JPS5977365A - Digital multimeter - Google Patents

Abstract

PURPOSE:To improve operability by prohibiting the automatic range control function when a zero adjusting function and an adjusting function are performed. CONSTITUTION:When neither the zero adjusting function non the adjusting function is performed, as no adjusting signal is inputted from an adjusting input terminal 1, the adjustment display signal 11 goes to the L level and the NOR gate is opened. Depending on the presence of a control signal to be applied to a manual range control input terminal 3, a manual range clock signal 10 or an automatic range clock signal 9 is inputted into a range control circuit 8 passing through NOR gates 6 and 7. As soon as an adjusting signal is inputted into the terminal 1, an adjustment detection circuit 2 words to turn the adjustment display signal 11 to the H level to close the NOR gate 7 and a range clock signal is prohibited to fix the range.

Description

[Detailed Description of the Invention] The present invention is a digital multimeter (hereinafter referred to as DMM).
This relates to the zero adjustment function and the adjustment function.

The purpose of the present invention is to fix the range at the same time during the zero adjustment function and the adjustment function in the DM'ML:f)"?F adjustment function and the adjustment function without performing manual range fixing operation. Our goal is to provide products with improved operability.

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In the conventional (7) 5.5-digit DMM auto range function, 1
Move down range at 80 counts or less, and 20
Move to up range when power is 00 or more. Further, the zero adjustment function and the adjustment function are canceled when the range is changed. Now, if an adjustment is made to set the last two digits to zero for an input of 183 counts, the count number will reach 100 counts, the range will move to the down range, and the adjustment function will be canceled.

In addition, in resistance measurement mode, even if the input terminal is placed in the shimmed state to cancel the fuse terminal resistance, etc. and the zero adjustment function is activated, the input terminal is opened once during resistance measurement, so the count number will be 2000 forces. When the range is above, the range moves to the up range and the zero adjustment function is released. In order to prevent the zero adjustment and adjustment functions from being canceled due to the range moving during measurement after zero adjustment and adjustment, manually perform range fixing operations for each zero adjustment and adjustment, and then The present invention eliminates these drawbacks, such as having to perform blade adjustment and adjusting operations, resulting in a product with very poor operability.The present invention eliminates this drawback, and allows manual range fixing operations to be performed in the zero adjustment function and adjustment function of the DMM. To provide a product with improved operability so that the range can be fixed at the same time during the zero adjustment function and the adjustment function.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an implementation circuit diagram according to the present invention, which is formed in a one-chip A/D converter TJSl, and includes an adjustment detection circuit 2. Auto/Runny Alrange Clock Generation Circuit 4. Mark display 5, NOR/7'-Toro, 7. It consists of a range control circuit 8.

When the zero adjustment function and the adjustment function are not performed, no adjustment signal is input from the adjustment input terminal 1, so the adjustment display signal 11 becomes L level, the adjustment display circuit 5 does not operate, and the NOR gate 7 is opened. Manual range control human power fa child 3
(C=r) When the o-pv multiplication signal is not input, the auto/manual range clock generation circuit 4 generates the auto range clock signal 9 so that the range corresponds to the input. NOR gate 6.7
The signal is input to the range control circuit 8 as the range clock signal 12. The range control circuit 8 outputs a range signal 13 to set it to a predetermined range. Also, when a control signal is input to the range control input terminal 3, the auto/manual range clock generation circuit 4 generates an auto range clock signal 9.
is inhibited, a clock is generated in the manual range clock signal 10 for each bushing, and the NOR gate 6.7
2, which is input to the range control circuit 8 as a range clock signal 12 and outputs a range signal 13 set to an arbitrary range. On the other hand, when an adjustment signal is input to the adjustment terminal 1, it is detected by the adjustment detection circuit 2, outputted as an adjustment display signal 11, and the mark display circuit 5 performs adjustment display and prohibits automatic display.

Also, since the adjustment display signal 11 is at H level, NOR
The gate 7 is closed, the range clock signal 12 is inhibited, and the range signal 13 is fixed to the range by the range control circuit 8. Furthermore, the timing for inhibiting the range clock signal 12 can be easily improved by simply connecting the conventionally used adjustment display signal to the NOR gate 7.

Therefore, the present invention provides a DMM zero adjustment function and an adjustment (four functions) that operate to fix the range to the relevant range at the same time during the zero adjustment function and the adjustment function without performing manual range fixing operation. We can provide products with improved properties.Also, 1 chip A
/ D conversion IJS Since it can be constructed in-house, it has extremely excellent effects such as stability, reliability, and improved mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an implementation according to the present invention. 1... Adjustment input terminal 2... Adjustment detection circuit 6... Manual range control input terminal 4..., t-)/Manual range clock generation circuit 5...Mark display circuit 6...NOR gate 7...NOR gate 8...Range control circuit 9...
Auto range clock signal 10...Manual range clock signal 11...Adjust display clock signal 1
2... Range clock signal 13... Range signal

Claims (1)

[Claims] A digital multimeter having a zero degree gamma adjustment function, an adjustment function, and an auto range function, characterized in that the auto range function is prohibited at the time of zero adjustment and at the time of adjustment, and the auto range function is fixed at the range.