JPS6180981A - Device for printed circuit - Google Patents

Abstract

PURPOSE:To prevent or reduce the spuriousness originated at clock signal transmission, by providing main and sub-printed circuit boards, and establishing clock signal utilization circuit on main printed circuit and a clock signal transmission pattern on sub-printed circuit. CONSTITUTION:A specified circuit pattern 12 is formed on one side of the main printed circuit board. This circuit pattern 12 connects circuits with each other. On the other side of the main printed circuit board, each kind of circuit, such as a D/A converter and digital processing circuit, is formed, and is connected electrically to the circuit pattern 12. There are placed a specified number of hole-through's 13 on the circuit board 11, and in the hole-through 13, a conductor 14 is placed and connected to the circuit pattern 12. A sub-printed circuit board 15 is then attached orthogonally to the main printed circuit board 11, and conductive pattern 17, 17 is formed on the sub-printed circuit board 15. By this constitution, the spuriousness, resulting from clock signal transmission, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printed wiring device, and is particularly suitable for application to a device incorporating a digital signal processing circuit.

[Technical background of the invention]

Color television receivers currently in use generally use analog signal processing. The television signal sent from the broadcasting station is an analog signal, and this signal is received in analog form and guided to a color television receiver. In the receiver, a desired channel is selected from the television signal using the cheese, converted to a video intermediate frequency, and then detected by a video detector to reproduce the video signal.

This video signal is supplied to the cathode ray tube together with the color signal to reproduce a predetermined color image on the cathode ray tube screen. This video signal is an analog signal.

Therefore, although the signal processing circuit also uses a linear IC or the like, there is a limit to the ability of analog signal processing to obtain higher quality images. This is because color television receivers have recently been used as displays for various devices2.
For example, it is used as an image reproducing device in video cameras, personal computers, video discs, character information transmission systems using public telephone lines, and the like. For these devices, in order to connect to the television receiver, the transmission side equipment converts it back into a high-frequency television signal and supplies it to the tuner, or connects it to the external connection terminal of the television receiver's video circuit through an interface circuit. (RGB terminals) to reproduce images on the cathode ray tube of a color television receiver. However, in many cases, the transmission side equipment handles digital signals, and even if this signal is supplied to a color television receiver, the receiver's circuit, which was originally designed for analog signal circuits, will not be able to handle digital signals. Currently, even if it is possible to process the signal, it is not possible to faithfully reproduce it. From these points of view, it was considered that the video circuit of a color television receiver could be converted into a digital circuit so as to be able to obtain high-quality reproduced images, and various research and development efforts and prototype production were carried out.

Some of them are starting to be commercialized. This digital circuit makes it possible to faithfully reproduce signals from various transmission devices.

[Problems with background technology]

By converting the above-mentioned video circuits into digital/L/circuits, the compatibility with the external equipment on the transmission side is improved, and the processing becomes more faithful, but from the point of view of the color television receiver itself. Since the television signal sent from the broadcasting station is originally an analog signal, this analog signal must be first converted into a digital signal and processed, and then the analog signal processing is performed again. An analog-to-digital converter (hereinafter simply referred to as an A/D converter) is used to digitally process this video signal, but according to the sampling theorem, the sampling frequency of the A/D converter is required to be about twice the signal band. In reality, higher sampling frequencies are used, such as 3 x fsc or 4 x fsc in television-related equipment.
(fsc is the reference frequency) is used. In the digital circuit, it is necessary to delay the video signal digitally processed by the A/D converter using a shift register, adjust the black level with an adder, and adjust contrast and color saturation using a 2 multiplier. .

All of these circuits are required to be synchronized to the sampling clock. This clock signal is 4 as described above.
Since it handles a very high frequency such as 14.31818 MHz of the X fsc, it has the disadvantage of causing problems such as spurious radiation and waveform distortion of high-speed clock pulses. This is because if a printed wiring board is used for the circuit and a clock pulse signal is transmitted to each circuit using a circuit pattern, the above-mentioned failure will occur due to the inductance component of the printed circuit pattern or the length K of the pattern. It will be done. Therefore, when constructing a circuit using a printed circuit board for analog processing in current color television receivers, special countermeasures against spurious noise must be taken.

