Particle-impact localizing device, a cathode-ray oscilloscope and a pick-up tube comprising such a device

This device comprises several charge-transfer shift registers integrated on the same semiconductor substrate and disposed one above the other along the axis Oy. The charge-transfer electrodes are common to all the registers and each package of charges injected under an electrode having received the impact of particles is transferred along axis Ox to underneath a diffused zone common to all the registers what causes currents to flow in two electrodes connected to the ends of the zone diffused along axis Ox.

BACKGROUND OF THE INVENTION 
The present invention relates to a particle-impact localizing device. It 
also relates to cathode-ray oscilloscopes and pick-up tubes comprising 
such a device. 
In the prior art devices are known for localizing the x and y coordinates 
of an emissive point P based on the following principle. 
Starting with a rectangular plate made from a material of uniform 
resistivity, two opposite sides of which are edged with an electrode made 
from a weakly resistive material, a current is injected at any point P on 
this plate by means of a DC voltage source connected between the plate and 
the electrodes. It is known that there will flow in each electrode 
currents i.sub.1 and i.sub.2 such that the x coordinate of point P, along 
an axis 0x perpendicular to the electrodes, is written: 
EQU x=(i.sub.1 -i.sub.2)/(i.sub.1 +i.sub.2). 
To know the y coordinate of point P along as axis 0y perpendicular to 0x, 
it is sufficient to dispose on the plate two other electrodes 
perpendicular to the first ones and to inject a current at point P using 
these electrodes. The y coordinate of point P is written as a function of 
currents i'.sub.1 and i'.sub.2 which flow in these electrodes: 
EQU y=(i'.sub.1 -i'.sub.1)/(i'.sub.1 +i'.sub.2). 
SUMMARY OF THE INVENTION 
The present invention relates to a localizing device which allows not only 
a sequential succession of points to be localized but a whole curve 
received simultaneously by the localizor. 
The particle-impact localizor of the present invention comprises: 
at least one flat sensitive surface caled principal surface having two 
orthogonal axes, 0x and 0y, which is subjected to the impact of particles 
causing a modification of the initial electric condition of the surface; 
means for the successive reading of the electric condition of the 
elementary surfaces, having the same dimension along axis 0y as the 
principal surface and following each other over the principal surface 
along axis 0x, and ensuring, for each elementary surface receiving an 
impact of particles, the passage in two electrodes of reading currents 
(i.sub.1 and i.sub.2) taken at the ends along axis 0x of each elementary 
surface. 
The particle-impact localizor of the present invention presents numerous 
advantages among which may be mentioned the fact that it allows 
localization of a curve by using scanning which is more rapid, because 
simpler, than television scanning. In fact, the sensitive surface of the 
localizor is divided along axis 0x into elementary surfaces which are 
determined either by the dimensions of the reading beam, or by the 
dimensions of the storage electrodes depending on the embodiments. The 
very existence of these elementary surfaces which are read one after the 
other allows localization along 0x whereas the measurement of the reading 
currents taken at the ends along axis 0x of each elementary surface allows 
localization along axis 0y of the impact point of the particles on a given 
elementary surface. 
The device of the invention associated with a memory which stores the 
successive values of the reading currents i.sub.1 and i.sub.2 may be used 
for recording electric signals, particularly when there is only available 
for study of these signals a standard oscilloscope not only having a 
memory or having a memory which is not very rapid. In fact, the memorized 
signals may be restored at an adjustable rate. 
The device of the invention may also be used in a pick-up tube of the 
vidicon type where it allows the impact of a light signal y=f(x) to be 
localized with simplified scanning by electron beam.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a diagram illustrating the principle of the localizors of the 
prior art. 
These localizors allow the x and y coordinates of an emissive point P to be 
known in a system of rectangular axes 0x and 0y. 
The principle which has been previously described is the following. 
We start with a rectangular plate 1 made from a material of uniform 
resistively. Two electrodes e.sub.1 and e.sub.2 edge two opposite sides 
parallel to the axis 0x of this plate. A DC voltage source E allows a 
current to be injected at any point P on the plate. This source is 
connected between the plate and the electrodes. If we call i'.sub.1 and 
i'.sub.2 the currents which flow in electrodes e.sub.1 and e.sub.2, the y 
coordinate of point P is written: y=(i'.sub.1 -i'.sub.2)/(i'.sub.1 
+i'.sub.2). 
