JPS5930287B2 - Storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a storage device having volatile memory backed up by a battery.

Semiconductor memories that have become widely used in recent years can be roughly divided into non-volatile ROM (Read Only Memory).
y), volatile RAM (RandomAccessMe
There are two types: mory). Among these, ROM is non-volatile, so the contents are saved even if the power is turned off, but the contents cannot be rewritten. In addition, it cannot be used when there is a frequent request to modify part of the contents of a program, and it is expensive. R.O.
Among the M memory devices, there are devices called E-PROM and PROM that can erase the written contents and allow rewriting, but this requires a special erasing device for erasing and writing. In addition, it requires a writing device, which requires time and equipment, making it unsuitable as a storage device that requires occasional changes to the contents as described above. On the other hand, RAM can meet the above-mentioned requirements because it can be freely written and read, its access time is fast, and its price is low.

However, on the other hand, RAM has the disadvantage that the stored contents are completely erased when the power is turned off. Recently, RAMs have been developed that can store contents even in such cases, but they are expensive and have complex drive circuits, so they cannot replace conventional RAMs.
There is also a C-MOS (complementary
yMetal Oxide Semiconductor)
There is a RAM with low power consumption such as a dry battery, etc., which can supply power for several days with a small battery such as a dry cell, and a rechargeable nickel on the printed circuit board on which this RAM is mounted.・Equipped with a reversible battery such as a cadmium battery, the RAM on this printed circuit board is usually connected to the main power supply.
The battery can be charged using part of the power supplied to the battery, and when the main power supply is cut off, power can be obtained from this battery and used to save the contents of the RAM.

For example, automatic chemical analyzers that quantitatively analyze the content of various enzymes dissolved in blood by applying various reaction reagents to a serum sample, which is a test subject, have a wide variety of measurement items; The number of possible items is 16 at most.

Generally, the measurement items are determined to some extent depending on the medical department. Furthermore, this device sequentially and continuously measures several hundred specimens at once. Furthermore, reaction times vary depending on the type of reaction reagent, and therefore the apparatus requires various and delicate controls, and measurement data must also be analyzed.

For this reason, electronic computers such as minicomputers or microcomputers have been made obsolete, and the aforementioned battery-backed RAM is used as a storage device to store data, control programs, data processing programs, etc. It is possible to change control program timing and program tables and to save data as needed, thereby suppressing increase in memory capacity as much as possible and reducing costs.
FIG. 1 is a circuit diagram of such a storage device backed up by a battery.

That is, in the figure, 1 is a low power consumption type RAM, 2 is a positive side bus for supplying DC voltage from the main power source to this RAM1, and 3 is a switching circuit for opening and closing this positive side bus 2. This switching circuit 3 uses, for example, a PNP type transistor as a switching element, and its emitter-collector is connected to the bus 2, and its base is grounded, so that when voltage is applied from the main power supply, the switching circuit 3 is immediately switched on. The switching element is turned on and supplies data to RAM1. 4 is nickel
It is a small rechargeable reversible battery such as a cadmium battery, and its positive side is connected to the positive side power input terminal DD of the RAM1 through a parallel circuit of a charging resistor R and a diode D, and its negative side is connected to the positive side power input terminal DD of the RAM1. It is grounded.

The tie auto D is connected to the electrical ground 4 in a forward direction. In such a storage device, while power is being supplied from the main power source, the switching circuit 3 is turned on to supply power from the main power source to the RAM1. Meanwhile, charging resistance R
Since power is also given to battery 4 from the main power supply via
This battery 4 is charged. When the main power is turned off, the switching circuit 3 is immediately turned off, and the bus 2 connecting with the main power is opened. On the other hand, since diode D is forward-connected to battery 4, power is supplied from battery 4 to RAMl via diode D.
The power supply is switched smoothly from the main power supply to battery 4 and the RA
The contents of Ml will be preserved. By the way, even if the memory is backed up using a battery, if the main power supply is out for a long time, or if the charging capacity decreases due to battery life, etc., the RAM will be backed up when the main power supply comes back on. The contents may have already disappeared.

In such cases, if you operate the device without knowing it, in the worst case scenario, the automatic chemical analyzer may move completely on its own and break down, or you may lose important data. At the very least, you will have to reinstall the necessary programs from the source tape. The present invention has been made in view of the above circumstances, and includes a circuit that compares the battery voltage and the main power supply voltage, and operates this circuit when the main power is turned on to check whether the battery voltage is sufficient for backup. If it is insufficient and the memory contents have not been saved, it is possible to issue a warning, stop reading from the memory, and at the same time take necessary actions such as rewriting necessary programs and other programs from the source tape. The purpose is to provide a storage device that enables

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a circuit diagram showing the configuration of this device, which is basically the same as the circuit in FIG. 1.

In this device, a comparison circuit 21 is further provided in the circuit shown in Fig. 1 to compare the voltage of the battery 4 and the voltage of the main power supply, and when the battery voltage does not reach the main power supply voltage, the main power supply is
The difference is that it is not connected to AMl. That is, the first
As shown in FIG. 2, where the same reference numerals are given to the same components as in the figure, one input terminal of the comparator circuit 21 is connected to the positive power supply input terminal VDD of RAMl, and the other input terminal is connected to the positive power supply input terminal of the main power supply. It is connected to a voltage dividing point of a voltage dividing resistor 22 for voltage dividing, which is connected between the voltage dividing resistor 22 and the ground point.

