JP2844764B2 - Electronic equipment with power supply discrimination function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention can selectively or simultaneously connect a battery power supply and a non-battery power supply, and determines whether a currently used power supply is a battery power supply or a non-battery power supply, The present invention relates to an electronic device having a power source determination function for estimating a remaining amount of a battery when a battery power source is used.

[Related Art] As a battery remaining amount calculating device of this type, the applicant of the present application integrates power consumption according to a use state according to a use time,
An apparatus for estimating the remaining amount by subtracting this from the power amount of a full charge has been filed earlier. FIG. 6 shows a configuration example applied to a camera-integrated video tape recorder (so-called camcorder). 10 is the camera section, 12 is the VTR section, 14 is the camera section 1
0 and a battery for supplying power to the VTR unit 12, and 16 is a camera unit.
10 and a system control circuit for controlling the operation of the VTR unit 12, 18
Is an instruction unit for inputting a predetermined instruction to the system control circuit 16,
20 is a display unit for displaying the operation state of the system control circuit 16,
22 is a counter for integrating the power consumption. Reference numeral 24 denotes a TV device that displays a playback image of the camera unit 10 or the VTR unit 12.

The camcorder shown in FIG.
The camera unit 10 and the VTR unit 12 are both in operation, and the current consumption is 2.4 A. In the playback mode, the camera unit 10 stops, only the VTR unit 12 operates, and the current consumption is 1.8 A.

When the operator inputs an instruction of the shooting / recording mode on the display unit 18, the camera unit 10 and / or the VTR unit 12 are supplied with power from the battery 14, and the operation according to the specified operation mode is started. At the same time, the counter 22 accumulates a count value per unit time according to each operation mode.

That is, a count coefficient corresponding to the power consumption of each operation mode is set, and the system control circuit 16 controls the counter 22 according to the operation mode. In the above example, since the current consumption is 2.4 A and 1.8 A in the shooting recording mode and the reproduction mode, respectively, the count coefficients are set to “4” and “3”, respectively. The counter 22 counts four at a time in the recording mode.
In playback mode, the count is incremented by three per second.

The system control circuit 16 fetches the value held by the counter 22 every time the main operation unit 13 including the camera unit 10 and the VTR unit 12 stops or suspends the operation, and calculates the power consumption of the battery 14 from the held value by calculation. The remaining amount is displayed on the display unit 20. The counter 22 is reset when the battery 14 is replaced.

By dividing the thus obtained remaining amount by the current consumption in the photographing / recording mode, it is possible to obtain and display a recordable recording time.

[Problems to be Solved by the Invention] However, in the above-described configuration, errors in power consumption due to switching of the use state or differences in fine mode settings are accumulated, and high accuracy cannot be obtained. Further, in the case of a partially used battery, there is a disadvantage that the remaining amount cannot be estimated at all. Furthermore, when using a home AC power supply as a power supply,
That is, in a device that can use a so-called AC adapter that converts commercial AC into DC, no consideration is given to the device, and the power consumption is integrated even when the AC adapter is used. And display is performed.

Therefore, an object of the present invention is to provide an electronic device having a power source discriminating function that solves such a problem.

[Means for Solving the Problems] An electronic apparatus having a power supply discriminating function according to the present invention can selectively or simultaneously connect a battery power supply and a non-battery power supply and has a plurality of operation modes having different load resistances from each other. Measuring a change in output of the power supply in accordance with a change in an operation mode of the electronic device, and determining whether a power supply currently used is a battery power supply according to the measured output change state of the power supply. Also, if the power supply currently being used is a battery power supply, the remaining battery capacity is detected by comparing the previously stored battery remaining capacity characteristic with the measured output change of the power supply, It has a function of notifying a user of information related to the detected remaining amount of the battery.

