JPS59105121A - Electronic apparatus - Google Patents

Abstract

PURPOSE:To improve the accuracy of the status of power supply voltage and to detect niuse to prevent the generation of malfunction by using an A/D converting means to detect the power supply status by an A/D converted output, and preventing an apparatus from malfunction. CONSTITUTION:The A/D converting means is used to detect the power supply status on the basis of the converted output and to prevent the apparatus from malfunction. For instance, data from an A/D input terminal 7 are A/D converted by a CPU6 and the A/D converted data are compared with refrence voltage VREF, and when the A/D converted data are larger than the reference voltage, a control program for a driving circuit 4 to drive a load 3 is continued. When the A/D converted data are less than the reference voltage, a timer is started, and every time up, the inclination of the A/D converted value Dn is compared with the inclination Ki determined by a time constant or the like at the disconnection of a power supply at that time. When the inclination of the value Dn coincides with the inclination Ki, the inclination is calculated up to the time when the power supply voltage reaches the value of a threshold VSH, and when the calculated value coincides with the inclination Ki, power off is discriminated and the program is shifted to a power off routine.

Description

[Detailed description of the invention] Technical field The present invention relates to electronic equipment controlled by a CPU.

BACKGROUND ART Conventionally, in an electronic device having a CPU, processing for the occurrence of an abnormal state of a power supply has been carried out by using a power supply voltage detection circuit and acting on the CPUK. In this case, the processed signal is output the instant the reference voltage for abnormality determination is exceeded, so there is no time for the CPU to process it, and in order to create time, it is necessary to change the reference voltage. Malfunctions may occur due to noise and the like, and for example, in industrial robots, intelligent robots, etc., there is a risk of leading to a serious accident.

FIG. 1 shows how an abnormal state of power supply voltage is detected in a conventional electronic device. FIG. 1 is a diagram showing the relationship between a drop in power supply voltage and a power-off detection signal SO according to a conventional detection method. Since the detection circuit (detection circuit) is conventionally known, its explanation will be omitted here.VSH is a threshold value;
When the power is turned off at TO, the power supply voltage V gradually drops from 24V to the threshold V8H at TI, and it is normal that the power-off detection signal S~1Q() m5ec is required for the first time. Until this T1, the power cutoff detection signal SO is not output, so the process control means advances the program, but when the paper that should not be stopped is fed, the development that must be done is performed immediately. There are cases where something bad happens to the copier.

Purpose In view of the above points, the present invention detects the state of the power supply voltage with high accuracy (and prevents malfunctions due to noise etc. Our goal is to provide electronic equipment with the following configurations.

