SU680156A1 - Sawtooth current generator - Google Patents

Description

one

The invention relates to the communications industry and can be used, for example, in scanning devices of transmitting television cameras.

A sawtooth generator is known, comprising a master oscillator, a pre-output amplifier and an output transistor stage, to the output of which an inductive load is connected, a constant supply voltage source and an increased voltage source introduced into the generator to provide the required return duration l.

In this generator, due to the unidirectional conductivity of the switching device, there is an increased energy consumption.

Of the known devices, the closest in technical essence and the achieved result is a sawtooth current generator, containing a series-connected master oscillator, a TC-agitator of power with a push-pull drive.

cascade, to the output of which inductive load is connected, one of the output stage cascades is connected directly to the first source of direct voltage, the other arm is connected to the second source of constant voltage through a diode, and to the source of increased voltage - through the switching element 2.

This generator also has an increased power consumption, since the switching element is designed as a device of one-sided conduction, as a result of which the current from the source of the placed voltage is asymmetrical. As a result, the power consumed from this source during the return stroke is comparable to the power consumed by the generator. during & forward travel from a source of constant supply voltage. In addition, in such a generator, the effective return time (current recovery stage) is shorter than the starting pulse duration, while at the end of the return stroke, a waiting stage occurs (the current in the load does not change), in which additional power is consumed. The purpose of the invention is to reduce energy consumption. The goal is achieved there that a saw-tooth generator containing series-connected reference generator and a power amplifier with a push-pull output stage, to the output of which an inductive load is connected, one of the output voltage arms directly connected to the first source of constant voltage , the other arm is connected to the second source of constant voltage through the diode and to the source of increased voltage through the switching element, the first and second voltage dividers are introduced and a comparison element, the first input of which through the first voltage divider is connected to the output of the push-pull output stage, the second input through the second voltage divider is connected to the second source of constant voltage, and the output is connected to the control input of the switching element. FIG. 1 shows the electrical functional scheme of the proposed ramp-shaped current | in fig. 2 - diagrams of currents and voltages. The sawtooth current generator contains a series-connected master oscillator 1, a power amplifier 2 with a two-stroke push-pull cascade 3a KN and a ductive load 4 (Fig. 1) connected via feedback resistor 5 to the housing 6. as an inductive load. 4, deflecting coils are used. One of the arms of the push-pull cascade 3 is connected to a constant voltage source 7, and the other to a constant voltage source 8 via a diode 9, and to a voltage generator 10 it is connected via a comparison switching element 11. In addition, the generator current loop contains 12 comparisons and dividers 13 and 14 are the same (Guy Epeme GT 11 comparisons can be jiOjraeH, for example, on an operating force or in the form of Schmidt, or in the form of a logic circuit containing and levels, for example, at stage bldg, and element I. Switching epodedum 12 can be performed, for example, & diode – wrench switch, one VrR ° IODE is connected to the shoulder of the two-stage cascade 3 voltage. One input of the comparison element 12 is connected to the divider 13 for example ((rig. 1), another to the source of the reference signal in the case of using an operational amplifier as element 12, this source can be implemented, for example, in the form of a voltage divider 14 connected between a constant voltage source 8 and a housing 6, using a logic circuit as an element 12, e.g. a coincidence circuit, a commonly used source of a generator trigger clock can be used as a voltage reference source. The master oscillator 1 can be in-line veins, for example, according to the saw-tooth generator circuit with a correction amplifier. It contains an operational amplifier with resistive feedback from the output to one of the inputs to which the capacitor is connected, the other input is connected through a resistor to a voltage divider connected between the output of the operational amplifier and the power supply. The output two-stage cascade 3 is made of transistors of the opposite type of conductivity, the emitters of which are connected to an inductive load 4. The proposed saw-tooth current generator works as follows. When the input clock of the master oscillator 1 triggers the sync pulses (reverse sweep), the output of the master oscillator 1 produces a sharp overvoltage (fkg. 