch-

sensitive illuminated fader knob and to a mixing desk fitted with one or more such faders.

Background to the Invention

A typical audio mixing desk may have 96 audio channels, each controlled by a fader. To help an -,perator of such a mixing desk to keep track of the source and function of each channel, it has long been common practice to use fader knobs of different colours to indicate the source (for example percussion, strings, woodwind and vocals) and function (for example record or playback) of each channel.

The introduction of digital mixing desks has largely rendered the use of fader knobs of

different colours impractical, since digital mixing desks enable each channel to be assigned from one source to another while the mixing desk is in use, so that fader knobs of colours that correctly indicated the source and function of their respective channels at the beginning of a recording session may become misleading during the course of that recording session Faders with motorised fader knobs are now common. A mixing desk incorporating such faders can be connected to a computer that has been programmed with a setting for each fader, such that in response to command entered into the computer the motorised fader knobs move to their programmed settings. In producing a recording the operator will often use such a programmed setting and make small manual adjustments to some of the fader knob settings, in order to obtain the optimum mix for the particular recording.

However, faced with a bank of 96 faders, it can be difficult for the operator to remember which fader settings he has manually adjusted.

Summary of the Invention

According to a first aspect of the invention there is provided a touchsensitive control element having illumination means to provide illumination of the control element, wherein the illumination means has first and second on states and is responsive to a touch on the control element to change from the first on state to the second on state so as to alter a characteristic of the illumination of the control element.

The invention therefore provides a control element that is operable to indicate whether the control element has been touched, wherein for example movement of the control element from a default setting is detected and causes a characteristic of the illumination of the control element to be altered.

Preferably the illumination means is comprised within or forms an integral component of the control element.

In changing from the first to the second on state' the illumination means may advantageously alter the colour of the illumination and/or the intensity of the illumination.

The illumination means may advantageously have one or more further on states, (e.g. a third' fourth or fifth on state) corresponding, for example, to different colours of illumination of the control element.

Preferably the on state of the illumination means is controlled, at least in part, by a first control signal, which control signal is generated or modulated in response to a touch on the control element.

Summary of the Invention

Preferahly the illumination means is comprised within or forms an integral component of the control element.

In changing from the first to the second on state, the illumination means may advantageously alter the colour of the illumination and/or the intensity of the illumination.

The illumination means may advantageously have one or more further on states, (e.g. a third, fourth or fifth on state) corresponding, for example, to different colours of illumination of the control element.

Preferably the on state of the illumination means is controlled, at least in part, by a second control signal, which control signal is generated or modulated in response to a command entered into computer means electrically connected to the control element.

Preferably the first and/or second control signal is a digital control signal.

The illumination means may advantageously comprise a plurality of light sources of different colours, conveniently a plurality of red, green and blue light sources, such that by blending of the light from the plurality of light sources, light with the appearance to a human observer of a wide range of different colours may be obtained.

The light sources may advantageously be light-emitting diodes (LEDs).

The LEI)s may advantageously be located sufficiently close to one another in the control element to obtain blending of light of different colours emitted from the LEDs.

Preferably the LEDs comprise tricolour LED integrated circuits (ICs) having a red. a green and a blue LED formed on a single IC Conveniently a plurality of tricolour LED ICs is provided in each illumination means In particular, the plurality of tricolour LED ICs may advantageously comprise first and second sets of tricolour LED ICs, and the illumination means may advantageously be operable, in response to a touch on the control element, to change the first set of LED ICs from the first to the second on state independently of the second set of LED ICs The illumination means may advantageously be responsive to a control signal applied to 3 the control element to change the first set of LED ICs from the first to the second on state independently of the second set of LED ICs.

The one or sets of I,ED ICs in the illumination means may preferably be provided with pulse width modulated (PWM) currents, the duty cycles of which may be altered so as to change the or each set of LED ICs from the first to the second on state.

Preferably the duty cycles of the PWM currents corresponding to the first and second on states of the or each set of LED ICs are stored at addresses in a programmable logic array which are addressable by the first and/or second control signal, where the first and/or second control signals are digital signals.

The control element may advantageously further comprise diffusion means adapted to fit over the illumination means to diffuse light therefrom. Preferably the diffusion means is moulded in a translucent plastics material, such as polyethylene. Preferably the plastics material has a transmittance of visible light of the order of 70%-

An external surface of the diffusion means may advantageously have a shotblasted finish, such that light transmitted by the external surface of the diffusion means is scattered, so as to give the control element the appearance of uniform illumination.

