JP4972976B2 - Self-scanning light-emitting element array chip, method for manufacturing self-scanning light-emitting element array chip, and optical writing head - Google Patents

Description

The present invention relates to a self-scanning light-emitting element chip, and more particularly, to a self-scanning light-emitting element array chip that compensates for a reduction in light amount of a light-emitting element due to the influence of wiring resistance. The present invention also relates to an optical writing head using such a self-scanning light emitting element array chip, and further to an optical printer, a facsimile machine, and a copying machine using such an optical writing head.
A light emitting element array in which a large number of light emitting elements are integrated on the same substrate is used as an optical writing head such as an optical printer head in combination with a driving IC. The inventors have paid attention to a three-terminal light-emitting thyristor having a PNPN structure as a constituent element of the light-emitting element array, and have already filed a patent application (see Patent Documents 1, 2, 3, and 4) that self-scanning of the light-emitting point can be realized. It has been shown that it is easy to mount as an optical printer head, that the light emitting element arrangement pitch can be made fine, and that the number of bonding pads can be reduced, so that a compact self-scanning light emitting element array can be produced.

  Furthermore, the present inventors have proposed a self-scanning light-emitting element array having a structure separated from the light-emitting element array that is a light-emitting part using the transfer element array as a shift part (see Patent Document 5).

FIG. 1 shows an equivalent circuit diagram of a diode-coupled self-scanning light emitting element array chip in which the shift section array 8 and the light emitting section array 10 are separated. This self-scanning light emitting device array (Self-scanning Light-emitting Device, hereinafter abbreviated as SLED) is composed of transfer elements T ₁ , T ₂ , T ₃ ..., Light emitting elements L ₁ , L ₂ , L _It consists of ₃ ... A three-terminal light-emitting thyristor is used for both the transfer element and the light-emitting element. That is, the gate electrodes of the transfer elements are coupled by the diodes D ₁ , D ₂ ,. V _GA is a power source (usually −5 V), and is connected from the V _GA line 13 to the gate electrode of each switch element via the load resistance _RL . The gate electrode of the transfer element is also connected to the gate electrode of the light emitting element. The gate electrodes of the transfer element T ₁ is connected to a start pulse terminal phi _S. The cathode electrode of the transfer element is connected to clock pulse terminals φ1 and φ2 via transfer clock pulse φ1 and φ2 wirings 11 and 12 alternately. Resistors R1 and R2 are current limiting resistors inserted in the wirings 11 and 12, respectively. A cathode electrode of the light emitting element passes through the light-emitting element feed line 14, is connected to the light emitting element feed terminal phi _I. The resistor _RI is a current limiting resistor inserted in the wiring 14.

A typical self-scanning light emitting element array chip pattern of 128 light emitting elements is shown in FIG. The same elements as those in FIG. 1 are denoted by the same reference numerals.
Reference numerals 1 to 4 denote bonding pads connected to the respective lines.

  Further, the present applicant has proposed a light-emitting element array with a lens in which a microlens is provided on the light-emitting element (see Patent Document 6).

  The reason for providing the microlens will be described below.

  A typical configuration example of a light emitting element array, a rod lens array, and a photosensitive drum used in a conventional optical printer is shown in FIG. 20 is a light emitting element, 22 is a rod lens array, and 24 is a photosensitive drum.

  While the effective aperture angle θ of the rod lens array 22 is 17 to 20 ° as a half angle, the light emitting element 20 basically emits light with a Lambertian distribution, and the light utilization efficiency is extremely low.

  In order to increase the light use efficiency, as shown in FIG. 4, a microlens array 28 is disposed immediately above the light emitting portion 26 of the light emitting element to narrow the directivity of light emission as much as possible. It is conceivable to increase the number of rays incident on the aperture angle.

  However, in general, in the light-emitting portion 26 of the self-scanning light-emitting element array used in the optical printer, as shown in FIG. 5, the electrode 27 blocks the vicinity of the center of the light-emitting portion. As shown in FIG. 4, the light emitting portion 26 has a substantially U shape. As shown in FIG. 4, when trying to narrow the directivity with a general microlens array, the light beam 29 in the vicinity of the optical axis desired to be incident on the microlens 28 corresponds to the light emission position from the electrode light shielding portion. As a result, the light utilization efficiency cannot be improved sufficiently.

  Therefore, a composite microlens as shown in FIG. 6 was used. FIG. 6A shows a state in which the composite microlens 30 is provided on the light emitting portion 26 of the light emitting element, and FIG. 6B shows the shape of the composite microlens. Show.

