JPH0659049A - Powder detector - Google Patents

Abstract

PURPOSE:To prevent the occurrence of maldetection resulting from the leaked propagation of vibration to a case at the time of the vibration of a two-terminal type piezoelectric element serving as a powder sensor. CONSTITUTION:A zinc die cast member is especially used for a case 1 to which a powder sensor element 5 composed of a metallic vibrating plate 3 having a fixed two-terminal type piezoelectric element 4 serving as a powder sensor is attached. The zinc die cast member acts so as to restrain the leaked propagation of vibration at the time of the vibration of the piezoelectric element 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder detecting device for detecting the presence or absence of powder such as toner in a copying machine.

[0002]

2. Description of the Related Art For example, the amount of powder such as toner used in a copying machine is consumed as the number of copies increases. It is necessary to supply various powders. For such a purpose, a powder detection device for detecting the presence or absence or the remaining amount of powder is used.

FIG. 4 is a block diagram showing the structure of a conventional powder detecting apparatus. A two-terminal type piezoelectric element 14 is used as a powder sensor, and the piezoelectric element 14 is swept through an oscillation circuit 21 via both terminals 14A and 14B. The presence or absence of powder is detected by detecting the phase by the phase detection circuit 22 by utilizing the change in the phase characteristic when the phase is swept.

The two-terminal type piezoelectric element 14 is swept and oscillated 21
When the piezoelectric element 14 is swept in a frequency range including the resonance frequency, the phase characteristic shows a smooth phase change having a peak near the resonance point when the pressure applied to the piezoelectric element 14 is almost constant, as shown in FIG. Indicates. In FIG. 5, the vertical axis represents the phase θ and the horizontal axis represents the frequency f. At this time, the piezoelectric element 14 exhibits capacitance as a property over the sweep frequency range.

On the other hand, when the pressure applied to the piezoelectric element 14 decreases, this phase characteristic shows a steep phase change having a peak near the resonance point, as shown in FIG. At this time, the piezoelectric element 14 exhibits an inductive property in the vicinity of the peak as this property.

On the basis of such an operating principle, when the powder is exhausted or the remaining amount thereof becomes small, the pressure applied to the two-terminal type piezoelectric element 14 as the powder sensor decreases and the phase characteristic as shown in FIG. Changes, so that the presence of powder can be detected by the inductive property appearing in the vicinity of this peak. On the other hand, in the presence of powder, since the pressure is almost constant, the phase characteristic changes as shown in FIG. 5 and the capacitance appears over the sweep frequency range, so that the presence of powder can be detected.

FIG. 3 shows the structure of a conventional powder detecting apparatus. Brass, iron-nickel alloy, and a nickel-alloy alloy are provided in an opening on one side of a substantially cylindrical case 11 having a flange 12 on the other side.
A powder sensor element 15 in which a piezoelectric element 14 serving as a powder sensor is fixed to a metal vibrating plate 13 made of stainless steel or the like is attached via an adhesive 19 such as silicon rubber.

The case 11 is made of, for example, a resin body integrally molded with the collar portion 12, and when the piezoelectric element 14 vibrates, the piezoelectric element 14 is elastically supported by the presence of the adhesive 19. Alternatively, the case 11 may be made of a metal material such as brass.

Electrodes 14A and 14B are provided on the front surface and the back surface of the piezoelectric element 14, respectively, and are connected to terminals 16A and 16B via lead wires 15A and 15B. Reference numeral 17 is a chip component 1 required for the operation of the powder sensor such as the sweep oscillation circuit.
8 is a printed circuit board to be mounted.

[0010]

By the way, in the conventional powder detection device, when the two-terminal piezoelectric element 14 vibrates, the vibration may leak and propagate to the case 11, so that a false detection is likely to occur. There is.

That is, when the vibration of the piezoelectric element 14 leaks and propagates to the case 11 when the piezoelectric element 14 is swept and driven,
The phase characteristic at this time does not show a clear waveform as shown in FIG. 5 or 6 depending on the presence or absence of powder, and the waveform may be distorted to show an intermediate waveform as shown in FIG.
Since it is difficult to discriminate between these waveforms as shown in FIG. 5 and FIG. 6, erroneous detection results.

The present invention has been made in consideration of the above problems, and the powder is such that the phase characteristics of the piezoelectric element can be clearly distinguished according to the presence or absence of powder to prevent erroneous detection. An object is to provide a detection device.

