JPS59500079A - Analog-to-digital converter using sampling cathode ray tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] name of invention Analog-to-digital converter using sampling cathode ray tube Background of the invention The present invention is particularly applicable to high-speed analog signal sampling techniques using cathode ray tubes (CRTs). It relates to sample analog-to-digital conversion technology.

By sampling a continuous analog signal, a series of discrete analog There are many applications that require obtaining voltage levels. If so, these Samples are used directly, but in most cases these samples are digital has been made into The most common high speed analog-to-digital converters (ADC's) , when an analog sample is taken, the analog ・Samples are digitized. i.e. the next sample of the continuous analog waveform Before the sandals are removed, a digital word (digita) representing the size of the analog sandal is created. l word) is created. The fastest of these analog-to-digital converters are called "flash converters", and these The converter uses many semiconductor comparators. Current silicon technology allows these An upper limit (upper 11mlt) is imposed on the device. This instantaneous converter is equivalent to 1 second. , it is possible to generate digital words with an accuracy of about 6 pins using 95 x 10 samples. can. However, a significant limitation of these devices is that when analog signals are sampled, There are significant errors that cause sudden changes in the area.

In other devices, at least one target of the electron gun is used together with a cathode ray tube (CRT). One analog charge-coupled device (CCD) is used. This charge-coupled device is a semiconductor The body has pockets of electric charge, and each pocket of electric charge has a pair. is proportional to the analog signal with the corresponding sample time. Accumulates the required number of samples These six samples are then output at low speed to a low speed analog-to-digital converter. is digitized and stored in low-speed memory. analog like this Digital converter and memory are not expensive, but comparable to high speed instantaneous converters. A large amount of power is required to drive a charge-coupled device at the sample rates available. Change Furthermore, the nonlinearity of charge-coupled devices is also a serious problem.

Therefore, the main object of the present invention is to Accurately, inexpensively, and continuously convert high-frequency analog signals at speeds significantly faster than standard converters. An object of the present invention is to provide an apparatus and a method that can perform sampling.

Summary of the invention The above purpose and other purposes are to Brightness modulation (1ntensity modulated) by analog signal This is achieved by the present invention. The electron beam crosses the target surface with the same curves and turns, The most common type is a circular shape or a turn, which is deflected repeatedly over the top. target surface At the top, there are shapes close together in a closed figure like a circle. , a number of conductive targets or targets are placed. These targets are When the cutting sweep is performed, a voltage proportional to the intensity of the electron beam is generated. The output is Consecutive samples of a continuous analog signal. These samples are retained and are sequentially digitized by an accurate, inexpensive, and slow variable analog-to-digital converter. Ru.

The features and advantages of various aspects of the invention, as well as other objects, are described in detail in the preferred embodiments below. It will become clear from the explanation. This will be explained below with reference to the attached drawings.

Brief description of the drawing Figure 1 shows a continuous analog waveform sampled by the technique of the present invention. C; FIG. 2 shows a preferred embodiment of the cathode ray tube sampling device according to the present invention. C; Figure 3 is a diagram of an electrical circuit used in conjunction with the sampling device of Figure 2; Figure 4 shows a complete test using the samples obtained by the systems of Figures 2 and 3. The system is shown in a block diagram.

Preferred embodiment Referring first to Figure 1, a sample of various electrical devices and systems is shown. Continuous analog waveform 11 is an example of the type of voltage waveform that is needed. is the indication. Although this waveform is similar to a sine wave, other forms of analog The techniques shown here work similarly for waveforms. various samples at regular time intervals. It is desirable to obtain voltage at times such as 13, 15, 17, and 19. and these Analog voltage samples are used directly in either equipment or systems are often digitized, and the sampling process must be preserved for digitization. It is done before holding.

Referring to FIG. 2, a typical shaped cathode ray tube vacuum envelope 21 has a narrow It has a standard type electron gun in one end, and a somewhat larger target surface 25 is provided in the other end. It is being This target surface 25 is a plurality of targets with which the electron beam from the electron gun 23 collides. target or support the target. The high voltage power supply 38 has a voltage of the order of 10,000V. Gives fast voltage. The anode line is grounded and the cathode ray tube (CRT) ) is connected to the anode 42 of the. A pair of polar plates 29 direct the beam 27 in the vertical direction. The pair of polar plates 31 are normally arranged to deflect the beam 27 in the horizontal direction. It is placed. Standard magnetic field deflection systems are made for similar purposes. In this example In this case, the beam 27 is run at a constant velocity over a circular pattern across the target surface 25. It will be done. Deflection circuit 33 applies a sine wave to conductor 35 and a cosine wave to conductor 37. This deflection is achieved by generating for the horizontal and vertical plates, respectively. Ru. The analog signal to be sampled is placed in the path of the electron beam via an amplifier 39. The grid 41 is applied to the grid 41 from the input analog signal. Its brightness or intensity as a function of time depends on the varying voltage applied to 1nt enity) in different words.

