JPH0695039B2 - Weighing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention comprises a weighing mechanism and a display device for calculating and displaying the weight after A / D converting the output of the weighing mechanism. Regarding the weighing device.

(Prior art and its problems) It is impossible to manufacture a uniform load cell in a weighing mechanism, such as a load cell, due to the accumulation of variations in the metal structure of the load cell, the processing accuracy, and the resistance that can be attached to the load cell. Is. Therefore, the span of the load cell (the output difference between no load and full load) differs depending on each load cell.

For this reason, in general, it is necessary to adjust the span after the weighing device is completed in the weighing device.

This span adjustment is performed by using a reference weight and adjusting the volume and the digital switch so that the difference between the output when the reference weight is not loaded and the output when the reference weight is loaded becomes a predetermined value.

Further, a span adjusting method described in Japanese Patent Laid-Open No. 56-125631 is also known. This span adjustment method adjusts the attenuator so that the level of the analog signal when the reference weight is loaded becomes a predetermined value and performs analog span adjustment, and the digital signal when the reference weight is loaded. A constant (span constant) is set in the weight setting device so that the output value (full scale output value) becomes a predetermined value, and digital span adjustment is performed.

On the other hand, recently, a weighing mechanism and a display device for calculating and displaying the weight after A / D converting the output of the weighing mechanism are separately configured,
By connecting them with a connecting cord, a weighing device with improved usability has been developed. In this type of device, the weighing mechanism and the display device are manufactured separately, and then they are combined to form a weighing device.However, in the conventional device of this type, whichever span adjustment method is adopted, The span adjustment could not be performed unless the measuring device was configured by connecting the measuring mechanism and the display device with a connecting cord.

For this reason, at the time of shipment from the factory, it is necessary to assemble the weighing mechanism, the display device, and the connection cord in separate boxes, and configure the weighing device at the customer's end, but to assemble it to adjust the span. In addition, after the span adjustment, it was necessary to separate each part again, which required much time and labor for span adjustment, resulting in poor productivity.

Further, when the span adjustment is performed with a certain weighing mechanism and a certain display device connected, if the weighing mechanism is replaced with another weighing mechanism, the span must be adjusted again using the reference weight.

For this reason, if the span is adjusted at the stage of shipping the product from the factory, and if the measuring mechanism and the display device are connected and the span is adjusted, the measuring mechanism and the display device must be packaged together. . This means that despite the fact that the weighing mechanism and the display device are configured separately,
This means that after the span adjustment, it is necessary to handle them as a unit, which is very inconvenient because of many restrictions in the manufacturing process, inspection process, and shipping process.

In order to solve this drawback, it is conceivable to adjust the span at the time of configuring the weighing device at the customer's end, but since a reference weight for adjustment is required to perform the span adjustment, it is not a realistic solution. Absent.

In addition, the above means that if the weighing mechanism fails at the customer (where the scale is used) and the weighing mechanism is replaced with another weighing mechanism, it is necessary to perform span adjustment using the reference weight. I mean. The span adjustment itself is a simple task, but the service person must bring a reference weight for this purpose. The reference weight for adjusting the span is 5 kg in the case of the maximum weight of 5 kg and can be carried, but it is practically impossible if the maximum weight exceeds 30 kg.

Therefore, in this case, the display device is brought to the maker and connected to the measuring mechanism to adjust the span, which is very troublesome.

(Object of the Invention) The present invention has been made in view of the above circumstances, and provides a weighing device in which a weighing mechanism and a display device are separately configured and which can perform span adjustment extremely easily. Is to provide.

(Structure of the invention) The technical means taken by the present invention to achieve the above-mentioned object are a measuring mechanism that outputs an analog signal according to a weight value, and a driving power is supplied to the measuring mechanism from the measuring mechanism. A display device for calculating and displaying the weight after analog-to-digital conversion of the output analog signal is separately configured, and the weighing mechanism has the weighing mechanism previously measured using a reference weight. The ratio between the span data and the span data of the reference load cell is indicated, and a ratio setting switch for setting the indicated ratio is provided in the measuring mechanism or the display device, and the display device is provided with the ratio setting switch. It is characterized in that correction means for correcting the output of the measuring mechanism based on the set value of the switch is provided.

(Operation) According to the above configuration, the measuring mechanism alone measures the ratio of the span of the measuring mechanism to the reference span, and the ratio is written at a predetermined position of the measuring mechanism, and the measuring device is connected to the display device. The span adjustment can be performed by setting the set value of the ratio setting switch to the above-described ratio at the time of configuring the above.

(Example) Explaining the span to span ratio in the present invention, first, a reference substrate provided with a reference load cell, a full load weight, and an A / D converter capable of reading the output of the load cell is prepared. (The reference substrate is the same as one incorporated in a display device described later.

(1) First, connect the reference load cell and the reference substrate and measure the output D _O under no load.

(2) Next, place the weight of full load on the reference load cell and measure the output _DF at full load.

(3) Calculate the reference span D _S by calculating D _O −D _O.

The reference span D _S is measured in advance as described above. Next, connect a load cell with an unknown span in place of the reference load cell, measure the output D _O ′ at no load, and measure the output D _F ′ at full load, and calculate the span D _S ′ = D _F ′ −D _O ′. calculate. Means the above span D _S 'ratio C = D _S / D _S of the' relative to the reference span D _S is the ratio of the span. As shown in FIG. 1, a sticker S indicating the span D _S ′ or the span ratio C may be attached to the measuring mechanism.

From the above C = D _S / D _S ′, D _S = C × D _S ′.

That is, by setting the ratio C in any circuit in the weighing device, the span D _S ′ of the load cell can be corrected to the span D _{S of the} reference load cell.

