GB2255207A - Indicating rotary position of shafts. - Google Patents

Abstract

Methods and apparatus are disclosed for determining the angular positions of one or more rotatable shafts and producing audible (speech) announcements reporting the position(s) of the one or more shafts. Announcements may be activated at predetermined times or time intervals or by externally generated signals such as a switch closure or visible, infrared, radiofrequency, audible or ultrasonic signal. Examples of devices utilizing the invention include: a talking analog clock that announces the time at a predetermined time (alarm) or time intervals (chimes) or by a switch closure or remotely activated sensor; an oven that announces the temperature setting of a rotary temperature control knob; and a television set that announces the channel number given by a rotary channel select dial.

Description

METHOD AND APPARATUS FOR COMBINING THE ROTATION ANGLE OF A SHAFT WITH AN ELECTRONIC SPEECH SYNTHESIZER IN DEVICES SUCH AS AN ANALOG TALKING CLOCK OR ROTARY DIAL FIELD OF THE INVENTION The present invention relates to methods and apparatus for interfacing mechanical and electrical components of electro-mechanical devices to produce meaningful audio outputs and more particularly to methods of generating audio messages which depend on the rotation angle of a shaft or shafts, which messages may be activated by a switch closure, analog signal, digital signal, or timer output.

INCORPORATION BY REFERENCE The entire disclosure of commonly owned U.S. Patent No.

4,214,125, entitled "METHOD AND APPARATUS FOR SPEECH SYNTHESIZING," issued July 22, 1980 is hereby incorporated by reference.

BACKGROUND OF THE INVENTION With the development of large scale integration (LSI) electronic circuit technology and concomitant advances in audio signal compression and synthesis, it has become common to find electronic speech and sound synthesizers in products such as advertising material in which an advertising message is spoken; dolls in which realistic laughs, cries, and gurgles are generated; talking books that produce sound effects as they are read; toy trains, trucks, or fire engines that make realistic sounds; answering machines in which synthesized time announcements are appended to incoming messages; voice messaging systems that allow the caller to leave messages for unavailable parties; computer software and games that produce speech, music, and sound effects to enhance the user interface; talking greeting cards in which the user can place his cwn message; educational products that assist learning by talking to the user; and digital clocks or watches (clocks or watches having digital readouts rather than hands that point to the time) that announce the time when a button is pressed.

Speech and sound synthesizers that fill these needs have been developed as LSI chips and are available from many companies. For example, Electronic Speech Systems of Hayward, California produces a family of about six different chips that fill different parts of this market need. The sound compression and synthesis technology in these products is described in U.S. Pat. No. 4,214,125, the disclosure of which is incorporated herein by reference.

In spite of the widespread acceptance and use of speech and sound synthesis in consumer products, there are some applications that have not, heretofore, been realized commercially. Such applications include devices which have visual indicators coupled to rotatable shafts or, more generally, devices in which the information required by the synthesizer (in order to prompt announcement of the correct information) is the rotation angle of a shaft or axis.

Examples of such devices include analog clocks and watches (in which the positions of the hour and minute hands visually indicate the time), television sets or radios (in which a dial both controls and indicates the station or frequency to which the device is tuned), and cooking ovens (in which a manually rotatable knob both controls and indicates the temperature).

The possibility of eliciting an audible announcement of the setting(s) or position(s) of the rotatable indicators contained in such devices would be greatly desirable under circumstances when the device is not visually accessible as, for example, when the person desiring to know the time or setting is visually impaired, when the ambient light level is too low or too distant to be legible, or when the device is outside the direct line of sight. In the discussion below, talking analog movement clocks and watches will be specifically discussed as one example of an application of the present invention, but the invention is not so limited.

