JP2003008386A - Crystal oscillator with resonance frequency temperature characteristic display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal oscillator capable of displaying the numerical values of first to fifth temperature coefficients without increasing a displaying area. SOLUTION: By using the presence of strong correlation between a third order temperature coefficient and a fifth order temperature coefficient and between a second order temperature coefficient and a fourth order temperature coefficient when approximating the temperature variation characteristic of the resonance frequency of an AT cut crystal oscillator by a fifth order expression with respect to the ambient temperature, only first to third order temperature characteristics are displayed by laser marking on a package surface to obtain the residual fourth and fifth order temperature coefficients, thereby a space for displaying marking is economized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal unit displaying a temperature coefficient of resonance frequency temperature characteristic.

[0002]

2. Description of the Related Art It is well known that an AT cut type crystal resonator has a temperature characteristic of its resonance frequency approximately having a third order temperature characteristic as shown in FIG. Generally A
It is well known that the change Δf of the resonance frequency f of the T-cut type crystal resonator with respect to temperature is given by the following equation and can be approximated by a cubic equation regarding the ambient temperature T. Δf / f = A ₁ (T-25) + A ₂ (T-25) ² + A ₃ (T-25) ³ (1) where T is ambient temperature, A1 is primary temperature coefficient, and A2 is Two
The secondary temperature coefficient, A3, represents the tertiary temperature coefficient, and the entire equation (1) is normalized with respect to the ambient temperature of 25 ° C. at which the inflection point of the cubic curve is located.

In general, when designing a temperature-compensated crystal oscillator, particularly for those having severe performance requirements for temperature compensation, the resonance frequency characteristics of each crystal oscillator are reflected in the temperature compensation circuit to provide more accurate temperature compensation. I'm trying to do. For example, as the inspection data of the crystal unit, the numerical values of the primary to tertiary temperature coefficients A _{1 to} A ₃ shown in the equation (1) are coded and displayed on the package by laser marking or the like. Then, in the assembly process, this is automatically read, and the content is usually reflected in the assembly and adjustment of the temperature compensation circuit.

However, when the required performance of the temperature-compensated crystal oscillator becomes more severe, it is necessary to approximate the temperature characteristic of the resonance frequency of the crystal resonator by the quintic equation shown in the equation (2) to further suppress the approximation error. Occurs. Δf / f = A ₁ (T-25) + A ₂ (T-25) ² + A ₃ (T-25) ³ + A ₄ (T-25) ⁴ + A ₅ (T-25) ⁵ (2) However, In order to use a fifth-order approximation formula such as the formula (2), the five temperature coefficients A1 to A5 must be coded and displayed on the crystal unit package. Therefore, the area for displaying the temperature coefficient increases, which is an obstacle to miniaturizing the package.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and is a crystal capable of displaying the numerical values of the temperature coefficients of the first to fifth orders without increasing the display area. It is intended to provide a vibrator.

[0006]

In order to solve the above-mentioned object, the invention according to claim 1 of a crystal resonator with a resonance frequency temperature characteristic display according to the present invention is the temperature of the resonance frequency of an AT cut type crystal resonator. In the AT-cut type crystal unit in which the change characteristics are approximated by a quintic equation regarding the ambient temperature, and the values of the temperature coefficient in the quintic approximation formula are coded and displayed on the package surface of the crystal unit by the quadratic equation, Based on the first correlation between the temperature coefficient and the fourth-order temperature coefficient and the second correlation between the third-order temperature coefficient and the fifth-order temperature coefficient, the second-order temperature coefficient or 4 at the package surface. The marking display of either one of the next temperature coefficient and one of the third temperature coefficient and the fifth temperature coefficient is omitted.

The invention according to claim 2 of the crystal resonator with a resonance frequency temperature characteristic display according to the present invention is characterized in that the temperature variation characteristic of the resonance frequency of the AT-cut type crystal resonator is approximated by a quintic equation relating to the ambient temperature. In the AT-cut type crystal resonator in which the values of the temperature coefficient in the fifth-order approximation equation are coded and displayed on the package surface of the crystal resonator by marking, the first temperature coefficient between the second-order temperature coefficient and the fourth-order temperature coefficient is obtained. Correlation, the second between the third-order temperature coefficient and the fifth-order temperature coefficient
And the relationship between the frequency deviation (Δf / f) of the resonance frequency at a specific temperature of the crystal unit and the primary temperature coefficient A1 are A1 = Ea (constant) × Δf / f + Eb (variable)
Based on the third correlation between the Eb and the second-order temperature coefficient or the third-order temperature coefficient that occurs when the first-order approximation
The values of / f and Eb (variable) are coded and marked on the package surface, and the secondary temperature coefficient A2
Alternatively, set either one of the fourth-order temperature coefficient A4 to A2 = Da
(Constant) × Eb ² + Db (Constant) × Eb + Dc (Variable)
Alternatively, A4 = Da (constant) × Eb ² + Db (constant) × E
quadratic approximation with b + Dc (variable) to obtain the third-order temperature coefficient A3
Alternatively, set either one of the fifth-order temperature coefficient A5 to A3 = Ca
(Constant) × Eb + Cb (variable) or A5 = Ca (constant) × Eb + Cb (variable) is linearly approximated, and the values of Dc (variable) and Cb (variable) are coded and marked on the package surface. The marking display of the value of either the secondary temperature coefficient or the quaternary temperature coefficient and the value of the tertiary temperature coefficient or the quintic temperature coefficient is omitted on the package surface.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the illustrated embodiments. Figure 1 shows the measured temperature characteristic of the resonance frequency of the AT-cut type crystal unit (2)
It is the figure which statistically showed the correlation between each 1st-5th temperature coefficient which performed the 5th approximation by a formula.

