JPH03144593A - Destaticizing device for copying machine - Google Patents

Abstract

PURPOSE:To make the contour of a destaticized area clear by specifying a distance Z when a light emitting diode LED is arranged on an inner side by the distance Z from the position of the leading edge of a partition. CONSTITUTION:It is assumed that pitch between chip LEDs 14a to 14c is Y, the thickness of the partition is X, the distance from the leading edge of the partition to a photosensitive drum 1 is L, and the distance from the leading edge of the partition to the center of the LED is Z. In order to superpose irradiating light beams on the photosensitive drum 1 when the LED is arranged in the deepest part to the maximum, Z<L(Y-X)/X holds. In order not superpose the light beams any more by arranging the chip LED nearest to the photosensitive drum 1 side to the maximum, Z>L(Y-X)/(X+Y) holds. Therefore, L(Y-X)/X>Z>L(Y-X)/(X+Y) is obtained from the above two formulas. By arranging the chip LEDs 14a to 14c so that the formula is satisfied, parts which are the troughs of the irradiating light quantity are overlapped on each other and the distribution difference of light quantity is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a static eliminator for erasing charges on a photosensitive drum of an electronic copying machine.

(Background of the Invention) An image forming apparatus such as an electronic copying machine exposes a photoconductor (the photoconductor drum will be explained below by taking the photoconductor drum as an example) in accordance with document information to form an electrostatic latent image. This is a device that forms a toner image, converts it into a visible image using toner, and transfers and fixes this toner visible image onto transfer paper.

In recent years, this type of image forming apparatus has been used in all fields of industry.

Incidentally, the static eliminator used in this type of image forming apparatus is a device that applies light to the non-image area of the photoreceptor drum to prevent toner from adhering to the non-image area (area outside the document area) and unnecessary pixel areas. This is a device for erasing the charge on the photoreceptor drum by irradiating it. For this purpose, it is composed of a plurality of light emitting elements, and is designed to be able to control lighting and lighting according to the size of the document area. A light emitting diode (hereinafter referred to as LED) is generally used as a light emitting element.

FIG. 14 is a configuration diagram showing the configuration of an image forming apparatus around a conventional static eliminator from a side direction. 1 is a photoreceptor drum constituting an image carrier; 2 is a 41F 711 pole that charges the photoreceptor drum 1 by corona discharge; and 3 is a static eliminator that erases the charge on the non-image area of the photoreceptor drum 1. Note that this static eliminator 3 has a plurality of LEDs arranged in a direction perpendicular to the paper surface.

FIG. 15 is a block diagram showing the structure of the static eliminator 3 in detail. 3a is a printed circuit board on which each component of the static eliminator is arranged; 3b is a driver IC for selectively driving the light source;
3c is a lamp house that holds a plurality of LEDs constituting the light source and separates the luminous flux from each LED. 3d is a light source composed of a plurality of LEDs held in a lamp house 3C.

(Problem to be solved by the invention) Incidentally, there is a demand for miniaturization of copying machines.

For this reason, photoreceptor drums, which occupy a considerable portion of the interior of copying machines, are becoming smaller.

However, various parts are crowded around the photosensitive drum of a copying machine. As the diameter of photoreceptor drums has become smaller,
It is expected that the area will become even more crowded.

Therefore, the static eliminator also needs to be made smaller.

However, the conventional static eliminator that irradiates light perpendicularly to the printed circuit board takes up a space corresponding to the size of the LED support board for holding the LED.

Therefore, miniaturization has been extremely difficult.

Therefore, even if it is desired to use a photosensitive drum with a small diameter, the size of the static eliminator becomes a problem, and a compact image forming apparatus cannot be realized.

It is also conceivable to use paired chip LEDs in order to downsize the static eliminator, but there are also problems in this case.

FIG. 16 is a diagram of a static eliminator using paired chip LEDs viewed from the light irradiation direction. In this figure, 0.4+++m
This is a case where corner pair LED chips are used. This paired chip LED is arranged on the cathode side electrode of the printed circuit board, and the anode side is connected to the anode side electrode via a wire (the electrode on the printed circuit board is omitted). When manufacturing such a static eliminator, pair chip LEDs are mounted on a printed circuit board (wire bonding).
Then install lamp house 3C. Therefore, when installing the lamp house 3c, it is sometimes necessary to open the lamp house opening (
window) cannot be made smaller.