An analog movement clock is usually a device having gears that are connected to hour and minute hands by shafts. The time is given by the position of these hands. By comparison, a digital clock is usually a fully electronic device whose time is read on a digital display as a series of numbers. It is relatively simple to interface the electronics of a digital clock with a speech synthesizer that announces the time because the time is kept as a digital quantity that is maintained and updated by the electronics. Thus, the electronic clock circuit can easily interface with an electronic speech synthesizer which obtains the current time as required to announce it upon request. Thus, a digital clock may have a fully electronic interface to a speech synthesizer.

By contrast, interfacing a speech synthesizer with an analog movement clock to allow the announcement of the current time when a verbal time announcement is requested is relatively much more difficult, because the interface between the clock and the synthesizer would necessarily be electro-mechanical and the time is not normally stored in the analog clock in either electric or digital electronic form. That is, the positions of the hour and minute hands on the analog movement clock must be relayed to the speech synthesizer electronics before this electronics has the information required to make the announcement. This problem has not been solved in the prior art in a reliable and cost effective manner, so analog movement talking clocks are not found in the market place.

A further problem associated with devices having visual indicators mounted on rotatable shafts in general and with analog movement talking clocks in particular is that they are frequently located at a distance from the person who desires to hear a time or other announcement, such as on the wall in a kitchen or an office, away from the bed in which a sleeper desires to know the time, etc. In such cases, it is inconvenient for the listener to move to the position of the clock and push a button, for example, in order to hear a time announcement. Thus, a method of remotely triggering a time announcement would be a desirable feature of a useful talking analog movement clock. This problem has not been solved in the prior art.

BRIEF SUMMARY OF THE INVENTION These problems and others are overcome in the apparatus and methods of the present invention. Generally, apparatus according to the invention includes an electronic speech synthesizer and one or more mechanisms for producing an analog voltage signal for each of the rotatable shafts whose position is to be announced or included in the announcement produced by an electronic speech synthesizer; the analog voltage signals are generated such that the magnitude of each signal corresponds to the angular position of the corresponding rotatable shaft.The apparatus also includes circuitry for converting the analog voltage signals into digital signals coded to represent the angular positions of the respective rotatable shafts suitable for input into the electronic speech synthesizer to select speech information stored in the synthesizer corresponding to the angular position of the rotatable shafts. The methods according to the invention include producing analog voltage signals whose magnitudes correspond to the angular positions of the one or more rotatable shafts; these analog voltage signals are then converted into digital signals appropriate to select sound information from an electronic speech synthesizer such that the audible output of the speech synthesizer announces information related to the angular positions of the rotatable shafts.

In one embodiment of the invention, the angular position of a dial, knob, or other visual indicator (such as a pointer) mounted on a rotatable shaft is converted to an analog voltage proportional to angular position of the visual indicator; the analog voltage is converted to digital signals appropriate to cause a sequence of phonemes, words, or the like to be produced by the voice synthesizer to audibly announce the position of the shaft. By proper choice of the contents of the phonemes, words, etc. stored in the memory of the voice synthesizer, the audible output can be chosen to announce a temperature (where, for example, the dial or knob is the temperature control knob of a household oven), a channel or frequency (where, the dial is the tuning knob of a television or radio), a time (where the dial is the face of a analog clock or watch), or the like.

In another embodiment of the invention, the angular positions of two (or more) dials, knobs, etc. mounted on rotary shafts are converted into a like number of analog voltage signals proportional to the angular positions of the rotary shafts. The two or more rotatable shafts may be concentric, parallel but spaced apart, spaced apart but not parallel, or, for more than two rotatable shafts, any combination thereof.

The analog voltage signals are then converted to digital signals appropriate to cause a sequence of phonemes, words, or the like to be produced which announce the combined position of the plurality of visual indicators. For example, the analog voltage signals proportional to the angular positions of the hour and minute hands of an analog clock can be converted to announce a single time.As an additional example, the analog voltage signals proportional to oven control knobs, one of which regulates temperature and the other a selected heating coil or other heating mode, could be converted to cause the voice synthesizer to announce "bake, 3500" or "broil, 5500." Another example of this second embodiment of the invention is a talking analog clock or watch which announces the time, corresponding to the angular positions of the hour and minute hands.