The control element may advantageously further comprise a cap adapted to fit over the diffusion means, and to further diffuse light from the illumination means. Preferably the cap is moulded in a translucent plastics material, such as polyethylene. Preferably the plastics material has a transmittance of visible light of the order of 70%.

An internal surface of the cap may advantageously have a shot-blasted finish, such that light transmitted by the internal surface of the cap is scattered, so as to improve the appearance of uniform illumination of the control element. The internal surface of the cap reflects a portion of the light transmitted by the diffusion means, which reflected light is scattered by the shot-blasted surface. A portion of the light reflected by the internal surface of the cap is incident on, and reflected by, the external surface of the diffusion means, which reflected light is scattered by the shot-blasted surface. This scattering of reflected light by the shot-blasted internal surface of the cap and external surface of the

s diffusion means further improves the appearance of uniform illumination of the control element. The plastics material comprising the cap may advantageously have mixed therewith an electrically conductive material, for example finely divided carbon, such that the cap is conductive. Preferably the touch-sensitivity is provided by means for detecting a change in the electrical properties of the control element, for example means operable to detect electrical grounding of the control element.

Preferably the control element includes a grounded conductive sheet. Preferably the grounded conductive sheet comprises a region of a printed circuit board on which the light sources are mounted. Thus the cap and grounded conductive sheet may advantageously form a pair of conductors which, in conjunction with the diffusing means, which is a dielectric, make up a capacitor, which capacitor is discharged to ground by a touch on the cap, enabling detection means to detect when the control element has been touched.

In one embodiment the control element is electrically connected to charging means, reference voltage generation means and voltage comparator means, the charging means being operable to establish a potential difference between the cap and a reference voltage generated by the reference voltage generation means, and the voltage comparator means being operable to detect if the magnitude of said potential difference drops below a threshold level, as will occur if the cap is touched so as to provide a current path from the cap to ground, and as a result to cause the illumination means to change from the first to the second on state.

In a preferred embodiment the charging means, reference voltage generation means and voltage comparator means are comprised within the control element.

Preferably the control element is adapted for attachment to the slider of an audio or video fader. The invention therefore provides a control element, for example a knob, for use on an audio or video fader, that can provide an indication of whether the knob has been moved from a default setting, and moreover can provide an indication of a channel which is assigned to the fader or of whether the channel is being used for recording or playback, which indication can be changed automatically in response to assignment of another channel to the fader or to a change to the use of the channel.

According to a second aspect of the invention there is provided a fader fitted with a touch-

sensitive control element in accordance with the first aspect of the invention.

According to a third aspect of the invention there is provided an audio or video mixing desk provided with one or more faders in accordance with the second aspect of the invention. Optionally the mixing desk is provided with computerized control means programmed to determine the on state of the illumination means of the control element.

The invention will now be described in greater detail by way of an illustrative example and with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a touch-sensitive fader knob in accordance with the first aspect of the invention; Figure 2 is a schematic view from above of the fader knob of Figure 1; Figure 3 is a block diagram of a divide-ty-64 ring counter' which forms part of a controller for two fader knobs of the type shown in Figures 1 and 2; Figure 4 is a block diagram of a pair of input decoders from the controller;

Figure 5 is a block diagram of a programmable logic array (PLA) from the controller; Figure 6 is a block diagram of a pair of signal lines from the controller; and Figure 7 is a state table that is implemented by the PLA of Figure 5.

Detailed Description of an Embodiment

The fader knob 10 of Figure 1 comprises a printed circuit board (PCB) 12 on which two rows of three tricolour light-emitting diode (LED) integrated circuits (ICs) are mounted, each IC comprising a red, a green and a blue LED. One of the two rows of tricolour LED ICs is shown in Figure 1, the ICs being designated by reference numerals 14, 16 and 18.

The knob 10 further comprises a diffuser 20 and cap 22.

The diffuser 20 is moulded in translucent polyethylene having a transmittance of visible light of the order of 70%. The diffuser has a lower portion in which two rows of three wells are formed, and an upper portion comprising two rows of three divergent lenses, the lenses having convex upper surfaces and concave lower surfaces One of the two rows of lenses is shown in Figure 1, the three lenses being designated by reference numerals 24, 26 and 28.

The dimensions and locations of the wells are such as to enable the diffuser to be placed over the PCB 12 so that each IC is accommodated in one of the wells, the internal surfaces of which are finished to a high degree of smoothness so as to increase their reflectivity.

