Control apparatus for an electronic device

(54) Name: Electronic device

The present invention relates to an electronic apparatus, preferably of the type radio receivers, tape recorders, audio amplifiers, TV receivers, etc. comprising means for individually adjusting a number of variable functions by the influence of certain specific and controllable electrically controllable means. The functions referred to here may be, for example, frequency, volume, stereo balance, bass correction, treble correction, etc.

Hitherto known devices of this type are usually performed with separate adjusting means for each of the variable functions. Typically, these adjusting means consist of knobs or levers that actuate potentiometers, torque capacitors or step switches. The position of the steering wheel or lever indicates the set level of operation. To indicate the frequency setting, a straight scale with pointers, which are mechanically coupled to the setting knob, is often used.

Thus, electronic apparatus of the aforementioned kind contains a plurality of more or less complicated mechanical adjustment means, although the main functions of the apparatus are entirely electronic. The mechanical designs lead to high manufacturing and assembly costs and make the appliances difficult to access.

7711298-5 at service. A large part of the faults that occur on modern appliances are also of a mechanical nature and this is of course a very annoying and costly consequence to the user of hitherto existing designs.

The object of the apparatus of the present invention is to enable structures where the mechanical components have been largely eliminated, thereby avoiding the disadvantages of hitherto existing structures.

This object is realized according to the invention mainly by the fact that the setting means comprise at least one level selector common to the variable functions and at least one address selector which, when actuated, is arranged to deliver to the number of variable functions corresponding function addresses, whereby each given function address can be entered at the control element, which in turn affects the electrically controllable means, whereby each of the variable functions becomes selectable by the address selector and each function level is adjustable by the common level selector.

Some exemplary embodiments of the invention are described in more detail below with reference to the accompanying drawings, in which Fig. 1 shows a block diagram of a combined radio receiver and stereo amplifier according to the invention; Fig. 2 shows a front panel for an apparatus according to Fig. 1; 3 shows an electrically controllable volume control; FIG. 4 shows an electrically controllable bass / treble control1; FIG. 5 Fig. 6 shows a detailed block diagram for memory decoding and operation of an electrically controllable station setting; an alternative type of level selector; Fig. 9 shows a back-up of a RAM memory; Fig. 10 shows a level indicator with LED indicators; Fig. 11 shows a block diagram of an output decoder.

The block diagram of Fig. 1 shows two speakers 1 and 2 powered by a power amplifier stage 3, which is fed by signals via a volume control 4, a stereo balance adjustment 5, a bass correction network 6 and a treble correction network 7 in a conventional manner.

The input to the volume control 4 can be connected to either a radio receiver part 8 (radio tuner), a turntable 9, via an input stage 10 For amplification and irregularity correction, or a tape recorder 11. The desired input signal is connected by a

7711298-5 signal selector 12 with metallic contacts, which are operated by relay coils. Conveniently, these may be reed relays. The tape recorder 11 also receives a signal from the amplifier stage 3 at its recording input. Even this signal can be connected with a reed relay.

For example, in a conventional radio receiver / stereo amplifier, each function, such as volume control1, stereo balance, bass control, treble control1 has its own dial for setting the desired level of function.

In a corresponding apparatus according to the invention there are no individual level setting means, but each variable function is electrically controllable by a single level setting means common to the variable functions. The control is via an output decoder 13 with drive steps, which also selects inputs to the volume control part.

The output decoder 13 is controlled by a memory means 14 which in turn receives signals from a level selector 15 and an address path 16 via level and address decoding circuits 17. The memory means also controls a level indicator 18 with drive steps, which shows which function level is set.

Fig. 2 shows an example of what a front panel 19 for a radio receiver / stereo amplifier of Fig. 1 can look like. The level selector 15 consists of a non-stop swivel steering wheel 20 and the panel has arrows which indicate which direction to turn the steering wheel for increase or decrease, respectively. reduction of functional level.

The address path 16 in this case consists of a keypad with a number of buttons, arranged in three rows. For example, the buttons may have the following functions and be marked in a corresponding way:

Top row 22: Αν / On, Turntable, Recorder, FM, AM

Middle row 23: Loudness, Rumble filter, Elevator filter, Newting / ABC

Bottom line 24: Volume, Balance, Bass, Treble, Station.

An indicator of thermometer type 25 shows with percentage mark which level has been set. In order to show which variable function is set, in the example shown, it is assumed that one has a display panel 26 with numbers indicating, for example, whether FM radio, AM radio, turntable is switched on and another display panel 27, which shows what frequency which is set when the radio function is used.

of course, each button on the panel can of course be provided with a corresponding lamp, which indicates when each function is set.

It seems that the front panel is much simpler and more manageable than a conventional radio receiver / stereo amplifier. The service is also extremely simple.