Further, the one input terminal of the comparator circuit 21 and the RAM1
A switch 23 is provided between the power supply input terminal 0D and the power supply input terminal 0D so that the switch 23 can be opened and closed, and a switch circuit 24 that responds to the output of the comparison circuit 21 is provided at the front stage of the switching circuit 3. When the voltage of 4 has reached a predetermined value sufficient for memory backup, the output of the comparison circuit 21 causes the switch circuit 24 to close the switch and connect the output side of the main power source to the switching circuit 3. Reference numeral 25 denotes a drive circuit that receives the output from the main power source to drive the switch 23 and closes the switch 23.

Next, the operation of this apparatus having the above configuration will be explained.

Assume that the main power has been stopped for a while and now the main power is turned on again. Then, the voltage of the main power source is appropriately divided through the voltage dividing resistor 22 and applied to the comparator circuit 21 as a reference voltage. This reference voltage is the minimum voltage required to preserve the contents of RAM1, and for this purpose, it is divided by a voltage dividing resistor 22 and set to this voltage. At the same time as the main power source is turned on, the voltage of the main power source is also applied to the drive circuit 25, and the drive circuit 25 operates to close the switch 23. As a result, the comparison circuit 21 receives the power input terminal of the RAM1 via the switch 23. D
voltage is applied. This voltage is the voltage of the battery 4 for memory backup since the switch circuit 24 and the switching circuit 3 are still in an open state. When these two inputs are applied, the comparator circuit 21 compares the battery voltage with reference to the reference voltage, and if the battery voltage is equal to or higher than the reference value, outputs and supplies it to the switch circuit 24.

Then, this switch circuit 24 operates and closes the switch. As a result, the output of the main power supply is applied to the switching circuit 3, so the switching circuit 3 immediately operates to pass the output of the main power supply and apply it to the power input terminal of RAMl. This means that RAMl has been switched from the battery 4 to the main power source. At the same time, the battery 4 is recharged via the charging resistor R. Further, since the main power supply output is applied to the one input terminal of the comparison circuit 21 due to switching to the main power supply, the comparison circuit 21 continues to output an output, and therefore the switch circuit 24 continues to operate. When the main power supply is stopped, the drive circuit 25 is stopped, so the switch 23 which is closed by the drive circuit 25 is opened, and therefore the comparator circuit 21 is closed.
The output of will disappear. As a result, the switch circuit 24 is opened, so that the voltage of the battery 4 is now applied to the RAM1 via the diode D, and the voltage is switched to backup by the battery 4. If the voltage of the battery 4 is lower than the specified value when the main power is turned on, no output is output from the comparator circuit 21, so the switch circuit 24 is also inoperative, and therefore the RAM l
There is no power supply. Therefore, since the contents can be read out, there is no possibility of malfunctions caused by obtaining completely random data or programs as in the past. In addition, when such a situation occurs in which the contents of RAM1 are not saved, the control device 31 is operated based on the output state of the comparison circuit 21 to operate the alarm device 32, as shown in FIG. At the same time, the control device 31 outputs the operation of the arithmetic circuit 33 that reads the contents from the RAM 1 and processes them, and the device 34 that controls various control sections of the automatic chemical analyzer according to the read pure control program. to stop state.

The operator looks at the display on the alarm device 32 and presses the keyboard 35.
, to manually write programs and data to RAM 1, or take out the source tape 36, hang it on the tape reader 37, and write it to RAM 1.
As a result, necessary data and programs are written to the RAM 1 via the controllers 38 and 39 of the keyboard 35 and tape reader 37. When the writing is completed, these controllers 38 and 39 output a completion signal. 31 is stopped. As a result, the alarm device 32 is stopped, and the arithmetic circuit 33 and the device 34 that controls the various control units of the automatic chemical analyzer are released from the stop and enter the operating state. In this way, the battery voltage for RAM backup is detected when the main power is turned on, and the output of the main power is given to the RAM only when the voltage value is sufficient for backup. If the battery voltage is too low, the contents of the RAM cannot be read at all, and this prevents malfunctions in control operations and errors in analysis caused by reading corrupted RAM contents. It is possible to provide a storage device that has excellent features such as being able to prevent

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with appropriate modifications within the scope of the gist thereof.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional device, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Fig. 3 is a block diagram showing an application example when the device according to the present invention is used in a control system. . 1...RAM, 4...Battery, 21...
... Comparison circuit, 22 ... Voltage dividing resistor, 23.
...Switch, 24...Switch circuit,
25... Drive circuit.

Claims (1)

[Claims] 1. In a device that uses a semiconductor memory as a storage medium that loses its memory contents when the power is cut off and is provided with a battery as a backup power source for this semiconductor memory, it operates on the output of a main power source that supplies power to the semiconductor memory. a switch, a circuit that divides the output voltage of the main power source to obtain a reference voltage corresponding to a voltage value necessary for retaining the memory contents of the semiconductor memory, and the battery obtained through this reference voltage and the first switch. A circuit that compares and detects whether the battery voltage has reached the reference voltage by comparing the voltages of 1. A storage device comprising: a circuit for providing a power source for a semiconductor memory; and a circuit for providing an alarm when the battery voltage does not reach a reference voltage.