A first embodiment of the present invention will be described with reference to FIGS. 1 and 2.
In the figure, 1 is a weighing mechanism, 2 is a display device, and the weighing mechanism 1 is provided with a load cell 3 and a weighing pan.

In the display device 2, first, a power supply 10 for the load cell 3 is provided, and an amplification section 6 for amplifying the output of the load cell 3 is provided. The amplifier 6 is provided with an amplification degree adjusting volume 11 so that the amplification degree can be adjusted.

The A / D converter 4 is connected to the amplification unit 6 to digitize the load cell output, and the A / D converter 4 is provided with a correction calculation circuit 7
Connect. The correction calculation circuit 7 corrects the digital output based on the span ratio set by the ratio setting switch 5.

The display arithmetic circuit 8 is connected to the correction arithmetic circuit 7 so that the output of the correction arithmetic circuit 7 can be displayed and displayed on the display unit 9.

In the first embodiment, when the ratio C is set in the switch 5 based on the seal S indicating the span ratio C, the output of the load cell 3 is corrected so that it becomes the same as the reference load cell. It is displayed on the display unit 9.

Although other embodiments will be described below, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The second embodiment will be described with reference to FIG. 3. In this embodiment, the ratio setting switch 5 is provided on the measuring mechanism 1a side.
Other configurations and operations are the same as those in the first embodiment.

The third embodiment will be described with reference to FIGS. 4 and 5. In this embodiment, a ratio setting switch 5 _C is provided in the amplification section 6, and a resistor network is provided in the amplification section 6 to provide the switch 5 _C. It is set by. Other configurations and operations are the same as those in the first embodiment.

The fourth embodiment will be described with reference to FIG.
The converter 4 is provided with a ratio setting switch 5 _d . When the A / D converter 4 is a double integration type, V _X : output of the load cell 3, N _X : output of the A / D converter 4, V _R : reference voltage, N: ratio setting switch 5 _d If it is an output count, Therefore, the output of the A / D converter can be corrected by setting the output count N of the ratio setting switch 5 _d .

To describe the fifth embodiment by FIG. 7, the display apparatus 2 _e of this example the ratio set to supply 10 of the load cell 3 Switch
_5e is provided and the other structure is the same as that of the above embodiment.

Next, regarding the ratio setting switch, the switch may be a variable resistor with a dial, but it may be a DIP switch with a combination of ON and OFF shown in FIGS.
As shown in FIG. 0, a disc 20 having serrations on its outer periphery may be rotated to adjust the numbers appearing on the display window 21, and a digital switch may be used.

Further, the installation location of the switch is not limited to the machine frame, and may be in the machine frame.

In addition, the weighing device is affected by gravitational acceleration, and the weight acceleration is different in each country, so if you set the ratio that takes these effects into account and write it on the sticker or set the ratio setting switch, It is suitable for products for export.

If the weighing mechanism and the display device are configured separately, the weighing device is not limited to a single weighing device, and may include a label printer, a packaging machine, a carrier machine, and the like.

(Effect of the Invention) As described in detail above, the weighing device of the present invention is a weighing mechanism that outputs an analog signal according to a weight value, and an analog output from the weighing mechanism while supplying driving power to the weighing mechanism. A display device for calculating and displaying the weight after A / D conversion of the signal is separately configured, and the measuring mechanism has span data of the measuring mechanism obtained by measuring using a preliminary reference weight. , The ratio with the reference span data is indicated, and a ratio setting switch for setting the indicated ratio is provided in the measuring mechanism or the display device, and the display device has a set value of the ratio setting switch. Since the correction means for correcting the output of the measuring mechanism based on the above is provided, the set value of the ratio setting switch is set to the indicated ratio when the measuring device is configured by combining the measuring mechanism and the display device. Do This allows you to easily adjust the span.

That is, if the weighing mechanism is connected to the reference board and the ratio is calculated and described, the span adjustment can be performed without using the reference weight regardless of which display device the weighing mechanism is combined with. .

Therefore, at the stage of shipping from the factory, there is no need for the work of constructing the weighing device by combining the weighing mechanism and the display device for adjusting the span, and the productivity can be improved. Further, even when the measuring mechanism is broken and only the measuring mechanism is sent to the customer, the span can be easily adjusted by resetting the ratio setting switch based on the ratio displayed on the mechanism.

Therefore, the intended purpose can be achieved.

[Brief description of drawings]

FIG. 1 is a three-dimensional view showing the appearance of a first embodiment of the weighing device of the present invention, FIG. 2 is the same block diagram, FIG. 3 is a block diagram of the second embodiment, and FIG. 4 is a block of the third embodiment. 5 and 5 are principle diagrams of the same ratio setting switch, FIG. 6 is a block diagram of the fourth embodiment, FIG. 7 is a block diagram of the fifth embodiment, and FIG. 8 is a three-dimensional view of a DIP switch. FIG. 9 is the same principle diagram, and FIG. 10 is a front view of the digital switch. In the figure, 1,1a, 1b: Measuring mechanism 2,2a, 2b, 2c, 2d, 2e: Display device 3: Load cell 4: A / D converter 5,5b, 5c, 5d, 5e: Ratio setting switch S : It's a seal.

Claims (1)

[Claims] 1. A weighing mechanism for outputting an analog signal according to a weight value, and driving power to the weighing mechanism and A / D conversion of the analog signal output from the weighing mechanism to calculate the weight. The display device for display is configured separately from each other,
In the measuring mechanism, the ratio between the span data of the measuring mechanism and the span data of the reference load cell, which is obtained by measuring with a reference weight in advance, is indicated, and a ratio setting switch for setting the indicated ratio. Is provided in the weighing mechanism or the display device, and the display device is provided with a correction means for correcting the output of the weighing mechanism based on the set value of the ratio setting switch.