  When the maximum position of the light emission intensity of the substantially U-shaped light emitting portion 26 is connected, a broken line 32 is formed. A part of four spherical lenses whose centers are located at or near both ends of the three line segments of the broken line 32 are provided, and a part of three cylindrical lenses having axes parallel to the three line segments are provided in the middle part thereof. The compound lens 30 is formed by arranging them adjacent to each other. Epoxy or acrylic resins are used as materials for such compound lenses. The compound lens can be formed by a 2P (Photopolymer) molding method.

  In FIG. 6B, points 33, 34, 35, and 36 indicate both ends of three line segments 32a, 32b, and 32c of the substantially U-shaped broken line 32 shown in FIG. 6A. The compound lens 30 is centered on a portion 43 of a spherical lens centered on a point 33, a portion 44 of a spherical lens centered on a point 34, a portion 45 of a spherical lens centered on a point 35, and a point 36. A portion 46 of a spherical lens. The compound lens 30 further includes a part of the cylindrical lens 48 having an axis parallel to the line segment 32a, a part of the cylindrical lens 50 having an axis parallel to the line segment 32b, and an axis parallel to the line segment 32c. Part of the cylindrical lens 52. A part of these four spherical lenses and a part of the three cylindrical lenses are arranged adjacent to each other as shown.

  FIG. 6B also shows a cross-sectional view taken along the line X-X ′ and a cross-sectional view taken along the line Y-Y ′ for understanding the shape of the compound lens.

  In this way, the composite microlens 30 is a special lens in which each part of the substantially U-shaped light-emitting portion 22 is aligned with the center of the optical axis of the spherical lens or the axis of the cylindrical lens, and a part of the spherical lens is combined with the cylindrical lens. Shape lens.

  By using a compound lens that matches such a substantially U-shaped light-emitting portion shape, for each portion of the substantially U-shaped light-emitting portion, each portion of the compound lens is used to direct the emitted light beam in the optical axis direction, that is, It can be refracted in the direction of the rod lens, and the directivity of Lambertian issuance can be narrowed in the direction of the rod lens.

  FIG. 7 shows a state where the compound lens 30 is provided on the light emitting unit 26.

JP-A-1-238996 Japanese Patent Laid-Open No. 2-14584 Japanese Patent Laid-Open No. 2-92650 JP-A-2-92651 JP-A-2-263668 JP-A-2005-39195

  As described above, one of the major features of the SLED chip is that the number of bonding pads can be reduced. However, the following problems exist. That is, as shown in FIG. 8, since the power supply wiring 14 to the light emitting point is at least one, the distance from the bonding pad 4 serving as the power supply point of the chip portion to each light emitting portion 26 is different. . For this reason, as the distance from the bonding pad 4 becomes longer, the current flowing to the light emitting portion decreases due to the influence of the voltage drop due to the wiring resistance. As shown in FIG. 9, the amount of light is approximately proportional to the current. Therefore, as shown in FIG. 10, a phenomenon occurs in which the amount of light decreases as the light emitting portion is further away from the bonding pad. This phenomenon is called shading in the chip with a light amount.

  When such an SLED chip is used as a light source for an optical printer or a copying machine, it is necessary to incorporate a correction circuit in the external drive circuit so that the amount of light is constant by eliminating shading in the SLED chip. It contributed to the up.

  An object of the present invention is to provide an SLED chip that can suppress the light amount shading in the chip, reduce the load relating to the light amount correction in the external drive circuit, and achieve the cost reduction of the entire optical writing head.

  Another object of the present invention is to provide an optical writing head using an SLED chip, and an optical printer, a facsimile machine, and a copying machine including such an optical writing head.

The first aspect of the present invention is:
A light emitting element array comprising a plurality of light emitting elements arranged in the main scanning direction;
Each light emitting element includes at least one power supply line extending in the main scanning direction for supplying current from a power supply bonding pad,
This is a self-scanning light emitting element array chip in which the area of the light emitting portion of each light emitting element is increased as the distance from the bonding is increased.

The second aspect of the present invention is:
A light emitting element array comprising a plurality of light emitting elements arranged in the main scanning direction;
A lens array composed of microlenses provided on the light emitting portion of each light emitting element;
Each light emitting element includes at least one power supply line extending in the main scanning direction for supplying current from a power supply bonding pad;
A self-scanning light emitting element array chip in which the light transmission efficiency of each microlens is increased as the distance from the bonding pad increases.

  According to the present invention, by gradually changing the area of each light emitting portion in the chip, the light output per unit current increases as the distance from the power supply bonding pad increases, thereby reducing the amount of light due to the influence of wiring resistance. Can compensate.