According to the actual measurement data confirmed by our company, A
As shown in FIG. 1 (a), the T-cut type crystal unit has 2
It was found that there is a strong linear correlation between the second-order temperature coefficient A2 and the fourth-order temperature coefficient A4. Further, as shown in FIG. 1B, it was found that there is a strong linear correlation also between the third-order temperature coefficient A3 and the fifth-order temperature coefficient A5. Therefore,
If only the temperature coefficients of A1 to A3 are displayed on the package of the crystal unit, even if the temperature coefficients of the remaining A4 and A5 are not displayed, even obtain the first-order approximation formula of FIG. 1 (a) (b) in advance. For example, it is possible to know the fourth and fifth temperature coefficients. Alternatively, either one of A2 and A4 and one of A3 and A5 may be displayed.

In the assembly process, the temperature coefficients A1 to A3 coded and displayed on the package surface are automatically read, and A is read from the read data.
4, the equipment may be programmed to automatically calculate A5. By doing so, there is no need to increase the space displayed in the package, and it is not necessary to change the format of the code displayed in the package. Therefore, for both the cubic approximation and the quintic approximation, Since the equipment can be shared and supported, the advantages will be great.

Next, a second embodiment will be described.
FIG. 2 shows the temperature characteristic of the AT-cut crystal unit, and shows how the curve of the temperature characteristic varies depending on the individual. Focus on a certain temperature point, for example, + 75 ° C. When the relationship between each coefficient of the fifth-order approximation formula and the frequency deviation (Δf / f) at + 75 ° C. was examined, it was found that there was a correlation (first-order) with the first-order coefficient A1 as shown in FIG. When this is expressed by an approximate expression, A ₁ = E _a × (Δf / f) + E _b (3)

As is apparent from FIG. 3, although the slope Ea of the equation (3) is almost the same, there is an individual difference (lot difference) in the y-axis intercept Eb. Therefore, the slope Ea is a fixed value, and Δf / f (+ 75 ° C.) and the y-axis intercept Eb are variables. Furthermore, when the relation between this intercept Eb and each temperature coefficient of the fifth-order approximation formula was investigated, as shown in FIG. 4A, a quadratic function-like correlation was found with the second-order temperature coefficient, and 3 A linear function correlation can be seen with the next temperature coefficient.

Secondary temperature coefficient A2 and tertiary temperature coefficient A3
When each of these is expressed as an approximate expression, A ₂ = D _a × E _b ² + D _b × E _b + D _c ... (4) A ₃ = C _a × E _b + C _b ... (5) Further, as shown in FIG. 1, A2 and A4, and A
A linear function-like correlation is seen between 3 and A5. Expressing this approximate expression, and _{A 4 = B a × A 2} + B b ··· (6) A 5 = A a × A 3 + A b ··· (7).

Here, Δf / f (+ 75 ° C.), Eb and C
Laser marking may be performed on the package by coding b and Dc as variables. Another factor, E
a, Da, Db, Ca, Ba, Bb, Aa, Ab, Ac
Is given in advance as a fixed value, so that the temperature coefficients A1 to A5 of the first to fifth orders can be obtained. In addition,
A procedure for obtaining each temperature coefficient of the second embodiment from the laser marking is shown in FIG. 5, which will be described below. First, FIG.
In the package, Δf / f (+ 75 ° C), Eb,
The values of the combination of Cb and Dc are coded and displayed as a 3-digit code as a whole. Therefore, the values of Δf / f (+ 75 ° C.) and Eb, which are the codes of the first digit and the second digit, are substituted into the equation (3) to obtain the primary temperature coefficient A1.

Next, E, which is the code of the second and third digits
Substituting the value of b, the combination of Cb and Dc into equation (4), 2
Next temperature coefficient A2 is calculated. Further, the value of Eb, the combination of Cb and Dc, is substituted into the equation (5) to obtain the third-order temperature coefficient A3. Next, the value of the secondary temperature coefficient A2 obtained by the equation (4) is substituted into the equation (6) to obtain A4, and the value of the tertiary temperature coefficient A3 obtained by the equation (5) is substituted into the equation (7). And 5th temperature coefficient A
You can ask for 5. The procedure for obtaining the first to fifth order temperature coefficients from the 3-digit code displayed on the package has been described above.