In another, preferred embodiment of the invention, one of the analog voltage signals can be sensed to both cause the angular position of the associated visual indicator to be announced, but also to check or ensure the accuracy of the announced position of a second visual indicator. For example, the correct hour to be announced by a clock changes within a relatively small range of movement of the hour hand of a clock and hence of a relatively small change in the magnitude of the analog voltage signal corresponding thereto. However, the analog voltage signal corresponding to the angular position of the minute hand of a clock can be sensed to ensure that the correct hour is being announced, so that the announced hour is dependent on both the position of the hour hand and that of the minute hand.

According to another aspect of the invention, the various embodiments of the invention will also generally include one or more actuators for activating the speech synthesizer circuitry to produce an audible announcement of the position(s) of the rotatable shaft(s) and thus of the visual indicator(s) or dial position(s). Such actuators may be used to cause the speech synthesizer to announce, for example, the temperature, channel, or time regularly and/or periodically, at a preset time or upon occurrence of a predetermined event, or on demand.Such actuators may include a timer, such as an alarm timer of a clock, or a mechanism which prompts the announcement in response to an external stimulus such as a change in position(s) of the rotatable shaft(s), the closing of a switch, a sensor responsive to a visible, infrared, or radiofrequency light signal, or sensor which detects a particular sequence of handclaps or other audible or ultrasonic sounds.

BRIEF DESCRIPTION OF DRAWINGS A more complete appreciation of the invention and many of the attendant features and advantages thereof will be better understood by reference to the following detailed description of specific embodiments thereof when considered in connection with the accompanying drawings.

FIG. 1 is a perspective, exploded view illustrating portions of a specific embodiment of a talking analog clock according to the invention and a method of measuring the angular positions of the clock's hour and minute hands.

FIG. la is a cross-sectional detail view of the talking analog clock shown in Fig. 1 as assembled.

Fig. lb is an electrical schematic illustrating the equivalent circuit of a specific talking analog clock according to the invention.

FIG. 2 is a block diagram of the electronic circuit associated with an analog movement talking clock that decodes the positions of the hour and minute hands from the voltage outputs of the mechanical device of FIG. 1, and announces the time.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS Mechanical design As an example of the general problem of interfacing the rotation angle of a shaft with speech synthesis electronics, the talking analog movement clock will be described. It will be understood that the term analog clock includes both clocks and watches.

One approach to achieve such an interface would be to control the position of the hands of the clock with electronics. That is, the time setting would be input to the electronics in the same manner as for a digital clock, via buttons that feed electronic signals to the electronics. As the time is changed in this way, the electronics causes the hands to move to the correct position by use of a motor that controls the hand position. Such a solution is relatively expensive and would be unreliable since the hands could be forced to a new position manually, with the result that there would be a loss of correlation between the actual position of the clock hands and the electronic signals used to move the hands.

A second approach would be to sense the position of the hands and to use this information to determine the electronic signals necessary to elicit an audible announcement of the time. For example, each motion of the minute or hour hand can cause a different switch to close because a contact on each of the hands touches contacts on the clock face. The switch closures are then monitored electronically. In its simplest form, this solution requires monitoring 60 switches for the minute hand and 12 switches for the hour hand, so it is mechanically and electrically clumsy. An improvement on this approach would be to sense contacts between a second hand and each of the minute and hour hands.The number of required contacts would then be three: a contact between the second hand and the minute hand; a contact between the second hand and the hour hand; and a contact between the second hand and the clock face which would sense when the second hand was in a known position such as the twelve o'clock position. In such an arrangement, the time could be determined electronically from the time delay between the second hand pointing straight up and being in contact with the minute and hour hands. While this solution would reduce the number of contacts to an acceptable level, it would complicate the electronics by requiring that time delays between contacts be measured, stored, and converted to useful information. In addition, the time cannot be known for up to a minute after it is changed, so the audible announcements of the time could be in error.In addition, this solution would require the presence of a second hand which many analog movement clocks lack.