An example of how the device is operated should be described here briefly.

When the appliance is switched on, it works exactly as when it was last switched on. For example, the digits FM 98.5 light up and indicate that 98.5 MHz FM station is connected. Volume level, bass correction etc are the same as previously set.

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If you want to switch to turntable access, the address button labeled Turntable is pressed and the digits 98.5 disappear and the letters FM are exchanged for disk. If you now want to change the volume level, you only need to turn the level selector dial 20 to the increase or decrease ratio. The indicator scale 25 shows immediately the corresponding change in the degree of equipment of the amplifier.

If, instead, you want to vary the treble correction, you press the address button labeled Treble and the indicator scale 25 immediately shows the diagonal setting. If it is in the neutral position, the scale shows 50% · Turning the knob 20 now affects the treble correction and the indicator scale 25 shows every change.

If you then want to change the balance setting, press the Balance address button and proceed as in the treble setting.

If both the address selector 21 and the level selector 20 are left untouched for an initial seconds, the address order is automatically switched to volume control, so that at any time by turning the dial you can change the volume without having to press buttons on the address selector. Thus, the indicator scale 25 normally shows the volume setting.

It will be apparent from the foregoing that the operation and operation of an apparatus according to the invention is extremely simple, and does not require more instructions than the setting of a conventional apparatus, despite the obvious simplicity of the front panel.

Fig. 3 shows the structure of the volume control unit 1 contained in the apparatus of Fig. 1. The signal enters the input 28 of the unit, passes through an input resistor 29, and is input to an operational amplifier 30, the output of which is connected to the output of the unit 31. Between the input of the operational amplifier 30 and ground are a number of resistors 32-35, which can be connected to ground via switches 36-39, which in turn are controlled by the drive stage 13. The switches have been shown as metallic contacts, and may for example be reed relays. In this case, the drive 13 feeds the coils on the reed relays. However, a cheaper solution is to use transistor switches, which today are available in the market isk large scale integrated circuits (LSI). Complete, electrically controlled volume control units of Fig. 3 are today commercially available as building elements in the electronics market.

In Fig. 3, only four resistance elements and four switches have been shown. In practice, eight elements are used, giving 2 - 1 = 255: 1 in the volume range. This corresponds, for example, to 48 dB volume range, which is fully sufficient in this attenuation. Of course, the switches are operated in binary code so that not only do you have eight steps on the volume setting, but the steps are very fine, less than 1 dB per step in an eight-step selector.

Fig. 4 shows an electrically controllable treble control1 which can be used in the apparatus of Fig. 1. The signal enters the input 40, passes through an input resistor 41 and is input to an operational amplifier 42, the output of which is connected

7711298-5 to the control output 43. The operational amplifier has two feedback outputs, one upper 44 for positive feedback and one lower 45 for negative feedback. A number of RC circuits 46-49 are connected between the amplifier input and the feedback outputs via switches 50-53, and the switches are in turn controlled from the drive stage 13. The switches can either be relays or transistor type switches as described above in connection with Fig. 3.

The odd-referenced RC circuits are connected to the output feedback 45 for negative feedback and, when connected, declining frequency characteristics are obtained. The circuits with even numbers have been connected to the output 44 for positive feedback and on their connection, rising frequency characteristics are obtained in the base register. When all the switches are open, straight frequency response is obtained and the level indicator 25 on the front panel of Fig. 2 shall show 50 °. If the falling frequency characteristic is desired, the RC circuit 47 is first switched on, it is desired that more falling characteristics are switched on instead of the circuit 49 and if the maximum falling characteristic is desired, both circuits are connected in parallel.

Similarly, three levels of increasing frequency characteristics can be obtained by switching either switch 51 or switch 50 or both.

A basic control network looks basically the same as Fig. 4, but the RC circuits are series circuits instead of parallel circuits. Both the treble control units and the basic control units in principle according to Fig. 4 are today commercially available as buildings.

Fig. 5 shows a detailed block diagram of an electrically controllable station wiper for the radio receiver part 8 of the apparatus according to Fig. 1. Frequency tuning takes place with a tuner 54 controlled by a capacitance diode, which means that the set frequency is determined by a DC voltage applied to the capacitance diode. Such diodes have long been commercially available and a number of commercial radio receivers use this type of frequency portion control instead of the conventional type of wired capacitors.

In this case, the DC voltage controlling the voltage controlled tuner 54 is supplied by a digital / analog converter 55 which is supplied with a well regulated DC voltage, and whose digital inputs 58 are controlled by the memory 14 of the amplifier of Fig. 1 via a register 57 and a latch 58. The memory 14 is only briefly connected to the register, which stores memory data until the memory is next connected via the latch 58. Each time the latch 58 is turned on, the contents of the register change to match the contents of the memory. Both register 57 and digital converter 55 are well-known, conventional building elements, which have long been in the trade, so it would be unnecessary to go into detail on how they work.