The third temperature coefficient A3 and the fifth temperature coefficient A
5 and 5 are respectively approximated by a linear expression, but a slightly curvilinear behavior can be seen from FIG. 1B, and it is needless to say that the approximation accuracy is improved by quadratic approximating these. In this case, it is more accurate by treating Aa, Ab, and Ac as fixed values using A ₅ = A _a × A ₃ ² + A _b × A ₃ + A _c (8) instead of the formula (7). Various temperature compensation data can be obtained.

In the crystal unit with the resonance frequency temperature characteristic display described above, the information on the first to third order temperature coefficients or the three-digit code is laser-marked on the package. However, the present invention is not limited to this. Instead of displaying the temperature coefficient information, the resistance temperature coefficient of the equivalent resistance may be displayed. In the embodiments of the present invention, the description of the display of the temperature characteristic of the equivalent resistance is omitted for simplification of the description.

[0018]

As described above, according to the present invention, in the temperature characteristic of the resonance frequency of the AT-cut type crystal unit, when the temperature characteristic is approximated by a quintic equation, the third-order temperature coefficient and the fifth-order temperature coefficient are , And the fact that there is a strong correlation between the second-order temperature coefficient and the fourth-order temperature coefficient, by displaying only the first- to third-order temperature coefficients on the package,
Since the following temperature coefficients are available and it is not necessary to display the 4th and 5th temperature coefficients on the package, it is extremely effective in providing a crystal unit with a temperature characteristic display that can save display space. Play.

[0019]

[Brief description of drawings]

FIG. 1 is a diagram showing the correlation of each temperature coefficient in a crystal unit with a temperature characteristic display according to the present invention.

FIG. 2 is a diagram showing variations in resonance frequency temperature characteristics of the crystal unit with temperature characteristics display according to the present invention.

FIG. 3 is a diagram showing a correlation between a primary temperature coefficient and a secondary temperature coefficient of a crystal unit with a temperature characteristic display according to the present invention.

FIG. 4 is a diagram showing a correlation between Eb and a first-order temperature coefficient or a second-order temperature coefficient of a crystal unit with a temperature characteristic display according to the present invention.

FIG. 5 is a diagram showing a procedure of a second embodiment relating to a crystal unit with temperature characteristic display according to the present invention.

FIG. 6 is a diagram showing a resonance frequency temperature characteristic of a crystal unit.

Claims (2)

[Claims] 1. A temperature change characteristic of a resonance frequency of an AT-cut type crystal resonator is approximated by a quintic equation relating to ambient temperature,
The temperature coefficient values in the following approximate equations were coded and marked on the package surface of the crystal unit A
In the T-cut type crystal resonator, based on a first correlation between the second-order temperature coefficient and the fourth-order temperature coefficient and a second correlation between the third-order temperature coefficient and the fifth-order temperature coefficient, Resonance frequency temperature characteristics characterized by omitting marking display of either the second-order temperature coefficient or the fourth-order temperature coefficient and the value of the third-order temperature coefficient or the fifth-order temperature coefficient on the package surface. Crystal unit with display. 2. A temperature change characteristic of a resonance frequency of an AT-cut type crystal resonator is approximated by a quintic equation relating to ambient temperature,
The temperature coefficient values in the following approximate equations were coded and marked on the package surface of the crystal unit A
In a T-cut type crystal resonator, a first correlation between the second-order temperature coefficient and the fourth-order temperature coefficient, a second correlation between the third-order temperature coefficient and the fifth-order temperature coefficient, and The relationship between the frequency deviation (Δf / f) of the resonance frequency at a specific temperature of the crystal unit and the first-order temperature coefficient A1 is linearly approximated to A1 = Ea (constant) × Δf / f + Eb (variable), and Eb and quadratic Temperature coefficient or 3
Based on the third correlation with the next temperature coefficient, Δf / f
And the value of Eb (variable) are coded and marked on the package surface, and one of the secondary temperature coefficient A2 and the quaternary temperature coefficient A4 is A2 = Da (constant) × Eb ² + Db (constant) × Eb + Dc. (Variable) or A4 = Da (constant) × Eb ² + Db (constant) × Eb +
Dc (variable) is quadratic-approximated, and one of the third-order temperature coefficient A3 and the fifth-order temperature coefficient A5 is A3 = Ca (constant) × Eb + Cb (variable) or A5 = Ca (constant) ×
Eb + Cb (variable) is first-order-approximated, the values of Dc (variable) and Cb (variable) are coded and marked on the package surface, and either the secondary temperature coefficient or the quaternary temperature coefficient is marked on the package surface. On the other hand, a crystal unit with a resonance frequency temperature characteristic display, wherein the marking display of either one of the third temperature coefficient and the fifth temperature coefficient is omitted.