DE2607132A1 - X:ray appts. with tube voltage control circuit - has current and time and control circuit for voltage and current time products - Google Patents

Abstract

The X-ray appts. has devices to set the tube voltage, the time and/or tube current or the current/time product. The set parameters are converted into proportional electrical quantities and passed to two interconnected, interdependent control circuits one for processing the tube voltage, current and time and the other for processing the tube voltage and current/time product. The two control circuits contain a function generator that reproduces the tube's load curve. The computation takes place in analog form and the transmission to the setting elements in digital form.

Description

X-ray machine

The present invention relates to an X-ray apparatus with means for setting the X-ray tube voltage, as well as optionally the time and / or the X-ray tube current or the current time / product and with an arithmetic unit for the calculation of the mutual dependencies of the set values in relation on the protection and the selected utilization of the X-ray tube.

It is well known in the case of X-ray machines that use rotary knobs or the like. Set values required for an X-ray examination directly or indirectly from the input means to an arithmetic logic unit that is based on by mechanical means assigned to him, the entered values for their permissibility possibly checked as a function of a predetermined utilization of the X-ray tube and the setting of the selected values using other mechanical means the executive bodies. Such Facilities required on the one hand, a very considerable mechanical effort and, on the other hand, quite a lot considerable precision.

The present invention is based on the object of an X-ray apparatus to create, which compared to the known embodiments by a substantially is characterized by a simpler conception based on a purely electrical basis, it is possible without any further measures, in particular the input means and the X-ray tube protection to be ordered separately from the recruitment bodies According to the invention the object is achieved in that the set values by means of suitable Components converted into proportional electrical quantities and analogously two with each other coupled, interdependent, on the one hand for processing the X-ray tube voltage, the X-ray tube current and the time and on the other hand for the processing of the X-ray tube voltage and the current-time / product provided control loops a function generator that stores the load curve of the X-ray tube electrically are supplied that the arithmetic operation in the arithmetic unit is analog and the transmission to the executing actuators as well as the display on suitable organs digitally and that the digitally set current / time / product values or the time values direct to the assigned elements causing the shutdown are transferred In a further development of the invention it is proposed that in the so-called Two- and three-point technology for setting the current time / product values and those for setting the time values and those for transferring these values required components are summarized and used together, and that the for the disconnection provided components partially summarized and common are exploited.

In an embodiment of the invention, a timer is provided, which are used as preselection counters for the digitally present on the one hand with the two-point technology Current-time / product values and for the other hand with the three-point technology digital present time values is formed0 based on one in the drawing more or The invention is explained in more detail in the exemplary embodiment shown in a less schematic manner: As can be seen from the drawing, adjustment means designed as rotary knobs, for example, are used X, Y, Z - Zt the most important data for an X-ray examination such as X-ray tube voltage (kV), X-ray tube current (mA) or current-time / product (mAs) or time (ms) entered. The entered, analogue values of the X-ray tube voltage and the X-ray tube current will each supplied to a conversion element 1, 2 and in proportional electrical quantities converted, on the one hand, a control loop explained in more detail below for the maximization of the X-ray tube current required for the two-point technique and on the other hand, are supplied to the executive organs via an A / D converter 3 The set depending on the desired technology, i.e. two or three-point technology, digitally available values of the current-time / product or the time are on the one hand directly via a common line that causes the shutdown, below supplied components explained in more detail and on the other hand via a D / A converter 4 in analog form to a second control loop, also explained in more detail below for the minimization of the time required with the two-point technique.

The control of the executive organs by means of digital signals is chosen for the purpose of achieving a high transmission accuracy, what in particular is important when the time can be set in a larger range.

In the so-called three-point technique, a multiplier is used 5 on the one hand the X-ray tube voltage directly and on the other hand the X-ray tube current via a changeover switch 6 which is in position I in the three-point technology. That at the exit of the Multiplier 5 then pending, the A signal corresponding to the actual kW value is then fed to an input of a comparator 7. A signal is applied to the other input of the comparator 7, which primarily is formed depending on the set time value in the D / A converter and over a second changeover switch 8 is fed to a function generator 9 to which the signal processed in relation to the permissible power value of the X-ray tube. The function provider 9 is then a setting member 10 downstream tet, with which the function generator 9 delivered signal depending on the desired utilization of the X-ray tube can be changed. Otherwise is between the setting member 10 and the comparator 7 a third changeover switch 11 is arranged, which is in position with three-point technology I is located. The comparator 7 supplies at its output via a fourth changeover switch 12 now a signal L or 0, with which the X-ray exposure is either released or is prevented, depending on whether the set actual power value is above or below the resulting permissible power value.