[Purpose of the invention]

The present invention aims to improve such drawbacks by providing a sub-printed wiring board separate from the main printed wiring board, and using this sub-printed wiring board to transmit the clock signal to each clock signal utilization circuit. An object of the present invention is to obtain a printed wiring device which prevents spurious noise.

[Summary of the invention]

The present invention has a main and sub printed wiring board, a clock signal utilization circuit is incorporated on the symbiotic printed wiring board, and a clock signal transmission pattern for transmitting clock signals to these clock signal utilization circuits is provided on the sub printed wiring board. A clock signal is supplied to the clock signal utilizing circuit from this transmission pattern.

[Embodiments of the invention]

Hereinafter, the printed wiring device according to the present invention will be explained in detail with reference to the drawings.

In FIGS. 1 and 2, a predetermined circuit pattern (work 2) is formed on the negative side of a main printed wiring board (11) made of a copper-clad laminate or the like. In this illustration, detailed patterns are omitted. This circuit pattern (12) is used to connect circuits to each other, and the main printed wiring board (
11) On the other side, a D/A converter and various circuit components for digital processing are arranged, forming a predetermined circuit pattern (12).
) electrically connected to the main printed wiring board (1
1) is provided with a predetermined number of through holes (13).

A conductor (14) connected to the circuit pattern (12) is provided in the through hole (13) to form a through hole. The circuit pattern (1) of this main printed wiring board (11)
On the 2) side, a sub printed wiring board (15) is installed perpendicular to the surface of the main printed wiring board (11). This sub printed wiring board (1
5) is provided with a locking leg (16) that protrudes outward on the negative side, and this locking leg (16) is connected to the main printed wiring board (
It is locked by inserting it into the through hole (13) of 1).

A pair of parallel conductor patterns for clock signal transmission (
17) (17') are provided, and a grounding pattern (18) is provided over the entire other plane. The main and sub-printed wiring board (o)Qs) has a ground pattern (18) and a circuit pattern (12) connected by soldering (19).
It is fixed electrically and mechanically by attaching it. Also, if necessary, a matching resistor (2 (3)) or a lead wire (not shown) for circuit wiring for supplying or deriving a clock signal is installed to balance the conductor patterns (17) (17'). In the illustrated case, the sub printed wiring board (15) is arranged in a substantially U-shape on the main printed wiring board (15), but in this case, the sub printed wiring board (15) Mutual conductor pattern (17) of plate (15) (1
7') are connected by a jumper wire (21), etc., and the ground pattern (18) is electrically connected between the ground patterns of the circuit pattern (12) of the main printed wiring board ((3)). , these sub or main sub printed wiring boards (11) (
15) each butter y, (17) (17' ) (18)
In addition to this method, the connection between them can also be made by direct soldering, or by other well-known connection methods. This sub-printed wiring board (15) can be constructed as shown in FIG. In other words, as shown in Fig. 3(a), the mounting leg (16)
a conductor pattern (17) parallel to the substrate (15) having
(17') is formed, and a perforation hole (22) for separation is provided at the location where it is divided into two parts. Next, as shown in Figure 3(b), each input/output 2 distribution lead wire (23) and resistor (
2 (3) Furthermore, a through hole (not shown) K in which necessary parts such as jumper wires (21) are provided at predetermined positions on the board (15).
insert. In the case shown, the conductor pattern (17) (17
Although the illustration is shown in the opposite direction to the actual insertion direction of the parts, the actual case is to reverse the front and back of the illustration and insert the parts from the top in the drawing. After the necessary parts are inserted into the through holes of the board (15) in this way, the necessary parts are soldered at once using a solder dip tank or a jet type soldering device. Thereafter, the wiring work is easily completed by dividing the board (15) into a plurality of parts along the perforations (22) as shown in FIG. 3(C). In this way, the wiring gradually opening printed wiring board (15) is attached to the main printed wiring board (11), and the lead wires (23) of the sub printed wiring board (15) are connected to the necessary locations on the main printed wiring board (11). The connection work is completed by soldering the other terminals of components such as and resistors (2 (3)). Figure 4 shows an overview of the circuits used in these printed wiring boards (11) (15). Figure 4 shows an example of a digitalized video circuit, with terminals (41)
An analog video signal is supplied to the A/D converter (42), and this analog video signal is converted into a digital video signal by an A/D converter (42). At this time, the converter (42) is supplied with a sampling clock signal from the reference oscillator (43). This reference oscillator (43) is 14-31818MH
Δ1 and z that oscillate at the oscillation frequency of z and have a phase difference of 180'
2 clock signals are generated. A video signal sampled and digitized by the A/D converter (42) using this zl clock signal is supplied to a video processor (44) and a deflection processor (45).

