JPS6173031A - Method for inspecting electric shaver sound - Google Patents

Abstract

PURPOSE:To decide a bad sound generated from a driving source part and a shaving part quantitatively by dividing the sound generated from the driving source part and the sound generated from the shaving part into respective cycle zones and detecting a value of the sound volume of each cycle zone. CONSTITUTION:The sound generated from an electric shaver 2 while driving is collected by a microphone 1. Then, the cycle zone of the sound generated from the driving source part, for instance, 1-2kHz and the cycle zone of the sound generated from the shaving part, for instance, 2-5kHz are abstracted respectively by BPFs 3, 4. Then, the outputs of each cycle zone are rectified 5, 6 and inputted to comparators 7, 8. Respective reference values 9, 10 are inputted to the comparators 7, 8 and compared with the measured values to detect the bad sound. Accordingly, since the values of the sound volume are detected by dividing into the cycle zones of the driving source part and the shaving part, the decision of the quality of the electric shaver can be made quantitatively and it is unnecessary to rely on a person's intuition.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for automating sound inspection and processes during quality inspection of electric shavers.

<cy> Conventional technology Since sound plays a large part in the quality of electric shavers, a method has traditionally been adopted to determine the quality of the product by inspecting the sound quality of the noise generated by the electric shaver while it is in operation. ing. The JIS (C-9614-79) standard stipulates the maximum standard amount for the sound volume generated by electric shavers.

In general, it is sufficient to just measure the volume according to this standard, but in the actual process, even those that meet the standard are further distinguished from quality in terms of sound quality in order to improve quality.

In terms of sound quality evaluation, a sound that seems to have good sharpness is rated as good.
Traditionally, in this type of sound inspection process, a full-time tester has been responsible for determining whether each electric shaver (101) has a dull sound as shown in Figure 8. A so-called sensory test method has been adopted in which the quality of the product is judged by listening to the sound generated by the product and comparing it with the sound produced by a limited sample (102) that serves as a reference prepared in advance.

However, this type of sensory testing method requires a highly skilled tester.Since the judgment criteria are not quantified, the judgment criteria can easily change depending on the physical condition of the tester. Regarding the process, it is desirable to stabilize the inspection and save labor by quantifying the criteria.

By the way, the symptoms of defective electric razors can be roughly divided into chattering noise generated from the drive source such as the motor, and vibration and dullness generated from the shaving part consisting of the outer and inner blades.Sensory tests also indicate that the drive source is defective. The defective products are sorted into those with defects in the shaved part and defects in the shaved part, and the defective products are sent to the respective repair processes.

One way to judge the quality of the noise produced by an electric shaver is to use the sound level meter described in Japanese Utility Model Publication No. 56-34266, in accordance with the above-mentioned JI 5 (C-9614-79) standard. A method of determining the volume may be considered, but with this method, it is not possible to distinguish between the respective defective symptoms of the sound generated from the drive source and the sound generated from the shaving section as described above.

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to quantitatively determine the defective symptoms of sounds generated from the drive source section and shaving section of an electric shaver, and to automate the sound inspection process. The purpose of the present invention is to provide a method of identification that can be used.

(d) Measures to solve the problem: Distinguish the sound components generated from an electric shaver during operation into a frequency band occupied by the sound generated from the drive source section and a frequency band occupied by the sound generated from the shaving section. Then, the quality of the electric shaver is determined by comparing the volume values in each frequency band with respective volume reference values of the drive source and shaving section that are set in advance for quality determination.

(e) As an example of the effect, the sound generated from a rotary electric shaver will be analyzed and the results will be explained.

The sources of sound in this type of rotary electric shaver are the motor sound as the drive source and the sliding sound between the outer blade due to the rotation of the inner blade.The noise generated from each part can be classified based on the noise generated from each part. Figure 2 shows the spectral distribution of sound comparing the case where the motor is driven without the inner cutter and the case where the motor and the inner cutter are allowed to be driven with the inner cutter attached.

In this figure, the horizontal axis represents the frequency f (Hz), and the vertical axis represents the relative value of the sound pressure level (dB).
) is plotted as a solid line, and the case with an inner blade (curve ■) is plotted as a dotted line. Looking at the spectral characteristics of the motor alone, the sound pressure level is high in the frequency band of 1 to 2 KHz,
Furthermore, when looking at the fine structure, it is recognized that peaks occur at intervals of approximately 200 to 300 Hz. The frequency of this peak is the rotational speed of the motor. (Hz), r
Corresponds to an integer multiple of M.

