JPH01150395A - Erroneous operation preventive circuit for electronic device - Google Patents

Abstract

PURPOSE:To prevent the function of an electronic device from being stopped at the time of insertion and pulling-out of units by a method wherein an erroneous operation preventive circuit for preventing an erroneous operation at the time of delivery and receipt of the signal between the units at the time of insertion and pulling-out of the units in and from the device is mounted in the units. CONSTITUTION:A power supply is supplied to a mounting state informing circuit 14, an enable signal reception circuit 11 and an input/output signal control circuit 12 by a power (f) from an external power supply (x) before a unit 30 is inserted. Here, as an enable signal (d) is not received, the circuit 11 transmits information that an output signal (a) is disable to the circuit 12. When the signal (a) is in disable state, the output part of the circuit 12 is brought into the state of a high impedance. In this state, when the unit 30 is inserted in a shelf 20, the circuit 12 does not bring an erroneous operation to a device because the signal (a) is in the state of a high impedance. When the unit 30 is mounted to the device, the unit performs a normal delivery and receipt of signal between other mounting finished units and the unit. Reversely, in case the unit 30 is pulled out of the device, the circuit 12 is never operated erroneously when the external power supply is ready-connected to the unit 30.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a malfunction prevention circuit for electronic devices.

[Conventional technology]

Conventionally, when inserting or removing a unit, the power to the electronic device has usually been stopped, and the functions of the electronic device have been temporarily stopped. However, due to the expansion of the scale of electronic devices and the diversification of their functions, this temporary stop is no longer acceptable. Therefore, in the past, the terminal dimensions of the connector section that connects to the electronic device of the unit were differentiated, such as long and short. Two types of terminals are used, and when the unit is inserted into an electronic device, the long terminal is connected first, followed by the short terminal, so that the unit is inserted and connected in stages.

[Problem that the invention seeks to solve]

In the conventional unit insertion/removal method described above, depending on the timing of unit insertion/removal when the electronic device is activated, there are problems in guaranteeing the power supply and guaranteeing the state level of the output signal during the transition period of unit insertion/removal. However, this method does not go so far as to prevent malfunctions of the system, and has the disadvantage that the function of the entire system may be temporarily stopped.

[Means for solving problems]

A malfunction prevention circuit for an electronic device according to the present invention includes a mounting state notification circuit that notifies the mounting state of each unit constituting the electronic device, and a mounting state notification circuit that issues a signal from the electronic device in response to the mounting state to execute or stop the operation of the unit. an enable signal receiving circuit that receives an enable signal to control the electronic device; an output signal control circuit that uses the enable signal to control signal output to other units that are not inserted or removed from the electronic device; and a power supply integrated circuit that logically ORs the power supplied from the external power source of the electronic device and the power supplied from the external power source of the electronic device and supplies power to the unit, Prevent equipment malfunction.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a circuit diagram of an embodiment of the present invention, and Fig. 2 is a circuit diagram of an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a state in which a unit to which the illustrated embodiment is applied is inserted into and removed from a shelf of an electronic device.

In FIG. 1, a malfunction prevention circuit 1 for an electronic device according to the present embodiment is shown.
The enable signal receiving circuit 11 is composed of an inverter circuit that logically inverts the enable signal d from the unit (not shown) in which the malfunction prevention circuit 1 is mounted, and the enable signal d from the enable signal receiving circuit 11 is logically inverted. The output signal control circuit 12 consists of a NAND circuit that performs the logical AND NOT of the input signal S from the unit and the input signal S from the unit, and outputs the output signal a. (omitted), and a power supply integrated circuit 13 that outputs the supplied power g by logical sum with the power f of the power supply g, and a mounting state notification circuit 14 that outputs a mounting state signal when it receives the supplied power g. .

FIG. 2 shows a state in which a unit 3o in which the malfunction prevention circuit l of this embodiment is mounted is inserted into and removed from a shelf 20 of an electronic device (not shown).

Next, the operation of this embodiment will be explained using FIG. 1 and FIG. 2 together.

At the time of inserting the unit 30 into the shelf 2o of an electronic device (hereinafter referred to as the device) and from the shelf 2° to the unit 3
When extracting 0, the power f from the external power supply is always supplied to the power supply integrated circuit 13.

Electric power f from the external power source is sent to the power source integrated circuit 13, passes therethrough, and is consumed within the unit 3o.

First, before the unit 30 is inserted, power is supplied to the mounting state notification circuit 14, the enable signal receiving circuit 11, and the turnout signal control circuit 12 using electric power f from an external power source.

Here, since the unit 3o has not yet been inserted into the shelf 2o, the enable signal d has not been received.
2, transmits information to disable the output signal a. The output section of the output signal control circuit 12 uses a device such as an open collector or 3-state, and becomes high impedance when disabled.

Next, in the above state, the unit 3o is inserted into the shelf 2°. Since the output signal of the unit 3o is high impedance, it will not cause malfunction to the device.

When the unit 30 is mounted on a device, first, the mounting state signal created by the mounting state notification circuit 14 is notified to the device, and the device side transmits an enable signal d in response to this mounting state signal. Therefore, this is received by the enable signal receiving circuit 11. The enable signal receiving circuit 11 transmits enable information 1, which is the logical inversion of the enable signal d, to the output signal control circuit 2812 in accordance with the enable signal d. The output signal control circuit 12 enables the output of the input signal according to the enable information.

Thereafter, this unit 3o performs normal signal exchange with other mounted units.

Furthermore, when the unit 30 is mounted on the device, the internal power supply of the device supplies power e to the power supply integrated circuit 13, so that from now on, the unit 30 can be operated using the internal power supply.
The connection between the unit 30 and the external power source may be removed.

Conversely, when the unit 30 is removed from the device, if the external power supply is connected to the unit 30 first, the output signal control circuit 12 will not malfunction because the power supply will be guaranteed even during the transition period when the unit 30 is removed. do not have.

〔Effect of the invention〕

As explained above, the present invention implements the malfunction prevention circuit according to the present invention in a unit constituting an electronic device, thereby eliminating a factor that causes malfunction of the electronic device when the unit is inserted or removed, thereby preventing the electronic device from malfunctioning. In particular, it is possible to insert and remove the unit without causing malfunction even when the electronic device is active, and in particular, it is possible to use the enable signal by the mounting state signal indicating that power is being supplied to the unit from the mounting state notification circuit. This has the effect of eliminating the temporary stoppage of the entire system's functions when a unit is inserted or removed, which conventionally occurs.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram illustrating an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a state in which a unit to which the illustrated embodiment is applied is inserted and removed from a shelf of an electronic device. DESCRIPTION OF SYMBOLS 1... Malfunction prevention circuit, 11... Enable signal receiving circuit, 12... Output signal control circuit, 13... Power supply integration circuit, 14... Mounting status notification circuit. Agent: Susumu Uchihara, patent attorney Figure 1 Figure 2

Claims (1)

[Claims] a mounting state notification circuit that notifies the mounting state of each unit forming the electronic device; and an enable signal that receives an enable signal issued from the electronic device in response to the mounting state and controlling execution or stop of the operation of the unit. a receiving circuit, an output signal control circuit that uses the enable signal to control signal output to other units that are not inserted or removed from the electronic device, and power supplied from an internal power source of the electronic device and an external power source of the electronic device. and a power integrated circuit that performs a logical sum with the supplied power and supplies power to the unit, thereby preventing malfunction of the electronic device when the unit is inserted or removed from the electronic device. Malfunction prevention circuit for electronic equipment.