A variation on the above approach would be to sense the positions of the gears in the gear mechanism that causes the hands to rotate. This approach suffers from all of the problems discussed above in addition to adding complexity to the already complex gear mechanism.

For the above reasons, the presently preferred approach of determining the position of the hands is to fix the hands with respect to the shafts that connect them to the gear mechanism, and to measure the rotation angle of the shafts. One example of such an approach is illustrated in FIG. 1, which shows an exploded perspective view of the shaft assembly 1 of the preferred embodiment of the invention. Shaft assembly 1 includes a minute hand shaft 2, an hour hand shaft 11, and an analog time measuring collar 9. Minute hand shaft 2 has, mounted to one end thereof, a pinion 3 that is part of and engaged to the remainder of the clock's gear mechanism (not shown); the clock's minute hand (not shown) is mounted to the other end of minute hand shaft 2. Minute hand shaft 2 also includes a minutes wiper 5 and a minutes contact 7. Minutes wiper 5 is conductive and resilient and is mounted to extend beyond the outer periphery of minute hand shaft 2. Minutes contact 7 is also conductive and is fixedly mounted with respect to the clock and positioned to form a sliding electrical contact with minute hand shaft 2, conveniently in the region of pinion 3. The minute hand shaft 2 is preferably metallic so that minutes wiper 5 is in electrical contact with minutes contact 7; other arrangements and materials that maintain electrical contact between minutes wiper 5 and minutes contact 7 will be apparent to those skilled in the art.

Minute hand shaft 2 fits concentrically inside the analog time measuring collar 9, which is made of insulating material and which does not rotate with the hour and minute hand shafts 2 and 11.

Hour hand shaft 11 fits concentrically over analog time measuring collar 9. It is preferably metallic (so as to be electrically conductive) and includes a gear 13 on one end and the hour hand (not shown) on the other. Gear 13 engages the remainder of the gear mechanism of the clock (not shown). Hour hand shaft 11 also includes an hours wiper 15 mounted inside the hour hand shaft 11 which is in electrical contact with an hours contact 17. Hours contact 17 is mounted to the remainder of the clock so as to be in sliding electrical contact with gear 13 and hours wiper 15.

Analog time measuring collar 9 contains an adjustment arm 10 and two resistance elements 19, 20, one of which (19) is in contact with minutes wiper 5, and the other of which (20) is in contact with hours wiper 15. Resistance elements 19, 20 are formed of a uniformly resistive but conductive material and mounted in sliding electrical contact with minutes wiper 5 and hours wiper 15, as illustrated in FIG. la. The two ends of each of the resistance elements 19, 20 are connected to an external potential source (not separately shown) by two wires that exit analog time measuring collar 9 along its adjustment arm 10. Conveniently (but not necessarily), the potential source is the source used to power the electronic speech synthesizer and associated circuitry to be discussed below.

Thus, electrical circuit 21, illustrated in FIG. 1b, is created by minute hand shaft 2, hour hand shaft 11, and analog time measuring collar 9. As minute hand shaft 2 and its associated minute hand rotate, the voltage on minutes contact 7 varies linearly with the rotation angle of minute hand shaft 2 from Vcc to 0 volts. Thus, this voltage provides instantaneous information on the position of the minute hand. Similarly, as the hour hand rotates, the voltage on hours contact 17 varies from Vcc to 0 volts, proportional to the position of the hour hand.

In summary, the preferred embodiment for the measurement of the positions of the hour and minute hands contains four wires between the analog clock movement and the electronics (Vcc, return, minutes contact 7, and hours contact 17). The voltage on minutes contact 7 gives the position of the minute hand and the voltage on hours contact 17 gives the position of the hour hand. These voltages are decoded by an electronic circuit (discussed below) that feeds electronic data regarding the time to the speech synthesizer circuit, which then announces the time in audible speech.