In this measurement, the motor was of a three-slot type (having three rotors (103) (10
4) (104) is a field magnet, and (105) is a coil. ) is used. In this case, the rotational speed of the motor is 70 to LOOHHz in frequency representation. The frequency r1 of each peak is determined by rs-3Xf'MX N (N is a natural number), and the frequency interval of the peaks is 3fMz210~300 (
Hz), and it can be seen that the spectral characteristics in FIG. 2 substantially match the theoretical values.

Furthermore, in FIG. 2, it is recognized that the sound pressure level increases in the frequency band of 2 KHz or higher when the inner cutter is attached. The sounds in this frequency band are considered to be mainly the sliding sounds of the inner and outer cutters. In this case, the frequency r2 of each peak is determined by r2-rPIXM (M is a natural number). However, the value of M is determined by the shape of the hole (107) of the outer cutter (106) shown in FIG. 4, and is a value corresponding to the number of holes corresponding to - amount.

As described above, the sound mainly generated from the motor and the sound mainly generated from the shaving section can be considered separately based on their spectral characteristics.

Next, Fig. 5 (a
) to (d), however, the rotation speed rPl of the motor varies even in the same type of electric shaver, and also varies depending on the driving voltage of the motor, so it is not always constant.
Therefore, the peak frequency of the spectral characteristic (i.e. f't-3
Variations occur in f'MN and f'zmf1.1M>.

For this reason, FIG. 5 shows the spectrum distribution in the form of a 1/3 octave width reduced.

Figure 5 (a) shows the spectral distribution of an electric razor in which both the motor and the shaving part were determined to be "good", and (b) shows the spectral distribution of the shaving part as "good".
(C) is the spectral distribution of an electric razor that was determined to be "good" but the motor was "defective"; (C) is the spectral distribution of an electric shaver that was determined to be "good" for the motor but "defective" for the shaving part. , (d) shows the spectral distribution of an electric razor in which both the motor and the shaving part were determined to be defective, the dashed-dotted line marked with the symbol ■ indicates the standard value for the motor sound, and the dashed-double line marked with the symbol ■ indicates the hair growth. This is a reference value for sound. Further, in the figure, hatched areas indicate areas where the motor noise exceeds the reference value, and hatched areas indicate areas where the rattling sound exceeds the reference value.

Now, in FIG. 5, when comparing the sound pressure levels of the non-defective product and the defective product, the sound pressure level of the non-defective motor product exceeds the standard value in the frequency band of 1 to 2 KHz. (Refer to FIG. 5(b)) ③ For defective shaved parts, the back pressure level in the frequency band of 2 to 5 KHz exceeds the standard value. (See Figure 5(c).) For products in which both the motor and the shaving part were found to be defective, the sound pressure levels in the frequency bands of 1 to 2 KHz and 2 to 5 KHz both exceeded the standard value.

(See Figure 5(d)) can be characterized as.

The present invention aims to automate the sound inspection by using the above-mentioned means based on the above-mentioned back analysis results, and detects the sound pressure level in the frequency band of 1 to 2 KHz and sets it in advance to determine the quality of the motor sound. The magnitude relationship with the reference value is compared, and if it exceeds the reference value, it is determined to be ``failure'', and if it does not exceed the value, it is determined to be ``good''. Also, to judge the quality of the shaved part, 2~
The sound pressure level in the 5KH2 frequency band is detected and compared in magnitude with a preset reference value, and if it exceeds the reference value it is determined to be 1 failure, and if it does not exceed it it is determined to be ``good''.

Embodiment FIG. 1 shows a block diagram of the basic configuration for carrying out the sound testing method of the present invention.

(1) is a microphone that picks up the mixed signals generated by the electric shaver (2) that is being operated, and (3) and (4) are band-pass filters that extract frequency components focused on the motor sound or hair stinging sound ( BPF), (5) and (6) rectify the respective outputs from the filters (3) and (4).
Flow circuit, (7) (8>c) A funparator that compares the output from the IHIJl path (5) and (6) with preset reference values (9) and (10) of motor sound or stinging sound. In such a configuration, the bandpass filter (3) (
The extraction frequency of 4> and the comparison voltage (reference value) of the humparators (7) and (8) may be adjusted as appropriate depending on the type of electric shaver to be inspected.

Since the determination results regarding the defective motor and the defective shaving unit are obtained as the outputs of the comparators (7) and (8),
This output signal is used to sort out good products and defective products.