[0013]

In order to achieve the above object, according to the present invention, a two-terminal type piezoelectric element is attached to an opening on one side of a cylindrical case through a metal vibrating plate. In a powder detection device for detecting the presence or absence of powder by utilizing a change in phase characteristics when sweep oscillation is performed, the case is composed of a zinc die-cast member.

[0014]

According to the structure of the present invention as set forth in claim 1, as a case in which a two-terminal type piezoelectric element is attached as a powder sensor via a metal vibrating plate, particularly by using a zinc die casting member, vibration of the piezoelectric element can be achieved. At this time, vibration can be prevented from leaking and propagating to the case.

According to the configuration of the present invention described in claim 2, 2
When the phase characteristic of the terminal type piezoelectric element changes from capacitive to inductive, it is determined that there is no powder.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the powder detecting apparatus of the present invention, in which 1 is a substantially cylindrical case having a flange portion 2 formed on the other side, and brass is provided in the opening portion on this one side. , A powder sensor element 5 in which a two-terminal type piezoelectric element 4 serving as a powder sensor is fixed to a metal vibrating plate 3 made of iron-nickel alloy, stainless steel or the like is attached via an adhesive 9 such as silicon rubber. .

Here, the case 1 is particularly made of a zinc die casting member. This zinc die cast member is formed by injecting molten zinc while applying pressure (for example, 1 kgf / cm ² or more) to a mold when forming zinc by a casting method (casting method).

Reference numerals 4A and 4B are electrodes provided on the front and back surfaces of the piezoelectric element 4, 5A and 5B are lead wires drawn from the electrodes 4A and 4B, and 6A and 6B are planted on the printed circuit board 7. 5A and 5B are connected terminals. On the printed board 7, a chip component 8 incorporating a sweep oscillation circuit for driving the piezoelectric element 4 and the like is mounted.

According to the present embodiment as described above, since the zinc die casting member is used as the case 1 supporting the powder sensor element 5, the zinc die casting member is used when the two-terminal type piezoelectric element 4 vibrates. , It acts to suppress the leakage propagation of vibrations. For this reason, when the piezoelectric element 4 is driven by the sweep oscillation circuit, particularly when there is no powder, the leakage propagation of this vibration during vibration of the piezoelectric element 4 is suppressed to a small level, and as shown in FIG. The phase characteristic with a sharp rising waveform can be obtained. Therefore,
Even if the waveform shown in FIG. 5 in the presence of powder is distorted, it can be clearly distinguished from this, and therefore false detection can be prevented.

Further, the zinc die casting member used as the case 1 can be formed at low cost and can be molded with high dimensional accuracy, and since the sound velocity is similar to that of the piezoelectric element 4 as compared with a material such as brass, vibration of the piezoelectric element 4 is reduced. Loss can be suppressed. (Sonic speed of piezoelectric element 3900m / s, sound speed of zinc die casting 4200m / s, sound speed of brass 4
700 m / s). As a result, it becomes possible to detect powder with higher sensitivity than conventional ones, so that it is possible to provide a powder detection device with excellent cost performance.

[0022]

As described above, according to the present invention, a zinc die casting member is particularly used as a case to which a powder sensor element made of a metal vibrating plate to which a two-terminal type piezoelectric element serving as a powder sensor is fixed is attached. Since it is possible to prevent the vibration from leaking and propagating to the case when the piezoelectric vibrator vibrates, it becomes possible to clearly distinguish the phase characteristics of the piezoelectric element depending on the presence or absence of powder, and Detection can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a powder detection device of the present invention.

FIG. 2 is a phase characteristic diagram obtained in the present embodiment when there is no powder.

FIG. 3 is a cross-sectional view showing a conventional example.

FIG. 4 is a block diagram showing a configuration of a powder detection device using a two-terminal type piezoelectric element.

FIG. 5 is a phase characteristic diagram conventionally obtained when powder is present.

FIG. 6 is a phase characteristic diagram conventionally obtained in the case of no powder.

FIG. 7 is a phase characteristic diagram for explaining a conventional problem.

[Explanation of symbols]

 1 case (zinc die casting) 3 metal diaphragm 4 2 terminal type piezoelectric element 5 powder sensor element

Claims (2)

[Claims] 1. A two-terminal type piezoelectric element is attached to an opening on one side of a cylindrical case via a metal vibrating plate, and a powder is utilized by utilizing a change in phase characteristics when the piezoelectric element is swept and oscillated. In the powder detection device for detecting the presence or absence of the above, the case is formed of a zinc die casting member. 2. The powder detection device according to claim 1, wherein it is determined that no powder is present when the phase characteristic of the two-terminal type piezoelectric element changes from capacitive to inductive.