Electronic block diagram A block diagram of the preferred embodiment of the electronics is shown in FIG. 2. These electronics are activated to produce an audio time announcement in four ways, the first of which is by a signal on an analog input 23. This input may come, for example, from a microphone that is responding to a hand clap, whistle, or other audio or ultrasonic signal; from an infrared sensor that is responding to a remote control device; from an optical sensor that is responding to an external light signal, or from a radio frequency sensor that is responding to an external radio signal. Sensors suitable for use in analog input 23 for each of these types of externally and remotely generated signals will be known to those skilled in the art. Additional modes of activating an audible time announcement are discussed in greater detail below.In any case, the data on analog input 23 is an amplitude modulated, time coded, signal that is detected by the electronic circuit of FIG. 2.

To conserve electrical power, much of the electronic circuit may be powered down in a quiescent mode while waiting for an external signal at analog input 23 or otherwise to request a time announcement. The first pulse of the signal on analog input 23 passes through an amplifier and peak detector 25 to produce a signal above threshold at the input to an analog voltage activator 27. The threshold level that determines whether a signal appears at this point is set by a fixed or variable external resistor 29. When analog voltage activator 27 receives an input signal, it causes the remaining circuitry to power up by applying voltage along line 31. The output signal from amplifier and peak detector 25 is then passed through an analog multiplexer 33 to a 7 bit analog-to-digital converter 35 where it is converted to a digital signal.The pattern of the amplitude variations of this digital signal is then analyzed by analog signal decode electronics 37 to determine if it is a valid request for a time announcement. For example, suppose that the analog input 23 comes from a microphone and the required signal is three claps of the hands within two seconds. The first clap causes the analog voltage activator 27 to put power on the remainder of the circuit and analog signal decode 37 then decides whether two more signals above threshold occur within two seconds.

If so, the output of analog signal decode 37 is activated to place a signal on the input of programmable logic array (PLA) 43. This produces an output which causes pot voltage 45 to put voltage Vcc on resistance elements 19, 20 in analog time measuring collar 9 of FIGs. 1 and la. The voltages on minutes contact 7 and hours contact 17 are then passed through the analog multiplexer 33 to the 7 bit analog-to-digital converter 35 where they are converted to digital signals that are analyzed by time decode logic 39 to obtain electronic data representing the current time. Time decode logic 39 is capable of converting the digitally converted electronic voltage signals representing the positions of the hands of the clock to, for example, signals indicative of hours and minutes.One suitable table for performing such a conversion, which could be stored in time decode logic 39 as a look-up table, is discussed below. This digital information is passed to PLA 43 where it is converted to a set of instruction signals that are fed to sound synthesizer 47, which generates the time announcement, converts it to an analog signal, and plays it to speaker 49.

The oscillation frequency of sound synthesizer 47, and hence, the digital data rate, are controlled by external RC network 51.

The analog output at minutes contact 7 must be decoded with an accuracy of better than one part in 60 to obtain the correct value for the minute hand position. For this reason a 7 bit analog-to digital converter 35 has been selected because it provides a precision of one part in 128. In other applications of the invention, analog-to-digital converters of lesser or greater precision may find use.

There are at least three other ways, illustrated in FIG. 2, to activate a time announcement. One of these is closure of the switch at time announce input 53. A second mode would be activation at a predetermined time (e.g., by setting an alarm) or at regular time intervals, referred to as a chime announcement, such as hourly or every 15 minutes. This announcement is activated by setting the alarm/chime on through grounding input 55, and waiting until the alarm/chime time occurs, at which time alarm/chime time switch 57 is closed.

The signals from these two inputs are analyzed by alarm/chime decode logic 41, which sends a signal to PLA 43 when the two events occur. An additional mode of activating a time announcement would be with a "snooze" control, analogous to that found on many alarm clocks. In this mode, if alarm/chime decode 41 is active and snooze input 59 is on, snooze decode logic 63 waits a fixed time (for example, five minutes) after the alarm goes off and, if the alarm/chime switch 55 is not off, causes a signal at the input to PLA 43 which triggers a time announcement. This process continues every fixed interval of time until alarm/chime switch 55 is turned off. The snooze decode logic 63 receives its timing information from oscillator and countdown circuit 61, which can also be used to produce timing pulses at precise one second intervals to advance the gears in the analog clock mechanism.Each of these three ways of triggering time announcements operate through the remainder of the electronics in a manner analogous to that described above for analog input signals.

