JP2018037625A - Signal transmission device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a signal transmission device that can be designed for a decrease in pitch between terminals compared with a case where the device does not has the present configuration, and an image forming apparatus.SOLUTION: A signal transmission device includes a plurality of terminal parts 40 linearly arranged on a first layer 100a of an LED driving board 261. A differential terminal part 400, part of the plurality of terminal parts 40, includes a first area 401 that has a first width and to which a connector terminal is joined by solder, and a pair of second areas 403 that has a second width larger than the first width and is connected to the first area 401 across the first area 401; and the pair of second areas 403 is connected to a differential line 42a formed on a fourth layer 100d with a through hole 404.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a signal transmission device and an image forming apparatus.

  In recent years, a printed circuit board corresponding to a narrow pitch of terminals has been proposed (see, for example, Patent Documents 1 and 2).

  The printed circuit board described in Patent Document 1 has strip-shaped pads arranged in parallel at a narrow pitch and lands connected to the pads, and the lands are alternately connected to the tips of the pads.

  The printed circuit board described in Patent Document 2 is attached to a conductive pattern by a soldering portion and includes a copper plate having a thickness corresponding to the current capacity.

JP-A-6-85463 JP 2003-234548 A

  An object of the present invention is to provide a signal transmission device and an image forming apparatus that can cope with a narrower pitch of terminals compared to the case where this configuration is not provided.

[1] having a plurality of terminal portions arranged linearly on one layer of the substrate;
Some terminal portions of the plurality of terminal portions are:
A first region having a first width and where the connector terminals are soldered;
A pair of second regions having a second width greater than the first width and connected to the first region across the first region;
The pair of second regions is a signal transmission device connected by a through hole to a line formed in another layer different from the one layer.
[2] The signal transmission device according to [1], wherein the pair of second regions are connected to the first region via an intermediate region.
[3] The signal transmission device according to [1], further including a solder resist layer formed so that the first region and the second region of the part of the terminal portions are exposed.
[4] The signal transmission device according to [2], further including a solder resist layer formed so that at least the first region and the intermediate region of the part of the terminal portions are exposed.
[5] The some terminal portions are a pair of differential terminal portions that transmit a differential signal superimposed on electric power, and the pair of differential terminal portions are connected to the pair of lines by the through holes. The signal transmission device according to [1].
[6] A plurality of exposure apparatuses provided for each of a plurality of colors;
A control board for generating an exposure signal for controlling the exposure apparatus from externally input data including image data or control data;
A plurality of drive substrates for generating a drive signal for driving the exposure apparatus from the exposure signal,
The control substrate or the drive substrate is an image forming apparatus provided with the signal transmission device according to any one of [1] to [5].

According to the first, second, and sixth aspects of the invention, it is possible to cope with the narrowing of the terminal pitch compared to the case where the present configuration is not provided.
According to the third and fourth aspects of the invention, when a part of the terminal portions is formed with the same thickness as the other terminal portions, the shortage of the current capacity is compensated by the solder that joins the connector terminal to the first region. be able to.
According to the fifth aspect of the present invention, it is possible to transmit a signal with less noise than in the case of transmitting a signal with a single wire.

FIG. 1 is a diagram illustrating a schematic configuration example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration example of the image formation control unit. FIG. 3 is a plan view showing a main part of the LED substrate. 4A is a plan view of the differential terminal portion, and FIG. 4B is a cross-sectional view taken along line AA in FIG. 4A. FIG. 5 is a plan view of the differential terminal portion according to the first modification. 6A is a view seen from the B direction in FIG. 5, and FIG. 6B is a view seen from the C direction in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the component which has the substantially same function, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

  FIG. 1 is a diagram illustrating a schematic configuration example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 includes an image reading unit (not shown) that reads a document image from a document, an image forming unit 2 that prints a document image read by the image reading unit on a sheet P, and a sheet P taken out by a pickup roll 31. And a tray unit 3 that supplies the image forming unit 2. The paper P is an example of a recording medium.

  The image forming unit 2 prints an original image on a sheet P by an electrophotographic method. The endless intermediate transfer belt 20 circulates and the intermediate transfer belt 20 has yellow (Y), magenta (M), and cyan. (C) and black (K) first to fourth image forming units 21Y, 21M, 21C, and 21K that primarily transfer toner images of each color, and first to first light beams modulated based on image data. And an LED printer head (LPH) 22 that forms an electrostatic latent image on the photosensitive drum 210 by exposing a photosensitive drum 210 (described later) of the four image forming units 21Y, 21M, 21C, and 21K. The LPH 22 is an example of an exposure apparatus. As the exposure apparatus, in addition to LPH, a scanning writing apparatus using a laser diode (LD) as a light source, an LD array in which a plurality of LDs are arranged in the main scanning direction, or the like may be used.