The video processor (44) includes a COD circuit for separating brightness signals and color signals, an adder 1 multiplier forming a contrast and brightness adjustment circuit, various gates, and the like. It is also possible to reproduce a sub-screen smaller than the main screen within the main screen and use the sub-screen as a monitor, but in this case, processing for the main screen and for the sub-screen is performed. This processing can be performed by a separate processor or within the same processor.

This video processor (44) is also supplied with the clock signal σ] and the clock signal z2, and the video processor ! ? The luminance signal and color signal processed in ``(44) are superimposed in an image superimposition circuit (46).
46) is also supplied with 82 clock signals from the reference oscillator (43), and the output of the double circuit (46) is again sent to the digital-to-analog converter (47) (hereinafter simply referred to as the D/A converter). It is converted into an analog signal. This D/A converter (47) output is KG
The signals are matrixed in a B matrix circuit (48) to obtain the RΦG-B signal at the output terminal. The gl and z2 clock signals are also supplied to the deflection processor (45) and are applied to synchronous signal separation, a countdown type oscillator, and the like.

In this way, each digital processing circuit uses a clock signal, and the aforementioned sub printed wiring board (15) is used to supply the clock signals zl and 22 to each circuit. That is, each digital processing circuit such as a λ/D converter (42), a reference oscillator (43), a video processor (44), a deflection processor (45), and an image superimposition circuit (46) is mounted on the main printed wiring board (11). ), and the clock signal supplied from the reference oscillator (43) to these digital processing circuits is transmitted using the sub-printed wiring board (15). For example, the 1-minute clock signal oscillated by the reference oscillator (43) is transmitted using the conductor pattern (17) of the sub-printed wiring board (15), and the z2 clock signal is transmitted using the conductor pattern (17'). and transmit it. Since this conductor pattern (17) (H') is wired in a substantially straight line, it can be transmitted over the shortest distance, so inductance components due to pattern routing etc. can be minimized, and each circuit can be supplied by wiring from this conductor pattern (17) (17') using components such as lead wires (23) and resistors (2 (3)).Of course, on the main printed wiring board (11) It is necessary to keep the clock signal circuit pattern (12) to a minimum and take care to shorten the pole cover turn length.And each circuit that uses the clock signal is connected to this sub-printed wiring board (15).
In order to make maximum use of the lead wires, the lengths of the lead wires (23) and the lengths of the circuit patterns (12) can be shortened by arranging them along the substrate (15).

Furthermore, the grounding pattern (18) of the board (15) makes it easy to balance the impedance between the conductor patterns (17) and (17') to the ground, and even if the balance is lost, it can be sufficiently compensated for by resistors (2 (3), etc.). It is possible,
By changing the connection position and value of this resistor (2 (3)), it is possible to change the digital circuit or change the input/output characteristics.In other words, the reference oscillator ( 43) to (al, glz) using pattern wiring in each circuit, and is characterized by the fact that only the conductor patterns (17) and (17') for clock signal transmission are arranged independently. When we conducted an experiment using a printed wiring device configured as follows, we confirmed the effects shown in Table 1 below.