When the lower portion of the diffuser has been placed over the ICs and abuts the PCB 12, as shown in Figure 1, cavities are defined between the upper surfaces of the ICs and the internal surfaces of the wells. Three such cavities are shown in Figure 1, designated by reference numerals 30, 32 and 34.

The following description applies equally to the ICs, cavities and lenses that are not shown

in Figure 1.

Light from the ICs 14, 16 and 18 passes through the cavities 30, 32 and 34 and is incident on the concave lower surfaces of the divergent lenses 24, 26 and 28. Approximately 70% of the light is transmitted by the lenses and passes through central portions of the lenses.

The remaining 300 of the light is reflected by the lenses and remains in the cavities until it passes through peripheral portions of the lenses or the lower portion of the diffuser. The cavity 32 is smaller than cavities 30 and 34, and lens 26 is thicker than lenses 24 and 28.

This is because some of the light from ICs 14 and 18 passes through the lens 26, in addition to the light from IC 16, which, in the absence of the aforementioned differences, would appear to be more brightly illuminated than lenses 24 and 28.

The cap 22 is moulded in translucent polyethylene with which powdered graphite has been mixed, and has a transmittance of visible light of the order of 70%. The cap has a resiliently deformable lower portion and an upper portion with a central depression. The lower portion of the cap fits over the diffuser, and forms a snap fit with the lower portion of the diffuser. With the cap fitted over the diffuser, the internal surface of the central depression of the cap abuts the upper convex surface of the lens 26. The upper surfaces of the lenses and the internal surface of the cap define two cavities, shown in Figure I by reference numerals 36 and 38.

The light passing through the lenses 24 to 28 passes through the cavities 36 and 38 and is incident upon the internal surface of the cap. Approximately 70% of the light is transmitted by the cap and passes through the upper portion of the cap. The remaining 30% of the light is reflected by the internal surface of the cap and remains in the cavities 36 and 38 until it passes through the lower portion of the cap.

The convex upper surfaces of the lenses and the concave internal surface of the cap are shot-blasted, which causes the light that remains in the cavities 36 and 38 to be scattered, thereby providing relatively uniform illumination of the cap.

The knob is shown schematically from above in Figure 2, the upper portion of the cap 22 having been cut away In addition to ICs 14, 16 and 18 and lenses 24, 26 and 28, ICs 40,

42 and 44 and lenses 46, 48 and SO are shown. The PCB 12 has been omitted from Figure 2 to allow the slot 52, by means of which the knob may be mounted on the slider of a fader, to be shown. The fader is not shown.

The PCB 12 further comprises OV and +5V rails, LED IC driver transistors, a ribbon cable, first and second flying leads, a comparator and a bistable multivibrator. These components are not shown in Figures 1 or 2.

The OV and +5V rails are electrically corrected to the ribbon cable, as are the output and reset input of the multivibrator and the inputs of the LED IC driver transistors. The first flying lead is connected to the +SV rail and the second flying lead is connected to an input of the comparator. The output of the comparator is connected to the set input of the multivibrator. In use, the ribbon cable is electrically connected to a fader, which fader supplies the OV and +SV rails, colour control signals to the LED IC driver transistors and supplies a reset signal to the reset input of the multivibrator in response to the fader being set to a default setting. The fader receives signals from the output of the multivibrator via the ribbon cable.

The first and second flying leads are electrically connected to the cap 22, by crimping between the diffuser 20 and the cap. The cap, together with the diffuser and the OV rail of the PCB forms a capacitor. When the fader is turned on, the capacitor is charged to +5V and the fader supplies a reset signal to the reset input of the multivibrator. When the cap is touched, as when an operator changes the position of the fader knob, the cap is grounded through the operator and the comparator generates a set signal at the set input of the multivibrator. The multivibrator changes state, which state change is detected by the fader, and the fader changes the colour control signals supplied to the LED IC driver transistors, causing the colour of the light produced by the LED ICs to change. If the fader knob is subsequently returned to the default setting, for example if the fader is reset to a programmed setting, the fader supplies a reset signal to the reset input of the multivibrator and changes the colour control signals to their original values.

The operation of a controller for driving first and second knobs of the type shown in Figures 1 and 2 of respective first and second faders will now be described. Such a controller could also be used to drive independently two rows of LEDs of a single knob of the type shown in Figures 1 and 2.

Figure 3 shows a divide-by-64 ring counter 54 made up of linked 4-bit counters 56 and 58.

Counters 56 and 58 are connected by the CLOCK line to a 10 kHz clock signal, and produce a 6-bit binary count on the CLKI to CLK6 lines. The ring counter cycles through binary 000000 to binary 111111.

