JP3158413B2 - Power supply for absolute encoder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a backup power supply system for supplying power to a device in place of a power supply when the power supply is cut off.

FIG. 3 is a configuration diagram of a conventional example of a backup power supply circuit.

Backup power supply circuit 26, a positive output and a positive output reverse current blocking diode backup battery 9 power E _S 10, 1
Consists of an OR connection through one. Since the voltage of the power supply E _S is set to be higher than the voltage of the backup battery 9, the power source E _S is the on state, power is supplied to the apparatus 20 via a blocking diode 10. At this time, since the reverse current blocking diode 11 reverse voltage is applied, reverse flow of current from the power supply E _S to backup battery 9 is prevented. When the power E _S is turned off (high impedance state or a low level), and supplies electric power to the device 20 backup battery 9 via a blocking diode 11. At this time, blocking diode 10 prevents the backflow of current from the backup battery 9 to the power supply E _S. Thus, backup power supply circuit 26, at least one output of the power supply E _S and backup battery 9 outputs a positive voltage to be applied to the blocking diode 10 or 11. A recent technology of this type of backup power supply circuit is disclosed in
There is a circuit described in Japanese Patent No. 107626.

A device that requires continuous power supply even when the power supply (hereinafter, referred to as a device power supply to distinguish it from a backup battery) is turned off, that is, a device that requires a backup battery (hereinafter, a device requiring a backup battery) , A first type device) is a volatile memory that stores data of an absolute encoder attached to a robot. After the power for the device is turned off and the robot stops, if the contents of the volatile memory are retained until the robot is turned on again, the robot cannot start the next operation. Therefore, the volatile memory receives the power supply from the backup battery at the same time as the power supply for the device is turned off, and retains its contents.

A normal device is a type 1 device such as the volatile memory described above and a device (hereinafter referred to as a second device) that can be inactive without supplying power while the device power is off.
Seed devices). Therefore, such a device supplies power by a dedicated cable connecting the backup battery or the backup power supply circuit to the first device and a dedicated cable connecting the device power supply and the second device. Receive.

FIG. 4 is a diagram showing an example of a backup power supply system including an absolute encoder device and a power supply unit thereof. 4, the same parts as those in FIG. 3 are denoted by the same reference numerals.

In the system shown in FIG. 4, the absolute encoder device 2A is separated from the power supply unit 1A, and the backflow prevention diodes 10, 11 are arranged on the absolute encoder device 2A side. V _MM and V _CC are a voltage for a volatile memory and a voltage of a power supply for a logic circuit (second type device), respectively. The voltage _VMM is supplied from a backup power supply circuit. Apparatus power source E _S is connected to the absolute encoder apparatus 2A via the switch circuit 5. Switch circuit 5
, The switching transistor 7 is opened and closed via the control transistor 8. In this system, a special cable 31 which transmits an output to the first type device backup battery 9, a dedicated cable 32 for transmitting the output of the device power source E _S to the two devices are used.

[Problems to be Solved by the Invention] In the above-mentioned backup power supply system, dedicated cables for connecting the backup battery or the backup power supply circuit to the first type device and the device power supply and the second type device are required. Therefore, there is a problem that the number of cables increases, and the number of failures due to disconnection increases.

An object of the present invention is to provide a backup power supply system with a small number of cables.

[Means for Solving the Problems] A power supply voltage supply apparatus for an absolute encoder according to the present invention includes a first device that requires continuous power supply even when the power supply for the device is cut off, A device for supplying a power supply voltage to an absolute encoder device having a second device that does not require power supply when the power supply is cut off, and outputs a backup battery and a voltage higher than the battery in an operating state. The power supply for the absolute encoder device, and the output voltages of the backup battery and the power supply for the absolute encoder device, respectively, are input, and a reverse current blocking diode that outputs the higher output voltage of the output voltages is OR-connected. Power supply that is arranged separately from the absolute encoder device and outputs an OR connection output. A power supply circuit, a cable for connecting the output of the power supply circuit to the first device of the absolute encoder device, and a power supply circuit provided for the absolute encoder device. Switching means for connecting the output of the power supply circuit to the second device only when the output voltage is higher than the output voltage of the battery and is equal to or higher than a predetermined value set to be equal to or lower than the device power supply voltage.