Embodiment FIG. 2 shows the configuration of an embodiment of the present invention. A power supply 1 is a 24V power supply for a load, for example, and is connected to a load B, and is driven by a drive circuit 4. 6 is a process control unit (CPU) of an electronic device such as a copying machine, and the drive circuit 4 is a CPU.
It is driven according to the signal from 6. The power supply of CPU6 is
An example is power supply 2 of 5■. The load power supply 1 is further voltage-divided by resistors R1 and R2 and connected to the A/D input cuff of the CPU 6. On the other hand, the reference voltage VREF for A/D conversion
is created by resistor R3 and resistor R4, and is input to reference voltage input 8. FIG. 6 shows the power supply voltage using the A/D conversion of the present invention when a voltage abnormality occurs in the load power supply 1 for some reason, for example, when the power is cut off. After the power is turned off at TO, the voltage gradually decreases (although the CPU 6 in FIG. 2 always refers to the A/D conversion data of this voltage, so the state of the power supply can be known at any time after TO. Therefore, do not wait until the power is turned off (but it is possible to determine the power-off status.Also, the processing time of the CPU is usually
Since the time required to execute one instruction is on the order of μS, the time constant of the power supply mentioned above is sufficiently long compared to that of a CPU. Therefore, it is possible to refer to the data that has been A/D converted a very large number of times after 1゛0.Therefore, it is possible to determine that the power has been cut off just by the slope of the voltage, without having to wait until rllrL.Power supply voltage Figure 4 shows a flowchart of the A/D conversion processing routine, which is one of the interrupts that determines a power outage based on the slope of CP'.
At U6, the data from the person/D person cuff is A/D converted (step (1)). Next, the reference voltage VREF' for A/D conversion (24 in this embodiment) is compared with the A/D conversion data (steps (2) and (3)).
. In step (2), if the data value and VREF are equal, the process returns to the main program that controls the process of the copying machine main body. Since this main program is well known, its explanation will be omitted here. This example is an example in the case of power supply; voltage drop, so the data value is
If you make it bigger than VREF, what is the process of the copier itself?
Return to the main program for IJ control 7. (Step (
6)). If the data value is smaller than VRgF', start the timer and use the A/D
The converted value is set as Di (step (4), (5
)), calculate the slope at that time, and compare it with the slope Ki determined by the time constant etc. at the time of power-off at that time (step (6)). If Di-Di-1- is 1, the slope is not the same as when the power was turned off, and the process returns to the main program that controls the processes of the main bodies of multiple machines. If Di-D
If i-1-Ki, calculate the step (force) and slope sequentially until the time Tn at which the value of VSH shown in Fig. 6 is reached.Then, if the calculated slope is equal to Ki (i-i~n), then If so, it is determined that the power is turned off, and the process proceeds to a power-off routine, which is one of the interrupts (step (7)).

FIG. 5 shows a flowchart of the power-off routine. In the A/D conversion processing routine shown in FIG. 4, it was determined that the power supply would be cut off before the voltage of the load power supply 1 shown in FIG. 2 reached V S )1 shown in FIG. In this power-off routine, necessary data is saved until the voltage of the power supply 1 reaches VSH. First, the magnification, number of copies, and copy density.

Operation modes such as cassette and sorting are saved (step (1)). Next, during copy execution, status signals such as jam status, number of sheets fed, number of sheets ejected, etc. are saved (step (2)). Next, the data in the agitator and the data in various registers are saved (step (6)). Then return to the main program.

The voltage of the power supply 1 for the load in Fig. 2 is restored again, and the voltage of the power supply 1 for the load in Fig.
The case where the threshold value V8H further reaches the value of VREF as shown in the figure will be explained with reference to FIGS. 4, 5, and 6. Similarly to the above, when the A/D conversion is performed and the converted data value becomes larger than the threshold value VSH, the timer is started, and each time the time elapses, the A/D converted value is converted to Di(i-
n-1), calculate the slope at that time, compare it with the slope Ki (i-r ~ l) determined by the time constant of voltage recovery, and calculate D
If it is i-Ki, it is determined whether the power should be restored and the process proceeds to the power restoration routine. After restoring the various data that had been saved, the program is returned to the main program and normal process control is performed. can be detected accurately (and reliably detected, and recently A/D
Since inexpensive single-chip CPUs with built-in converters have become widespread, it is possible to provide electronic devices that are extremely small and highly accurate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the drop in power supply voltage and the power supply detection signal SO according to a conventional detection method. FIG. 2 is a diagram showing the configuration of one embodiment of the present invention. FIG. 6 is a diagram showing how a power supply voltage drop is detected using A/D conversion according to the present invention. FIG. 4 is a flowchart of a Φ conversion processing routine according to one embodiment of the present invention. FIG. 5 is a flowchart of the power-off routine. FIG. 6 is a diagram showing how the power supply voltage is restored. 1 is the power supply for the load 2 is the power supply for casting 4 is the active circuit
6 is load 6 is CI) L) Applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. An electronic device having a CPU, characterized in that the electronic device is configured to use an A/1) conversion means to detect a power state based on the conversion output thereof, and to prevent malfunctions of the electronic device.