JP2008228536A - Information equipment and direct current voltage supplying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide information equipment capable of preventing malfunctions of devices due to slow start-up of DC voltage generated, at turning on of the power. <P>SOLUTION: A DC power supply output unit 1A supplies power with a plurality of devices 2, except an FeRAM2c by outputting +3.3V for control. A DC power supply output unit 1B, an electric power system power supply, outputs +12V, for example. A DC power supply output unit 1C supplies voltage, only with the FeRAM2c. The FeRAM2c, one of the devices 2, is controlled by the device 2d supplied voltage from the DC power supply output unit 1A. The device 2d performs control of writing and reading data by outputting address signals, data signals and read/write signals, or the like, to the FeRAM2c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to information equipment and a DC voltage supply method, and more particularly, to a power supply technique for an image processing apparatus and information equipment having a nonvolatile storage element such as a digital copying machine and a printer.

Various types of devices such as ICs (integrated circuits) are mounted, and the electrical equipment boards (hereinafter abbreviated as "boards") of information equipment that are supplied with a plurality of different DC voltages are limited in how the voltage rises and in the order of input. There is something. This is because when a plurality of power supplies are used, irregularities occur in the slew rate (rise speed) and level of the rising waveform of the power supply voltage when the power is turned on. As a result, a malfunction of the device may occur.
For example, when power is supplied to different boards from different DC power supply circuits even with the same supply voltage, the current value varies depending on the load on the board, so the devices and elements are stable. There will be a difference in the time to reach the specified voltage that operates. In this case, the rising waveform of the DC voltage supplied to the substrate having the larger current value is gentler than that of the other substrate (the slew rate of the rising waveform is reduced). Therefore, a malfunction may occur if a non-volatile memory element such as a FeRAM (Ferroelectric Random Access Memory) is mounted on the substrate having a gentle DC voltage rising waveform. Non-volatile memory elements are expected to retain data even when the power is turned off, so they often store important information such as various setting values and billing information for information devices. Not only does this cause problems, but it also causes economic losses.
However, it is troublesome for the user to consider the power-on sequence. Even when power is supplied from the same DC power supply circuit to the same board, the power-on sequence is controlled when devices and elements, such as unstable CPUs or logic circuits, access nonvolatile memory elements. Even if it does not solve.
As a power-on control method, when power is input to each power source, the power monitoring circuit checks whether each power source is turned on, and only when all power sources are turned on, A method has been proposed in which the switching elements directly connected to the output terminal of the power supply are simultaneously turned on (see, for example, Patent Document 1). This eliminates the need for the user to consider the power-on sequence.
JP 2002-10488 A

However, as described in Patent Document 1, even if the control is performed so that the power is turned on at the same time, the element can be prevented from being destroyed. The problem of unevenness of time remains, and the problem of device malfunction due to unstable operation of the nonvolatile memory element or the like cannot be solved.
An object of the present invention is to solve such a problem of the conventional technique, and an object of the present invention is to provide a power supply technique capable of preventing malfunction of a device due to a gradual rise of an output voltage generated when power is turned on.

In order to solve the above problem, an information device according to claim 1 is an information device including a nonvolatile memory element, wherein a first DC power supply circuit that supplies a DC voltage to a device that operates using a DC voltage; And a DC voltage supplied to the nonvolatile memory element is supplied from the second DC power supply circuit.
The information device according to claim 2 is the information device according to claim 1, wherein at least one of the devices controls data access to the nonvolatile memory element.
The information device according to claim 3 is the information device according to claim 1 or 2, wherein the nonvolatile memory element is FeRAM.
According to a fourth aspect of the present invention, there is provided the information device according to the first, second, or third aspect, comprising: a voltage monitoring unit that monitors a rising voltage of the first DC power supply circuit; and the second DC power supply circuit. Switching means for turning on / off a DC voltage supply to be supplied to the nonvolatile memory element, the switching means monitoring that the DC voltage of the first DC power supply circuit has risen to a predetermined voltage value. The DC voltage supply is turned on as the means detects.
The DC voltage supply method according to claim 5 is a DC voltage supply method for supplying a DC voltage to a device, wherein the first DC power supply circuit supplies a DC voltage for control to the device, and the second DC power supply circuit. Supplies a DC voltage to the non-volatile memory element, and monitors the DC voltage output from the first DC power supply circuit when the first DC power supply circuit and the second DC power supply circuit rise, and the DC voltage is The DC voltage supply from the second DC power supply circuit is started after rising to a predetermined voltage value.
The DC voltage supply method according to claim 6 is the DC voltage supply method according to claim 5, wherein at least one of the devices controls data access to the nonvolatile memory element.