2, a) and the amplifier 2 is locked (turned off). One of the arms of the push-pull output stage 3 is also locked (Fig. 2, c), and the current through the other arm increases sharply ($ 2, b), reaching the high current in inductive load 4 at the end of the drive, From this moment, the voltage at the high-grade output of the load 4 peaKq rises (Fig. 2, d). This voltage, removed from the splitter 13 (Fig. 1) is compared in the element 12 with the reference one (c), and at the output of the comparison element 12 a voltage drop appears (Fig. 2e) under the action of which the switching element b2 opens, connecting the shoulder of the push-pull cascade 3 to the source 10 at amp voltage (Fig. 1), while the diode 9 is locked and disconnects the shoulder of the cascade G from power supply 8, the current in the inductive load 4 (flow through the shoulder of the amplifier in cascade 3 to source 1O and from it) is first reduced to zero | and then, reversing the voltage, begins to increase (FIG. 2.6). The voltage at the highly variable load 4 is set at the voltage level of source 10 (Fig. 2, d). In the reverse stroke, the current increase ceases, and it is set to the maximum value (standby stage) (Fig. 2.6), and the voltage at the high-differential output of load 4 decreases sharply (Fig. 2, d). Comparison element 11 monitors the moment when this voltage drops to the level of the reference voltage (ACTUAL 14), at this moment the trailing edge of the control signal is formed at its output, under the action of which the switching element 12 closes. A source . 10, the overvoltage is turned off, the diode 9 is opened, and the current of the inductive load 4 is applied to the source 8 of the generator. The voltage (Fig. 2, d) drops to a level less than the voltage (Fig. 2, d shown by the dotted line) from divider 14. Thus, during the return stroke, the current {Fig. 2, e) the source 1O is symmetrical (the current flowing from the source 10 is equal to the current flowing into it). In the absence of dividers 13 and 14, as well as elements 11 and 12, the current of source 10 during the waiting phase is maximum and is wasted uselessly, significantly increasing power consumption. Elements 11, 12 and dividers 13, 14g allow symmetric current to flow through source 10, thus avoiding the useless energy consumption during the standby stage and, consequently, reducing the power consumption of the generator. Between the trigger pulses (forward sweep), the current in the inductive load 4 varies according to the sawtooth law in accordance with the voltage of the driving oscillator 1, alternately flowing one through the first and then through the other from the arms of the push-pull stage 3. The use of the elements 11, 12, as well as dividers 13, 14 in the sawtooth generator provides a significant reduction in power consumption. For example, when used in a generator of a printing deflecting system with an inductance of 0.1 a H at a current of 1000 mA, a return time of 7 ms at a horizontal frequency with an increased voltage of 2OV and a supply voltage of 6V, a generator with a known switching element Consumption blows during the return stroke, the average current is 25 mA and, accordingly, the msms is sufficient. In the proposed Gewarator, the average current of 5 mA is consumed (imperfect symmetry of the current of the V-axis) and the corresponding power is 100 mW. Aemavt 11 on the operative usbtepte consumes msif (usti (with a voltage of 6 V supply) & 50 mW. Thus, the current generator consumes during the reverse 0da 150 mW, 3.5 times less, h & l gene congestion with known transfer device. In the case of an elo tape 12 in the form of a coincidence circuit, the power consumed by element 12 can be reduced to a few milliwatts, which will further reduce the power consumption of the preferred sawtooth current generator (as compared to the known similar generators). The use of the proposed generator makes it possible to reduce the energy consumption of a television camera as a whole, which is especially important for small-sized portable portable systems and special-purpose systems. The formula is a generator. A sawtooth generator containing a series-connected master oscillator, a power amplifier with a push-pull output stage, to the output of a connected inductive load, and one of the arms of the output cascade is connected to the first source of direct voltage, which is not directly applied. the shoulder is connected to the second source of constant voltage through the diode, and to the source of increased voltage through the switching element, which is the fact that, in order to reduce energy consumption the first and second voltage dividers and equalizer: whose input through the first voltage divider is connected to the output of the two-pressure output stage, the second input to the second voltage divider is connected to the second constant voltage source, and the output is connected to control input to the switching element. Sources of information taken into account in the examination

7th

1.Patent of France No. 2212730, CL. N 04 I 3/16. 12.28.73

2. The UK patent number 1313513, cl. NRT, 11.04.73.