On the target surface 25 there are a number of separate conductive targets, such as adjacent targets 43 and 45. or are placed. These targets preferably each have the same dimensions and are separated from each other. a circular path equidistant apart and coinciding with the path scanned by beam 27. It is completely enclosed. The targets are electrically isolated from each other and One or more conductors connect through the envelope 21 to external processing circuitry. mark The loads connected to each external conductor, such as 43.45..., are only capacitive. Therefore, each voltage is an analog of the moment the electron beam 27 sweeps across the target. It is proportional to the value of the log signal 11.

The electron beam 27 travels at a constant speed, and the targets 43, 45°... are equally spaced in a closed path. , samples are taken periodically and continuously.

Scanning pattern of the electron beam 27 corresponding to the pattern of the conductive targets 43, 45... The turn need not be circular, but such a turn is most convenient. Conductivity Targets 43, 45... are arranged in a continuous pattern and an electronic beam is passed over the targets. As long as the program 27 scans within the same main turn, the input analog waveform will be continuously sampled. If the electron beam scanning speed and spacing between targets are matched, That is, most commonly, as long as the scan rate is constant and the distances between the targets are equal, The process is guaranteed to occur periodically.

Each of the targets 43, 45... is simply made from a metal conductor. on this metal conductor is proportional to the intensity of the electron beam when it hits the target, and is proportional to the intensity of the electron beam that crosses the target. An amount of charge is stored by the electron beam that is inversely proportional to the velocity of the electron beam. for each target conductor The voltage thus generated is generally proportional to the amount of charge stored in a capacitive load. is inversely proportional to. Target 43.45...In order to obtain higher voltage output, A type that amplifies the charge received from the electron beam 27 more than a regular metal conductor. is preferred. An example of such a device is an electron impact semiconductor (electron bomb). There is a mbarded semiconductor diode. This die Ords are known to be of primary commercial use in various types. child When the accelerating voltage is on the order of 10,000 V, the diode in the cathode ray tube The main feature is that for each incident electron, on the order of 2,000 electrons are generated. It is a sign. And when a suitable reverse bias is applied, a large number of electrons are extracted from the iode to an external circuit.

Referring to FIG. 3, the target electrodes 43, 45, An example of an external circuit used with... is shown below. Diode 43.45・ Each of... is connected to a separate sample-and-hold circuit 47, 49..., respectively. has been done. Each diode target 43, 45... is connected to a common positive voltage power supply conductor 51. and a second terminal of each diode is connected to Each is connected to a separate sample-and-hold circuit. Furthermore, sample-hole The code circuit is shown as an example. The second terminal of diode 45 is connected to the storage capacitor. It is connected to ground potential via a capacitor or storage capacitor 53, and this storage capacitor The capacitor 53 is generated within the diode target 45 by the electron beam 27 of the cathode ray tube. Accumulates the applied charge. Therefore, the terminal voltage of the capacitor is the electron beam 2 Input analog signal at sample instant 7 scanned across diode 45 It is proportional to the value of 11. Capacitor 53 is discharged by FF, T switch 55 is controlled, and the FET switch 55 connects the capacitor according to the input signal of the circuit 57. Short-circuit both ends of 53. By operating the FET switch 55, sample-hold The circuit 49 is reset and the electron beam 27 is scanned across the diode target 45. Be prepared to accept another charge at the next time. The capacitor 53 has a source FET No. Z in the follower circuit (source follower circuit) This source follower circuit has a low input voltage with respect to ground potential. An impedance output is generated on conductor 61. The voltage between the conductor 61 and the ground point is It is proportional to the samples of the input analog waveform 11.

Referring to FIG. 4, output conductor 61 and the outputs of the other sample-and-hold circuits are Multiplex and hold circuit (rnultiplex and hold c circuit) and then the analog voltage signal is applied to the analog-to-digital The signal is input to a converter 65. The output of an analog-to-digital converter is an analog These are in the form of digital words that represent the size of each sample in waveform 11. The digital words are stored in digital memory 67. The control circuit 69 is shown in FIG. The cooperative operation of each of these elements is carried out in a unified manner, and the sample on the track 57 is Cleaning pulse or reset pulse to hold circuit 49 and line A synchronizing signal to the deflection circuit 33 is applied to the line 34.