  According to the present invention, when the power is turned on, the rising of the DC voltage supplied to the nonvolatile memory element becomes steep, so that the nonvolatile memory element can be prevented from malfunctioning, and an information device having a stable operation when the power is turned on is provided. Can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram showing a main part of a power supply unit of the digital copying machine according to the first embodiment. As shown in the figure, the power supply of this digital copying machine (hereinafter simply referred to as a copying machine) is a power supply unit 1, a plurality of devices 2 that operate using a plurality of types of DC voltages supplied from the power supply unit 1, This is performed by an electrical board (printed board) 3 on which these devices are mounted. In this example, the power supply unit 1 has a commercial AC power supply as an input and includes three DC power supply output units.
The DC power supply output unit 1A outputs + 3.3V for control, and supplies power to devices other than the FeRAM 2c among the plurality of devices 2 described above.
The DC power supply output unit 1B is a power system power supply, for example, outputs + 12V and supplies power via a device 2b which is one of the devices 2. The device 2b is a power transistor that outputs a large direct current supplied to the load 4 such as a motor, and the device 2a that is supplied with + 3.3V in one of the devices 2 is, for example, a buffer circuit through which a relatively large current flows. It is. In this example, the device 2a drives the device 2b.
Further, the DC power supply output unit 1 </ b> C supplies a voltage only to the FeRAM 2 c shown as one of the devices 2. The FeRAM 2c is controlled by a device 2d which is one of the devices 2 and is supplied with a voltage from the DC power supply output unit 1A. That is, the device 2d performs control to write or read data by outputting an address signal, a data signal, a read / write signal, or the like to the FeRAM 2c. In addition, the ground (GRD) of each DC power supply output part is mutually connected.

With such a configuration, when the + 3.3V DC voltage rises, the logic state of the device 2a is indeterminate which of the two states, but one of the logic states is supplied from the DC power supply output unit 1A. Current flows to GRD via device 2a. In the case of the other logic state, when + 12V rises first, the current supplied from the DC power supply output unit 1A flows to the GRD via the device 2a and the device 2b. That is, the load impedance at the time of rising of the DC power supply output unit 1A is small, so that a relatively large current flows, and as a result, the rising to + 3.3V is slow as shown by the dotted line in FIG.
If the FeRAM 2c is supplied with power from the DC power supply output unit 1A in the same manner as the other devices 2, it is supplied with a non-standard DC voltage at the time of slowly rising, and the stored data is rewritten. Such a malfunction may occur. However, in the first embodiment, as described above, the FeRAM 2c is individually supplied with a voltage from the DC power supply output unit 1C, and the load of the DC power supply output unit 1C is only the FeRAM 2c having a large impedance. As a result, the rise to +3.3 V becomes steep as shown by the solid line in FIG.

FIG. 3 is a main part schematic circuit diagram relating to the power supply unit of the present invention. In the figure, the same parts as those in FIG. Further, the DC power output unit 1B that is a power source of the power system is omitted.
As shown in the figure, the power supply unit 1 has a primary side circuit 11 common to each DC power supply output unit to which commercial AC power is input, and a primary side winding common to each DC power supply output unit. Includes a transformer 12, a DC power supply output unit 1A, a DC power supply output unit 1C, etc. each having a unique winding.
The DC power supply output unit 1A includes a rectifier circuit 13a and a smoothing circuit 14a including a coil L and a capacitor C. Similarly, the DC power supply output unit 1C includes a rectifier circuit 13c and a smoothing circuit 14c including a coil L and a capacitor C.
With such a configuration, when commercial AC power is input to the primary side circuit 11, a stepped-down AC voltage is output to both ends of the secondary side winding of the transformer 12, and the AC voltage is rectified and smoothed. And output from the output terminals 15a and 15c.
As described above, the output of the output terminal 15a is supplied to the device of the DC power supply output unit 1A shown in FIG. 1, and the output of the output terminal 15c is supplied to the FeRAM 2c of the DC power supply output unit 1C shown in FIG. Supplied with rising characteristics. That is, it is supplied to the FeRAM 2c with a steep rise.
As described above, according to the first embodiment, a device malfunction, for example, in a nonvolatile memory element such as FeRAM, due to a gradual rise of a DC voltage generated at power-on, an error of stored data is caused. Reading and writing errors can be prevented.