  The LPH 22 includes an LED array in which a plurality of LEDs (light emitting diodes) are arranged in the main scanning direction, and LED boards 220Y, 220M, 220C, and 220K on which the LED array and the LED driving circuit are mounted (when these are collectively referred to) "LED substrate 220") and a lens array that images the light beam emitted from the LED array on the photosensitive drum 210.

  Each of the image forming units 21Y, 21M, 21C, and 21K includes a photosensitive drum 210, a charger that uniformly charges the surface of the photosensitive drum 210, and an electrostatic latent image formed on the surface of the photosensitive drum 210 by the LPH 22. The image forming apparatus includes a developing device that develops an image with each color toner to form a toner image, and a primary transfer roller that presses the intermediate transfer belt 20 against the photosensitive drum 210.

  The intermediate transfer belt 20 is stretched around a plurality of rollers 23A, 23B, and 23C, and circulates and moves by torque from any of the rollers 23A, 23B, and 23C.

  The image forming unit 2 is disposed at a position facing the roller 23C with the intermediate transfer belt 20 interposed therebetween, and the toner image formed on the intermediate transfer belt 20 is secondarily transferred to the paper P supplied from the tray unit 3. And a fixing unit 25 for fixing the toner image transferred onto the paper P onto the paper P.

  The image forming unit 2 includes an image formation control unit 26 that controls an image forming operation. The image formation control unit 26 includes a controller board 260 and a plurality of LED boards 220. Each of the controller board 260 and the LED board 220 is an example of a signal transmission device or a board.

(Configuration of image formation control unit)
FIG. 2 is a diagram illustrating a schematic configuration example of the image formation control unit 26. FIG. 3 is a plan view showing a main part of the LED substrate 220. 4A is a plan view of the differential terminal portion, and FIG. 4B is a cross-sectional view taken along line AA in FIG. 4A. In FIG. 3, illustration of connector terminals is omitted.

  As shown in FIG. 2, the controller board 260 and the LED board 220 are connected by a plurality of (four in this embodiment) power branch lines 121a to 121d. The image formation control unit 26 is configured to use one power branch line 121a among the plurality of power branch lines 121a to 121d as a differential transmission path, and to transmit the differential signal superimposed on the power branch line 121a. Yes. In FIG. 2, 122 is a ground line. By connecting a plurality of power branch lines 121a to 121d from the controller board 260 to the same LED board 220, the current value per power branch line is lowered so as to satisfy the allowable current value of the connector or cable used. Electric power can be supplied. FIG. 2 schematically shows the connectors 19 and 27.

(Configuration of controller board)
The controller board 260 includes a signal generating unit 10 that generates an exposure signal for driving the LPH 22 from externally input data including image data or control data obtained by an image reading unit (not shown), and a power input terminal. 11 and a power line 12 to which power (for example, 12V) is supplied. The signal generation unit 10 is configured by, for example, an application specific integrated circuit (ASIC) or a reconfigurable circuit (FPGA: Field Programmable Gate Array).

  The signal generator 10 superimposes the generated exposure signal on the power line 12 and the power branch line 121a, and transmits them to the LED boards 220Y, 220M, 220C, and 220K. The power line 12 exposes the power supply units 12 a and 12 b on the first layer of the controller board 260. The exposure signal is an example of a differential signal.

  The differential transmission path 13 includes a pair of first lines 14 formed on the first layer of the controller board 260, a pair of power lines 12 coupled to the pair of first lines 14, and a pair of first lines. 14 and a plurality of pairs of second lines 16 formed on the fourth layer of the controller board 260 and branched by the coupling unit 15.

  The coupling unit 15 is a part where the power line 12 is coupled to the differential transmission path 13, and is also a part where the first line 14 of the differential transmission path 13 is branched into a plurality of pairs of second lines 16.

  The power supply unit 12b is connected to the first line 14 via the coil L so that the differential signal is not transmitted to the power supply unit 12b side. A capacitor C for cutting a direct current component is inserted in the first line 14. The power input terminal 11 is connected to the power supply unit 12a through the power line 11a formed in the first layer, and the power supply unit 12a is connected to the power supply layer formed in the third layer through the through hole. To the power supply unit 12b through a through hole. A ground layer is formed on the second layer of the controller substrate 260.

(LED board)
The LED boards 220Y, 220M, 220C, and 220K generate an LED drive signal from the exposure signal from the controller board 260, and drive the LPH 22 with the LED drive signal. In FIG. 2, 28 is a power supply unit, 29 is an LED drive circuit (ASIC) including a memory for LED light quantity adjustment parameters, and 30 is a DC-DC converter for LED drive. In the LED board 220, an exposure signal is transmitted from the controller board 260 to the differential transmission path 42 via the power branch line 121a.