The digitized sample values held in digital memory 67 can be used for many purposes. It can be used for any purpose. One common use is in display devices. The sample is used for digital-to-analog conversion from digital memory. A display that allows the analog signal to be read out to the device and visualized It is displayed by the ray device 71. Display device 71 is most commonly a cathode. A line tube display, but other types may be used, such as an X-Y recorder. .

In many applications of such sampling equipment, a continuous series of analog waveforms is It is desirable to know the exact number of samples, such as 1000. So In this case, the number of targets 43, 4.5 etc. (Figure 2) is equal to the number of samples required at one time. Each target can be configured in a manner similar to circuit 49 described above (FIG. 3). It has a separate sample-and-hold circuit. Multiple sample-hold circuits? These various outputs are passed through the multiplexer hold circuit 63 one by one from time to time. are fed into one analog-to-digital converter, and after the complete set is obtained, each Digitize the sample. However, when the number of samples is large, individual Providing a target such as 43.45 makes the cathode ray tube sampling device physically larger and It's going to be expensive.

Therefore, use a smaller number of targets 43.45... than the expected number of consecutive samples. It is preferable to do so. In such a case, each sample-hold like circuit 49 The voltage stored by the circuit is reduced after the electron beam impinges on its target. as quickly as possible to a similar analog voltage storage in circuit 63 (FIG. 4). .

'Once the H pressure is transmitted from a particular sample-and-hold circuit, such as circuit 49, , the storage capacitor reversely discharges to create a new voltage by receiving a clear pulse. Prepare the circuit to receive. This transmission and clearing requires that the electron beam This must be done before it can be circulated again. desired number of samples Once the samples are stored in circuit 63, the samples are connected to analog-to-digital converter 65. Continuously given and digitized. Of course, multiple applications can be used to speed up the process. Analog-to-digital converters can be used in parallel, but anyway The type of analog-to-digital converter 65 used here is one of high quality. It is one. This means that the speed of signal digitization is critical in this system. It is possible because it is not.

An alternative to such a configuration is to use fewer targets 43.45 than consecutive samples to be taken. If the sample-and-hold circuit is A seed switching mechanism is installed in the target conductor so that each time the beam strikes the target, Targets may be connected sequentially to different sample-and-hold circuits.

In either case, the number of targets 43, 45... Sufficient voltage is required so that the suddenly generated voltage can be acquired and accumulated within one revolution of the electron beam. It must be worth it. In certain instances using various features of the invention, the exact 199 targets were used. In this case, the sampling rate is 2GHz is sufficient. If the analog signal has a minimum of 2 samples per cycle, then the The maximum possible bandwidth of the signal is I GHz.

If an odd number 199 is used as the number of targets, the geometry and rotational speed of the electron beam selectively use a sampling rate slower than the maximum design rate without changing any of the There are advantages to being able to do so. Double the sampling rate (a factor o f　two)　i, during the first electron beam sweep, every second diodes are used. The remaining alternate diode (alternate d iode) are used sequentially in the second circular sweep of the electron beam. similarly and lower the speed by four times (i.e., one-fourth of the maximum speed sampling rate), the signal from every fourth target throughout the target row is used. In both of these cases, a large number of analog signals are taken. The samples are continuous. Automatically for each rotation of the electron beam, every 2nd, 4th The desired samples are applied to the diodes for each diode or for each desired multiple. This is a specific This is because several diodes are used. This number is usually an odd number; Depending on the desired sampling reduction factor and the rotational speed of the electron beam, other than 199 You can definitely use it as well. Up to 2, 10, 20, 40, 100 times, etc. It is standard to have the ability to choose to reduce the sampling rate.

In a particular example of the shape of the diode target 43.45, its width is 0.381/la n (15ml1ls) and each interval along the circle is 0.127/ram ( 5mi is) open. The transverse dimension of the electron beam 27 is as small as possible. Generally speaking, the diameter is 0.127/mm to 0.254/mm (5 to 1 mm). It is within the range of ゜mls). The voltage output of the target diode is 43.45 for each target. ... has a width, so the analog that occurs while the electron beam crosses that finite width That portion of waveform 11 (FIG. 1) is integrated.

