JPH0428193Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a backup power supply circuit that backs up the operation of the control section of an electronic device for a predetermined period of time when the power supply of the electronic device is interrupted or interrupted. .

(b) Prior Art Conventionally, as a backup power supply circuit that backs up the operation of the control section of electronic equipment for a predetermined period of time when the power supply to the electronic equipment is interrupted or interrupted, for example, the "SCHEMATIC DIAGRAM &PRINTED" model FVH-722 manufactured by Fischer Co., Ltd.
CIRCUITBOARD (U, S, A)'', pages 12 to 13 disclose a circuit as shown in Figure 3 is an example of a general circuit diagram, and Figure 4 shows the backup time and FIG. 3 is a characteristic diagram showing the relationship with backup voltage.

To explain the drawing number and structure in Fig. 3, 1
is a switch that turns on and off the input of AC power supply 2,
3 has a tap on the secondary winding side, and the switch 1
4 is a rectifier circuit that rectifies the negative voltage of the secondary voltage obtained by the secondary winding of the transformer 3. 5 is a rectifier circuit that divides the secondary voltage with a tap. The rectifier circuits 6 and 7 that rectify the positive voltage obtained by
12 and 13 are terminals for inputting DC negative voltage (e.g. -20 volts) and DC positive voltage (e.g. +5 volts) smoothed by the integration circuits 6 and 7, respectively; 14; is MPU1 as a data processing means that inputs DC positive voltage.
5 and a memory 16;
19 is a display unit that operates based on the output of the drive circuit 18; 20 is a DC positive voltage line between the terminal 13 and the information processing means 17; 21 and ground, and absorbs DC positive voltage noise and keeps the information processing means 17 running for a predetermined period of time (e.g.
22 is the electrolytic capacitor 20 and the line 2
1 and the terminal 13 of the electric charge charged in the electrolytic capacitor 20.
When blocking discharge to the side, a reverse current blocking diode, 2
3 is an electrolytic capacitor connected between the DC negative voltage line 24 between the terminal 12 and the drive circuit 18 and the ground, and absorbs the noise of the DC negative voltage; 30 is a load impedance connected between the line 24 and the ground. resistance. In addition, the horizontal axis in Fig. 4 is the time axis, and T ₀ is the power off time,
T ₁ indicates the backup limit time in Fig. 3, and the vertical axis indicates the voltage axis, and V _B
is the input positive voltage to the terminal 13, Vf is the rising voltage of the reverse current blocking diode 22, and υ is the information processing means 17
The lowest operating voltage, -V _P , indicates the input negative voltage to terminal 12, and the dashed line indicates the backup voltage.

(c) Problems to be solved by the invention However, in the above case, the electrolytic capacitor 23
The charged charges were wasted and discharged to the ground side of the control unit 14 and the resistor 30 at the same time as the power was turned off at time T ₀ .

Further, assuming that the current consumption I _D by the control unit 14 is approximately constant and the capacitance of the electrolytic capacitor 20 is C _B , the backup time T _BU1 is T _BU1 = |T ₁ −T ₀ | =C _B (V _B −Vf−υ)/I _D ... From the formula, in order to lengthen the backup time T _BU , the capacitance C _B of the electrolytic capacitor 20 should be made large, and a shot key diode with a small rising voltage should be used as a reverse current blocking diode. etc., which caused problems such as increased costs.

(d) Means for solving the problems The present invention has been made to solve the problems mentioned above, and is a method for controlling electronic equipment that operates with a direct current positive voltage and a direct current negative voltage and controls a load. In the backup power supply circuit of the section, a first capacitor connected between the DC positive voltage line and the ground, a second capacitor connected between the DC positive voltage line and the DC negative voltage line, and a second capacitor connected between the DC positive voltage line and the DC positive voltage line. A backup circuit comprising a diode which is in the forward direction with respect to the control section, and whose cathodes are connected to the connection points with the first and second capacitors, and which discharges the electric charge charged in the first and second capacitors only to the control section. The above problem is solved by a power supply circuit.

(e) Effect: According to the backup power supply circuit of the present invention, since the control section operates with a DC positive voltage and a DC negative voltage, in addition to the positive charge of the first capacitor, a DC positive voltage and a DC negative voltage are generated. The negative charge of the second capacitor connected between the lines can also be used for backing up the control section, which has the effect of extending the backup time without increasing costs.

(f) Examples The details of the present invention will be specifically explained with reference to illustrated examples. FIG. 1 is a circuit diagram showing an embodiment of the backup power supply circuit of the present invention, and FIG. 2 is a characteristic diagram showing the relationship between backup time and backup voltage in FIG. 1.