A vital unit of the apparatus according to the invention is the level selector 15 of FIG. 1, and some particularly suitable embodiments thereof are shown in FIGS. 6a-6e.

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According to Fig. 6a, the level road steering wheel 20 at the rear has a series of equally wide reflecting 59 and reflecting 60 segments, for example, black and white segments.

In Figure 6a, only eight white and eight black segments are shown, but a more practical number is 32 white and 32 black segments. As better illustrated in Fig. 6b, two phototransistors 61 and 62 are arranged close to the underside of the level setting knob 20 in such a way that they are affected by the white and black fields. Each phototransistor has a light source 63, 64 which can be, for example, LEDs. The two phototransistors with associated light sources have been positioned phase-shifted 90 ° to the black and light fields as shown in Figure 6b. The signals from the phototransistors 61 and 62 vary between 0 and, for example, + 10 V when switching from dark to light or vice versa. Therefore, when the level knob 20 is rotated in a decreasing direction, the signal from phototransistor 61, called V 61, and the signal from phototransistor 62, called V 62, will change with time as shown in Fig. 6c. If the knob is turned instead of in the increase direction, the signals will vary with time as shown in Fig. 6d.

A suitable decoding circuit which sorts signals for increase and decrease is shown in Fig. 6e. The signal V 61 from phototransistor 61 is switched on as shown between ground and two diodes 65 and 66, while the signal from phototransistor 62 is switched between two diodes 67 and 68. An increase output 69 and a decrease output 70 are present, and these is connected to the diodes shown in the figure and in addition to capacitors 71, 72 and resistors 73, 74.

Assuming the voltage V 61 is zero, no positive pulse can be input to the reducing output 70, because any such pulse would be shorted by the diode 66 and the phototransistor 61 via the output V 61. However, a positive pulse can be output to the reducing output 70 if the voltage V 61 is +10 V, because in this case the diode 66 is blocked by the voltage V 61. A positive pulse can be input to the decrease output via the diode 68 and the capacitor 72 only when the voltage V 62 increases from 0 to +10 V. By studying Figures 6c and 6d, it is seen that the combination diode 66 barred / voltage V 61 positive only occurs when the level dial 20 is rotated in the decrease direction. In this case, therefore, a number of pulses are output at the decrement output corresponding to the number of transitions we take / black current passing past the phototransistor 62. Similarly, it can be seen that as the level path gear 20 is rotated in the increase, a corresponding number of pulses out at the increase output 69 while the decrease output remains untouched.

the increase output and decrease output are connected to the two inputs of a reversible counter 75 of conventional type and this in turn is coupled to memory 14 via latches, which is only indicated in principle. When memory 14 is connected to the counter 75, the counter first receives signal to copy the memory contents, then the memory is disconnected most of the time, but it tests the reversible counter from time ti in another and copies through the write latch the contents of the counter each

7711298-5 once it tests. Thus, if the level selector dial 20 has been moved since the last time the memory was tested, the memory content will be changed the next time the memory is tested, and a new level setting has been registered.

Another vital unit of the apparatus according to the invention is the address selector 16 and a suitable embodiment is shown in Fig. 7.

The address selector, shown in Fig. 2, consists of a number of push buttons with different functions. In the embodiment illustrated in Fig. 7, the push buttons actuate switches which interconnect two lead sets ABC and abcde, which are arranged in matrix pattern, whereby each button corresponds to a coordinate in the matrix pattern. One set of wires (ae) goes parallel to a decoder 76, while the other pair of wires is fed cyclically by a three-stage latch 77, which also feeds inputs A, B, C to the decoder 76. When, for example, the second button 78 is pressed. middle line 23, a signal will be output on line b only when the latch is in position B. A coincidence circuit in the decoder 17 notes this, and gives a corresponding signal to the memory 14 If the memory is binary, an 8-bit memory is sufficient to handle all 15 buttons shown in Figure 7 and Figure 2. Only eight wires exist between the pushbutton kit and the rest of the device, even though 15 buttons are included.

Returning to Fig. 1, it will now be appreciated that the variable functions, volume, stereo balance, bass control, treble correction can be realized in electrically controllable design. In the embodiments described above, the variable functions are digitally controlled beyond all except the radio tuner portion, which is 1 non-voltage controlled. It is of course possible to use a digitally controlled frequency setting instead, in the manner described for the volume control, but with variable capacitors instead of resistors. It is also possible to use voltage controlled volume controls etc, by using nonlinear elements for the gain control. Such voltage controlled volume control elements as well as bass and treble control elements are commercially available. If such, non-voltage controlled elements are selected, only a digital / analog converter is connected between the voltage controlled element and the memory function, as shown for the frequency control of FIG. Of course, other forms of electrically controlled variable functions can of course be used, without affecting the invention.