Furthermore, since the photoreceptor drum has a cylindrical shape, if the window of the lamp house is large, there is a problem that the demarcation of the static elimination area becomes unclear. That is, as shown in FIG. 17, due to the broadening of the irradiation angle, the angle of incidence on the drum surface becomes larger at the edge of the irradiation light. As a result, the contours between the image area and the non-image area become vague. This becomes a problem especially when creating a binding margin (binding margin mode). FIG. 18 is an explanatory diagram showing the result when copying is performed in the binding margin mode. There is a charge-eliminating area A at the edge of the transfer paper and at the center in the direction perpendicular to the direction of drum movement (this is called the sub-scanning direction), and the rest of the area is an area (image area) B where the charge is not removed.
,C. In such a case, due to the above-mentioned drum shape and spread of the irradiation angle, blurring occurs in the sub-scanning direction between the charge-eliminating area and the non-charge-eliminating area. This blurring causes deterioration of image quality.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to construct a compact static eliminator suitable for small-diameter photoreceptor drums, and to eliminate static electricity in the static elimination area without causing a difference in the distribution of irradiated light. An object of the present invention is to realize a static eliminator for a copying machine that can make outlines clear.

(Means for Solving the Problems) The present invention solves the above-mentioned problems. A static eliminator for a copying machine for erasing unnecessary electric charge includes: a printed circuit board on which an LED driving IC and an LED are arranged, a linear end surface facing the photoreceptor drum; A plurality of LEDs are arranged in a straight line with a pitch of Y, and an LED house has an opening 1 on the linear end surface side of the pudding+-U board and has a light-shielding partition wall with a thickness of X at a predetermined position. In this case, when the LED is disposed a distance Z inside from the tip position of the partition wall, L (Y-X)/X>Z>L (Y-X)/(X+Y
).

(Function) In the static eliminator for a copying machine of the present invention, the irradiation light from the LED is generated in a direction parallel to the printed circuit board surface and illuminates the photosensitive drum, so that the area occupied by the static eliminator in the copying machine is reduced. Furthermore, since the irradiation light from the LED is emitted in parallel to the substrate surface, the opening area of the LED house becomes smaller, and the static eliminator becomes smaller. Furthermore, the spread of the emission angle is suppressed, and the outline of the static elimination area becomes clear. By arranging the LED within a predetermined range from the position of the tip of the partition wall, the valley of the irradiation light amount varies by −q, and no difference in light amount distribution occurs.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram showing the configuration of a static eliminator 10 according to an embodiment of the present invention.

11 is a printed circuit board on which each component of the static eliminator is arranged;
2 is a driver IC 13 for selectively driving the light source;
is mounted on the printed circuit board 11, with an opening formed on the linear end surface side of the printed circuit board 11, and a light emitting element house (hereinafter referred to as (referred to as LED house), 1.4a~1
4 is an LED placed on the printed circuit board 11, 15 is an L
LED house 13 to protect ED from toner contamination
This is an LED cover made of a transparent plate attached to the opening of the LED cover.

FIG. 2 is a front view showing the state of the static eliminator of this embodiment when viewed from the opening (iE surface) direction.

FIG. 3 is a sectional view of the photosensitive drum 1 when viewed from the axial direction.

In this case, due to the size of the document and the copying magnification, the image area A in FIG. 1 is the effective image area width of the photoreceptor drum 1, and the areas B and C adjacent to the image area A are It is a non-image area.

The static eliminator 10 includes chip LEDs (chip LEDs in the present invention refer to paired chip LEDs and surface-mounted component LEDs) over the entire axial width 2 of the photoconductor drum 1 so as to face the surface of the photoconductor drum 1. A large number of electrostatic latent images are arranged, and before the electrostatic latent image is developed, light is irradiated to erase the charges in the non-image areas B and C.

In this example, the chip LEDs 14 are linearly arranged at regular intervals along the linear end surface of the printed circuit board 11.

The LED house 13 has an opening so as to emit light parallel to the surface of the printed circuit board 1.

As shown in FIGS. 2 and 3, by irradiating light in a direction parallel to the surface of the printed circuit board 11,
Even considering the distance between the wire of the chip LED 14 and the LED house 13, the height H of the opening (irradiation window) of the LED house
can be kept very small. Therefore, the area occupied by the static eliminator 10 in the copying machine can be considerably reduced.

In other words, compared to conventional static eliminators that use molded LEDs and irradiate light in the direction horizontal to the printed circuit board, or those that use chip LEDs that irradiate light in the direction perpendicular to the printed circuit board, this method It can be seen that the static eliminator in this example is quite thin.