FIGS. 6 and 7 show a block diagram of an implementation circuit based on the above basic configuration and a flowchart of its operation.

This embodiment shows a case where control is performed using a microcomputer (hereinafter referred to as microcomputer) so that the sound inspection process can be completely automated.

In FIG. 6, (11) is a microphone that picks up the mixed noise generated from the electric shaver while it is being driven; (12) is a bandpass filter A that extracts frequency components focused on motor sound from the output of the microphone (11); 13)
Similarly, is a bandpass filter B, (L4) (15) which extracts a frequency component focused on the tingling sound from the output of the microphone (11). C) Outputs from the bandpass filters A (12) and B (13) The t-current devices A and B, <16017) that rectify the t-current device A and B (15) are A/D converters A and B, (18) and (19) that convert the analog output of the t-current device A (14) and B (15) into digital signals. is the I10 port A (
boat number 1) and B (port number 2), and (20
) is the I/O port A (18) and H B (1
9) (7) It is a microphone that processes data.

In the case of this embodiment, the setting reference value used for determining the quality of the motor sound and the scratching sound can be done by the program of the microcomputer (20), and the determination of the magnitude relationship with respect to the reference value can also be performed by the calculation by the microcomputer (20). This can be done by processing. Furthermore, detection of the sound pressure level of motor noise and stinging noise is carried out by selecting the port numbers of I10 ports A (18) and B (19) of the interface by a program, and
Since the information taken in can be instantaneously switched, it is possible to judge whether the motor sound and the stinging sound are good or bad by temporally serial processing.

Data processing within the microcomputer (20) will be explained based on FIG.

First, set the interface port number to 1, and
Frequency band (1) focusing on the motor sound of 0 port A (18)
Data A after analog-to-digital conversion of the sound pressure level (~2KHz) is input into the microcomputer (20), and the difference A- from the sound pressure level reference value B set in advance by the program is
B is calculated, and when A-B is positive, it is determined that "motor is good", and when it is negative, it is determined that "one motor is good", and the result is output.

Next, successively set the interface port number to 2,
Data C after analog-to-digital conversion of the sound pressure level in the frequency band (2 to 5 KHz) focusing on the stinging sound of I10 boat B (19>) is imported into the microcomputer (2o), and the sound pressure level is set in advance by the program. Calculate the difference CD from the standard value, and if CD is positive, 1 shaved part is defective.
, if it is negative, it is determined as "shaving head" and the result is output.

As described above, electric razors that have been determined to be defective are
Good products are distinguished from non-defective products by manually or automatically removing them.

(G) Effects of the Invention As explained above, the present invention distinguishes the sound components generated from an electric shaver during operation by adjusting the frequency band occupied by the sound generated from the drive source section and the frequency band occupied by the sound generated from the shaving section. The quality of the electric shaver is determined by comparing the volume values in each frequency band with the volume reference values of the drive source and shaving part set in advance for quality determination. Because it is a product, it is possible to quantify the criteria for determining the quality of electric razors without relying on human intuition as in the past, making quality inspections more stable, and also automating inspections and increasing the number of units inspected per unit time. You can also aim for
It has a great effect on improving efficiency and saving labor in the inspection process, and the profits in the production process are significant.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of the sound inspection method of an electric shaver of the present invention, Fig. 2 is a spectrum analysis diagram of the sound generated by an electric shaver, and Fig. 3 is an outline of an embodiment of the drive source section. 4 is a top view of an embodiment of the shaving section, and FIG. 5 is a spectral distribution diagram of different electric razors whose quality was determined by sensory testing. (a) shows that both the motor and the shaving section are good. (b) is a product with a good motor quality, (c) is a product with a defective shaving part, and (d) is a product with a defective motor and shaving part. 7 is a flowchart explaining the operation of FIG. 6,
FIG. 8 is an explanatory diagram of a conventional sensory testing method.

Claims (2)

[Claims] (1) Divide the sound components generated from an operating electric shaver into a frequency band occupied by the sound generated from the drive source section and a frequency band occupied by the sound generated from the shaving section, and calculate the volume in each frequency band. A sound inspection method for an electric shaver, characterized in that the quality of the electric shaver is determined by comparing the value with preset sound volume reference values of a drive source and a shaving part for quality determination. (2) A sound component in a frequency band of 1 to 2 KHz is used to determine the quality of the driving source part, and a sound component in a frequency band of 2 to 5 KHz is used to determine the quality of the shaving part. A method for inspecting the sound of an electric shaver according to claim 1.