JPH0523373B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronic balance, and more particularly to an electronic balance equipped with a weighing chamber or a windshield case.

<Prior Art> Highly sensitive electronic balances with small reading limits are sensitive to the movement of airflow hitting a weighing pan because of their high sensitivity. Therefore, in such an electronic balance,
In order to prevent wind from hitting the dishes, a capacity chamber (sometimes called a windshield case) is provided that is separated from the outside world by a windshield, and the plates are placed inside this capacity chamber. When loading and unloading a sample on this plate, open the door provided in the weighing chamber.

<Problems to be solved by the invention> By the way, there is no electronic balance in the weighing room.
A certain amount of heat flows in due to the heat generated by electronic circuit components such as ICs. This inflow of heat creates a slight temperature difference with the outside air, and when the door is opened, convection occurs within the capacity chamber. This convection does not subside instantly even when the door is closed. Therefore, when the door is opened, the sample is placed on the pan in the weighing chamber, and the door is closed, it may appear as if an accurate weighing value is displayed, but the value is not completely affected by convection. It often happens that the value differs from the true measured value at the time of settling. Therefore,
In such a case, there are problems such as reading an incorrect measured value, or it being unclear at what point the measured value should be read, resulting in a decrease in work efficiency.

The present invention has been made to solve these problems.

<Means for Solving the Problems> The configuration of the present invention will be explained based on the basic conceptual diagram shown in FIG.

A pan that engages the load sensing portion is located within the weighing chamber. The weighing chamber is equipped with a door for loading and unloading the sample onto a plate. The load on the plate is detected by the load detection section and sent to the calculation section at predetermined time intervals. The arithmetic unit determines the measured value by averaging the data sent within a set averaging time using a known method. Furthermore, data fluctuation/stability is determined based on whether the data is within a set stability detection range.

In addition to the above known configuration, the present invention includes a sensor that detects the opening/closing status of the door. Further, the memory stores preset times for the set values of the data averaging time and the stability detection width. Then, after the door is closed and a time corresponding to each of the above-mentioned setting values has elapsed, permission to read the measured value is given. This reading permission is given in the form of a display or sound of a buzzer or the like to notify the worker, or permission to externally transfer data.

<Function> The time it takes for convection to subside to the point that it does not affect the weighing value after the door is closed depends on the sensitivity of the electronic balance and the special characteristics of the balance, such as the weighing chamber and the shape of the pan. Furthermore, since it differs depending on the setting values of the averaging time for calculating weighing values and the stability detection width for determining stability, the waiting time should be set according to each setting value, taking into account the characteristics of the balance, etc. By setting this, reading permission is always granted after an optimal amount of time has elapsed, making it possible to achieve the initial purpose.

<Example> Examples of the present invention will be described below based on the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

A capacity chamber 2 is formed above the load detection section 1, and a plate 1a is arranged inside this capacity chamber. The capacity room 2 has doors 3 and 4 on the left and right.
is provided. The opening/closing status of the doors 3 and 4 is detected by photocells 5 and 6, respectively. That is, as shown in FIG. 3, for example, when the door 3 or 4 is completely closed, a black painted portion 3a or 4a is provided at a location corresponding to the placement position of the photocell 5 or 6, and this is attached to the photocell 5 or 6. When detected at 6, a closing signal for the door 3 or 4 is generated.

The closure signals from photocells 5 and 6 are
It is input to the AND element 7 , and its AND output is taken into the control section 9 via the input/output port 8 .

The control unit 9 is composed of a microcomputer, and includes a CPU 9a, a ROM 9b, and a RAM 9c.
etc. In addition to the input/output port 8 described above, the control unit 9 includes a load detection unit 1, an indicator 10,
An operation key 11 is connected.