Not only is it smaller (thinner), but the broadening of the illumination angle is also suppressed. As shown in FIGS. 3 and 4, since the window for illumination n= of the static eliminator 10 has become smaller (height H of the irradiation window has been suppressed), the angle of incidence with respect to the photoreceptor drum 1 has become smaller. This also has the effect of making the outline of the static elimination area clearer.

Therefore, even when removing static electricity from only an arbitrary area of a document, it is possible to eliminate static electricity with a clear outline. In this case, the height H of the window 0 is preferably in the range of 0.5+am to LOmm.

This is because if it is larger than 3°On+I++, the irradiation angle becomes too wide, and if it is less than 05 questions, the amount of light decreases too much.

Further, if it is less than 051WI11, the amount of light may become less than the specified value due to toner staining, which is not preferable.

Furthermore, since the printed circuit board 11 also serves as the bottom of the lamp house, less material is required, which is economical.

With this configuration, chip LEDs can be automatically and easily mounted, throughput can be increased, and costs can be reduced. If the chip LED is a paired chip, it can be mounted in the same process as the mounting process for other paired chip components.In addition, in the case of a surface mount LED, it can be mounted in the same process as the general surface mounting process (chip capacitor 1 chip resistor, etc.). It can be mounted in the process.For this reason, the L of the mold
There is no need for a dedicated process like when implementing ED.

Here, the characteristic parts of the present invention will be explained.

FIG. 5 is an enlarged view showing the main part of FIG. 1 in order to explain where the chip L E D 1.4 is arranged.

This figure shows a case in which the LEDs are arranged as far back as possible (at a position away from the photoreceptor drum 1) so that the irradiated light from adjacent LEDs does not overlap on the photoreceptor drum 1''.

In this figure, 14a to i 4 c are chip LEDs.
It is. Then, the pitch between the chip LEDs is Y, the thickness of the partition wall is X, the distance from the tip of the partition wall to the photosensitive drum 1 is subtracted, and the distance from the tip of the partition wall to the center of the LED is Z. still,
In this diagram, the LED is placed as far back as possible, so the Z
It is maxed out.

Moreover, i of L E D 1.4 b on the photosensitive drum 1
[If the position that hits the surface is expressed in coordinates with the origin 0 (0, 0), the center position of the LED is A (0, L + Zma
), the position where the irradiation light from the LED hits the tip of the partition is B(
Y/2-X/2. L), A point at a distance from the photosensitive drum 1 between AC +; ff1c (0, L), LED
The position where the irradiated light that has passed through point B from 14b hits the photosensitive drum 1 can be expressed as D (Y/2.0).

In such a case, since the triangle ABC and the triangle ADO are similar, the relationship AC:AO-BC:Do holds true. When Z is determined from this formula, Z<L (Y-X)/X...■.

In addition, FIG. 6 shows that by arranging the chip LEDs as close to the photoreceptor drum 1 as possible, the irradiation light from adjacent LEDs is 4 (
A case is shown in which the images are overlapped on the photoreceptor drum 1 minute by minute. Therefore, in this figure, the chip LED is placed as close as possible to the front, so it is Z min.

If we calculate 2 from this case, we get Z>L (Y-X)/(X+Y) = ■.

Therefore, from the above equation, L (Y-X)/X>Z>L (Y-X)/ (X+Y
)...■ is required. Chip L E so as to satisfy this formula
By arranging D 1.4, the portions that would become valleys in the amount of irradiated light overlap with each other, so that no difference in light amount distribution occurs.

In addition, the above calculation is performed from the chip LED to the printed circuit board 1.
1 and reaches the photoreceptor drum 1 along the line 1. Therefore, in the case of light that passes through the vicinity of the top plate of the LED house 13 from the chip LED and reaches the photoreceptor drum 1, there will be a slight deviation from the double calculation, but the error due to spread is small. There is no problem because there is.

By the way, various changes can be made to the shape that satisfies the formula (2). Preferred conditions in such a case will be explained below.

When determining the thickness X of the partition wall, if it satisfies the following: Y/20≦X≦2Y/3...■, the contour of the static elimination area becomes clear and no difference in light quantity distribution occurs.

Similarly, if the following condition is satisfied: 1/(2Z)≦X≦10/Z − .

When determining the LED arrangement position, Y/20≦
Even if Z≦2Y...■ is satisfied, the contour of the static elimination area becomes clear and no difference in light amount distribution occurs.

Here, the reversal rate of the inner surface (particularly the partition surface) of the LED house 13 will be explained.

