JPH01210360A - Electronic parts drive device - Google Patents

Abstract

PURPOSE:To make possible the drive of each electronic parts, on the same conditions, on a single-tier substrate regardless of the position of the parts by driving a single selected electronic part, using two drive circuits arranged at both ends of a pattern formed along a plurality of electronic parts. CONSTITUTION:On a printed circuit board of an LED printing head for instance, LED arrays 11-1n are linearly arranged on a substrate 1. Lateral patterns 31-3n are linearly formed on the substrate 1 along LED arrays 11-1n. Pads 21-2n for the LED arrays are connected with the corresponding lateral patterns 31-3n and wire 61-6n. IC's 2, 3 as a drive circuit are arranged near one end and the other of LED arrays 11-1n. IC pads 41-4n for IC's are connected to the left and right ends of the lateral patterns 31-3n through wire 51-5n. Transistors 71-7n as a selection circuit selects a single LED from among the LED arrays 11-1n.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic component drive device suitable for use in an LED print head of an electrophotographic recording device.

[Conventional technology]

In an LED print head, a large number of wirings are required to send bit data (turn-on/off data) to a plurality of linearly arranged LED arrays. If these wirings are configured to intersect in the middle, short-circuit accidents are likely to occur. Therefore, the present applicant previously proposed a method of wiring so as not to cross each other in Japanese Patent Application No. 58-141879.

FIG. 2 shows the principle of the connection method.

In the same figure, C1, C2, and C3 are linearly arranged L
It is an ED array (chip). Each LED array has a plurality of signal pads b1 to bm.

P□ to Pm are signal pads of a connection pattern to be described later, and are formed on the substrate on which the LED arrays are arranged, corresponding to the signal pads b1 to bm of each LED array. Corresponding signal pads b to bm and Pl to Pm are connected to each other by wire bonds (not shown). S11 to Smi are connection patterns that connect the signal pads Pi to Pm or bi to bm.

Signal pads b□ to bIIl of adjacent LED arrays are arranged symmetrically. Therefore, the corresponding signal pads P□ to Pm of the connection pattern facing the LED arrays C1 and C2 are connected to each other in the connection pattern S11.
Corresponding signal pads bi to bm of LED arrays C2 and C3 are connected by connection patterns S1□ to Sm2. By connecting in this manner, the signal pads b1 to bm of the LED arrays C1, C2, and C3 can be connected to each other without intersecting the connection patterns S11 to Smi.

[Problem to be solved by the invention]

In this way, in the conventional method, the connection terminals (pads) of adjacent LED arrays are connected symmetrically.
The order of serially input data must be reversed for each chip, which has the disadvantage of increasing the burden on the control circuit system. Furthermore, since the total length of the connection pattern becomes longer, its resistance becomes larger, and the difference in voltage drop between the LED array near the data input end and the LED array far from the input end cannot be ignored. That is, the farther from the input terminal, the lower the data voltage and the lower the brightness of the light output from the LED array. Furthermore, not only connection pattern comrades,
In order to prevent the ground pattern from intersecting with the ground pattern, there is a drawback that the substrate must have a two-layer structure.

Therefore, the present invention aims to reduce the variation in signal deterioration depending on the position of each chip, eliminate the need to change the order of inputting data to each chip, and realize a device that can have a single-layer substrate structure. It is.

[Means to solve the problem]

The electronic component driving device of the present invention includes a plurality of electronic components arranged on a substrate, a number of patterns formed on the substrate along the plurality of electronic components and corresponding to connection terminals of each electronic component, and a plurality of patterns formed on the substrate along the plurality of electronic components. A plurality of wires connecting connection terminals of electronic components to corresponding patterns, a first drive circuit connected to one end of the pattern, and a second drive circuit connected to the other end of the pattern. , and a selection circuit that selects one electronic component from a plurality of electronic components.

[Effect]

For example, a pattern is formed along a plurality of linearly arranged electronic components, and connection terminals of each electronic component are connected in parallel to this pattern.

Signals are supplied to one electronic component selected by the selection circuit from two drive circuits connected to both ends of the pattern. When the position of each electronic component is far from one drive circuit,
Since it is close to the other drive circuit, the voltage drop due to the difference in distance from the drive circuit is averaged out. Furthermore, not only is it not necessary to change the data input order for each electronic component, but the board can also have a one-layer structure.

〔Example〕

FIG. 1 is a plan view of a printed wiring board of an LED print head to which the electronic component driving device of the present invention is applied. In the figure, 1 is a substrate made of ceramic or the like. 11 to 1n
is a plurality of LED arrays as electronic components arranged linearly on a substrate 1, and each LED array has a plurality of pads 21 to 2n as connection terminals. 31 to 3
n is a horizontal pattern formed linearly on the substrate 1 along the ED arrays 11 to 1r3j, the number of which is equal to the number of pads 21 to 2n. Pads 21 to 2n of each LED array are connected to corresponding horizontal patterns 31 to 3n by wires 61 to 6n. 2.3 is an IC as a driving circuit, and the LED array 11 to i
They are arranged near one (left) end and the other (right) end of n' (horizontal patterns 3'1 to 3n). Each I
The IC pads 41 to 4n of C are connected to the left and right ends of the horizontal patterns 31 to 3n, respectively, via wires 51 to 5n. The ICs 2 and 3 are connected to a connector 5 formed on the left end of the board 1 via a control pattern 4. 71 to 7n are transistors as selection circuits, and their collectors are connected to the back electrodes (not shown) of each LED array 11 to 1n, and their emitters are connected to the ground pattern on the substrate 1 (not shown) connected to the connector 5. (not shown) are connected to each other, and their bases are further connected to the connector 5 via patterns 81 to 8n.