Although various aspects of the invention have been described with respect to specific embodiments, the invention may be claimed as amended. will be found to be protected within the full scope of the law.

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Claims (1)

[Claims] 1. A method of sampling electrical analog signals at regular intervals. Multiple electrically independent conductors substantially equally spaced around a closed loop path A constant speed is passed over the closed loop path that includes the element and is located within the vacuum envelope. a step of repeatedly scanning an electron beam at a certain degree; Each of the conductive elements is exposed to the analog signal by the electron beam while impinging on the electron beam. said analyzer before impacting said surface so that it is charged to a level proportional to the amplitude of the signal. a step of modulating the brightness of the electron beam by a log signal; individually storing beam-induced voltages, the closed loop of the electron beam the cross-sectional dimension in the direction of the loop path is smaller than the area of the conductive element along the closed loop path; and the sample is obtained continuously at high speed. . 2 In the step of scanning the electron beam, the electron beam passes over the conductive element. scanning each of the conductive elements with the electrical current impinging on the conductive element; The invention is characterized in that it generates an amplified output current according to the incident current of the child beam. The method described in Item 1 of the Scope of Request. 3 In a method of sampling continuous analog signals at periodic intervals, a circular At constant velocity in the beam path and on the target surface within the vacuum envelope, the cross-section is substantially at four points. substantially scanning an electron beam of dimension; positioning a plurality of electrically independent conductive elements at equal intervals; While the electron beam impinges on the conductive elements, each of the conductive elements The electron beam charges the analog signal to a level proportional to the amplitude of the analog signal. a step of modulating the brightness of the electron beam by the analog signal; a step of individually storing the electron beam induced voltage of each element, and A method characterized in that it can be obtained continuously at high speed. 4 In the method of digitizing continuous analog signals, the target surface inside the vacuum envelope is Transverse the upper part in a continuous closed loop path もS repeatedly scanning an electron beam of substantially point-sized cross-section; process of positioning a plurality of electrically independent conductive elements spaced around a path and each of the conductive beams while the electron beam impinges on the conductive element. are charged by the electron beam to a level proportional to the amplitude of the analog signal. brightness modulating the electron beam by the analog signal so as to A voltage proportional to the intensity of the electron beam when impinging on the conductive element is applied to the conductive element. The process of storing each electrical element individually and the process of applying after all of the said samples have been stored. the voltage level stored such that the analog signal is digitized at a reasonable speed; and converting each of the electron beams into a digital signal. the beam is scanned at such a speed that it impinges on one of said conductive elements at periodic intervals. A method characterized by: 5. Storing the digital signal, and extracting the digital signal from the stored digital signal. Claims further comprising a step of reproducing a display of an analog signal. The method described in section 4. 6 The step of positioning the conductive elements involves positioning a plurality of semiconductor diode elements. determining that each of the semiconductor diode elements generates an amplified output current according to the incident current of the electron beam impinging on the The method described in any one of claims 3, 4, or 5, characterized in that Law. 7. Many consecutively repeated samples of the analog signal are the number of conductive elements with which the beam collides is exceeded by an effective amount. Claims 1, 2, 3, 4, or 5. the method of. 8. The step of individually storing the voltage for each conductive element c. Sample-hold storing the voltage of the circuit and the electron beam impinging on the next of the conductive elements; before converting the voltage signal from the sample-and-hold circuit into another analog voltage storage device. transmitting a plurality of electrically conductive elements greater than the number of electrically conductive elements within the vacuum envelope. Claim characterized in that a number of consecutive samples are taken from said analog signal. Section 1, Section 2, Section 3. The method according to any one of paragraphs 4 and 5. 9. The step of positioning the conductive elements involves positioning an odd number of conductive elements around the closed loop path. The electron beam is directed to the closed loop path using every Xth target. using all of the conductive elements by rotating X times around the conductive Slowing down the sampling rate for applications that maintain full utilization of the The method according to claim 4 or 5, characterized in that: 10 The number of conductive elements that the electron beam collides with is exceeded by an appropriate amount. Take a number of consecutively repeated samples from the analog signal and further The step of positioning the elements uses an odd number of conductive elements around the closed loop path. and the electron beam is rotated around the closed loop path X times using every X target. By rotating all of the conductive elements, complete use of the conductive elements can be achieved. characterized by slowing down the sampling rate for applications consisting of maintaining A method according to any one of claims 4 or 5. 