FIG. 7 is a characteristic diagram showing the relationship between the position from the optical axis on the drum surface and the amount of irradiated light when the reflectance is 40% and 10%. Further, FIG. 8 is a characteristic diagram showing the relationship between the position from the optical axis on the drum surface and the copy optical density [OD]. In these figures, 0D-0 means that the toner does not stick to the surface due to static electricity removal, and 17.0D-1 means that the toner adheres to the drum surface without static electricity removal and becomes black. .

At a reflectance of 10%, the edges of the light amount distribution are sharp and the spread is small. On the other hand, when the reflectance is 40%, the tail of the light amount distribution is widening. Also, at a reflectance of 40%,
It can be seen that the halftone region from 0D=O to 0D=1 (the part where incomplete charge removal is performed) is wide, and so-called blurring is likely to occur. For this reason, it has been confirmed through experiments that the partition wall surface must have a light-shielding property, and specifically, a reflectance of 30% or less is desirable.

Furthermore, in the conventional static eliminator that irradiates in the direction perpendicular to the substrate, it is impossible to accurately arrange the distance from the photoreceptor drum 1 due to the deflection of the printed circuit board. In other words, due to the deflection of the printed circuit board, the L in the center of the static eliminator
The distance from the photosensitive drum 1 differs between the ED and the end LED.

On the other hand, in this embodiment, since the irradiation is performed horizontally to the printed circuit board, no error occurs due to the deflection of the printed circuit board. Furthermore, by positioning the chip LED with reference to the linear end surface of the substrate, the distance from the photosensitive drum 1 can be determined extremely accurately. Therefore, the amount of light +1-1 light is also rlE accurate.

FIG. 9 is a block diagram showing another embodiment of the present invention. In the embodiment shown in this figure, the shape of the tip of the partition wall of the LED house is the same as that described above.

That is, the partition wall portion is configured to become thicker toward the tip. In this case, the thickness of the partition wall is f at the tip.
ll11 is determined. Furthermore, as shown in FIG. 10, even in the case where the partition wall has a thinner tip, the thickness X is measured at the tip. Further, when the partition wall has a curved tip as shown in FIG. 11, the above-mentioned Z is measured at the tip of the partition wall that has a curved surface. Note that it is also possible to use partition walls having shapes other than those shown here.

By the way, when performing static elimination with the configuration as explained above, the size of the pair chip LED: 0.4 mm square LED pitch Y: Bmm.

LED position Z: 3mm Partition wall part X of LED house: 1 question.

The best results were obtained when the reflectance of the inner surface of the LED house was 30% or less.

It is important to make the wall thickness of the LED house uniform because it improves accuracy. That is, when manufacturing an LED house by injection molding, a molten polymer is put into a mold and taken out after cooling. At this time, because the wall thickness is uniform, cooling and assimilation progresses uniformly, there is little distortion and warping, and J-method accuracy is achieved accurately.

In addition, modified PPE (
PPE (polyphenylene ether))/PS (polystyrene)-based resin, PPE/PBT (polybutylene thiphthalate), PPE/PET (polybutylene thiphthalate), PPE/PCT (poly 1-4-cyclohexane dimethylene tephthalate)) , Chemical resistant PPE (PPE/PA (polyamide) resin), Glass-filled (0-40%) modified PPE.

Polycarbonate (PC), Polyamide (PA), Polybutylene phthalate (PBT), Polybutylene phthalate (PET), Glass reinforced PET (GF-P
ET), poly 1-4-cyclohexane dimethylene tephthalate (PCT), polyacetal (POM), polymethylene pentene (PMP), glass fiber reinforced PMP (FR-PMP), ethylene vinyl alcohol (polymer (EVOH), Polyphenylene sulfide (PPS), polyarylate (PAR), polysulfone (PSF), polyarylsanphone (PASF), polyethersulfone (PES), polyetherimide (PEI), ketone polymer (polyetheretherketone) (P.E.
EK), polyketone, etc.), imide polymers (polyimide (PI), polyamideimide (PAr), etc.), fluororesins (polytetrafluoroethylene (PTFE))
etc.), acrylic acid resins, liquid crystal polymers (LCP), etc., and composites thereof can be used.

In addition, the materials of the LED cover 15 include polycarbonate (PC), acrylic acid resin, Boria Relay 1-(PAR), liquid crystal polymer (LCP), polybutylene tephthalate (PBT), polyethylene terephthalate 1-(PET), etc. can be used.

In addition, if you are using it without worrying about toner staining, use L.
It is also possible to omit the ED cover 15, and there is no problem.

FIG. 12 is a cross-sectional view showing the structure of another embodiment of the present invention as viewed in the direction of the printed circuit board. Further, FIG. 13 shows a cross section (12th
FIG. 2 is a cross-sectional configuration diagram showing a section taken along line AA' in the figure.