  As shown in FIG. 3, the LED substrate 220 has a plurality of terminal portions 40 arranged in a straight line, a ground layer 41, a power supply unit 28, and a differential transmission path 42.

  Connector terminals are soldered to all or a part of the plurality of terminal portions 40, and the connector 27 shown in FIG. 2 is connected to the connector terminals. Some of the plurality of terminal portions 40 are a pair of differential terminal portions 400 for transmitting an image signal superimposed on a voltage. The first region 401 where the connector terminal of the differential terminal 400 is soldered has the smallest width. The width of the first region 401 is, for example, 0.1 mm or less, 0.05 mm or less, or 0.03 mm or less. Moreover, the thickness of the 1st area | region 401 is 0.07 mm or less, 0.035 mm or less, or 0.018 mm or less, for example.

  The pair of differential terminals 400 is connected to the power branch line 121 a connected to the controller board 260 via the connector 27. The pair of differential terminal portions 400 are connected via a through hole 404 to a pair of differential lines 42a formed in the fourth layer 100d shown in FIG. The pair of differential lines 42 a formed in the fourth layer 100 d is connected to the pair of differential lines 42 b formed in the first layer 100 a through the through holes 43. The pair of differential lines 42b formed in the first layer 100a is connected to the pair of differential lines 42c via the capacitor C. A ground layer 41 is formed on the first layer 100a. The first layer 100a is an example of one layer.

  The power supply unit 28 formed on the first layer 100a of the LED substrate 220 is connected to the differential line 42b via the coil L so that a differential signal is not transmitted to the power supply unit 28 side. The capacitor C inserted between the differential lines 42b and 42c is for cutting a DC component.

A pair of differential terminals 400, as shown in FIG. 4 (a), first has a width _{W 1,} the first region 401 to which the connector terminals 50 are soldered, the first width _{W 1} And a pair of second regions 403 having a _second width W2 larger than the first region 401 and connected to the first region 401 via the intermediate region 402 in the longitudinal direction across the first region 401. The pair of second regions 403 are connected to the pair of differential lines 42b formed in the fourth layer 100d by through holes 404. The fourth layer 100d is an example of another layer different from one layer.

Specific examples of differential terminals 400, copper thickness a thickness 0.035 mm, the first 0.3mm width _{W 1,} the second width _{W 2} and 0.65 mm. When only one of the second regions 403 is provided, the allowable current value is 0.3 A, and considering the current fluctuation of 5%, the maximum value of the flowing current is 0.315 A, which is insufficient by 0.015 A. According to the present embodiment, by providing a pair of second regions 403, it is possible to secure a current capacity of 0.3A × 2 pieces, and it is possible to handle up to 0.6A.

  The connector terminal 50 has an L shape including a base portion 51 and an upright portion 52, and the base portion 51 is joined to the first region 401 of the differential terminal portion 400 by soldering. The bottom surface of the base portion 51 that contacts the first region 401 of the differential terminal portion 400 has a width of 0.2 mm and a length of 0.5 mm, for example.

  For example, a printed circuit board with four conductive layers is used as the LED substrate 220, but a printed circuit board with six or eight conductive layers may be used. As shown in FIG. 4B, the LED drive substrate 261 includes first to fourth layers 100a to 100d, and insulating layers 101a to 101c are provided between the first to fourth layers 100a to 100d, respectively. It has been. The insulating layers 101a to 101c are made of an insulating material such as glass epoxy resin.

  The second layer 100b is the ground layer 17 formed on almost the entire surface of the second layer 100b. The ground layer 17 is an example of a conductive layer. In the ground layer 17 of the second layer 100b, an opening 17a for allowing the through hole 404 to pass therethrough is formed.

  The third layer 100c is a ground / power supply layer 18 in which a ground layer and a power supply layer are formed. The ground / power supply layer 18 has a power supply layer formed at a necessary position, and a ground layer formed around the power supply layer. The ground / power supply layer 18 has an opening 18 a for allowing the through hole 404 to pass therethrough. 3 is connected to the power supply layer of the ground / power supply layer 18 through a through hole.

(Modification 1)
FIG. 5 is a plan view of the differential terminal portion according to the first modification. 6A is a diagram viewed from the B direction in FIG. 5, and FIG. 6B is a diagram viewed from the C direction in FIG. 5.

  In the differential terminal portion 400 of the first modification, the solder resist layer (the hatched portion in FIG. 5) 405 is formed so that each of the first region 401, the intermediate region 402, and the third region 403 is exposed. Is formed. Note that the solder resist layer 405 may be formed so that at least the first region 401 and the intermediate region 402 are exposed.