  In addition, according to the present invention, a lens is formed on the light emitting portion, and the light transmission efficiency of the lens is improved as the distance from the power supply bonding pad increases, so that it is possible to compensate for a decrease in light amount due to the influence of wiring resistance.

  Embodiments of the present invention will be described below with reference to the drawings.

  One of the factors that determine the amount of light emitted by the SLED is the area of the light emitting portion. The amount of light is proportional to the area of the light emitting part cathode island excluding the part where the light is extracted to the outside, that is, the electrode and the wiring part serving as the light shielding area. By utilizing this characteristic, the area of the light emitting part cathode island is gradually increased as the distance from the power supply bonding pad increases, thereby compensating for the decrease in light amount due to the influence of wiring resistance and eliminating shading in the light amount chip. be able to.

  The compensation for the reduction in the amount of light will be described in detail.

となる。したがって、発光部サイリスタＬ_ｎまでの配線抵抗ｒ_ｎは、

となる。ここで、ρは配線の抵抗率〔Ω・μｍ〕、ｗは配線幅〔μｍ〕、ｄは配線厚さ〔μｍ〕である。
ａ＝（ρ／ｗｄ）×（２５３８０／ｑ）とすると、（２）式は次式で表される。
ｒ_ｎ＝ａ（ｎ−１） ・・・・・（３）
ｎ番目の発光部サイリスタＬ_ｎがＯＮしているときに流れる電流Ｉ_ｎは、

１≫ａ（ｎ−１）／Ｒ_Ｉ であるので、（４）式は、次式で近似できる。

光量Ｌ_ｎは電流Ｉ_ｎに比例するから、比例係数をｂとすると、

となる。一方、光量Ｌ_ｎは発光部面積Ｓ_ｎに比例するから、比例係数をｃとすると、
Ｌ_ｎ（Ｓ）＝ｃＳ_ｎ ・・・・・（７）
配線抵抗による、光量低下を発光部面積で補完して、すべての発光点の発光光量をｎ＝１番目の光量に合わせこむためには、以下で導出されるように、発光部の面積Ｓ_ｎ変調して設計すればよい。

Ｌ_ｎ＝Ｌ_ｎ（Ｉ）＋Ｌ_ｎ（Ｓ） ・・・・・（９）
Ｌ_ｎ＝Ｌ_１とするには、（８），（９），（６）式から、

となる。

It becomes. Thus, the wiring resistance _{r n} to the light emitting portion thyristors _{L n,}

It becomes. Here, ρ is the wiring resistivity [Ω · μm], w is the wiring width [μm], and d is the wiring thickness [μm].
Assuming that a = (ρ / wd) × (25380 / q), the equation (2) is expressed by the following equation.
r _n = a (n−1) (3)
The current _{I n} flowing when n-th light emitting unit thyristor _{L n} are turned ON,

Since 1 >> a (n−1) / R _I , Equation (4) can be approximated by the following equation.

Since the amount of light L _n is proportional to the current I _n, a proportionality coefficient is b,

It becomes. Meanwhile, since the amount of light L _n is proportional to the light emitting portion area S _n, when the proportionality coefficient is c,
L _n (S) = cS _n (7)
In order to compensate the light amount reduction due to the wiring resistance by the light emitting portion area and to match the light emitting amount of all the light emitting points to the first light amount, the light emitting portion area _Sn modulation is derived as will be derived below. And design.

L _n = L _n (I) + L _n (S) (9)
In order to set L _n = L ₁ , from the equations (8), (9), (6),

It becomes.

Now, let us consider the equation (8). The first light quantity is a function of the external drive voltage and the external load resistance. The current drive voltage is -5V, but in order to obtain the same amount of light even when driven at -3.3V, the external load resistance must be reduced at the same ratio as the voltage. As can be seen from the equation (8), since the gradient of the light amount is proportional to 1 / R ₀ ² , changing the drive voltage to the low voltage side greatly deteriorates the light amount variation due to shading. This shading can be easily corrected without changing any conventional manufacturing process by modulating the area of the light emitting part as shown in equation (10) only by mask design.

Specifically, an SLED chip was produced as follows. Now generally of being used SLED having 128 light-emitting points in 600dpi emitting portion feed line (phi _I wiring) 14 has a thickness of 1.2 [mu] m, a width of 20 [mu] m, the first light emitting point and the 128 light-emitting The distance between the dots is 42.3 μm × 127 = 5372 μm, and the wiring material is Al (resistivity 2.8 μΩcm). Therefore, an electric resistance of 5Ω is provided between the first light emitting point and the 128th light emitting point. Exists. A difference in energization current caused by a voltage drop corresponding to the resistance of 5Ω is generated as a difference in light amount. The in-chip current distribution of the actually produced SLED chip is approximated by a linear regression line with the current of each light emitting part as y (mA) and the light emitting point number as x as shown in FIG.
y = −0.0026x + 13.2 (11)
Met. FIG. 12 shows this linear regression line.

