DE971205C - Electron beam storage tubes - Google Patents

Description

ISSUED DECEMBER 24, 1958

W i8o69VIIIc / 2ig

has been named as the inventor

Electron beam storage tube

The invention relates to an electron beam storage tube with a signal input electrode, a dielectric storage layer applied on this and a grid electrode, which in front of the dielectric storage layer is arranged.

In the case of a type of quickly accessible memory with short storage, the one in newer ones Memory or storage systems have become electron discharge devices according to the type of beam storage tube, especially the tube, which is known as a barrier tube is known, used. Such tubes are known in the art.

In such a barrier tube, the dielectric storage layer is known as a dielectric disk can be executed, with a surface attached to a conductive electrode, which acts as a signal input electrode serves. An electron beam system sends a concentrated electron beam onto the other face of the dielectric Disk or storage layer, through a barrier grid immediately in front of the dielectric Disc or storage layer is arranged. When operating such a tube, the beam is in deflected in two coordinate directions. For example, it can be periodic in one direction and after Choice to be distracted in the other direction, or he can be turned on and on to a particular one Point on the dielectric storage layer can be deflected if a completely arbitrary Access is desired. The operation of the facility basically comprises two processes, namely on the one hand the storage or recording process and on the other hand the acceptance or reading process. The potential changes during the recording process

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or the charge of the acted upon elementary areas of the dielectric storage layer accordingly the size of the input signal, the change in charge being caused by the signal from the The time that the beam remains on the surface depends on the time. During the reading process removes the charges on the elementary surfaces as a result of the action of the electron beam.

Basically, the charge and discharge of the elementary surfaces arise from the emission of secondary electrons; the flow of the secondary electron current can be different Manner and provides an output display of the during the recording process stored information. In general, the mode of operation of the barrier tube has so far existed in that the signals stored on the storage layer were read by making the changes of the secondary electron current released at the dielectric layer, which leads to a large collecting electrode. In this way of working, however, there are several larger ones Problems. On the one hand, the signal picked up at the collecting electrode is very small because it is not all emitted secondary electrons are detected by the collecting electrode. The number also depends of the collected electrons depends on the position of the emission centers in the storage layer. Consequently changes in the size of the signal at the collecting electrode occur independently of the stored information as a function of the position of the emission center on the dielectric surface. This effect is called "interference signal". An interfering signal has a weakening of the output or Reading signal result. A third disadvantage of this mode of operation is that there is always one certain number of secondary electrons is emitted when the beam hits the arrangement, even if larger or smaller amounts are occasionally during the recording or reading from secondary electrons. The equilibrium value of the secondary electron current at the collecting electrode represents a »basic value«, on which the reading information is superimposed. Changes in the number of secondary electrons collected also affect the "basic value"; accordingly, the correct detection of the Type of information stored more difficult.

A disruptive interaction between input and output signals can be found among these Circumstances cannot be easily avoided. Installation is therefore an additional measure a shield electrode between the output signal electrode and the storage layer or the Recommended on contact arrangement.

By reading the stored information directly on the memory arrangement, i. H. by Reading of the signal caused by the secondary electrons which the storage layer and not by those who arrive at the collecting electrode the problem of collecting electrode efficiency and the changes in the subset of the collected Release secondary electrons. You can almost completely eliminate the interfering signal and increase the output signal.

However, difficulties remain with the immediate application, which is in itself very desirable of the recording or input signal to the landing device. It must take into account the fact that the output signal is taken directly from the landing arrangement, it must be taken into account that there are two signals which differ by at least three orders of magnitude differ from each other. This means that an amplifier is used to amplify the output signals is connected to the incidence arrangement, must not be strongly disturbed by the considerably larger input signals. This disorder exists in particular in a known proposal, according to which the input signal is immediate applied to the grid electrode and the output signal from the conductive electrode of the on-strike arrangement is removed. With such an arrangement leaves recording and reading, d. H. the input and output circuits, not effective from each other separate.

The invention, on the other hand, wants the direct connection of both the reading and the Allow recording circle to the impingement arrangement, the circles effective and im are essentially completely electrically isolated from one another.

This goal is achieved with an electron beam storage tube with a signal input electrode, a dielectric storage layer applied on this and one arranged in front of it Grid electrode achieved in that, according to the invention, the inner conductor is connected to the signal input electrode and to the grid electrode used as the signal output electrode, the outer conductor of a are connected to known coaxial line system and that a portion of the coaxial Line system forms a coil.

The input signal means and the output signal pick-up means are connected to the coaxial line coupled.