[Operation] With the configuration described above, it is possible to automatically determine whether or not the power supply currently being used is a battery power supply, thereby preventing the calculation of the remaining battery charge from being inappropriately executed. it can.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration block diagram of one embodiment of the present invention.
30 is a camera unit, 32 is a VTR unit, 34 is a camera unit 30 and a VTR unit 32
, A reference numeral 35 denotes an AC adapter for converting AC power to DC, and reference numeral 36 denotes a selection switch for selecting the battery 34 or the AC adapter 35. The DC voltage selected by the selection switch 36 is applied to the power input terminal of the camera unit 30 via the switch 37, and is applied to the power input terminal of the VTR unit 32 via the switch 38. 40 is the operation of the camera unit 30 and the VTR 32, and
System control circuit that controls the opening and closing of switches 37 and 38, 42
Is an instruction device for inputting a predetermined operation instruction to the system control circuit 40, 44 is a measurement circuit for measuring a DC voltage selected by the switch 36, 46 is an output of the measurement circuit 44 and an operation signal from the system control circuit 40. The arithmetic circuit calculates the remaining amount of the battery 34, the display device 48 displays the remaining battery amount calculated by the arithmetic circuit 46, and the 49 determines whether the battery 34 is used or the AC adapter 35 is used. It is a circuit, and in the illustrated embodiment, it is determined by the output of the measuring circuit 44.

FIG. 4 shows a display mode of the display device 48 using seven-segment elements.

In the present embodiment, two types of loads are connected to the battery 34 to be measured, and the respective internal electromotive voltages (open circuit voltages) v are measured. The remaining amount of the battery 34 is estimated based on the comparison. That is, the relationship between the internal resistance R, the internal electromotive voltage v, the output voltage V, and the output current I of the battery 34 in each consumed state is measured by the circuit of FIG. r ₁ and r ₂ are load resistances for measurement, and 50 is a switch for selecting the load resistances r ₁ and r ₂ . r ₁ is the load resistance of, for example, recording mode, r ₂ is the load resistance in the other modes. The current in the case of connecting the switch 50 to the load r ₁ I _1, V ₁ the voltage drop due to the load r _1, the current in the case of connecting the switch 50 to the load r ₂ I _2, the voltage drop due to the load r ₂ V When _2, R = a _{(V 2 -V 1) / (} I 1 -I 2) (1), when the output voltage of the battery 34 V, the output current is I, is v = V + IR (2) Therefore, v = V + I (V ₂ −V ₁ ) / (I ₁ −I ₂ ) (3)

Since the internal electromotive voltage v is not greatly affected by the internal resistance R, the fluctuation is relatively small, and corresponds well to the remaining battery capacity. A relation curve between the internal electromotive voltage v and the remaining battery level is obtained in advance, and the above-mentioned I ₁ , I ₂ , V ₁ , V ₂ , V, I are measured during use, and if the curve is applied to the relation curve, the The remaining battery level at the time can be estimated.

As an example, a more specific description will be given, taking as an example a case in which continuous use in a recording mode of camera photographing is assumed and the remaining battery power is displayed as a value T converted into usable time.

For each battery used in the camcorder, the internal electromotive voltage v
A characteristic curve showing the correspondence between the above and the usable time T (remaining amount) is measured in advance. In this case, in order to improve the accuracy, the characteristic values are obtained by averaging the measured values of a plurality of batteries of the same or a plurality of types that may be used. FIG. 5 shows a characteristic curve in the case of a Ni-Cd secondary battery. The data of the characteristic curve 60 is stored in the memory of the arithmetic circuit 46.
On the other hand, in the case of the AC adapter, the output DC voltage does not decrease with the passage of time, and therefore, for example, a substantially linear characteristic 62 shown by a broken line is obtained.

When it is desired to estimate the remaining amount in another operation mode, T may be multiplied by a coefficient k corresponding to the current consumption.

Next, the processing procedure of the remaining amount display will be described with reference to FIG. The operation starts when the power is turned on. First, the operation mode is set to the stop mode (S1).
The output voltages V ₁ is measured to determine the output current I ₁ corresponding to the stop mode by the arithmetic circuit 46 (S2). Then, the recording pause state (S3), measuring the output voltage V ₂ of the battery 34 in the measurement circuit 44 obtains a current value I ₂ corresponding to the recording mode by the arithmetic circuit 46 (S4). Then, v is obtained from equation (3), and the remaining amount T is obtained from the characteristic curve (S5).

Check whether the mode has been changed (S6), and if changed, reset the timer (S10).
The timer starts counting (S7), and circulates through S6 to S8 until a predetermined time elapses (S8). After a predetermined time has elapsed, the flag F is set to 1 (S9), and the timer is reset (S10). The flag F is a flag indicating whether to perform the integration calculation processing or the recalculation processing. If the same processing continues for a predetermined time, F = 1, the integration calculation processing described later is performed, and the mode remains unchanged. , The recalculation processing described later is performed while the flag F remains 0.