[Operation] When the power supply for the device is in the operating state, the power supply circuit outputs the output of the power supply for the device. As a result, the output of the power supply circuit becomes higher than the predetermined value, and the switching means connects the output of the power supply for the device to the second device. Therefore, both the first device and the second device receive power from the device power supply. When the power supply for the device is in the cut-off state, the power supply circuit outputs the output of the backup battery. As a result, the output of the power supply circuit becomes lower than the predetermined value, and the switching means is cut off. Therefore, only the first device receives power supply from the backup battery.

As described above, the power supply device for the absolute encoder according to the present invention can perform the same function as the conventional backup power supply system by using only the output of the power supply circuit. Can be done.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of a backup power supply system of the present invention, and FIG. 2 is a voltage sensor IC 13 of FIG.
FIG. 3 is a diagram showing voltage detection characteristics of FIG.

The backup power supply system of the present embodiment includes a power supply circuit 1 and a device 2. The power supply circuit 1 and the device 2 are installed separately from each other, and the device 2 is supplied with power from the power supply circuit 1 via a cable 3. The device 2 of the present embodiment is an absolute encoder device 2, in addition to the encoder main body, a volatile memory (not shown) for storing the initial position of the encoder and the number of generated pulses as a first type device, and a pulse as a second type device. It includes a logic circuit (not shown) for counting and calculating. 4.5V logic circuit
The above (5V ± 10%) logic circuit voltage V _CC is required. Volatile memory is always operated at a voltage almost equal to the logic circuit voltage V _CC, and when the power supply for the device is turned off, the stored contents are lost. Requires 3V backup voltage to hold. Hereinafter referred to the voltage applied to the volatile memory and the memory voltage V _MM. Further, the absolute encoder device 2 includes the switching means 4 of the present invention, and the configuration and function thereof will be described later in detail.

The power supply circuit 1 includes a switch circuit 5 and a backup power supply circuit 6.

The switch circuit 5 has the same configuration and function as the switch circuit 5 in FIG. 4, and the same components are denoted by the same reference numerals. When the base signal S is at a high level, device power source (not shown) E _S is connected to a backup power supply circuit 6. In this embodiment, the voltage of the device power source E _S is with respect to the ground potential + 5V. The backup power supply circuit 6
It has the same configuration and function as the backup power supply circuit of FIG. 3, and the same components are denoted by the same reference numerals. The output voltage of the backup battery of this embodiment is +3 V with respect to the ground potential. The output of the backup power supply circuit 6 is transmitted to the absolute encoder device 2 via the cable 3 and supplies the memory voltage _VMM .

The switching means 4 comprises a voltage sensor IC 13, a switching transistor 12, and an inverter 14. The PNP switching transistor 12 connects the output of the backup power supply circuit 6 transmitted by the cable 3 to a logic circuit. The voltage sensor IC 13 detects the output of the backup power supply circuit 6 and controls the connection of the switching transistor 12 based on an inverted signal of the detected output. The voltage sensor IC 13, as shown in FIG. 2, which is the input voltage and outputs a high level only when the above specific voltage threshold V _T is used. In this embodiment, the voltage threshold
V _T is higher than the output voltage (3V) of the backup battery,
Epson SC, smaller than the output voltage (5V) of the power supply for equipment
1770 series ICs are used. Therefore, when the backup power supply circuit 6 outputs the voltage (5 V) of the power supply for the device, the switching transistor 12 is turned on, and when the output of the backup battery (3 V) is output, the switching transistor 12 is turned off.

 Next, the operation of this embodiment will be described.

