JPS60247169A - Semiconductive flow speed detector - Google Patents

Abstract

PURPOSE:To detect a flow speed and a flow direction with good accuracy, by applying electric current or potential so that the temp. of a semiconductive flow speed detection element is definite temp. higher than that of a fluid and detecting the temp. difference at positions before and behind the flow speed detection element in the flow direction. CONSTITUTION:A heat generating transistor 2 is provided to the center of a semiconductive substrate 1 and temp. measuring transistors 3a, 3b are provided to both sides of said transistor 2 to constitute a semiconductive flow speed detection element 4. Collector potential VC is outputted to the heat generating transistor 2 so that the temp. of the semiconductive flow speed detection element 4 is definite temp. higher than that of a fluid detected by a temp. measuring transistor 5 and detected. The collector potential difference of the temp. measuring transistors 3a, 3b is detected. In this case, a flow speed Vf outputs potential in linear relation to collector potential VC and a flow direction has cosine relation to the potential difference VO and these outputs are operated to calculate the flow speed and the flow direction. Therefore, the flow speed and the flow direction can be calculated with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor flow rate detector for detecting the two-dimensional direction and flow velocity of a fluid flow, and particularly relates to a method for detecting the output thereof.

[Technical background of the invention and its problems]

The prior art will be explained with reference to FIGS. 81 to 3. 1st
The figure shows a semiconductor flow rate detection element 4 in which temperature measuring transistors 3m and 3b are formed at the center C2 of a semiconductor substrate 1, and symmetrical positions ζ on both sides of the heat generating transistor 2, and this semiconductor The flow velocity detection element 4 and the transistor 5 for measuring the temperature of the fluid are connected to a semiconductor flow velocity detector driving circuit as shown in FIG. 2, thereby forming a semiconductor flow velocity detector. The semiconductor flow velocity detector drive circuit detects the semiconductor flow velocity from the temperature measurement transistors 3m and 3b of the semiconductor flow velocity detection element 4 and the fluid temperature measurement transistor 5 by utilizing the fact that the base-emitter voltage of the transistor is proportional to the temperature. The temperature of the element 4 and the fluid is detected, and heat generation is controlled by changing the flowing current of the heat generating transistor 21 via the operational amplifier 6 so that the semiconductor flow rate detection element 4 is maintained at a constant temperature higher than the temperature of the fluid. It is something.

This semiconductor flow rate detection element 4 detects as an output the difference o between the collector potentials of the two temperature measuring transistors 3a and 3b of the semiconductor flow rate detection element 4, which changes in accordance with the flow rate (2).The third factor is , the fluid has three transistors 2, 3
FIG. 4 shows the flow velocity-output characteristics when flowing in the transverse direction of 8.3 btl, and FIG. 4 shows the dependence of the output on the flow direction when the flow velocity is constant. In this way, the output of conventional semiconductor flow velocity detectors depends on the flow velocity and flow direction, so flow velocity measurement can only be performed when the flow direction is determined.The flow direction can be detected by using the directional dependence of the output. In this case, there was a drawback that detection could not be performed unless the flow velocity was constant, and the conditions for use as a detector were limited. In addition, in the flow velocity-output characteristic, the output tends to saturate as the flow velocity increases, and the linearity is poor, and the disadvantage is that only a small output of about 15 nLv can be obtained with a wind of 3 m/me, for example. there were. It is desired to improve these characteristic defects.

[Purpose of the invention]

The purpose of the present invention is to improve the above-mentioned shortcomings of semiconductor flow rate detectors, such as change in output depending on the flow direction and non-linearity of the output, and to obtain a large output with good linearity compared to the flow rate (2). Another object of the present invention is to provide a semiconductor flow velocity detector capable of detecting the flow direction.

[Summary of the invention]

The present invention is designed so that the temperature of a semiconductor flow rate detection element, which has a heat generating element in the center of a semiconductor substrate and temperature measuring elements formed on both sides sandwiching the heat generating element, is maintained at a constant temperature higher than the temperature of the fluid. The heating element is made to generate heat, and the current flowing through the heating element that changes depending on the flow rate of the fluid, or the potential or voltage that changes in response to the current, is detected, and at the same time, the temperature between the two temperature measuring elements is detected. By detecting the temperature difference that occurs between the two as a current difference or voltage difference, the flow velocity and flow direction of the fluid can be detected.

〔Effect of the invention〕

According to the present invention, it is possible to perform accurate flow velocity detection and secondary flow direction detection of the fluid using a detector configuration similar to the conventional one.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to FIGS. 5 to 8. FIG. 5 shows the semiconductor flow velocity direction detector of this embodiment. The semiconductor flow rate detection element 4 has the same structure as that in the conventional semiconductor flow rate detector shown in FIG.

The drive circuit of the semiconductor flow velocity detector is also the same as that of the conventional example, and the semiconductor flow velocity detection element 4 is maintained at a constant temperature higher than the temperature of the fluid (2) The drive circuit for generating heat is made to generate heat by the transistor 2 for heat generation. The current flow 0 flowing through the transistor 2 changes depending on the flow velocity, and in this embodiment, the current flow 0
The collector potential ■0 of the heat generating transistor 2, which changes in response to the current, is detected as one of the outputs. At the same time, the difference in the collector potential of the two temperature measuring transistors 3a and Jb of the semiconductor flow velocity detection element changes in accordance with the flow velocity. is also detected as an output.