  The slope of this straight line hardly varies with the 3 million chips produced in the past. As can be seen from Equation 11, 13.2 mA at the first emission point and 12.9 mA at the 128th emission point, that is, when the first emission point is used as a reference, the 128th emission point is 2.5% current. It can be seen that there is a decrease (this is a typical value when the SLED is driven at −5 V). Since the amount of light is proportional to the current, the amount of light is similarly reduced by 2.5%. On the other hand, it has already been described that the amount of emitted light is proportional to the area of the light emitting part from which the amount of light is extracted.

  As shown in FIG. 13, since the area of the light emitting part 26 is proportional to the area of the cathode island (S = a × b), the main light emitting part area of the first light emitting point is used as a reference, as shown in FIG. The dimension of the light emitting portion cathode island was designed so that the light emitting portion area at the 128th light emitting point was increased by 2.5% by changing the length a in the scanning direction. About the light emission point between the 1st-128 light emission points, it designed so that an area might increase equally. When the light amount (3000 chips) of the completed SLED chip was measured, the light amount shading, that is, the slope of the linear regression line was almost zero, and the light amount variation in the chip was 3σ / average light amount = 0 as the standard deviation σ. .014 (1.4%).

  From the above results, it was found that the light amount distribution (shading) due to the wiring resistance that can be approximated by the linear regression line can be corrected.

  Since the area modulation of the light emitting portion implemented to achieve the present invention only needs to design the mask pattern at the time of forming the cathode island, the SLED is excellent in terms of light quantity variation without changing any conventional manufacturing process conditions. You can make chips.

In Example 1, the effect of the invention was confirmed with the currently produced SLED chip for driving -5V. In the future, it will be necessary to drive the SLED chip with -3.3 V, which is the drive voltage of the external drive circuit, for cost reduction. A -3.3V drive SLED chip having 256 emission points at 1200 dpi was actually produced. As a result, when the in-chip current distribution of the SLED chip was examined in the same manner as the expression (11) in Example 1, the current of each light emitting unit was y (mA), the light emitting point number was x, and y = −0. 0039x + 13.1 (x = 1... 256) (12)
It can be approximated by a temporary regression line. FIG. 12 shows Formula 12 in comparison with Formula 11.

  When the first light emission point is 13.1 mA and the 256 light emission point is 12.1 mA, that is, based on the first light emission point, the 256 light emission point has a current decrease of 7.6%. A decrease of 7.6% is also seen in the measured value of the light quantity, which is consistent with the fact that the light quantity is proportional to the current.

The major difference between Example 1 and Example 2 is the drive voltage of the SLED chip. In the −5V drive described in Example 1, the change in the amount of light due to shading was 2.5%. By doing so, it can be seen that about three times as much shading has occurred. Reason, so as not to change the supply current to the light emitting portion of the SLED chips, when you try to -3.5V the drive voltage from -5V, it is necessary to reduce the external load resistance SLED chip external phi _I wirings . For this reason, the influence of the wiring resistance in the chip becomes relatively large, and as a result, three times as much shading occurs.

  In the same manner as in Example 1, the dimensions of the light emitting portion cathode island were designed so that the light emitting portion area of the 256 light emitting point was increased by 7.6% based on the light emitting portion area of the first light emitting point. The light emission points between the first to 256 light emission points were distributed so that the area increase was increased by an equal difference. When the light amount (3000 chips) of the SLED chip completed by designing the mask in this way was measured, the shading of the light amount, that is, the slope of the temporary regression line was almost zero, and the variation in the light amount in the chip was the standard deviation σ. 3σ / average light quantity = 0.017 (1.7%), and there was a remarkable effect in suppressing light quantity variation due to shading that was 7.6%.

  Since the area modulation of the light emitting portion implemented to achieve the present invention only needs to design the mask pattern at the time of forming the cathode island, the SLED is excellent in terms of light quantity variation without changing any conventional manufacturing process conditions. You can make chips.

  In this embodiment, the area of the light emitting part cathode island is changed by changing the length a in the main scanning direction, but the area b is changed by changing the length b in the sub scanning direction or a and b at the same time. The same effect can be obtained even if modulation is performed.

  In the first and second embodiments, the area of the light emitting unit cathode island is modulated. However, the same effect can be obtained by modulating the area of the feeding electrode that blocks the light amount of the light emitting unit.