In addition, in some embodiments of the invention the speech synthesizer may be activated to produce other than time announcements by putting a digital signal on general purpose input 61. PLA 43 as shown in FIG. 2 also produces output Q0 65 which may be used in some embodiments of the invention to control external functions (such as mouth motion) in synchronism with the audio output.

Electronic details PLA 43 has 5 inputs, 48 terms, and 8 outputs that comprise the information sent to sound synthesizer 47 and pot voltage 45. Each output bit is an OR expression of any combination of the terms and each term is an AND expression of any combination of the inputs or the complements of the inputs. A term is TRUE only if all the inputs are in a specified condition, either "high", "low," or "don't care." The programming of the PLA causes the sound synthesizer to execute proper time announcements. In addition, it offers versatility and variability to these announcements. For example, sometimes it can cause the time announcement to be "Its seven twenty two" and other times it can be "The time is twenty two minutes after seven." Suitable circuitry and programming for PLA 43 will be apparent to those of skill in the art.

Sound synthesizer 47 contains a memory in which compressed speech and sound data are stored, decode logic to decompress this stored data and produce a digital output, a pulse width modulator that converts the digital output to an analog signal, and an amplifier to drive the speaker. The methods of compressing and synthesizing the audio data are described in U.S. Pat. 4,214,125 and will not be discussed here. The remainder of the circuitry in sound synthesizer 47 is conventional and known to those skilled in the art.

In the preferred embodiment of the invention, time decode logic 39 is selected to operate in a manner such that the hour announced is dependent on the positions of both the hour and the minute hands, rather than just the hour hand alone. This is done for the following reasons. Since the motion of the hour hand between times of 1:59 and 2:01 is negligible, there is a risk of announcing 1:59 incorrectly as 2:59, or 2:01 incorrectly as 1:01 if precautions are not taken. The method of solving this problem in the preferred embodiment is to make the hour in a time announcement depend on the position of the minute hand as well as the hour hand.For example, in the above cases, if the minute hand is between 0 and 30, the hour TABLE I Minute Hour Hand An Range 0-11.5 12-23.5 24-35.5 35-47.5 48-59.5 nounced Hour 58-2.5 59-3.5 0-4.5 1-5.5 2-6.5 12 Hand 3-7.5 4-8.5 5-9.5 6-10.5 7-11.5 1 Range 8-12.5 9-13.5 10-14.5 11-15.5 12-16.5 2 13-17.5 14-18.5 15-19.5 16-20.5 17-21.5 3 18-22.5 19-23.5 20-24.5 21-25.5 22-26.5 4 23-27.5 24-28.5 25-29.5 26-30.5 27-31.5 5 28-32.5 29-33.5 30-34.5 31-35.5 32-36.5 6 33-37.5 34-38.5 35-39.5 36-40.5 37-41.5 7 38-42.5 39-43.5 40-44.5 41-45.5 42-46.5 8 43-47.5 44-48.5 45-49.5 46-50.5 47-51.5 9 48-52.5 49-53.5 50-54.5 51-55.5 52-56.5 10 53-57.5 54-58.5 55-59.5 56-0.5 57-1.5 11 announcement should be 2, while if the minute hand is between 30.5 and 59.5, the hour announcement should be 1.

More generally, let the position of the hour hand around the dial be described in units of 0 to 60 with a precision of 0.5. Thus, for example, an hour hand position between 15 and 20 nominally corresponds to hour 3. In these units, Table I describes the preferred method of decoding the hour hand dependent on the position of the minute hand.