A feature of the present invention is that the above two outputs are detected simultaneously.

Figure 6 shows the flow velocity-output characteristics of the collector potential vO that changes depending on the flow velocity νf and the flow velocity (2), and it is possible to obtain an output that is larger and has better linearity than the output of a conventional semiconductor flow velocity detector. Since the output has a characteristic that it exhibits almost no dependence on the flow direction unlike conventional semiconductor flow velocity detectors, the flow velocity vf can be measured accurately from the output.

FIG. 7 shows a temperature measuring transistor 3a.

The output ■ obtained between the collectors of 3b. This shows the directional dependence of the fluid in the flow velocity vf, the fluid flow direction (0
) and the output ■o have the following relationship.

Vo=t'fCxIsθ As mentioned above, the collector potential vO of the heat generating transistor 2
From the change in , vf can be determined as uf=A・Δ■o, so this and the output V. From the above equation, the flow direction θ (-0≦θ
≦180). In other words, as shown in FIG. 8, vO and ■. If we input into the arithmetic circuit and perform the calculation, we get
It is possible to simultaneously detect flow velocity υf and flow direction θ (within a range of 180°), which was not possible with conventional semiconductor flow velocity detectors.

The present invention is not limited to the above-mentioned embodiments (but is not limited to the above embodiments), and can be implemented with various modifications as separately described below.

(1) From the characteristics of the transistor, the collector current is o-2
Since the emitter current is n, as shown in the fifth factor, it is also possible to detect the base potential VB or the emitter potential Vm instead of the collector potential VO as an output.

(2) In the configuration of the semiconductor flow velocity detector driving circuit, the constant current source can be replaced with a resistor (-) as shown in FIG.

(3) When the semiconductor flow rate detector of the present invention is used under conditions where there is little temperature fluctuation of the liquid or used only for direction detection, the temperature measuring transistor can be replaced with a resistor.

(4) Figure io uses two sets of semiconductor flow velocity direction detectors of the present invention, from 0 to 3609.7. This figure shows the arrangement of a semiconductor flow velocity detection element in an application example for detecting the flow velocity and direction of flow. The semiconductor flow rate detection elements are arranged 90 degrees apart from each other. By calculating the outputs from the two sets of semiconductor flow velocity detectors, the flow velocity and flow direction (θ to 360°) can be determined.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of a semiconductor flow velocity detection element, which is a flow velocity detection element, and Fig. 2 is a circuit diagram of a conventional semiconductor flow velocity detector.
FIG. 3 is a flow velocity-output characteristic diagram, FIG. 4 is a direction-dependent output characteristic diagram, FIG. 5 is a circuit diagram of a semiconductor flow velocity detector according to an embodiment of the present invention, and FIG. 6 is a flow velocity-output characteristic diagram. An output characteristic diagram, FIG. 7 is a direction dependence characteristic diagram of the output, FIG. 8 is a diagram showing the output signal processing method, and FIGS. 9 and 10 are semiconductor flow velocity detectors according to other embodiments of the present invention. FIG. 1... Semiconductor substrate, 2... Heat generating transistor, 3
8.3b...Transistor for temperature measurement, 4...Semiconductor flow rate detection element, 5...Transistor for temperature measurement of fluid, 6...Amplifier for O, 7m, 7b...Constant current source. Applicant's agent Patent attorney Suzue Takehiko Drawing I'I]
(No changes to the original contents) Figure 1 Figure 2 Figure V+ Figure 3 Figure 4 Figure 6 Figure Vl Commissioner of the Japan Patent Office Kazuo Wakasugi 1. Display of the case Japanese Patent Application No. 103028 No. 103028 2, Name of the invention Semiconductor flow velocity detector 3, Person making the amendment Relationship to the case Patent applicant αm Toshiba Corporation 4, Agent 5, Voluntary amendment

Claims (3)

[Claims] (1) A semiconductor flow rate detection element in which a temperature measurement element is formed in the center of the same semiconductor substrate (two heat generation elements and a temperature measurement element at symmetrical positions on both sides of the heat generation element), and a semiconductor flow rate detection element in which a fluid In a semiconductor flow velocity detector comprising: a drive circuit that causes the heat generating element to generate heat so as to maintain the temperature at a constant temperature higher than the temperature, the current flowing through the heat generating element and contributing to heat generation; C2, comprising means for detecting a correspondingly changing potential or voltage, and means for detecting a temperature difference occurring between two temperature measuring elements of the semiconductor flow rate detection element between a current difference or a potential difference;
A semiconductor flow velocity detector characterized in that the outputs of these detection means are calculated to measure the flow velocity of the fluid and the two-dimensional direction of the flow. (2) The semiconductor flow velocity detector according to claim 1, wherein the heat generating element formed in the semiconductor flow velocity detection element is a transistor. (3) The semiconductor flow rate detector according to claim 1, wherein the temperature measuring element formed in the semiconductor flow rate detection element is a transistor.