These wirings can be realized by forming each pattern on only one surface of the substrate 1.

Next, the operation will be explained. Connector 5 from an external circuit (not shown)
The data input to IC2 is passed through control pattern 4.
and 3 and are latched.

This latched data is stored in pads 41 to 4n of IC2.
, horizontal patterns 31 to 3n via wires 51 to 5n.
is supplied to the left end of the Similarly, the same data is supplied to the right end portions of the horizontal patterns 31 to 3n via pads 41 to 4n and wires 51 to 5n of the IC3.

Selection data is also input to the connector 5, and this selection data is transmitted to the transistor 71 via patterns 81 to 8n.
(An IC for driving the transistors 71 to 7n may be provided separately, and the transistors 71 to 7n may be driven via the IC.)

One selected transistor is turned on, and the other unselected transistors are turned off. The turned-on transistor connects the back electrode of the corresponding LED array to the ground pattern via its collector and emitter. As a result, the data supplied to both ends of the horizontal patterns 31 to 3n is transmitted via the wires 61 to 6n and the pads 21 to 2n.
input to one selected LED array. That LE
The D array turns on or off the LED of each bit in response to input data.

When one LED array is finished driving, a new LED array is selected next and new data is input serially in the same order. The plurality of LED arrays connected in parallel in this manner are time-divisionally driven by two ICs one by one.

Now the output current of IC2 and 3 is 12, i3, horizontal pattern 3
Assuming that the specific resistance of the 1 to 3n film is ρ, the width of the film is W, and the arrangement pitch (average section length) of each LED array is 1, the voltage drop in each LED array due to the horizontal patterns 31 to 3n is r as follows. It becomes like this.

Δr1t is 12ρw/1+i3ρw/(nl)i,=i
If 3=i, W" constant and ρ=constant, the above equation becomes Δrx1=1 pW (1/l + 1/nl). Similarly, Δr, □=i pW (1/(21)+1/ ((n-1)
l))Δr1. =i pW(1/(31)+1/((n
-2)l))Δr1n=i pW(1/(nl),+'
l/l).

The main term in parentheses in the above equation means the reciprocal of the distance from each LED array to IC2, and the crest means the reciprocal of the distance from each LED 17 ray to IC3. In a given LED array, when the distance to IC2 is long (short), the distance to IC3 is short (long).

Therefore, if the total length of the horizontal patterns 31 to 3n is L, the value in parentheses (sum of main term and crest) in the above equation is 1/L.
It can be approximated by Δr=iρw/L, and the voltage drop in any LED array is constant. Also, in the end, one LED array becomes two
Since it will be driven by two ICs at the same time, assuming that the voltage drop can be ignored, the drive current will also be approximately doubled,
High-intensity light emission is achieved compared to when driven by one IC.

The present invention has been described above using the case of driving an ED array as an example, but the present invention can also be applied to the case of driving other electronic components.

〔Effect of the invention〕

As described above, according to the present invention, one selected electronic component is driven by two drive circuits placed at both ends of a pattern formed along a plurality of electronic components, so that each electronic component is It can be driven under the same conditions regardless of the position. Further, wiring processing for this purpose can also be realized with a single layer structure substrate. Furthermore, there is no need to reverse the order of data input to electronic components for each chip.

[Brief explanation of the drawing]

Figure 1 shows an LE+ to which the electronic component drive device of the present invention is applied.
FIG. 2, which is a plan view of the printed wiring board of the print head, is an explanatory diagram of a conventional method of connecting an electronic component drive device. 1... Board 2.3... IC 4... Control pattern 5... Connectors 11 to 1n... LED array 21 to 2n... Pads 31 to 3n... Horizontal pads 41 to 4n ...IC pads 51 to 5n, 61 to 6n...Wires 71 to 7n
...Transistors 81 to 8n...Pattern patent applicant Oki Electric Industry Co., Ltd.

Claims (1)

[Claims] A plurality of electronic components arranged on a substrate, a number of patterns formed on the substrate along the plurality of electronic components and corresponding to the connection terminals of each electronic component, and a plurality of patterns formed on the substrate along the plurality of electronic components, and a plurality of wires connecting the connection terminals to the corresponding patterns; a first drive circuit connected to one end of the pattern; a second drive circuit connected to the other end of the pattern; An electronic component driving device comprising a selection circuit that selects one electronic component from among electronic components.