With three-point technology, the X-ray exposure is switched off by that the time value entered at the setting element Z 'is in digital form an input one Digital comparator 13 is supplied, at the 14 other input of which a resettable Counter is connected, which has a fifth switch 15 with a time pulse generator 16 is connected. If the comparator 13 determines that the counter 14 is dependent the signal supplied by the time pulse generator 16 corresponds to the other input signal, so the switch-off signal is given by him.

In the so-called two-point technique, in turn, the multiplier is used 5 on the one hand, the X-ray tube voltage is fed directly. The other hand is the multiplier 5 an automatically generated as a result of regulation, at the set current time / product value maximum possible X-ray tube current supplied.

This is done by using the set current-time / product setpoint is fed to an input of a third comparator 17. The second entrance this one The comparator 17 is initially based on the momentary detuning of the control loops depending on the transmitter 18 for the X-ray tube current and a transmitter 19 for the time automatically in a multiplier 20 resulting current-time / product actual value fed. If there is still a deviation, the comparator 17 influences the Encoder 19 in the sense of reducing the time, which means that the encoder 19 via the switch 8, which is now in position II Function generator 9 of the connected via the switch 11, which is still in position I. Comparator 7 is influenced in terms of a change in the permissible power value, from which an increase in the X-ray tube current results, through the transmitter 18, This X-ray tube stream now formed is fed to the multiplier 20, which forms a new current-time / product actual value. If there is still a deviation from the current-time / product setpoint, there is a further reduction in time and an increase in the X-ray tube current made until at the set current-time / product setpoint value differs from the specified load and the set utilization of the X-ray tube is more dependent, minimally possible Time value and a maximum possible current value.

The shutdown is carried out in such a way that the adjustment element takes place directly Z outgoing digital current-time / product values to one input of the digital comparator 13 are supplied. The counter 14 is in turn connected to the other input, which is now located in position II switch 15 with a voltage-frequency converter 21 is connected. The voltage-frequency converter 21 receives one from the X-ray tube current (mA.) dependent voltage, which is converted into a proportional frequency. the The frequency pulses resulting therefrom are counted in the counter 14 and signal-wise fed to the comparator 13, which in turn the switch-off signal if they match supplies.

The so-called one-point technique is just like the others Techniques fed the X-ray tube voltage to one input of the multiplier 5, while the other input via the switch 6 in position II with is connected to the transmitter 18 for the X-ray tube current. This encoder 18 is of a transmitter 22 for an initial value of the power with falling load over the in Position II located switch 11 by the comparator 7 in connection with the multiplier 5 influenced so that the X-ray tube voltage corresponding maximum X-ray tube current is set, which is then not shown Means is lowered according to the nomogram of the X-ray tube, with the shutdown e.g. made by an automatic exposure machine, also not shown will.

- patent claims -

Claims (3)

Claims 4.ß) X-ray apparatus with means for setting the X-ray tube voltage and optionally the time and / or the X-ray tube current or the current time / product and with an arithmetic unit for calculating the mutual Dependencies of the set values in relation to the protection and the selected Utilization of the X-ray tube, characterized in that the set values converted into proportional electrical quantities by means of suitable components (1,2,4) and analogously two interconnected, interdependent, on the one hand for the processing of the X-ray tube voltage, the X-ray tube current and the time, and on the other hand for processing the X-ray tube voltage and the current-time / Product provided control loops with a load curve of the X-ray tube electrically storing function generator (9) are supplied * -that the arithmetic operations analog in the arithmetic unit and the transmission to the executing actuators as well the display on suitable organs takes place digitally and that the digitally adjusted Current-time product values or the time values directly to the assigned, the Shutdown causing elements (13-16,21) are transferred. 2.) X-ray apparatus according to claim 1, characterized in that at the so-called two- and three-point technology for setting the current time / product values and those for setting the time values, and for transferring these values required components (4) are combined and used together, and that the components (13 - 16, 21) provided for disconnection are partially combined and are shared. 3.) X-ray apparatus according to claim 2, characterized in that one Timer (14) is provided as a preselection counter for the one hand at the Two-point technology digitally present current-time / product values and for the other with the three-point technology digitally present time values is formed.