Because of the coil portion of the coaxial line, the two conductors are essentially the same Inductance, and the mutual inductance between the two conductors is equal to the self-inductance of every leader. The input or recording signal is between these two conductors created. The charging current for the capacitance between the grid electrode and the input signal electrode is required flows along the inner conductor to the storage layer and returns along the outer conductor so that the currents flowing in the two conductors effectively cancel each other out in the coil-shaped part and do not induce a voltage on this inductance. However, if the information is read becomes, the surface of the dielectric storage layer becomes a grid electrode via the capacitance and equal to the input signal electrode

charged and discharged early enough, so that in the two conductors of the coaxial line current is in the same Direction flows. This current generates an output signal voltage on the coil-shaped part the coaxial line that can be fed to an output circuit.

The storage tube may be a barrier tube of the type discussed above or a known tube be with dielectric islands. With a tube with

ίο dielectric islands is a multitude of individual small dielectric areas or islands arranged on a signal input electrode. A barrier grid is not used, but a field compensating grid is used in front of the dielectric Islands attached. In embodiments of the invention with such devices, the charging currents the same as described above. However, this is where the capacitor lies, which is when reading of the stored information is discharged, essentially only between the dielectric Storage layer and the signal input electrode, so that the current is almost only in the inner conductor of the coaxial line flows.

The reading signal can be picked up directly on the coil-shaped part of the coaxial line be e.g. B. by a connected amplifier, or it can be picked up by an amplifier to a transformer inductively coupled to the coil-shaped part connected. In addition, it is largely prevented that the recording signal on the spool-shaped Part of the output line appears by the signal input electrode and the dielectric Parts of the impingement assembly are completely shielded, e.g. B. in that the impingement arrangement effectively from the outer conductor of the coaxial line, in particular from a shielding part is surrounded, which is connected to the outer conductor and to which the grid electrode or the field-compensating grid is attached.

It can be useful to have a magnetic one in the coil-shaped part of the coaxial line system To build in the core.

Further particularities of the invention emerge from the following description of the in FIG Drawing illustrated embodiments. In the drawing shows

Fig. Ι the schematic representation of an embodiment the storage tube according to the invention,

Fig. 2 shows a simplified schematic circuit for the reading and recording circuits of the arrangement according to Fig. 1,

3 shows a graph of the currents and voltages for various operating conditions the arrangement according to FIG. 1,

4 shows the schematic partial representation of another embodiment of the invention Storage tube using a dielectric island tube.

Fig. Ι shows an embodiment of the invention, in which a barrier grid storage tube 10 is used. As is known in the art, For example, the tube 10 may advantageously be an electron beam system in an evacuated flask made of glass, for example with a cathode 11, a heater 12 and accelerating and focusing electrodes 13, 14 and 15, which have an electronic lens form, also baffles 16 and 17, a collecting electrode 18, a shield 19 and finally contain an impingement arrangement 20. The landing assembly 20 includes a signal input electrode 22, a dielectric storage layer 23 and a grid electrode 24, which directly is arranged in front of the dielectric storage layer 23. The signal input electrode 22 and the dielectric storage layer 23 are enclosed in a shielding element 26 on which the grid electrode is attached.

With storage tubes of this type, the information by an electrostatic charge in a certain zone of the surface of the dielectric Storage layer 23 is stored. To bring such a negative charge to the surface, the electron beam is switched on, while the signal input electrode is temporarily on a positive Potential is raised. This temporarily increases the potential of the front surface of the dielectric Storage layer raised by a capacitive effect. The electron beam charges Then this surface with negative electrons so far that its potential on the potential of the Grid electrode drops, which is the equilibrium potential. During the charging process the secondary emission electrons emanating from the dielectric storage layer return to it back and cannot escape. When the beam goes somewhere else and the potential of the Signal input electrode returns to the normal value, the charge is retained and leaves the dielectric surface at negative potential.

In this embodiment of the invention, the recording circuit is the positive recording potential during the described storage process applied to the signal input electrode, from a coaxial line 28, the inner Conductor 29 to the signal input electrode 22 and its outer conductor 20 to the shielding element 26 and are thus connected to the grid electrode 24. The coaxial line 28 has a part 32 wound as a coil, the two conductors 29 and 30 being the same in this part Have inductance and mutual inductance equal to the self-inductance of each conductor is. A source 33 of input recording signals is between the inner conductor 29 and the outer conductor 30 of the coaxial line 28 connected.

When a recording signal is applied through the source 33, a current flows along the inside Conductor 29 so that the inner capacity is charged, and then returns to the outer Head back. The coil-shaped part of the coaxial line acts as a non-inductive winding, and ideally it appears if there is no

in the presence of the beam current, there is no voltage between the grid electrode 24 and the earth.