To obtain the x coordinate of point P, it is similarly necessary to inject 
a current at point P using two electrodes e'.sub.1 and e'.sub.2 covering 
the other two edges of plate 1. 
FIG. 2 shows a charge-transfer localizor in accordance with the invention. 
This localizor comprises a principal surface formed by several 
charge-transfer shift registers r.sub.1, r.sub.2, r.sub.3. . . disposed 
one above the other along axis 0y. 
These registers are integrated on the same semiconductor substrate 2 
covered with an insulting layer 3. The most currently used semiconductor 
substrate is silicon. 
Insulting diffusions consisting in overdoping of the substrate which raises 
the inversion threshold and thus opposes any storage of the charges allows 
several registers to be formed, in a known way, isolated from each other 
on the same substrate. 
On insulating layer 3, electrodes 4 are disposed parallel to one another 
and to axis 0y. These electrodes are common to all the registers. 
The semiconductor substrate is subjected to the impact of particles which 
may come from light radiation, from the image of the screen of a 
cathode-ray oscilloscope projected on the substrate by means of an optical 
system for example. This light radiation may reach the localizor either 
from the side where electrodes 4 are to be found, which must then be 
photosensitive, or from the other side. The particles which the localizor 
receives may also be electrons, the electrons of the beam of an 
oscilloscope for example. 
Electrodes 4 determine on the substrate 2 elementary surfaces. The charges 
due to the impact of the particles which are stored under the electrodes 
are read by simultaneous transfer of the charges into all the registers, 
from one electrode 4 to the following one, in direction 0x, as far as a 
diffused zone 5 common to all the registers. 
To cause the transfer of charges from one electrode to the next, electrodes 
3 may be subjected to three period clock signals having the same period T, 
but shifted in phase with respect each other .phi..sub.1, .phi..sub.2, 
.phi..sub.3. 
The transfer of the charges in a given direction may also be obtained, in a 
known way, by using structure heterogenities such as an oxide 
overthickness or impurity concentrations in the substrate. 
The diffused zone 5 is of the opposite type to that of the substrate. It 
dimension along axis 0y is at least equal to the dimension which the whole 
of the registers occupies along axis 0y. The charges from all the 
registers are then transferred under this diffused zone 5. 
The curves which the device shown in FIG. 2 allows to be localized must 
have only one value of y for each value of x. 
The operation of the localizor of the invention takes place in two stages: 
in a first stage, the localizor is subjected to the impact of the 
particles; 
in a second stage, the localizor is withdrawn from the impact of the 
particles and the transfer of charges is caused under zone 5. At a given 
moment, it is known (by taking into account the number of clock pulses for 
transferring charges under zone 5), which electrode 4, i.e. which 
elementary surface, has received the impact which created the charges 
present under zone 5. Localization along 0x is thus achieved. To achieve 
localization along 0y, the principle of the localizors of the prior art is 
used. The ends along 0x of zone 5 are connected to two electrodes e.sub.1 
and e.sub.2 connected to two amplifiers 6. The amplifiers 6 deliver 
currents i.sub.1 and i.sub.2 on arrival of each package of charges under 
diffused zone 5. 
The normed difference of currents (i.sub.1 -i.sub.2)/(i.sub.1 +i.sub.2) 
gives the y coordinate. Furthermore, the sum of the currents gives the 
intensity of the light radiation or of the electron beam received. 
Currents i.sub.1 and i.sub.2 are stored separately, in analog form or after 
digitalization, as in the case of FIG. 1 where the memories are referenced 
at 7. Currents i.sub.1 and i.sub.2 may also be processed in real analysis 
time so as to obtain the ration (i.sub.1 -i.sub.2)/(i.sub.1 +i.sub.2) 
which is then stored. 
The speed of localization of the impact of the particles which is achieved 
by means of the device of FIG. 2 may be adapted to the speed of the 
circuits processing currents i.sub.1 and i.sub.2. 