11 Placed at one end of the vacuum envelope to generate an electron beam and direct the electron beam to the an electron gun directed toward the other end of the vacuum envelope; a plurality of electrically insulated conductive elements arranged in close proximity; connecting means for electrically connecting to a plurality of external conductive wires; means for repeatedly scanning said electron beam at a constant speed along a circular path; receiving an analog electrical signal and responsive to a time-varying amplitude of said analog electrical signal; means for modulating the brightness of the electron beam, wherein the analog electrical signal is transmitted at high speed. periodic samples are taken at and the samples appear on the external conductor. A sampling cathode ray tube characterized by: 12 The conductive element is configured to absorb electrons of the beam that impinge on the conductive element, respectively. Claims characterized in that the number is amplified as a current flowing out from the conductive element. 12. The sampling cathode ray tube according to item 11. 13. Claim 11, characterized in that the number of the conductive elements is 199. The sampling cathode ray tube according to item 1 or 12. 14. Using a cathode ray tube to sample continuous analog electrical signals, the cathode An electron beam whose cross section is substantially point-sized toward a target area within a vacuum envelope. In an analog-to-digital converter comprising an electron gun that irradiates the analog receiving an electrical signal from the electron beam and adjusting the brightness of the electron beam before impinging on the target area; a receiving means for modulating the analog electrical signal by a change in amplitude; On top of that, there is a closed loop that circulates regularly independent of the analog electrical signal. a deflection means for deflecting the electron beam at a predetermined velocity function; a plurality of electric currents arranged successively close to each other around the circumference of the closed loop in the area; a conductive element that is electrically insulated; compared to the size of the electron beam when the beam last passes over the conductive element. storage means for storing the analog signal, and a power supply connected to each of the storage means; and a conversion means for converting the pressure level into a digital signal, wherein the analog electrical signal is An analog-to-digital converter characterized in that it is digitized. 15. The storage means for storing the analog signal individually stores the analog signal for each of the conductive elements. The sample and hold circuit connected separately and the said analyzer stored in separate storage means. transmitting a log signal and storing the log signal before the electron beam reaches the conductive element again. and means for clearing the continuous analog electrical signal taken from said continuous analog electrical signal. characterized in that the number of consecutive samples is greater than the number of conductive elements in the cathode ray tube; 15. An analog-to-digital converter according to claim 14, characterized in that: 16 the number of conductive elements located within the closed loop pattern is odd; A storage means for storing the analog signal is arranged so that the electron beam passes around the closed loop. storing the analog signal from every X conductive element during one movement; the number of storage means for storing the conductive elements and the analog signal; is before the Xth beam cycle in which the electron beam revolves around the closed loop. It is determined that all of the conductive elements are utilized and a sample of the transducer is Claim 1, characterized in that the speed of scanning can be changed by changing the value of X. The analog-to-digital converter according to item 4. 17. The means for storing the analog signal is 1, 2, 4°10.20.40. Claim 1, characterized in that it includes means for setting X to any one of Analog-to-digital converter according to item 6. 18. Receive the digital signal from the digital signal conversion means and convert it into an original continuous analyzer. It is characterized by further comprising means for reproducing and displaying the appearance of the log electric signal. The analogue according to any one of claims 14, 15, or 16. A display device equipped with a digital converter. 19 In a method of sampling continuous analog electrical signals at periodic intervals, standard A technique for scanning an energy beam substantially over a target surface at a constant speed and in an annular beam path. and a plurality of energy responsive elements are arranged on the target surface at equal intervals along the annular beam path. positioning the child and causing the energy beam to impinge on the energy responsive element; At the moment when the energy responsive element shining the energy beam by the analog signal such that each The process of modulating the electron beam intensity and the amount of electricity induced by the electron beam from each energy responsive element individually. and a step of accumulating energy into the energy responsive element. generates an amount of electricity proportional to the intensity of the energy beam when it impinges on the A sampling method characterized in that samples are obtained continuously at high speed. 20 In a method of digitizing continuous analog electrical signals, continuous closed Repeatedly scanning an energy beam of substantially point size in cross-section along a loop path nine times and placing a plurality of independent energy-responsive elements spaced apart on the target surface. positioning the closed loop path around the closed loop path; intensity modulating the energy beam and upon impingement on the energy responsive element; A voltage proportional to the intensity of the energy beam is applied to each energy responsive element individually. storing and converting each of the stored voltage levels into a digital signal; During the process, the energy beam strikes the energy responsive element at periodic intervals. The energy beam is scanned at such speed that it impinges and records all of the sample. The analog signal is digitized at a moderate speed after being stored. How to do it.