Examples of other features of the design of the electronic circuitry which may be used, but would not be required, in other embodiments of the invention are: - If analog input 23 comes from a microphone, then the microphone and speaker functions could be serviced by a single device since sound synthesizer 47 may have tri-state outputs.

- Analog multiplexer 23 can be provided with pull up resistors on its inputs so the output of analog-to-digital converter 35 has a definite value when inputs hours contact 17 or minutes contact 7 are floating. These contacts could be floating because there would typically be a gap between the two ends of resistance elements 19, 20. Such a gap cannot cause an error in the time that is synthesized since it occurs at a minutes reading of 60, and this reading has a voltage of Vcc associated with it either with a gap or without a gap.

- Resistance elements 19, 20 and wipers 5 and 15 are preferably designed to minimize the possibility of shorting the two ends of the resistance elements 19, 20 to each other by the wiper arm motion. This is achieved by making one end of each resistance element physically higher than the other.

- The output of pot voltage 45 preferably has a finite impedance to protect the circuit and batteries in the event that the motion of minutes wiper 5 or hours wiper 15 causes this output to be shorted to return.

- The circuitry could be designed to eliminate multiplexer 33 by including analog-to-digital converters (sized to have the resolution necessary for the particular signal being converted) separately for each of the signals, such as the voltages from hours contact 17 and minutes contact 7, which need to be converted for input to PLA 43.

Since the remainder of the electronics described in FIG.

2 is well-known within the current art, it is not further described.

While the above is a complete description of the preferred embodiments of the invention, other arrangements and equivalents are possible and may be employed without departing from the true spirit and scope of the invention. The terms and expressions which have been employed here are used as terms of description and not of limitations, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the appended claims.

Claims (14)

CLAIMS:

1. An apparatus for producing a speech announcement representative of the angular position of each of at least one rotatable shaft comprising: means for producing at least one electronic signal, each of which is representative of the angular position of a corresponding one of the at least one rotatable shafts; a electronic speech synthesizer operable to produce a speech announcement in response to the at least one electronic signal.

2. The apparatus of claim 1 including means for activating the electronic speech synthesizer to accept the at least one electronic signal and to be operable to produce the speech announcement.

3. The apparatus of claim 1 including a sensor which is operable in response to a remotely generated signal to activate the electronic speech synthesizer to produce the speech announcement.

4. The apparatus of claim 1 wherein the speech announcement is representative of the angular position of at least two rotatable shafts.

5. The apparatus of claim 4 wherein the speech announcement is the time corresponding to the positions of at least two hands of a clock, each of which is mounted on a rotatable shaft.

6. The apparatus of claim 1 wherein each of the at least one electronic signal is an analog voltage signal and further comprising means for converting each of the at least one electronic signal to a digital signal representative of the angular position of a corresponding one of the at least one rotatable shaft.

7. A talking analog clock comprising: a first rotatable shaft having an hour hand mounted thereto; a second rotatable shaft having a minute hand mounted thereto; means for generating first and second signals representative of the angular position of the first and second rotatable shafts; an electronic speech synthesizer; means for accepting the first and second electronic signals by a speech synthesizer to cause the speech synthesizer to produce an audible announcement of the time in hours and minutes.

8. The talking analog clock of claim 7 further comprising means for activating the electronic speech synthesizer to produce the announcement of the time.

9. The talking analog clock of claim 8 wherein the activating means includes a switch which, upon closure, activates the electronic speech synthesizer.

10. The talking analog clock of claim 8 wherein the activating means includes timing means for generating a signal to activate the electronic speech synthesizer at a predetermined time.

11. The talking analog clock of claim 8 wherein the activating means includes a sensor responsive to a remotely generated signal to activate the electronic speech synthesizer.

12. The talking analog clock of claim 11 wherein the sensor is responsive to a remotely generated visible, infrared, radiofrequency, audible, or ultrasonic signal.

13. The talking clock of any of claims 7-12 wherein the hour announced is dependent on the angular position of the minute hand.

14. An apparatus substantially as herein described with reference to the accompanying drawings.