The in such a way in this point or in this zone of the surface of the dielectric Information stored in storage layer 23 is subsequently read by the electron beam returns to this point. The beam makes when it hits the dielectric Layer releases more secondary electrons than primary electrons hit the layer; these are repelled from the surface, thereby raising the potential to that effect of the grid electrode. In this way of working, the potential does not become more positive than that Grid electrode, because in this case the secondary electrons return to the surface and would not escape. In equilibrium, the dielectric surface gives as many electrons free as you arrive and remains at the grid electrode potential.

It is thus evident that when the information is read, the surface of the dielectric Storage layer via the capacitance to the grid electrode as well as to the signal input electrode is discharged at the same time. Accordingly, current flows in the inner conductor 29 and in the outer conductor 30 in the same direction. These currents generate a signal voltage on the coil-shaped Part 32 of the coaxial line 28, which can be read on an output circuit. at This particular embodiment is a resistor 34 parallel to the coil-shaped part 32 and a Output amplifier 35 connected in parallel to resistor 34 and to coil-shaped part 32. Thus, in the ideal case, the application of the recording signal to the signal input electrode results alone no signal at the output amplifier. First the one directed at the storage layer Electron beam triggers a signal by the residual current, i. H. the one around the secondary electron flow part decreased electron beam current, causing a surge in current at the output amplifier.

The detection and display of these current pulses form the reading process. It is a Feature of this invention to eliminate interfering signals from the reading circuit caused by others Sources are induced as the electron beam current.

A schematic circuit diagram of the reading and recording circuits of the embodiment according to FIG. 1 is shown in FIG. In this schematic circuit diagram, each conductor of the coil-shaped part 32 is an inductance L and a mutual inductance if, which is advantageously equal to L. Inner conductor 29 connects one inductance to the signal input electrode, represented by point 36, while outer conductor 30 connects the other inductance to the grid electrode, represented by point 37. The capacitance C ₁ , which is the capacitance between grid electrode and signal input electrode, lies between points 36 and 37. C ₂ is the capacitance between grid electrode and earth, which is relatively large, while C _{3 is} the capacitance between signal input electrode and Is earth, which is very small due to the shielding effect of the shielding element 26 and the structure of the impingement electrode. R, the equivalent resistance of the outer conductor of the coaxial line 28, is also very small.

While the recording signal source 33 is connected between the two coils, the output amplifier 35 is connected to the load resistor 34 between the grid electrode and the ground. During the charging of the capacitance C ₁ , in the ideal case, current flows from the source 33 via the input coil L to the capacitance and via the output coil L back to the source 33. As mentioned below, however, not all of the current returns, so that the currents in the two coils are not quite the same value.

When the beam returns to the charged point on the dielectric storage layer, to Reading the information stored in this point becomes the charge on the dielectric Layer eliminated and current flows through both the input conductor and the output conductor the coaxial line to earth. This can be visualized as an electric generator 40 is present, which is connected to a point 43 representing the dielectric surface is, which has a capacitance between the dielectric surface and the Signal input electrode constituting the first capacitor 41 with the signal input electrode and one representing the capacitance between the dielectric surface and the grid electrode second capacitor 42 is connected to the grid electrode. The reading signal source is thus an assumed power source whose yield is actually the difference between the Primary and secondary electron current on the dielectric surface corresponds. This one Power source and its current path do not actually exist, but are only assumed, were the connection lines of the source in the circuit are indicated by dashed lines.

The coil-shaped part 32 can advantageously be produced in that a coaxial Cable is coiled with the outer and inner conductors as the two self-inductors an air core coil. However, as shown in FIG. 2, a magnetic one can also be used Core are used. In a special embodiment, for example, there is the coil-shaped part made of a wire that is wound in a copper tube on a ferromagnetic ferrite core. From the above it follows that when the beam suddenly hits a certain Point of the dielectric storage layer 23 is directed, four possible cases are to be considered, namely:

Case ι: No charge has previously been stored and no recording voltage has been applied;

Case 2: No charge is previously stored and a recording voltage is applied;

Case 3: A negative charge is previously stored and no recording voltage is applied;

Case 4: A negative charge is previously stored and a recording voltage is applied.

In Fig. 3 are the current curves of the currents to and from the memory array for each of them Cases shown as a function of time, with one sufficient to achieve equilibrium large pulse duration is required. The shape of the voltage pulses generated in the reading circle is also shown. In case 1, only the number leaves of secondary electrons the surface which corresponds to the equilibrium. In case 2 there should be a reading of the information on the point, and there is a temporary one Lack of secondary electrons while charging and a gradual return to

ao equilibrium value takes place. In case 3, the previously stored information should be read off go, and there is an excess of secondary electrons while the surface is discharging followed by a gradual return to normal. It is also a residual current present, which, as described above, flows inductively in the coil-shaped part 32 and here the output signal voltage induced. In case 4 the current has the equilibrium value as in case 1, because the positive recording pulse alone the negatively charged surface at the potential of the Grid electrode should lead back.