As a level selector, a steering wheel with heart rate markings and optical reading has been illustrated above. Instead, an alternative form of level selector according to Fig. 8 can be used. The level selector here consists of two pushbuttons 77 and 78 with associated contacts 79 and 80, which switch on and increase. reduce input to counter 75 of FIG. 6e.

Instead of a knob with pulse sensing means, an oscillator 81 of suitable oscillation frequency is used, and a pulse former 82. The oscillator and pulse former are continuously connected, and all one does with the pushbuttons 77 and 78 is to determine whether to connect them to the amplifier. or decrease input and how long. By holding

7711298-5 increase button pressed for a certain time, a number of pulses will be registered in the direction of increase and the longer the button is pressed the more pulses are recorded. Thus, the device of Fig. 8 is in all parts equivalent to the device of Figs. 6a-6d, with the only difference being that it is the duration of the indentation which determines the change of set value, rather than the magnitude of the rotary motion. It should be obvious that other forms of level setting means may also be used, for example, a direct current potentiometer, which is in turn decoded by an analog / digital converter before the signal is stored in memory. The invention is in no way affected by what type of level selector is used.

In the functional block diagram of Fig. 1, discrete block functions such as decoding means, memory means, etc. are indicated. These functions can be obtained either by analogy, ie by drawing threads between the various elements, or a microprocessor can be used to control all logical functions. memory control etc. In this latter case, the instructions for how the logic is to be handled will be contained in a read-oniy memory (ROM), which replaces most of the wiring in the discrete system. This solution has the advantage that the program can easily be changed without soldering, and today both price and reliability in a microprocessor are advantageous compared to hardware. However, the functional block diagram of Fig. 1 is the same, whether using hardware or microprocessor. Only the electrical wiring scheme is changed.

Most read and write memory (RAM) memory devices are currently dependent on continuous supply voltage. If such memory means which lose memory function in the event of voltage loss1 are used, they should be supplied via a small rechargeable accumulator, which is charged as long as mains voltage is connected to the apparatus. In this way, the apparatus will automatically return to the last set position when switched on, as described in connection with Fig. 2. Instead of using a core memory or a bubble memory, no continuous supply voltage is needed.

The majority of read and write memory means (RAMs) depend on a continuous supply voltage. If using memory means which, in the event of a power failure · lose the memory function, they should be supplied via a rechargeable accumulator, which is charged as long as the mains voltage is connected to the device. In this way, the appliance will automatically return to the setting that prevailed when the appliance was last switched off.

However, if you use a core memory or a bubble memory, you do not need a continuous supply voltage.

Fig. 9 shows the connection of a RAM in the block diagram of Fig. 1.

If the RAM 14 is equivalent, it is conveniently backed up with an accumulator 83. The level and the address decoders activate a certain position in the memory 14. The stored memory value can either be read or rewritten and changed depending on the desired function.

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Thus, if the memory is performed with CMOS technology, the accumulator 83 introduces a resistor 84 and a diode 85, thereby preventing the memory information from being lost in the event of voltage loss.

As previously mentioned, the level indicator may be of the thermometer type and as shown in Fig. 10 consist of a plurality of indicators 86, preferably in the form of LEDs, which are coupled in matrix to obtain the minimum number of connections. From the decoder 17, a decoded and statically locked function is obtained via a latch circuit, which through anode driver 87 and a cathode driver 88 actuates the LED indicators 86. The circuits also include resistor 89 for current limitation.

Fig. 11 shows a possible configuration of the output decoder 13 according to Fig. 1, which can thus consist of a logic which activates a certain output for a certain address. The decoding can be done with a binary decoder 90, for example a 4:10 decoder where the decoded the addresses act as a clock for the various latch circuits 91-95, which output locked static output data. The data flow to the latch circuits is common because only one latch circuit is activated at a time.

In the embodiment of Fig. 2, the volume control function is constantly switched on, with a certain time delay after the last second level function has been used. The circuits shown do not show in detail how this is accomplished, but it will be obvious to those skilled in the art that all that is needed is a time delay circuit which instantaneously closes a contact parallel to the void setting address. The time delay means can easily be restarted each time an address button is pressed, and especially in the case where a microprocessor is used, the time delay can be easily started each time an active level setting is made. In this way, you can use as much time as possible to search between different stations, for example without risking automatic return to volume control. However, the unit automatically returns to volume control a few seconds after you stop selecting the stations.

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