When using the absolute encoder device 2 connects the output of the device power source E _S and the base signal S to a high level in the backup power supply circuit 6. Backup power supply circuit 6 when the apparatus power source is operating state supplies memory voltage V _MM in the volatile memory and outputting the output voltage of the device power source E _S. At this time, since the switching means 4 is turned on, the backup power supply circuit 6 supplies the logic circuit voltage V _CC to the logic circuit. When the device power supply is turned off, the backup power supply circuit 6 outputs the output voltage (3 V) of the backup battery. At this time, since the switching means 4 is turned off, the backup power supply circuit 6 supplies only the memory voltage _VMM . As described above, by the operation of the switching means, the same effect as the conventional backup power supply system can be achieved only by the cable 3 for transmitting the output of the backup power supply circuit 6.

 Next, a second embodiment of the present invention will be described.

In this embodiment, the negative power of the device power supply and the backup battery is supplied to the device. In this case, the forward direction of the backflow prevention diode of the backup power supply circuit is directed from the device side to the device power supply side or the backup battery side. Further, the absolute value of the negative voltage with respect to the ground potential (positive potential) of the power supply for the device is set to be larger than the absolute value of the negative voltage with respect to the ground potential of the backup battery. Therefore, the backup power supply circuit outputs a negative output of the device power supply when the device power is on, and outputs a negative output of the backup battery when the device power is off.

Voltage threshold V _T of the switching means is lower than the negative output of the backup battery, the negative output or more values of device power supply,
That is, the absolute value of the negative output of the backup battery is set to be greater than the absolute value of the negative output of the device power supply. Then, when the output voltage of the backup power supply circuit falls below the voltage threshold V _T, i.e. only when the absolute value of the output voltage of the backup power supply circuit is equal to or greater than the absolute value of the voltage threshold, the switching means backup The output of the power supply circuit is connected to the second type device. When the power supply for the device is in the off state, the negative output of the backup battery supplies power only to the first type device.

[Effect of the Invention] As described above, in the backup power supply system of the present invention, the absolute value of the voltage threshold is equal to or less than the absolute value of the output of the power supply for the device and larger than the absolute value of the output of the backup battery. By setting the output of the backup power supply circuit to the second type device only when the absolute value of the output of the backup power supply circuit is equal to or greater than the predetermined value, the output of the backup power supply circuit The same function as the conventional backup power supply system can be achieved by only the transmission of the power supply, and as a result, the number of cables connecting the power supply circuit and the device can be reduced, and the effect of reducing the failure due to the disconnection of the cable can be reduced. is there.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the backup power supply system of the present invention.
FIG. 2 is a diagram showing a voltage detection characteristic of the voltage sensor IC 13 of FIG. 1, FIG. 3 is a diagram of a conventional example of a backup power supply circuit, and FIG. 4 is an absolute encoder device and its structure. FIG. 2 is a diagram illustrating an example of a backup power supply system including a power supply unit. DESCRIPTION OF SYMBOLS 1 ... Power circuit, 2 ... Absolute encoder device, 3 ... Cable, 4 ... Switching means, 5 ... Switch circuit, 6 ... Backup power supply circuit, 7, 12 ... Switching transistor, 8 ... Control Transistor, 9 ... backup battery, 10, 11 ... reverse current blocking diode, 13 ... voltage sensor IC, 14 ... inverter.

Claims (1)

(57) [Claims] 1. A first device that requires continuous power supply even when the power supply for the device is cut off, and a second device that does not require power supply when the power supply for the device is cut off.
A device for supplying a power supply voltage to an absolute encoder device having a device, a backup battery, and a power supply for an absolute encoder device that outputs a voltage higher than the battery in an operating state, the backup battery and the backup battery. Each of the output voltages of the power supply for the absolute encoder device is input, and among those output voltages, the output terminal has an OR connection of a backflow prevention diode that outputs a higher output voltage, and is arranged separately from the absolute encoder device. A power supply circuit that outputs an output of an OR connection; a cable that connects an output of the power supply circuit to a first device of the absolute encoder device; and a power supply circuit that is provided so as to be assigned to the absolute encoder device. The detected value is the output of the backup battery. A power supply voltage supply device for an absolute encoder having switching means for connecting an output of the power supply circuit to a second device only when the voltage is higher than a predetermined value set to be equal to or lower than the device power supply voltage.