Figure 4 shows a 6-bit data latch 60 and 3 to 6 bit decoders 62 and 64. The Dl to D3 lines accept a 3-bit digital colour code in the range binary 001 and binary 110, in which 001 represents red, 010 represents green, 011 represents blue, 100 represents yellow. 101 represents purple and 110 represents white, and which code determines the colour of light produced by the LED ICs of the first knob. The D4 to D6 lines accept a similar 3hit digital colour code which determines the colour of light produced by the LED ICs of the second knob.

Pairs of 3-bit colour codes applied to the Dl to D6 lines are stored by the data latch 60, and applied to the Q1 to Q6 lines of the latch. The Q1 to Q3 lines are connected to the inputs of 3 to 6-bit decoder 62 and the Q4 to Q6 lines are connected to the inputs of the 3 to 6-bit decoder 64. The decoder 62 accepts the 3-bit colour code and asserts one of the COLT S1 to COL1_S6 lines corresponding to the decimal value of the 3-bit colour code.

Thus if, for example, the colour code were binary 100 (decimal 4), the COLI_S4 line would be asserted. The operation of decoder 64 is identical with that of decoder 62.

Figure 5 shows a programmable logic array (PLA) 66, which controls the LED ICs of the first knob. The PLA is connected to the CLKI to CLK 6 lines and to the COL1_SI to COL1_S6 lines. The LPI RED, LPI GRN and LPI BL lines of the PLA control the_ _ flow of current to the red, green and blue LEDs, respectively, of the LED ICs of the first knob.

Figure 6 shows two signal lines IP_LEVEL1 and IP_LEVEL2, which are connected to first and second faders, respectively, operated by the first and second knobs. The first and second faders reset the IP_LEVEL1 and IP_LEVEL2 lines, respectively, if the fader is fully open, otherwise the IP LEVEL1 and IP_LEVEL2 lines are set. The LEVEL1 and LEVEL2 lines are connected to the {P_LEVEL1 and IP_LEVEL2 lines via inverters, such that the LEVELI line is set when the IP LEVEL1 is reset, and vice versa. The FADER_OPEN1 and FADER_OPEN2 lines are not involved in controlling the colour of light produced by the LED ICs.

The LEVELI line is connected to the PLA 66 shown in Figure 5. The LEVEL2 line is connected to an identical PLA (not shown), which controls the LED ICs of the second knob. The state table of Figure 7 illustrates the operation of the PLA 66 of Figure 5.

Considering the first line of the table, designated by reference numeral 68, LP1_RED is set while the 6-bit binary count on the CLK1 to CLK6 lines is between binary 000000 and binary 110000, if the first fader is fully open, such that the LEVELI line is set, and COL.I_SI is set, corresponding to the 3-bit colour code binary 001, representing red.

Considering the fifth line of the table, designated by reference numeral 70, LP1_REI) is set while the 6-bit binary count on the CLK1 to CLK6 lines is between binary 000000 and binary 000110, if the first fader is not fully open, such that the LEVEL1 line is reset, and COLI_SI is set. Current therefore flows through the red LEDs for a greater proportion of the counter cycle when the LEVEL1 line is set, than when the LEVELI line is reset.

Considering the third and sixteenth lines of the table, designated respectively by reference numerals 72 and 74, LP1_RED is set while the 6bit binary count on the CLK1 to CLK6 lines is between binary 000000 and binary 001000. if the first fader is fully open and COLI_SS is set, corresponding to the 3-bit colour code binary 101, representing purple,

and LP1_BL is set while the 6-bit binary count on the CLK1 to CLK6 lines is between binary 100000 and binary 110000, if the first fader is fully open and COL1_S5 is set.

Current can be seen to flow through the blue LEDs for a greater proportion of the counter cycle than is the case for the red LEDs. This is because of the considerably higher optical efficiency of the red LEDs, compared with the blue LEDs, and the relative insensitivity of the human eye to blue light as compared with red light. The light produced by the LED ICs would otherwise appear to be predominantly red, rather than purple.

t will be apparent that the above description relates only to one embodiment of the

invention, and that the invention encompasses other embodiments as defined by the foregoing summary of the invention.

Claims

1. A touch-sensitive control element comprising illumination means to provide illumination of the control element, wherein the illumination means has first and second on states and is responsive to a touch on the control element to change from the first on state to the second on state so as to alter a characteristic of the illumination of the control element.

2. A control element according to claim 1, wherein the illumination means is comprised within or forms an integral component of the control element.