Table 1 Table 1 shows 1 channel from 1 domestic channel in IF' and F band.
Measurements were made for 2 channels, and F spurious is the spurious that enters the video intermediate frequency printed wiring board, and F spurious is the spurious that enters the antenna from these digital boards. As can be seen from Table 1, an effect of 7 dB on IF spurious and 4 to 9 dB on F spurious was obtained, indicating that it is extremely effective in preventing spurious.

In the above explanation, the case where the clock signal transmission conductor patterns (17) (17') are arranged parallel to the negative side of the sub-printed wiring board (15) has been explained, but the present invention is not limited to this, and various modifications can be made. Application is possible. For example, only on one side of the sub printed circuit board (15) are three patterns (17) (17'') (two clock transmission conductor patterns (17) (17') and a grounding pattern (18)).
18) can be wired in parallel, and the pattern closest to the main printed wiring board (11) can be configured as the ground pattern (18). Δ20 If two clock signals are not used, it is also possible to configure it with one conductor pattern (17) or (17'), and as the clock signal increases or decreases, this conductor pattern (17) (17') This can be done by increasing or decreasing the number. Furthermore, these conductor patterns (17) (17') are attached to the substrate (15), respectively.
), and it is also possible to wire the conductor pattern (17) (17') between the two ground patterns (18).
), various modifications or combinations such as arranging them are possible.

There is no limitation to the water illustrated embodiment. And the board (1
The shape of 5) is not limited to the U-shaped arrangement, but may be linear, or a large number of them may be arranged side by side, or the sub printed wiring board (15) may be a separate piece from the main printed wiring board (11). They can also be spaced apart so that they face each other. The method for fixing the main and sub-printed wiring boards [(11) and (15) is not limited to this method, and the lead wires of the parts may be folded back to the opposite side to the main printed wiring board. When connecting to the circuit pattern (12) of (11) or other parts, it is recommended to cut out the sub-printed wiring board (15) at a predetermined position to improve workability and prevent changes in the position of the lead wire. It is also possible to configure a structure to prevent this.

〔Effect of the invention〕

As explained above, according to the present invention, in circuits that use digital signals, high frequency clock signals are generated by using a sub-printed wiring board provided separately from a main printed wiring board incorporating these digital circuits. Since the clock signal is transmitted to the same circuit, it is possible to supply the clock signal over the shortest distance, which prevents and reduces spurious noise, and since it is constructed separately, it is relatively easy to design the pattern width, etc. This is possible and is advantageous in terms of design. Furthermore, when the clock signal transmission conductor pattern and the ground pattern are used in pairs, the transmission characteristics can be improved.
If the pattern width of the sub-printed wiring board and the distance to the ground pattern are selected to provide characteristic impedance, matching can be achieved by adding a fixed resistor to the clock signal generation circuit side and the power receiving side. can. Furthermore, when using multiple clock signals and clock signals with inverted phases, wiring the conductor patterns for these clock signals in pairs can maintain a balance between the two. Since the conductor patterns are inverted, the spurious signals are canceled out between the conductor patterns, which has various advantages such as the ability to further reduce spurious signals.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing a printed wiring device according to the present invention, FIG. 2 is the same (cross-sectional view), and FIG. 3 is a perspective view showing a sub-printed wiring board constituting the printed wiring device according to the present invention. , 4th
The figure is a circuit configuration diagram showing an example of a digital circuit incorporated in the printed wiring device of the present invention. 11... Main printed wiring board 12
・・・・・・・・・・・・・・・ Circuit pattern 15...
・・・・・・・・・・・・Sub printed wiring board 17, 17'
......Conductor pattern 18...
...Grounding pattern attorney Noriyuki Chika Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) A main printed wiring board into which a digital circuit is incorporated, and a sub printed wiring board combined with this board and provided with a small number of conductive patterns for transmitting clock signals and arranged on the circuit pattern side of the board. A printed wiring device featuring: (2) The printed wiring device according to claim 1, wherein the conductor pattern is composed of a pair of conductor patterns for transmitting clock signals whose phases are inverted with respect to each other. (3) The printed wiring device according to claim 1 or 2, wherein the sub printed wiring board is provided with a conductive pattern and a grounding pattern.