In this embodiment, instead of the chip L E D 1.4 consisting of a pair of chips in the static eliminator of the embodiment shown in FIG.
Surface mount components LED16 are used.

That is, even if a surface mount component is used in place of a bare chip, the same effects as in each of the above-described embodiments can be obtained.

In addition, in the above-mentioned embodiment, an LE is set for each adjacent chip LED.
A partition wall was installed in House D, but it was installed only where necessary to match the paper size of the transfer paper and the division of the static elimination area.
It is also possible not to provide partition walls in other parts.

(Effects of the Invention) As described in detail above, in the present invention, unnecessary parts on the photoreceptor drum are illuminated by being arranged so as to face the surface of the photoreceptor drum at a distance, and by illuminating the photoreceptor drum. A static eliminator for a copying machine for erasing electric charge includes a printed circuit board on which a light emitting element driving IC and a light emitting element are arranged, a linear end surface facing the photoreceptor drum, and a printed circuit board parallel to the linear end surface on the printed circuit board. a plurality of light emitting elements arranged linearly at a pitch Y, and a light emitting element house having an opening on the linear end surface side of a printed circuit board and having a light-shielding partition wall with a thickness X at a predetermined position, When the light-emitting element r is arranged at a distance Z inside from the tip position of the partition wall, L (Y-X)/X>Z>L (Y-X)/(
X+Y). As a result, the LED
It becomes possible to reduce the height of the house, making it possible to configure the static eliminator with a thin design, and also to suppress the spread of the amount of irradiation light in the rotational direction of the photoreceptor drum, resulting in differences in the distribution of the amount of irradiation light. will no longer occur. In addition, by arranging the light emitting elements within a predetermined range from the tip of the partition wall, the troughs of the irradiated light amount overlap each other, and the outline of the static elimination area becomes clear without causing any difference in the light amount distribution. . Therefore, the present invention provides a compact static eliminator suitable for small-diameter photoreceptor drums, and also realizes a static eliminator for a copying machine that can make the outline of the static neutralization area clear without causing a difference in the distribution of irradiated light. I was able to do that.

[Brief explanation of the drawing]

1 is a configuration diagram showing the configuration of a static eliminator according to a first embodiment of the present invention, FIG. 2 is a front view showing the JL plane of the static eliminator according to the embodiment shown in FIG. FIG. 4 is an explanatory diagram showing the irradiation angle of the defrosting device of the embodiment shown in FIG. 1, and FIG. 5 is a diagram showing the arrangement of LEDs. 11 ((An explanatory diagram explaining η・1 angle, Figure 6 is an explanatory diagram explaining the arrangement of LEDs and the irradiation angle, Figure 7 is a characteristic diagram showing the characteristics of the drum position and irradiation light amount, and Figure 8 is the drum A characteristic diagram showing the characteristics of position and copy density. FIG. 9 is a cross-sectional configuration diagram showing the configuration of another embodiment of the present invention. FIG. 10 is a cross-sectional configuration diagram showing the configuration of still another embodiment of the present invention. , FIG. 11 is a cross-sectional configuration diagram showing the configuration of still another embodiment of the present invention, FIG. 12 is a cross-sectional configuration diagram showing the configuration of still another embodiment of the present invention, and FIG. 13 is shown in FIG. 12. 14 is a side view showing a conventional static eliminator together with a photoreceptor drum; FIG. 15 is a waste configuration diagram showing the external structure of the conventional static eliminator; Figure 17 is a configuration diagram showing the configuration of a conventional static eliminator in detail, Figure 17 is an explanatory diagram illustrating the state of the irradiation angle in the drum rotation direction of the conventional static eliminator, and Figure 18 shows how static electricity is removed on transfer paper. It is an explanatory diagram (not shown).

Claims (1)

[Claims] Discharge of a copying machine is arranged to face the surface of a photoreceptor drum at a distance L, and is used to erase unnecessary charges on the photoreceptor drum by illuminating the photoreceptor drum. In the apparatus, a printed circuit board (on which a light emitting element driving IC and a light emitting element are arranged, and whose linear end face faces the photoreceptor drum) is installed.
11), a plurality of light emitting elements (14) linearly arranged on the printed circuit board (11) parallel to the linear end surface at a pitch Y, and an opening on the linear end surface side of the printed circuit board (11). and a light-emitting element house (13) having a light-shielding partition wall with a thickness -X)/X>Z>L(Y-X)/(X+Y).