Next, a second embodiment of the present invention will be described.
In the second embodiment, an example of a method for controlling the supply of power to be supplied to the device 2d or the like that controls the FeRAM 2c in FIG. 1 to be simultaneous or faster than the power supplied to the FeRAM 2c will be described. .
FIG. 4 is a schematic block diagram of a DC power supply unit according to the second embodiment. As shown in the figure, the DC power supply unit includes a voltage comparison circuit (for example, a differential amplifier) 21 and a secondary battery 22 for supplying a reference voltage to the comparison circuit 21 in addition to the configuration of FIG. A switching element 23 is provided between the smoothing circuit 14c and the output terminal 15c of the power output unit 1C. Therefore, power from the DC power supply output unit 1C is not supplied to the FeRAM 2c until the output voltage of the DC power supply 1A (output terminal 15a) becomes the reference voltage.
In the second embodiment, the output voltage of the DC power supply output unit 1A is monitored by the comparison circuit 21, the secondary battery 22, and the like.

The operation of the second embodiment will be described according to the operation flow shown in FIG.
FIG. 5 is a flowchart showing the operation of the DC power supply unit according to the second embodiment.
In the second embodiment, the comparison circuit 21 monitors the output voltage of the DC power supply 1A (output terminal 15a) (step 1), and the voltage does not rise above the reference voltage value given by the secondary battery 22. (No in step 2), the output of the comparison circuit 21 is at the low level, and therefore the switching element 23 is in the OFF state. Therefore, even if the + 3.3V voltage output from the DC power supply output unit 1C rises, the voltage at the output terminal 15c is around 0V. When the output voltage of the DC power source 1A becomes equal to or higher than the reference voltage value provided by the secondary battery 22 (Yes in step 2), the output of the comparison circuit 21 becomes high level, thereby turning on the switching element 23. In this way, + 3.3V of the rising DC power supply output unit 1C is supplied from the output terminal 15c to the FeRAM 2c (not shown) (step 3).
Non-volatile elements such as FeRAM 2c do not operate even when a control signal is received from the device 2d side unless a DC voltage is applied. Therefore, according to the second embodiment, as a result of an indefinite logic state in the period in which + 3.3V gradually rises in the group of devices 2 to which + 3.3V is supplied from the DC power supply 1A, the device 2d is brought into the FeRAM 2c. Even if an erroneous control signal is output, it is possible to avoid a situation in which the data in the FeRAM 2c not receiving power supply is rewritten.

As described above, the case where the nonvolatile memory element is FeRAM has been described. However, the nonvolatile memory element is not limited to FeRAM. It is also possible to supply a different DC voltage such as a rated + 5V instead of + 3.3V to a part or all of the control system device 2d that is supplying + 3.3V.
Note that until the rising of the voltage of the DC power supply supplied to the nonvolatile memory element such as FeRAM is steep or until the device that accesses the nonvolatile memory element is supplied with the power of the standard operating voltage, The power supply should be stopped.

1 is a schematic block diagram illustrating a main part of a power supply unit of a digital copying machine according to a first embodiment. FIG. 6 is a diagram for explaining rising characteristics of a digital copying machine power supply according to the first embodiment. It is a principal part schematic circuit diagram which concerns on the power supply part of this invention. It is a schematic block diagram of the direct-current power supply part which concerns on 2nd Embodiment. It is a flowchart which shows operation | movement of the DC power supply part which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply part, 1A DC power supply output part, 1C DC power supply output part, 2 device, 2c FeRAM, 3 Electrical component board, 4 Load, 12 Transformer, 13 Rectifier circuit, 14 Smoothing circuit, 15 Output terminal, 21 Comparison circuit, 22 Secondary battery, 23 switching element

Claims (6)

  An information device including a nonvolatile memory element includes: a first DC power supply circuit that supplies a DC voltage to a device that operates using a DC voltage; and a second DC power supply circuit. An information device, wherein a DC voltage to be supplied is supplied from the second DC power supply circuit.   The information device according to claim 1, wherein at least one of the devices controls data access to the nonvolatile memory element.   3. The information device according to claim 1, wherein the nonvolatile memory element is FeRAM.   4. The information device according to claim 1, 2, or 3, wherein voltage monitoring means for monitoring a rising voltage of the first DC power supply circuit, and DC voltage supply supplied from the second DC power supply circuit to the nonvolatile memory element. Switching means for turning on / off the switching circuit, and the switching means detects the DC voltage as the voltage monitoring means detects that the DC voltage of the first DC power supply circuit has risen to a predetermined voltage value. Information equipment characterized by turning on voltage supply.   In a DC voltage supply method for supplying a DC voltage to a device, a first DC power supply circuit supplies a control DC voltage to the device, a second DC power supply circuit supplies a DC voltage to a nonvolatile memory element, and When the first DC power supply circuit and the second DC power supply circuit start up, the DC voltage output from the first DC power supply circuit is monitored, and after the DC voltage rises to a predetermined voltage value, the second DC power supply is monitored. A DC voltage supply method, comprising: starting DC voltage supply from a power supply circuit.   6. The DC voltage supply method according to claim 5, wherein at least one of the devices controls data access to the nonvolatile memory element.

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