JPH0124374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention of this application relates to the delay time and pulse width temperature when configuring a pulse delay device using an inverter IC or the like in a delay line that employs an LC distributed constant circuit or an LC lumped constant circuit. The present invention relates to an impedance matching circuit that also enables compensation.

First, a conventional delay device employing a distributed constant circuit will be described with reference to FIG. 1 of the accompanying drawings. IC is an inverter IC for waveform shaping, and W is a brush wiper that slides on the coil. In this case, a fixed contact system without a brush wiper may be used. L is the inductance of the coil, and C is the capacitance between the coil and the ground electrode. Delay time Td, characteristic impedance
Zo is expressed by the following formula.

Td=√. Zo=√ Normally, in the circuit diagram in Figure 1, the terminating resistor Ro
is equal to the characteristic impedance Zo.

Ro=Zo Figures a, b, c, and d in FIG. 2 illustrate voltage waveforms at the points indicated by arrows a, b, c, and d in FIG. 1, respectively.

That is, FIG. 2a is the input waveform, and PW is the input pulse width. In the figure, b is the inverter output of the input waveform, c is the delayed waveform, d is the inverter output of the same, and PW' is the output pulse width. Further, Td+ is a rising delay time, and Td- is a falling delay time.

What you should be aware of is the phenomenon that an IC outputs an inverted output when the input reaches the threshold voltage Vth. That is, when shaping waveform c in FIG. 2 into waveform d, if threshold voltage Vth is between H level voltage Vh and L level voltage Vl, rise delay time Td+ and fall delay time Td-.
will be the same, so no variation in pulse width will occur. However, in general, there are no ICs that operate as if the threshold voltage Vth is in the middle as mentioned above; for example, in the case of a TTL IC, Vh = 4V, Vl =
0.6V, Vth = about 1.3V, so Td+ is larger than Td-, and the output pulse width is smaller than the input pulse width PW.
PW′ becomes smaller.

Furthermore, since the threshold voltage Vth has temperature characteristics, Vth is maintained low as the temperature rises. Therefore, in the circuit diagram shown in FIG. 1, even at room temperature, Td+ is larger than Td-, and the output pulse width is smaller than the input pulse width.
Moreover, this tendency becomes more pronounced as the ambient temperature rises.

FIG. 3 shows an embodiment of a circuit diagram according to the invention of this application. In the figure, Ri is an input resistance, Ro is a terminal resistance, and Rth is a resistor that has a negative coefficient with respect to temperature and is a so-called thermistor. 3rd below
A method for selecting the resistance value of each resistor shown in the figure will be explained. First of all, the parallel resistance value R=1/1/Ro+1/Rth of the terminating resistor Ro and thermistor resistor Rth at room temperature is set to be equal to the characteristic impedance Zo=√. Above characteristic impedance Zo
The voltage waveform shown in Fig. 2b is divided by the input resistor Ri to obtain the waveforms shown in Figs. Set the input resistance Ri so that

Also, in accordance with the temperature characteristics of the threshold voltage Vth, the ratio between the terminating resistor Ro and the temperature compensation resistor (thermistor resistor) Rth is determined so that Vh in the waveform c above is always twice Vth. In this way, the values of each resistance Ri, Ro, and Rth are set.

Figures 4c and d show the relationship between the two waveforms from the circuit of Figure 3 determined as described above at temperatures of 0°C and 60°C.
This is illustrated in the figure.

5 and 6 illustrate another circuit diagram embodiment according to the invention of this application. In either circuit, the values of the resistors Ri, Ro, and Rth can be determined using the same calculation method as that used in the circuit shown in FIG. 3 above. Rpo shown in FIG. 6 is a so-called posistor, which is a resistor that has a positive coefficient with respect to temperature, contrary to a thermistor.

Next, an embodiment of a delay device incorporating a circuit according to the present invention will be described.

In FIGS. 7 and 8, the upper end protrusion 6 of the hollow formed by the cylindrical base 3 and the housing 4 fits into the hole 9 provided in the housing 4, and the base 3 is inserted into the lower surface of the cavity. Hole 1 provided in the center of
A substantially cylindrical rotor 5 made of a non-conductor such as epoxy resin with protruding legs 7 fitted into the rotor 5 is fitted into the rotor 5, and a screwdriver etc. If you insert and rotate,
The rotor 5 is rotatable about the leg portion 7. An annular groove 11 having a U-shaped cross section and opening toward the housing 4 is formed in a part of the rotor 5 on the outside of the upper end protrusion 6 of the rotor, and an O-ring 12 is inserted into this groove.
is inserted, and this O-ring is crimped between the housing 4 and the rotor 5 to prevent unnecessary substances such as dust and grease from entering the inside.