To explain the figure number and structure of Figure 1, 2
A first line 5 connected between the terminal 13 and the information processing means 17 and the DC positive voltage line 26 and the ground, absorbs the noise of the DC positive voltage and backs up the information processing means 17 for a predetermined time when the power is turned off. An electrolytic capacitor (for example, 2200 μF) 27 serves as a capacitor, one of which is connected between the connection point with the electrolytic capacitor 25 and the line 26 and the terminal 13, and a DC negative voltage line 28 between the terminal 12 and the drive circuit 18. 29 is an electrolytic capacitor (for example, 220 μF) as a second capacitor, the other of which is connected to the electrolytic capacitor 25, which absorbs DC negative voltage noise and backs up the information processing means 17 for a predetermined time when the power is turned off. 27 and between the connection point with the line 26 and the terminal 13, and the electrolytic capacitor 2
This is a diode that prevents the charges charged in the terminals 5 and 27 from being discharged to the terminal 13 side. In addition, other components in FIG. 1 that are the same as those in FIG. 3 are given the same figure numbers, and FIG _{. 2} is a characteristic diagram similar to that in FIG. The backup limit time, V _PEAK , indicates the peak value of the backup voltage.

To explain the circuit operation with reference to FIG. 1, by turning on switch 1, a DC positive voltage (for example, +5 volts) is input to terminal 13, and a DC negative voltage (for example, -20 volts) is input to terminal 12, which causes an electric field to be input. If the capacitance of the capacitor 27 is _CP , then the electrolytic capacitors 25 and 27 each have a charge of Q _B =C _B (V _B -Vf) ... Q _P =C _P (V _B -Vf + V _P ) ... After being charged, a positive DC voltage is input to the information processing means 17, and a negative DC voltage is input to the drive circuit 18, so that the control unit 14 operates. Here, the memory 16 and the drive circuit 18 each have a direct current positive voltage,
It is operated not only by a DC negative voltage but also by a control signal from the MPU 15, and some kind of display is made on the display section 19 as a load by the output signal of the drive circuit 18 which operates in this way.

Next, if there is a power outage, instantaneous interruption, or switch 1 is turned off at time T ₀ for some reason, terminals 12 and 1
The power input to 3 becomes zero, and electrolytic capacitor 2
The charges Q _B and Q _P charged in cells 5 and 27 are effectively supplied to the information processing means 17 by the diode 29 without being discharged to the terminal 13 side, and the MPU 15 and the memory 16 have a longer backup time than the formula. (for example, 3 seconds). This backup time T _BU2 is T _BU2 = | T ₂ − T ₀ | ≒ (Q _B + Q _P ) − (C _B − C _P ) υ/I _D ...... Substituting the equation and the equation, T _BU2 =T _BU1 +C _P (V _B −Vf−υ+V _P )/I _D ...... In general, V _P >>V _B −Vf−υ in the formula, so the backup time shown in the formula
It can be seen that T _BU2 is sufficiently longer than the backup time T _BU1 shown in the equation.

Next, referring to FIG. 2, when the power input to the terminals 12 and 13 becomes zero at time _T0 , most of the charge in the electrolytic capacitor 27 is discharged to the electrolytic capacitor 25, and the electrolytic capacitors 25 and 2
7 reaches equilibrium, the voltage across the electrolytic capacitor 25 temporarily increases as shown by the broken line and reaches the peak value V _PEAK , after which it is input to the information processing means 17 and output to the MPU 15 and memory 16. While the operation is backed up, it is attenuated, but as is clear from a comparison of FIGS. 2 and 4, the backup time T _BU2 is sufficiently longer than the backup time T _BU1 . Here, V _PEAK is control unit 1
4, and the amount of discharged charge of the electrolytic capacitors 25, 27 that provides V _PEAK after time T ₀ exceeds the amount of charge charged in the electrolytic capacitors 25, 27 before time T ₀ . Never. Therefore, when calculating V _PEAK , V _PEAK ≦V _B - Vf + C _P / C _B + C _P V _P ..., so that V _PEAK is less than the maximum allowable rated voltage of the control section 14 and the desired backup time can be obtained. Electrostatic capacitance C _B of electrolytic capacitors 25 and 27,
All you have to do is determine C _P.

(g) Effects of the invention According to the backup power supply circuit of the invention, since the control section operates with DC positive voltage and DC negative voltage, in addition to the positive charge of the first capacitor, DC positive voltage and DC The negative charge of the second capacitor connected between the negative voltage lines can also be used to back up the control section, thereby extending the backup time of the control section without adding any additional components or increasing costs. This has the advantage of making it possible to

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of the backup power supply circuit of the present invention, Figure 2 is a characteristic diagram showing the relationship between backup time and backup voltage in Figure 1, and Figure 3 is a diagram of a conventional backup power supply circuit. FIG. 4, which is a circuit diagram showing an example, is a characteristic diagram showing the relationship between the backup time and backup voltage shown in FIG. 3. Explanation of main drawing numbers, 14...control section, 19...display section, 25, 27...electrolytic capacitor, 26,2
8... line, 29... diode.

Claims (1)

[Scope of utility model registration request] In a backup power supply circuit for a control unit of an electronic device that operates with a DC positive voltage and a DC negative voltage and controls a load, a first capacitor connected between a DC positive voltage line and a ground, and the DC positive voltage line , and a second capacitor connected between the DC negative voltage line, which is in the forward direction with respect to the DC positive voltage line, and whose cathode is connected to the connection point with the first and second capacitors,
A backup power supply circuit comprising a diode that discharges charges stored in the first and second capacitors only to the control section.