The recording signals applied to the storage layer are of the order of magnitude of several tens of volts, while the reading signals picked up by the amplifier 35 in the Order of magnitude of a few millivolts. The reading signals can then of course on any desired value can be amplified. The application of the very large recording signals does not interfere with the operation of the sensitive amplifier connected to the reading circuit. in the In the ideal case, as described above, there should be no signal at all at the coil-shaped part 32 Application of the recording signal occur; however, is actually due to the nonexistent Equilibrium of the currents in the inner and outer conductors induces a very small signal. This non-existent equilibrium is partly due to other capacities within the tube caused. It is therefore appropriate that the signal input electrode and the dielectric Storage layer are essentially completely shielded from the rest of the tube. Accordingly surrounds in the embodiment of the invention shown in Fig. 1, the shielding element 26, which is a Continuation of the outer conductor 30 is to complete these elements.

However, there is very little direct capacitance between the signal input electrode and the other elements in the tube, particularly the shield 19 and the central electrode 18, through the holes in the grid electrode. The shield 19 is advantageously earthed and the collecting electrode 18 can be connected directly to earth, e.g. By connecting it to the shield 19, or it can be connected to earth via a resistor, as shown in FIG. This capacitance can therefore be viewed as the capacitance between the signal input electrode and earth; it is shown as capacitance C ₃ in FIG. Accordingly, not all of the charging current flowing in the inner conductor 29 as a result of the recording signal returns via the outer conductor 30. A very small fraction flows as a displacement current through the holes in the grid electrode to earth. A second effect which prevents the desired perfect current balance is caused by the finite resistance of the outer conductor of the coaxial line. The charging current therefore induces a low voltage between the grid electrode and earth. However, this voltage can be kept very small, well below the value of the read output signal, so that it is not difficult to distinguish between the two types of induced signals.

The resistance of the outer conductor 30 is shown as resistance R in the schematic circuit diagram of FIG. To reduce the value of this resistance, it may be appropriate to use a hollow copper tube with a relatively thick wall as the outer conductor 30.

If it is desired to further reduce the small residual error signal that occurs as a result of the recording signal applied to the memory layer, different types of quenching arrangements can be used. Such an order is indicated in Fig. 2 where an erase pulse generator 45 is from the recording pulse source 33 is operated so that an erase pulse of suitable sign and size is applied directly to the reading amplifier 35, e.g. B. directly to the load resistance 34 to cancel the residual error signal that appears on that resistor.

In Fig. 4, another specific embodiment of the invention is shown in which the Storage tube consists of a tube with dielectric islands. In the embodiment according to FIG. 4 the memory array consists of a signal input electrode 50 on the front surface thereof small points or islands 51 of dielectric material are attached. Before the dielectric Islands 51 and between these and the remainder of the tube corresponding to Fig. Ι can be executed, a field compensation grid 52 is arranged. The grid 52 is through the Shielding element 26 held, which surrounds the impingement electrode.

In this particular embodiment, the output amplifier 35 is attached to the coil-shaped part 32 coupled via an inductive winding 55, whereby a transformer coupling with a

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compared to the direct coupling method according to Fig. ι increased signal is achieved.

Claims (5)

Patent claims: i. Electron beam storage tube with a signal input electrode, one attached to it dielectric storage layer and a grid electrode arranged in front of it, thereby characterized in that the inner conductor is connected to the signal ίο input electrode (22, 50) (29) and to the grid electrode (24, 52) used as the signal output electrode, the outer conductor (30) are connected to a known coaxial line system and that a section of the coaxial line system (29, 30) forms a coil (32) (FIGS. 1 and 4). 2. Storage tube according to claim 1, characterized in that the outer conductor (30) of the coaxial line system with the grid electrode (24, 52) via a memory arrangement comprehensive envelope (26) is connected. 3. Storage tube according to claim ι or 2, characterized in that the coil-shaped Part (32) of the coaxial line system (29, 30) contains a magnetic core. 4. Storage tube according to one of claims ι to 3, characterized in that the means for taking off the output signal to the coil-shaped part (32) of the coaxial Line system (29, 30) are coupled (Fig. 4). 5. Storage tube according to one of claims ι to 3, characterized in that the means for picking up the output signal on the outer conductor (30) of the coaxial line system (29, 30) are connected at a point which is between the coil-shaped part (32) and the storage arrangement lies (Fig. 1). Considered publications:
U.S. Patent Nos. 2,598,919, 2,624,780. 1 sheet of drawings (809 691/7 12.58) © 609 708/286 11.56