The control unit 9 collects detection data of the load on the plate 1a from the load detection unit 1 every moment, and stores it in the ROM 9b.
Operation key 1 based on the program written in
The weighing value is calculated according to the averaging time and stable detection width established by 1, and the value is displayed on the display 10.
to be displayed. In other words, the averaging time is the time taken to calculate the weighing value by averaging the data collected over several seconds when averaging the load detection data, for example, 6 seconds, 12 seconds, or 18 seconds. You can choose one. In addition, the stable detection width is a reference width for determining whether the output data from the load detection section 1 is in a stable state or fluctuating, and the output data is continuously within the width for a predetermined number of times. When the data has stabilized, it is determined that the data is in a stable state, and the average value based on the number of data for the above-mentioned averaging time is calculated to determine the metric value. When it is determined that the data is fluctuating, in order to cope with the fluctuation, the measured value is changed moment by moment by averaging a smaller number of data and displayed on the display 10. This stable detection width can be selected, for example, from either 0.1 mg or 0.3 mg.

The above averaging time and stable detection width can be selected by operating the operation keys 11. In other words, due to the nature of their work, for example, when performing extremely high-precision measurements, the measurer may choose an averaging time of 18 seconds and a stable detection width of 0.1 mg; Rather, in the case of work where efficiency is given priority, an averaging time of 6 seconds and a stable detection width of 0.3 mg will be selected.

The ROM 9b has doors 3 and 4 closed together in accordance with the combination of the above-mentioned averaging time and stable detection width, based on various characteristics such as the shape of the weighing chamber 2 and the pan 1a of the electronic balance. Stores the time from when the convection occurs until the convection no longer affects the measured value. i.e. averaging time 18
For the highest accuracy measurement when a stable detection width of 0.1 mg is selected, for example, 10 seconds, or 6 seconds,
When 0.3 mg is selected, the above-mentioned time corresponding to each combination is set in advance, for example, as 5 seconds, and is stored in the ROM 9b.

When the signal from AND element 7 is input, CPU9a
waits for the elapse of a set time corresponding to the selected averaging time and stable detection width, and then grants reading permission. That is, reading is permitted after the set time has elapsed after both doors 3 and 4 are closed. As shown in FIG. 4, which is a front view of the display unit 10, the reading permission mark 10
This is done by notifying the measuring person by lighting up a or by sounding a buzzer or the like. Furthermore, when transmitting measurement data to the outside from the input/output port 8, the configuration may be such that the data is transferred after waiting for the determination of permission for reading.

<Effects> As explained above, according to the present invention, reading permission is granted after the time set according to the selection of the averaging time and the stable detection width has elapsed after the door of the weighing chamber was closed. This eliminates the possibility of accidentally reading weighing display values that include errors caused by convection in the weighing room, and also improves work efficiency because the measurer only needs to wait for permission to read before reading. It also leads to improvement. Furthermore, since the time from when the door is closed until reading permission is granted corresponds to the selected averaging time and stability detection width, the optimal time is always set, so there is no need to waste time. It's efficient and you don't have to wait for a long time.

[Brief explanation of the drawing]

Figure 1 is a basic conceptual diagram showing the configuration of the present invention;
The figure is a block diagram showing the configuration of an embodiment of the present invention.
The figure is a diagram explaining the relationship between the doors 3, 4 and the photocells 5, 6, and FIG. 4 is a front view of the display 10. 1... Load detection part, 1a... Dish, 2... Weighing chamber, 3, 4... Door, 3a, 4a... Black painted part,
5, 6...Photocell, 7...AND element, 8...
...I/O port, 9...Control unit, 9a...CPU,
9b...ROM, 9c...RAM, 10...display unit, 10a...reading permission mark, 11...operation key.

Claims (1)

[Claims] 1. In an electronic balance having a weighing chamber with a door that can be opened and closed and a plate that engages with a load detection section, the sensor detects the opening and closing status of the door;
Equipped with a memory that stores a preset time corresponding to the averaging time of the load detection data for calculating the weight value and the stability detection width for determining the stability of the weight value. An electronic balance characterized in that it is configured to permit reading of weighing values after a set time has elapsed.