3. A control element according to claim 1 or 2, wherein in changing from the first to the second on state, the illumination means is operable to alter the colour of the illumination and/or the intensity of the illumination.

4. A control element according to any preceding claim, wherein the illumination means has one or more further on states.

5. A control element according to claim 4, wherein the one or more further on states correspond to different colours of illumination of the control element.

6. A control element according to any preceding claim, wherein the on state of the illumination means is controlled, at least in part, by a first control signal, which control signal is generated or modulated in response to a touch on the control element.

7. A control element according to any preceding claim, wherein the on state of the illumination means is controlled, at least in part, by a second control signal, which control signal is generated or modulated in response to a command entered into computer means electrically connected to the control element.

8. A control element according to claim 6 or 7, wherein the first and/or second control signal is a digital control signal.

9. A control element according to any preceding claim, wherein the illumination means comprises a plurality of light sources of different colours, such that by blending of the light from the plurality of light sources, light with the appearance to a human observer of a wide range of different colours may be obtained.

10. A control element according to claim 9, wherein the light sources are light-emitting diodes (LEDs).

11. A control element according to claim 10, wherein the LEDs are located sufficiently close to one another in the control element to obtain blending of light of different colours emitted from the LEDs.

12. A control element according to claim 11, wherein the LEDs comprise tricolour LED integrated circuits (ICs) having a red, a green and a blue LED formed on a single IC.

13. A control element according to claim 12, wherein the tricolour LED ICs comprise first and second sets of tricolour LED ICs, and the illumination means is operable, in response to a touch on the control element, to change the first set of LED ICs from the first to the second on state independently of the second set of LED ICs.

14. A control element according to claim 13, wherein the illumination means is responsive to a control signal applied to the control element to change the first set of LED ICs from the first to the second on state independently of the second set of LED ICs.

15. A control element according to claim 13 or 14, wherein the one or more sets of LED ICs in the illumination means are provided with pulse width modulated (PWM) currents, the duty cycles of which are alterable so as to change the or each set of LED ICs from the first to the second on state.

16. A control element according to claim 15 when dependent from claim 8, wherein the duty cycles of the PWM currents corresponding to the first and second on states of the or each set of LED ICs are stored at addresses in a programmable logic array which are addressable by the first andlor second control signal.

17. A control element according to any preceding claim, wherein the control element further comprises diffusion means adapted to fit over the illumination means to diffuse light therefrom.

18. A control element according to claim 17, wherein the diffusion means is moulded in a translucent plastics material, and has a transmittance of visible light of the order of 70%.

19. A control element according to claim 18, wherein an external surface of the diffusion means has a shotblasted finish, such that light transmitted by the external surface of the diffusion means is scattered, so as to give the control element the appearance of i uniform illumination.

20. A control element according to any of claims 17 to 19, wherein the control element further comprises a cap adapted to fit over the diffusion means, and to further diffuse light from the illumination means.

21. A control element according to claim 20, wherein the cap is moulded in a translucent plastics material, and has a transmittance of visible light of the order of 70%.

22. A control element according to claim 20 or 21, wherein an internal surface of the cap has a shot-blasted finish, such that light transmitted by the internal surface of the cap is scattered, so as to improve the appearance of uniform illumination of the control element.

23. A control element according to any of claims 20 to 22, wherein the plastics material comprising the cap has mixed therewith an electrically conductive material, such that the cap is conductive.

24. A control element according to claim 23, wherein the touchsensitivity is provided by detection means for detecting a change in the electrical properties of the control element.:

25. A control element according to claim 24, wherein the control element includes a grounded conductive sheet comprising a region of a printed circuit board on which the light sources are mounted, and the cap and grounded conductive sheet form a pair of conductors which, in conjunction with the diffusing means, make up a capacitor, which capacitor is discharged to ground by a touch on the cap, enabling the detection means to detect when the control element has been touched.

26. A control element according to claim 25, wherein the control element is electrically connected to charging means, reference voltage generation means and voltage comparator means, the charging means being operable to establish a potential difference between the cap and a reference voltage generated by the reference voltage generation means, and the voltage comparator means being operable to detect if the magnitude of said potential difference drops below a threshold level, as will occur if the cap is touched so as to provide a current path from the cap to ground, and as a result to cause the illumination means to change from the first to the second on state.

27. A control element according to claim 26, wherein the charging means, reference voltage generation means and voltage comparator means are comprised within the control element.

28. A control element according to any preceding claim, wherein the control element is adapted for attachment to the slider of an audio or video fader.