Fan-shaped groove 1 formed around the axis of base 3
3 is bored in the base 3. The entrance portion 14 of this groove is wider than the groove bottom portion 15 and is configured to form a stepped portion 16 . A coil body support plate, which will be described later, is formed inside the wide portion and locks the coil body.

After a conductive adhesive is injected into the fan-shaped groove 13 as a ground electrode, the coil body α is accommodated therein. That is, when inserting and fixing the coil body α into the groove 13, first inject an appropriate amount of conductive adhesive into the bottom 15 of the groove 13, then press fit the coil body from above the groove, and hold the coil body for a predetermined period of time. After the adhesive has solidified, the coil body is fixed in the groove and the capacitance C can be formed.

Incidentally, an appropriate number of one or more fan-shaped grooves in the base 3 can be formed in the base 3 to accommodate a corresponding number of coil bodies. Furthermore, the base is not cylindrical,
By forming the base into a rectangular shape, providing one or more linear grooves in the base, and attaching a rod-shaped coil body to the base, it is possible to obtain a device that performs the same function as the configuration with the cylindrical base and fan-shaped grooves.

When the coil body α is accommodated in the groove 13, a first coil support plate 1 is provided on the outside of the groove 13 in order to lock the coil body so that it does not move within the groove.
7. A second coil support plate 18 is integrally formed with the base 3 on the inside, and a plurality of protrusions 19 are provided on these support plates, and these protrusions 19 are normally provided.
The coil α inserted and fixed in the groove is held between the outside and the inside, and the coil body α is locked so that it does not fall out of the groove.As will be described later, a ground electrode is provided at the bottom of the groove. When the conductive adhesive is injected and applied to the core, the adhesive enters the gap formed by the protrusion and the coil body α, thereby fixing the coil body within the groove.

Next, the configuration of the coil body α used in the present invention will be explained. A composite magnetic material made of soft ferrite powder dispersed in a polymer material is used for the core 33 which is to be the core of the coil wire 34. This material is known to have better high frequency characteristics than conventional ferrite, and is used as a radio wave absorbing material. Usually, this core 33 is made into a sheet,
It is generally known from experiments that good high frequency characteristics can be obtained by winding a coil wire 34 around this to form an inductance.

In the present invention, the core 33 made of the composite magnetic material is formed into a sheet shape, and the coil wire 34 is placed on top of the core 33 made of the composite magnetic material.
The elasticity and flexibility of this material are utilized to form a ring-shaped delay line, which forms a circular delay line with a small volume. It is possible to prevent leakage magnetic flux caused by uneven distribution. In the figure, 34' is a lead wire of the coil body. The coil body α configured as described above is fixed to the bottom part 15 of the fan-shaped groove 13 with a conductive adhesive injected in advance, and is further held between the coil support plates 17 and 18, respectively, and housed so as not to fall out. Ru.

The base 3 is manufactured by injection molding, and a hole 20 is provided at one location at the bottom of the groove 13 due to the mold structure. This hole 20 is provided so as to be located above a ground terminal 21d of a plurality of insert terminals 21, which will be described later, and the conductive adhesive applied in the groove 13 flows into this hole as described above. At the same time, the capacitance electrode applied to the coil body α is automatically connected to the ground terminal 21d.

Reference numeral 22 shown in FIGS. 8, 10, 11, and 12 is a ceramic substrate. Figure 11,
FIG. 12 is an enlarged view of the ceramic substrate. A conductive part 30, an input resistor Ri, a terminating resistor Ro, and a temperature compensation resistor, such as a thermistor Rth, are mounted on the upper surface of the ceramic substrate 22. In this case, the above resistors are printed and fired on the ceramic substrate, and then a trimming device or the like is installed. As explained in connection with the circuit diagram, it is easy to obtain the required resistance value calculated in advance. In this case, the paste of the conductive portion 30 is poured into the hole 23 of the ceramic substrate, which will be described later, and is fired. Next, if the metal pin 24 is inserted into the hole 23 drilled in the ceramic substrate 22 and spot welding is performed on the pin 24, the pin 24 will fit into the pin hole 23.
It is electrically connected to the conductive part 30 via. In order to mount the ceramic substrate 22 configured as described above into the square recess 32 provided under the base 3 from below (FIG. 8), the pin 24 is inserted into the through hole 31 provided in the base 3 (FIG. 9). ) from below and make it protrude above the base 3, and using adhesive,
Fixed to. In FIG. 8, reference numeral 21 indicates a plurality of terminals formed on the base 3 by insert molding. Symbol 21a is a power supply terminal, 21b
is an input terminal, 21c is an output terminal, and 21d is a ground terminal. 26 is IC, 27, 28 are terminals 21
This is a bonding wire that connects the IC and the terminal 21c, and the IC and the terminal 21c. Also, 35 and 36 are IC2
6 and the conductive portion 30 of the ceramic substrate 22, respectively. Ceramic substrate 22 is inserted into recess 32 as described above, and after each connection is completed, recess 32 is filled with adhesive.