After resetting the timer (S10), check the mode (S1
1) According to each mode (stop, recording, recording pause), a value obtained by converting the battery consumption value into the remaining amount is set in a variable t (S12, 13, 14), and the current values Ia, Ib, Ic is set to the variable I (S15, 16, 17). Thereafter, according to the flag F (S18), when F = 1 (integration calculation processing), first, the flag F is returned to 0 (S19), and the consumption amount t
Is subtracted (S20), and the latest remaining value T is displayed (S21).

When F = 0 (recalculation processing) (S18), the output voltage V after the mode change is measured, and the internal electromotive voltage v is obtained using the current I set in S15, 16, 17 (S22). V calculated this time
Then, the difference Δv between the calculated value and the previously calculated value v is calculated (S23). At this point, I ₁ , V ₁ and I ₂ , V ₂ substituted into equation (3) are exchanged. Thereafter, similarly, in the T operation step, the suffixes “1” and “2” are exchanged as needed. After S23, the latest remaining value T is obtained (S24).

The absolute value of Δv obtained in S23 is compared with a predetermined threshold Vth (S25). If it is greater than Vth, the battery is used as a power source because the capacity has decreased, and if it is greater than Vth, it can be determined that the battery is the AC adapter 35. However, even in the case of a battery, there is a relatively flat portion in the center of the characteristic curve 60.
If it is less than Tth, it is determined to be an AC adapter (S2
7).

When the battery 34 is used, the estimated remaining amount T is displayed (S21), and when the AC adapter 35 is used, the remaining amount display is deleted, or FIG. 4 (c). "FUL
Switch to a display unique to the AC adapter, such as "L" (S2
7) Turn off the power saving timer to prevent battery consumption (S28).

After S21 or S28, the process returns to S6, and the steps after S6 are cyclically executed.

Although an AC adapter has been described as an example, an adapter for a car battery used in an automobile may be used. Also switch
Although the battery 34 or the AC adapter 35 was selected by 36, the AC adapter was connected in parallel with the secondary battery,
The configuration may be such that power is supplied from the AC adapter to the camera unit and the VTR unit 32, and the battery is charged.

In the present embodiment, not only can the remaining amount be estimated with high accuracy even at the time of mode switching, but also the estimated remaining amount value is appropriately updated even when continuously used without mode switching. In addition, even if a non-battery power supply is used, an inappropriate remaining amount is not displayed.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, it is possible to automatically determine whether or not the power supply currently used is a battery power supply. Despite this, the inconvenience that the calculation of the battery remaining amount is executed is eliminated, and the result of the battery remaining amount detection can be prevented from being affected by the use of the non-battery power supply. Further, according to the present invention, a mechanical detection mechanism for detecting whether or not the power supply currently used is a battery power supply is not required, and the device can be reduced in size and weight, and The configuration of the device can be simplified, and it is particularly useful for a portable device such as a video camera.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a circuit for explaining the operation principle of this embodiment, FIG. 3 is an operation flowchart of this embodiment, and FIG. FIG. 5 is a characteristic curve of the internal electromotive voltage of the battery versus the remaining amount, and FIG. 6 is a block diagram showing the configuration of a conventional example. 30: Camera part, 32: VTR part, 34: Battery, 35: AC adapter, 40:
System control circuit, 42: pointing device, 44: measuring circuit, 46: arithmetic circuit, 48: display device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Wako Tobe 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Tamagawa Office of Canon Inc. In-house (56) References JP-A-59-211972 (JP, A) JP-A-61-164170 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 5 / 222-5 / 257 H01M 10/42-10/48 H02J 7/00-7/12

Claims (1)

(57) [Claims] 1. An electronic device having a plurality of operation modes in which a battery power source and a non-battery power source can be selectively or simultaneously connected and having different load resistances from each other, wherein the power source of the electronic device is changed according to a change in the operation mode of the electronic device. Measure the change in output, according to the measured output change state of the power supply, determine whether the current power supply is a battery power supply, if the current power supply is a battery power supply, The remaining battery level is detected by comparing a previously stored battery remaining capacity characteristic with a measured change in the output of the power supply, and information relating to the detected remaining battery level is notified to the user. An electronic device having a power source discriminating function, comprising: