JP2914643B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image device such as an LED head and an image sensor, and more particularly, to an array of image array chips (hereinafter abbreviated as an image array) on a substrate, and individual image array chips on a first wiring. And a reduction in the density of the first wiring of the image device in which the image elements are connected by wire bonding.

[0002]

2. Description of the Related Art In an image device such as an LED head or an image sensor, a high-density first wiring is required, so that a thin film electrode is wired on a glass substrate. For example, in the case of an image device having a resolution of 300 DPI, the arrangement pitch of the first wiring is basically required to be 84.7 μm, and it is impossible to form this by etching a copper foil on a printed circuit board. For this reason, a thin film electrode formed by a vacuum process on a glass substrate is used, but this increases the cost of the image device.

As a countermeasure against this problem, it has been proposed to divide the first wiring into two and arrange one on each side of a column of the image array (Japanese Patent Laid-Open No. 4-366658). FIG. 10 shows a first wiring in a conventional example. In the figure, 01 is a hard printed board, 02 is a second board, L1
L3 is an LED array mounted on the second substrate 02.
Numerals 03 and 04 denote first wirings, each comprising 32 signal lines, and numeral 05 a row of bonding pads. In the conventional example, since the first wiring is divided into two, the first wirings 03 and 04 can be realized by etching the copper foil on the hard printed circuit board. However, the LED array L1 and the like have a common electrode on the bottom surface. The second substrate 02 is used to connect to the common electrode without being hindered by the first wirings 03 and 04, and the common electrode is once connected to the second substrate 02. Then, it is connected to the first substrate 01 by wire bonding. In this case, the cost of the image device increases because the second substrate 02 is provided, and the mounting accuracy of the LED array L1 and the like decreases. For example, the second substrate 02
The height of the LED array L1 and the like changes. Further, the LED array L1 to the first wirings 03, 04
It becomes difficult to position relative positions such as the above, and the bonding distance is extended.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the density of the first wiring to one half and to reduce the through hole density to one fourth as compared with the case where the first wiring is provided on one side of the column of the image array. The object of the present invention is to make it possible to use an inexpensive substrate such as a rigid printed circuit board by lowering it. It is also an object of the invention to connect the corresponding picture elements in a number of picture arrays in common.

[0005]

According to the present invention, there are provided a plurality of image array chips arranged linearly in a longitudinal direction on an upper surface of a rectangular substrate;
An image device provided with a plurality of first wirings bonded to individual image elements of the array chip;
The wiring is disposed on one of the two sides of the image array chip row, and is bonded to one side of the two adjacent image array chips so as to commonly connect corresponding image elements in each image array chip. And a U-shaped wiring on the other side, which is provided on the other side and is bonded to connect the corresponding image elements of each of the two adjacent image array chips in common. And the U-shaped wiring on one side and the U-shaped wiring on the other side
The U-shaped wiring is divided into two image array chips, and each image element is connected to one of the U-shaped wiring on one side and the U-shaped wiring on the other side. By electrically connecting the second wiring and the one-sided U-shaped wiring via a through hole,
The divided U-shaped wirings on one side are connected to each other, and the second wiring and the U-shaped wiring on the other side are connected through a through hole.
The U-shaped wires on the other side are electrically connected to each other by electrically connecting the U-shaped wires.

[0006] In addition to the LED head shown in the embodiment, the image device may be any device having a large number of image arrays, such as an image sensor and a PLZT optical head, arranged on a substrate in rows.

[0007]

According to the present invention, a U-shaped wiring on one side and a U-shaped wiring on the other side are provided on both sides of a row of the image array chip. As a result, the density of each first wiring is reduced to half. The U-shaped wiring on one side and the U-shaped wiring on the other side
It is composed of two image array chips and is separated from each other. The corresponding image elements of each image array chip are commonly connected via a U-shaped wiring on one side or a U-shaped wiring on the other side. The U-shaped wiring on one side and the U-shaped wiring on the other side provided for every two image array chips are connected to the second wiring provided on the lower surface of the substrate via through holes, so that the entire image device is Over, the corresponding image elements of each image array chip are commonly connected. The density of the through holes is reduced to half by providing one side of the U-shaped wiring on one side of the row of the image array chip and providing the other side of the U-shaped wiring on the other side. The U-shaped wiring on one side and the U-shaped wiring on the other side are U-shaped, and one wiring is bonded to two image elements, so one through hole corresponds to two image elements. I do. For these reasons, the density of the through-holes is reduced to 1/4 as a whole.

When the first wiring density is reduced to 、 and the through hole density is reduced to ４, an inexpensive hard printed circuit board such as glass epoxy can be used. And through holes can be easily manufactured by machining or the like. For this reason, conventional glass substrates and thin film wiring by vacuum process,
A substrate that is extremely simple and easy to manufacture can be used as compared with a multilayer wiring formed by via hole processing by exposing or developing an ultraviolet curable resin.

Preferably, the above-mentioned image array is provided with a row of first electrode pads on one side of a row of picture elements on a semiconductor substrate and a row of second electrode pads on the other side. And two image elements at the center of the image array are connected to the same row of electrode pads, and each of the image elements except the two image elements at the center is shifted from the center to the left and right by first and second electrodes. The image elements at both ends of the array are connected to the same row of electrode pads alternately connected to the row of pads, and the first row of electrode pads is connected to the U-shaped wiring on one side, and the second electrode The row of pads is bonded to the U-shaped wiring on the other side. This relates to the connection between the image elements and the electrode pads in the image array, for example, assuming that there are 64 image elements per image array. In this case, the two image elements at the center are the image elements of dot numbers 32 and 33, which are connected to the same row of electrode pads. , 32, 33, 35,
, 63 image elements are connected to one row of the electrode pads. .., 31, 34, 3
.., 64 are connected to the other row of electrode pads. When a row of image elements is connected to a row of two electrode pads in this way, and this image array is connected to the U-shaped wiring in a unit of two, for example, an image element having a dot number of 64 and an image element having a dot number of 1 are obtained. Are commonly connected to the same wiring,
Similarly, the image element of dot number 63 and the image element of dot number 2 are commonly connected. In this way, the corresponding image elements (in this case, the sum of the dot numbers is the number of image elements per image array + 1) are commonly connected.

Conversely, for example, when all the image elements of the odd dots of the image array are connected to the electrode pads of the first row and all the elements of the even dots are connected to the electrode pads of the second row, One wiring is complicated. In this case, the electrode pad connected to the last element (dot number 64, etc.) of the array is in the second column, and the electrode pad connected to the first element (dot number 1) of the next array is in the first column. is there. On the other hand, in the folded wiring, the element of dot number 64 and the element of dot number 1
Are connected to the same individual wiring. Therefore, if the row of the electrode pad of the element of the dot number 64 is different from the row of the electrode pad of the element of the dot number 1, the connection to the first wiring becomes difficult.

To eliminate this problem, the first wiring must be crossed or the image data is rearranged on the driving IC side. To cross the first wiring means to make a portion where the two first wirings cross each other. For example, the U-shaped wiring on one side enters the U-shaped wiring on the other side and the U-shaped wiring on the other side. Also enters the one side of the U-shaped wiring. This is the first
The wiring pattern is complicated, and the first is
Wiring cannot be realized. Rearranging the image data on the drive IC side involves rearranging the data in the drive IC so that the first wiring does not cross, which complicates the drive IC.

[0012]

1 and 2 show an embodiment using an LED head as an example. In FIG. 1, reference numeral 2 denotes a hard printed board such as a glass epoxy board, and LED arrays L1 to L
40 are arranged linearly. Here, the resolution is 300 DPI
A4 size paper, the LED array pitch of each LED array L1 to L40 is 84.7 μm, and the LE per array
The number of D is 64. Two sets of first wirings 4 and 6 are provided on the upper surface of the substrate 2, one U-shaped wiring 4 is on the upper side in the drawing of the LED array column, and the other U-shaped wiring 6 is on the drawing. Placed under In the embodiment, since time-division driving is performed for each LED array, the total number of first wirings is 64,
This is divided into ず つ, and the U-shaped wiring 4 on one side and the U-shaped wiring 6 on the other side are each provided with 32 signal lines. Reference numeral 8 denotes a row of bonding pads, in which pads for wire bonding to electrodes connected to each LED of the LED arrays L1 to L40 are arranged in a row. The row 8 of each bonding pad is arranged in units of two LED arrays, and the number of pads is の of 64 LEDs.
Is connected to the wiring on one side, and is responsible for two LED arrays.

Reference numerals 10 and 10 denote first wiring leading portions provided on the left and right sides of the substrate 2, each comprising 64 signal lines.
2 and 12 are drive ICs. First wirings 4 and 6 in embodiment
Is that the LED array is divided every two LED arrays. For example, the first wiring 4 is provided for every two LED arrays, and a row 8 of bonding pads is provided at a wiring end near the LED array. Then, the first wiring 4 ends at the row 8 of the bonding pads. This means that the first wiring 6
Similarly, the row 8 of the bonding pad is terminated,
The row 8 of the bonding pad includes the LED arrays L1 to L40.
In the vicinity of. The divided first wirings 4 and 6 are connected to each other using the through holes 14. The lead-out portion 10 of the first wiring has a through-hole row 16 in which 32 through-holes 14 are arranged. The through-hole 16 is provided on the first wiring 6 via the wiring on the lower surface (back surface) of the substrate 2. The connection is made from a plurality of through holes 14 (collectively referred to as a row 22 of through holes). Similarly, the lead portion 10 of the first wiring
Is provided with a row 18 of through holes composed of 32 through holes 14, and is connected to a row 20 of through holes of the first wiring 4 via the lower surface of the substrate 2. Row 2 of through holes
At 0, the number of through holes is also 32. Since the through-holes require a large wiring area, the through-hole rows 20 and 22 are preferably provided in a plurality of rows, and more preferably diagonally in the direction of the first wirings 4 and 6.
For example, each through hole requires a wiring width of about 0.5 mm per one including a gap with the surrounding wiring. In the embodiment, the rows 20 and 22 of the through holes are each two rows, and are turned back at the center to be substantially four rows. The rows 20 and 22 of the through holes are arranged at an angle of about 45 degrees in the direction of the first wirings 4 and 6.

FIG. 2 shows wiring on the lower surface of the substrate 2. 2
Reference numerals 4 and 26 denote second wirings each composed of 32 signal lines, and the second wiring 26 on the other side is used to connect to the first wiring 6. , And connected to the first wiring 6 via a row 22 of through holes. The second wiring 24 on one side is the first
For connecting to the wiring 4, a row of through holes 18
Is connected to the first wiring lead-out portion 10 through the column, and is connected to the first wiring 4 through the row 20 of through holes.

Returning to FIG. 1, a common electrode is provided on the bottom surface of the LED arrays L1 to L40, and is connected to the common electrode terminal 30 on the upper surface of the substrate 2 via a gap between the first wirings 6 and 6. L
Other configurations of the ED head, such as a housing and a lens array, are well known, and description thereof is omitted here.

The operation of the embodiment will be described. Time-division driving is performed in LED array units, and L of each LED array L1 to L40 is
Since the number of EDs is 64 each, the number of required first wirings is 6
There are four. In the embodiment, this is divided into 32 lines each of the first wirings 4 and 6, and in each of the first wirings 4 and 6, the signal line changes in the middle and turns back once, so that each of the first wirings 4 and 6 Thus, the number of signal lines viewed along the longitudinal direction of the substrate 2 is 32 × 2 = 64. When a hard printed board 2 such as a glass epoxy board or the like is used and a signal line is provided by etching a copper foil, wiring can be performed with a line width of 50 μm and a gap between the lines of 50 μm. Therefore, the first wirings 4, 6
Is 6.4 mm of 64 × 100 μm. The length of each of the LED arrays L1 to L40 is 84.7 μm ×
Since 64 is about 5.4 mm, and two arrays are 10.8 mm, the first wirings 4 and 6 having a width of 6.4 mm can be accommodated.
Thus, the first wirings 4 and 6 can be realized by etching the copper foil using the hard printed board 2.

Each through hole 14 has 0.5
mm wiring width is required.
6 mm is required. Therefore, in this embodiment, four rows are arranged diagonally. When the number of through holes per row is set to 8 and arranged at an angle of 45 degrees, the wiring width becomes 0.5 × 8 mm.
It becomes 2.8 mm of 1.414. In addition, there are 24 wiring widths of 2.4 mm without through holes, and wiring can be performed with a total of 5.2 mm per row. LED array L1
The length of each L40 is 5.4 mm, and the rows 20, 22 and the like of 5.2 mm per hole are provided in two rows. Therefore, even if the through holes 14 are used, wiring can be performed without difficulty. It is to be noted that the provision of the through holes 14 is easy because the rigid printed circuit board 2 is used.

The first wirings 4 and 6 include LED arrays L1 to L
A row 8 of bonding pads is provided near 40.
Therefore, the bonding distance is short, and among the 64 bonding wires per array, 32 wires are directed to the upper side of the drawing and 32 are directed to the lower side of the drawing, so that wire bonding is easy and the possibility of short-circuiting is low. Next, as is clear from comparison with the conventional example of FIG. 10, in the embodiment, the width in the vertical direction in the figure occupied by the first wirings 4 and 6 is about 1/2 of the conventional example.
In the conventional example of FIG. 10, the first wirings 03 and 04 extend toward the LED array side from the bonding pad row 05 and are folded back, and the width of the first wirings 03 and 04 is about twice as large as one side of the bonding pad row 05. Has become. On the other hand, in the embodiment, the row 8 of the bonding pad is the end of the first wiring 4, 6. As a result, the width of the first wirings 4 and 6 can be reduced to about 1/2 of the conventional example, and the width of the substrate 2 can be reduced. Also, row 8 of bonding pads and LED array L1
To L40 can be reduced to facilitate wire bonding.

Next, in the conventional example, the second substrate 02 is used in order to connect the common electrodes on the back surface of the LED array L1 and the like without intersecting with the first wirings 03 and 04. However, in the embodiment, since the first wiring 6 is separated for every two LED arrays, the first wiring 6 can be connected to the common electrode terminal 30 from a gap between them.

[0020]

Second Embodiment FIG. 3 shows a second embodiment. In the figure, reference numeral 32 denotes a new hard printed board, reference numeral 34 denotes a new first wiring, which passes the first wiring 34 through the back surface of the LED arrays L1 to L40, and shows a row 8 of bonding pads on the first wiring 34 side. Provided on the upper side. Therefore, the LED array L
An interlayer insulating film (not shown) was provided between 1 to L40 and the first wiring 34. The other points are the same as those of the embodiment of FIGS. In comparison in terms of effect, the embodiment of FIG. 3 requires an interlayer insulating film, and since the rows 8, 8 of the bonding pads are arranged on one side of the LED arrays L1 to L40, wire bonding becomes difficult.

[0021]

Third Embodiment A third embodiment will be described with reference to FIGS. FIG. 4 shows the LED array 40. This LE
The D array 40 is preferably used in each of the embodiments shown in FIGS. Reference numeral 42 denotes luminous bodies provided in 64 rows and 1 row per array, and 44 denotes electrode pads, which are arranged in two rows above and below the row of luminous bodies 42. The feature of the arrangement of the electrode pads 44 is as follows.
This is a point that is folded back and symmetrical with respect to the symmetry axis 46 located at the center. The axis of symmetry 46 is at the longitudinal center of the array 40 and its orientation is parallel to the short direction of the array 40.
As a result, the first luminous body 42-1 and the last luminous body 42-6
4 appear in the same row of electrode pads (lower row in the figure). In this manner, the light-emitting members 42-1, 42-64 at both ends are connected to the electrode pads 44-1, 44-64 in the same row, and the connection relationship with the light-emitting member 42 pad 44 is symmetrical at the center of the array.
The ED array 40 is called a line-symmetric array.

FIG. 5 shows a modified LED array 50 for comparison. Numeral 54 denotes electrode pads which are arranged in two rows on the upper and lower sides of the light emitting body 42, except that they are 180 degrees symmetric with respect to a rotation axis 56 orthogonal to the main surface of the array 50. As a result, the first light emitter 42-1 is connected to the lower electrode pad row, and the last light emitter 64-1 is connected to the upper electrode pad row. An array 50 that is symmetrical about the center point of the array by a 180 degree rotation is referred to as a point symmetric array.

FIGS. 6A and 6B show how the connection to the first wirings 4 and 6 is changed between the line symmetric array 40 of FIG. 4 and the point symmetric array 50 of FIG. Array 5
0). Reference numeral 60 in the figure is a wire bonding pad. In array 40, electrode pads 44-64 connected to the last illuminant (dot number 64) in the left array
And the electrode pad 44-1 connected to the first light emitter (dot number 1) of the right array appears in the same column. And these two electrode pads 44-1 and 44-64 are the first
The connection should be made to the same individual wiring in the center of the wiring 6, and being in these same columns facilitates connection to the first wiring 6. This means that the electrode pads 44-
The electrode pads to be connected to the same individual wiring, not limited to 1, 44-64, appear on the same column. The connection relationship between the pads is determined by the sum of the dot numbers, and the two pads whose sum of the dot numbers is 65 are on the same row. For example, in the above example, the electrode pad 44-connected to the dot number 64 and the dot number 1-
1,44-64 appeared in the same row. By the way, drive IC1
2 has a function of inverting the direction of image data for each array. This is a result of using the folded wiring, and is not a function provided specifically for the embodiment. The electrode pads 44-64 and the electrode pads 44 in the next array
If -1 are connected to the same individual wiring, each luminous body 4 naturally
2 is connected to the individual wiring at the correct position.

On the other hand, in the point-symmetric array 50, the patterns of the first wirings 4 and 6 become complicated. Most of the known LED arrays are point-symmetric, so that the same orientation is obtained even if the array is mounted in the wrong orientation (reversed 180 degrees). However, in point symmetric array 50, pads 54-64 of the left array and pad 5 of the right array
4-1 is in a different column, so that the first wiring 6 must be drawn through the bottom of the array 50 to the opposite side. Similarly, the electrode pads 54-2 and 54-63
Are in another column, and the first wiring 4 must also pass through the bottom of the array 50. For this reason, the first wiring 4 and the first wiring 6 intersect at the same portion. In this specification, this is called the intersection of the first wiring. The condition for avoiding the intersection of the first wirings 4 and 6 is that the array is line-symmetric. To avoid the intersection in the point-symmetric array 50, the data must be rearranged by the drive IC 12. That is, when driving the array on the left side of FIG.
The odd-numbered dot image data is supplied to the first wiring 4, and the odd-numbered dot image data is supplied to the first wiring 6 in the right array.
Then, even-dot image data must be supplied to the first wiring 4. This is a rearrangement of even-numbered data and odd-numbered data.

FIG. 8 shows a wiring pattern of the hard printed circuit board 82 in the third embodiment. In the figure, 84 is a row of through holes, 86 is a third first wiring, and 88 is a fourth first wiring. The first wirings 86 and 88 are folded wirings, and connect the image arrays L1 and L40 at both ends to the driving IC 12.
The difference from the wiring pattern of FIG. 1 is that the number of through holes is reduced. For example, if each array is 64 dots, the number of arrays is 40, and the number of through holes is counted in units of 64, in FIG. 1 there are 20 sets of arrays, and there are two drive ICs 12 on both sides. Is 20 + 2
22 sets. In the pattern of FIG. 8, there are 19 groups of groups for every two arrays, and there are first wirings 86 and 88 connected to the driving IC 12 and the arrays L1 and L40 at both ends, so that two sets of through holes are required. The total number of through-holes becomes 21 sets, and one set of through-holes can be reduced.

[0026]

Fourth Embodiment In the array 40 of FIG. 4, rows of the electrode pads 44 are provided above and below the light-emitting body 42. However, if the electrode pads 44 are provided on one side in a two-row staggered pattern, the image apparatus of FIG. 9 is obtained.
In the figure, reference numeral 92 denotes a hard printed circuit board, and the number of through-hole sets is the total number of arrays ÷ 2 + 1 (21 sets in the embodiment).
Becomes Otherwise, it is similar to the substrate 32 of FIG.

The embodiment can be variously modified in other respects. For example, on the side of the first wiring 4, like the first wiring 03 of the conventional example of FIG. 10, a continuous folded wiring without through-hole connection may be used. In addition, the first wirings 4 and 6 are folded wirings whose directions are changed by 180 degrees on the way.
The rows 8, 8 of the bonding pads are arranged in LED arrays L1 to L
Since they are arranged in a straight line in parallel with the 40 columns, they may be simple line-shaped wirings without folds.

[0028]

According to the present invention, the density of the first wiring is reduced by half.
And the density of through holes is reduced to 1/4, so that a hard printed board or the like can be used, and the cost of the image apparatus can be significantly reduced. Further, corresponding image elements in each image array can be commonly connected to each image element via a U-shaped wiring on one side, a U-shaped wiring on the other side, and a second wiring.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a substrate used in an image apparatus according to an embodiment.

FIG. 2 is a plan view of a main part of a lower surface of a substrate used in the embodiment.

FIG. 3 is a plan view of a main part of a substrate used in a second embodiment.

FIG. 4 is a plan view of the LED array according to the embodiment.

FIG. 5 is a plan view of an LED array according to a modified example.

FIG. 6 is a view showing a connection relationship with a first wiring in the LED array of the embodiment.

FIG. 7 is a diagram showing a connection relationship with a first wiring in an LED array according to a modified example.

FIG. 8 is a plan view of a main part of a substrate used in the third embodiment.

FIG. 9 is a plan view of a main part of a substrate used in a fourth embodiment.

FIG. 10 is a plan view of a main part of a substrate used in a conventional image device.

[Explanation of symbols]

 2, 32 hard printed board 4 U-shaped wiring on one side 6 U-shaped wiring on the other side L1 to L40 LED array 8 Row of bonding pads 10 First wiring lead-out part 12 Drive IC 14 Through hole 16, 18 Through hole Rows 20, 22 Rows of through holes 24, 26 Second wiring 30 Common electrode terminal 34 U-shaped wiring on the other side 40, 50 LED array 42 Light emitter 44, 54 Electrode pad 46 Line symmetry axis 56 Point symmetry axis 60 Wire bonding Pads 82, 92 Rigid printed circuit board 84 Row of through holes 86 Third first wiring 88 Fourth first wiring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-203668 (JP, A) JP-A-3-42253 (JP, A) JP-A-63-307956 (JP, A) 143644 (JP, A) JP-A-61-10283 (JP, A) JP-A-56-80066 (JP, A) JP-A-56-159179 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) B41J 2/45 B41J 2/455

Claims (1)

(57) [Claims] An image in which a large number of image array chips arranged linearly in a longitudinal direction and a large number of first wirings bonded to individual image elements of the array chip are provided on an upper surface of a rectangular substrate. The device, wherein the first wiring is disposed on one of both sides of an image array chip row, and shares a corresponding image element in each image array chip of two adjacent image array chips. The U-shaped wiring on one side is bonded to be connected, and the corresponding image elements on each image array chip of two adjacent image array chips disposed on the other side are bonded to commonly connect. The other side of the U-shaped wiring, and the one side of the U-shaped wiring and the other side of the U-shaped wiring,
Each image element is divided into two image array chips, and each image element is connected to only one of the U-shaped wiring on one side and the U-shaped wiring on the other side. By electrically connecting the second wiring and the one-sided U-shaped wiring through a hole, the separated one-sided U-shaped wiring is connected to each other and the through-hole is connected to the U-shaped wiring. An image apparatus, wherein the separated U-shaped wiring on the other side is mutually connected by electrically connecting the second wiring and the U-shaped wiring on the other side.