FIG. 13 is a side view with the coil body α and the fan-shaped current collector plate 25 attached to the base 3 and the housing 4 removed. The fan-shaped current collector plate 25 is made of a good conductor, such as brass, and has leg parts 25' bent into an L-shape, and the through holes h formed in the leg parts 25' are welded to the ceramic plate 22. One of the pins 24 is inserted from below and connected to the leg portion 25' by soldering. Further, both ends 34', 34' of the coil body α are connected to the remaining two pins 24 by winding and soldering, respectively. The rotor 5 has a pair of fingers 29,2.
A wiper W having a diameter of 9' is attached, and one wiper finger 29 slides on the coil body α and the other wiper finger 29' slides on the current collector plate 25 in accordance with the rotation of the rotor 5. The delayed signal generated at this time is guided to the ceramic substrate 22 via the current collector plate 25 and pins 24.

Next, the operation of the present invention will be explained. A signal input from the input terminal 21b passes through the bonding wire 27 and enters the IC 26, and after being inverted, it passes through the bonding wire 35, the input resistor Ri on the ceramic substrate, and is guided to the coil body α to become a delayed signal. As already explained, the wiper W fixed to the rotor 5 has a pair of fingers 29, 29', and as the rotor 5 rotates, the finger 29 slides on the coil α, while the wiper 29' simultaneously slides on the current collector plate. 25. Therefore, at any position set by rotating the rotor 5,
The wiper W catches the delayed signal and sends it to the current collector plate 2.
5. The delayed signal is guided to the ceramic substrate 22 through the pin 24 fixed to the ceramic substrate 22, and the delayed signal is passed through the bonding wire 36, inverted again by another IC, and then passed through the bonding wire 28. It is taken out from the output terminal 21c. By sliding the wiper W on the coil body α and the current collector plate 25, the delay time can be finely adjusted, and the delay time aimed at by the present invention can be adjusted anywhere within the variable range. The pulse width and temperature characteristics can be obtained easily and accurately. It is also possible to use a fixed type delay line by pulling out a tap from the coil in place of the wiper.

As described above, according to the present invention, the L, C, IC as a delay element, and the impedance matching resistor that also serves as temperature compensation for the IC are housed in an extremely small package, thereby producing a pulse with extremely stable temperature characteristics. A delay device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a distributed constant circuit diagram of a conventional example. Figure 2a,
b, c, and d are voltage waveform diagrams at the points indicated by arrows a, b, c, and d in FIG. 1, respectively. FIG. 3 is an embodiment of a circuit diagram of a delay device according to the present invention.
FIGS. 4c and 4d show two waveforms produced by the circuit of FIG. 3. FIGS. 5 and 6 each show another embodiment of a circuit diagram of a delay device according to the present invention. 7 to 13 illustrate an embodiment of a delay device according to the present invention. Figure 7 is a side view. FIG. 8 is a sectional view taken along the X-Y line in FIG. 7.
Figure 9 is a plan view of the base. FIG. 10 is a plan view of the ceramic substrate incorporated into the bottom of the base. FIG. 11 is an enlarged plan view of the ceramic substrate. FIG. 12 is a side view of FIG. 11. FIG. 13 is a perspective view with the housing and rotor of FIG. 7 removed. α is the coil, C is the capacitance, L is the inductance, W is the wiper, Ri is the input resistance, Ro is the termination resistance, Rth is the temperature compensation resistance, Vth is the threshold voltage, 5 is the rotor, 14 is the groove entrance, 15 is the groove bottom , 16 is a stepped portion, 17 is a first coil support plate,
18 is a second coil support plate, 20 is a hole, 22 is a ceramic substrate, 25 is a current collector plate, 26 is an IC, 27,
28 is a bonding wire, 29, 29' are wiper fingers, 30 is a conductive part, 34 is a coil wire,
34' is a lead wire, 35 and 36 are bonding wires, and 33 is a core.

Claims (1)

[Claims] 1. In a pulse delay device that performs waveform shaping by incorporating an inverter IC into a delay line using an LC distributed constant or LC lumped constant circuit, by using a temperature compensation resistor as an impedance matching resistor, the delay time and output pulse width can be adjusted according to the temperature. A pulse delay device characterized by having no dependence.