  When the base portion 51 of the connector terminal 50 is joined to the first region 401 of the differential terminal portion 400 with the solder 44, at least the first region 401 and the intermediate region 402 are exposed when the solder resist layer 405 is peeled off. Therefore, due to the wettability of the solder 44, the solder 44 is made thicker as shown in FIGS. 6A and 6B than when the solder resist layer 405 in the intermediate region 402 is not peeled off at all. Can do.

Specific examples of differential terminals 400, copper thickness a thickness 0.018 mm, the first 0.3mm width _{W 1,} the second width _{W 2} and 0.65 mm. When only one second region 403 is provided, the allowable current value is 0.15 A. However, by providing a pair of second regions 403, a current capacity of 0.15 A × 2 can be secured. . However, considering the current fluctuation of 5%, the maximum value of the flowing current is 0.315 A, so that 0.015 A is insufficient. According to the present embodiment, the solder 44 wets up to about 2/3 (JISC 0099) of the thickness (for example, 0.1 mm) of the base portion 51 of the connector terminal 50 due to wettability, and the thickness of the thinnest portion. t is 0.03 mm. Although the characteristics vary depending on the composition of the solder 44, the general solder conductivity is about 1/10 that of copper, and a current capacity of 0.024A corresponding to a solder thickness of 0.03 mm can be added. It can be increased to 0.324A. That is, even if the thickness of the differential terminal portion 400 is made thinner than that of the first embodiment, the shortage of current capacity can be compensated for by the solder 44.

(Modification 2)
In the differential terminal portion 400 of the present embodiment, the pair of second regions 403 are connected to the first region 401 via the intermediate region 402 in the longitudinal direction across the first region 401. The pair of second regions 403 may be connected to the first region 401 with the first region 401 interposed therebetween.

(Modification 3)
In the second modification, the solder resist layer 405 may be peeled off so that the first region 401 and the pair of second regions 404 are exposed.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications and implementations are possible without departing from the scope of the present invention. For example, although the LED board 220 has been described as an application example of the signal transmission device of the present invention, the present invention can be applied to the controller board 260 in the same manner.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming part, 3 ... Tray part, 10 ... Signal generation part,
DESCRIPTION OF SYMBOLS 11 ... Power supply input terminal, 11a, 12 ... Power line, 12, 12a, 12b ... Power supply part,
13 ... differential transmission line, 14 ... first line, 15 ... coupling part, 16 ... second line,
17 ... Ground layer, 17a ... Opening, 18 ... Ground / power supply layer, 18a ... Opening,
19 ... Connector, 20 ... Intermediate transfer belt,
21Y, 21M, 21C, 21K ... Image forming unit,
22 ... LPH, 23A, 23B, 23C ... roller, 24 ... secondary transfer roller,
25... Fixing unit, 26... Image forming control unit, 27... Connector, 28.
29 ... LED drive circuit, 30 ... DC-DC converter,
31 ... Pickup roll,
40 ... terminal portion, 41 ... ground layer, 42 ... differential transmission line, 42a to 42c ... differential line,
43 ... through hole, 44 ... solder,
50 ... Connector terminal, 51 ... Base part, 52 ... Standing part,
100a ... 1st layer, 100b ... 2nd layer, 100c ... 3rd layer, 100d ... 4th layer,
101a to 101c ... insulating layer,
120 ... Through hole, 121a to 121d ... Power branch line, 122 ... Ground line,
210 ... photosensitive drum, 260 ... controller board,
220, 220Y, 220M, 220C, 220K ... LED substrate,
400 ... differential terminal portion, 401 ... first region, 402 ... intermediate region,
403 ... second region, 404 ... through hole, 405 ... solder resist layer,
P ... paper

Claims (6)

A plurality of terminal portions arranged linearly on one layer of the substrate;
Some terminal portions of the plurality of terminal portions are:
A first region having a first width and where the connector terminals are soldered;
A pair of second regions having a second width greater than the first width and connected to the first region across the first region;
The pair of second regions is a signal transmission device connected by a through hole to a line formed in another layer different from the one layer. The pair of second regions are connected to the first region via an intermediate region,
The signal transmission device according to claim 1. A solder resist layer formed so as to expose the first region and the second region of the partial terminal portion;
The signal transmission device according to claim 1. A solder resist layer formed such that at least the first region and the intermediate region of the terminal portion are exposed;
The signal transmission device according to claim 2. The some terminal portions are a pair of differential terminal portions that transmit a differential signal superimposed on power,
The pair of differential terminal portions are connected to the pair of lines by the through holes,
The signal transmission device according to claim 1. A plurality of exposure apparatuses provided for each of a plurality of colors;
A control board for generating an exposure signal for controlling the exposure apparatus from externally input data including image data or control data;
A plurality of drive substrates for generating a drive signal for driving the exposure apparatus from the exposure signal,
The image forming apparatus including the signal transmission device according to claim 1, wherein the control substrate or the driving substrate is provided.

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