The localizing speed may be very high. The frequency of transfer signals 
.phi..sub.1, .phi..sub.2, .phi..sub.3 may go from 10 to 100 MHz. 
The localizing speed may also be very low since it is possible to obtain 
storage of the data in the silicon for several minutes if the silicon is 
cooled to a low temperature. 
The localizing device shown in FIG. 2 may be used, as we have seen, for 
storing the coordinates of the curve y=f(x) which appears on the screen of 
the oscilloscope. To display this curve again, it is sufficient to apply 
to the plates of a cathode-ray oscilloscope the stored coordinates. 
FIG. 3 shows a pick-up tube of the vidicon type comprising a localizing 
device in accordance with the invention. 
This tube comprises a vacuum envelope 11 in which there is placed an 
electron gun which comprises a linear emitting cathode 13, a heating 
filament 12 and a cylindrical control grid or Wehnelt 14. The focusing and 
deflection devices for the electron beam emitted by the cathode are shown 
symbolically and referenced at 15. The focusing is magnetic, the 
deflection may be magnetic or electrostatic. 
This tube comprises a localizing device in accordance with the invention 
which is formed from a rectangular resistive plate 9 whose two opposite 
sides, along axis 0x, are edged by an electrode, e.sub.1 and e.sub.2, made 
from a weakly resistive material. Each electrode is connected to an 
amplifier 6 which supplies reading currents i'.sub.1 and i'.sub.2. This 
resistive plate 9 receives on one of its faces f.sub.1 light radiation, 
symbolized by a wavy arrow, whose impact it is desired to localize. Plate 
9 is transparent to this radiation. The other face f.sub.2 of plate 9 is 
covered with a photoconducting layer 8. 
Resistive plate 9 may be made from tin or indium oxide and electrodes 
e.sub.1 and e.sub.2 may be formed from copper, gold or silver strips . . . 
of a thickness varying from 0.1 to a few microns. 
FIG. 4 shows a front view of the device of the invention used in the tube 
of FIG. 3. 
Photoconducting layer 8 is periodically scanned by the electron beam 10 
emitted by cathode 12. This electron beam is lamellar, i.e. that it has a 
small dimension along axis 0x and that its dimension along axis 0y is at 
least equal to that of resisive plate 9. Finally, this electron beam moves 
along axis 0x, perpendicularly to electrodes e.sub.1 and e.sub.2 ; the 
lamellar electron beam 10 determines during its movement the elementary 
surfaces of photoconducting layer 8 on which it neutralizes the charges 
created by illumination by causing currents, i'.sub.1 and i'.sub.2, to 
flow in electrodes e.sub.1 and e.sub.2 carried by plate 9. 
Electron beam 10 is subjected to scanning along 0x which may be very rapid, 
from a few microseconds to 10 microseconds. It is possible to adapt the 
scanning speed to the passband of the circuits processing signals i'.sub.1 
and i'.sub.2. The sum of the intensity of the reading currents is of the 
order of 300 n A and the signal-to-noise ratio is high. Finally, the 
resolution is greater than 500 points along 0x and of the order of 300 to 
400 points along 0y for a rectangular resistive plate of 9.5.times.12.5 
mm. 
The same device may be used in an oscilloscope for localizing the electron 
beam of the oscilloscope. It is then deposited on a support grid from 
which it is separated by an insulation means. The device then operates by 
using the principle of induced conductibility. 
When it is desired to localize an oscillogram formed by a curve having 
several values of y for the same value of x, as is the case in FIG. 5, it 
is sufficient to use several devices D.sub.1, D.sub.2, such as those which 
have just been described, disposed one above the other along 0y. 
These devices deliver currents i'.sub.1 and i'.sub.2, i.sub.3 and i.sub.4 
which allow localization of several impact points along 0y for the same 
value of x. The scanning of the sensitive surfaces along elementary 
surfaces (by a lamellar electron beam, by clock signals .phi..sub.1, 
.phi..sub.2, .phi..sub.3 applied to charge-transfer electrodes . . . ) may 
be advantageously common to the different devices D.sub.1, D.sub.2 . . .