  In the first and second embodiments, the area of the light emitting unit cathode island is modulated. However, the same effect can be obtained by modulating the area of the power supply wiring that blocks the light amount of the light emitting unit.

  Of course, the cathode island, the feeding electrode area, and the feeding wiring area may be combined.

  It has already been described that the use efficiency of light emitted with a Lambertian distribution can be increased by the compound lens. By modulating the light transmission efficiency of this compound lens, the light amount shading in the chip can be corrected.

  FIG. 15 is a top view when the compound lens 30 is formed in the light emitting portion of the SLED chip. The maximum efficiency of the compound lens is obtained when the center line of the light emitting unit 30 matches the center line of the compound lens.

  The SLED chip with lens is manufactured as follows.

  FIG. 16 shows a process of manufacturing an SLED chip with a compound lens of a self-scanning light emitting element array.

  First, as shown in FIG. 16A, a Cr film 102 is applied on a quartz glass substrate 100, and then an array of openings 104 is formed in the Cr film by photolithography. FIG. 17 is a plan view of a quartz glass substrate with a Cr film obtained by patterning such an aperture array.

  Next, the quartz glass substrate 100 with a Cr film is subjected to liquid phase etching using hydrofluoric acid, so that a recess 106 as shown in FIG. The shape of the recess corresponds to the shape of the compound lens in which the spherical lens and the cylindrical lens described in FIG. 6 are closely arranged.

  Thereafter, the entire Cr film 102 is removed. FIG. 16C shows the state. This is used as a stamper (molding die) 130 in the following steps.

  On the other hand, as shown in FIG. 16D, the surface of the SLED wafer 112 is subjected to a line-shaped mask with a resin adhesive tape 132 on the portion including the bonding pads 82.

  After the UV curable resin 110 is applied to the masked SLED wafer 112, as shown in FIG. 16E, a stamper 130 whose surface is coated with a release agent is pressed to pressurize the resin. The resin is developed by irradiating ultraviolet light 114 from the stamper side.

  Finally, as shown in FIG. 16 (F), after the stamper 130 is released, the adhesive tape 132 applied to the SLED wafer 112 is peeled off together with the cured resin thereon, so that FIG. ), A lens array is prepared at a predetermined position, and the resin is removed from the bonding pad 82.

  In the compound lens forming process as described above, the light transmission efficiency of the lens can be adjusted by shifting the lens forming position.

  FIG. 18 shows a change in lens light transmission efficiency when the formation position of the compound lens is shifted in the main scanning direction (x direction). It can be seen that the amount of emitted light can be adjusted by changing the lens formation position. Since the lens formation position can be easily adjusted by the design of the photomask, it is not necessary to change the conventional stamper formation conditions, so the cost does not increase.

  As described in the second embodiment, in the SLED chip having a resolution of 1200 dpi and 256 light emitting points, there is a light amount reduction (shading) of 7.6% from the first light emitting point to the 256 light emitting point. It is known that the amount of light is about 1.5 times greater by matching the center of the compound lens and the light emitting unit, but as shown in FIG. Since there is no proportional relationship, stamper design is difficult.

  In the present embodiment, an area where the light amount linearly changes with respect to the positional deviation amount in the range of the lens deviation amount of 1 to 2 μm is used. It can be seen that the amount of light is reduced by 7.5% when the compound lens is shifted in the x direction in the range of 1 to 2 μm. The stamper for lens formation was designed so that the deviation amount in the x direction of the lens of the 256th emission point was +1 μm and the deviation amount in the x direction of the center of the lens of the first emission point was +2 μm. Since the intervals between the 256 compound lenses are designed to be equal, the compound lens formed on the SLED chip has a slight lens shift amount from the 256 light emitting point to the first light emitting point. It will be.

  When the light amount of 2500 SLED chips with a lens formed in this way was measured, the light amount in the chip was 3σ / average light amount = 0.025 (2.5%), assuming that the standard deviation σ of the light amount variation is There was a remarkable effect in suppressing variation in the amount of light due to the shading of 7.6%.

  In this embodiment, the lens is shifted in the + direction, but the same effect can be obtained by shifting in the-direction.

  Also, the same effect can be obtained by shifting the compound lens in the sub-scanning direction (y direction). FIG. 19 shows changes in lens light transmission efficiency when the formation position of the compound lens is shifted in the y direction.

  In the above description, the light amount is modulated by slightly shifting the position of the compound lens in the main scanning direction (x direction) or the sub scanning direction (y direction). However, in addition to this, the lens shape is changed. Thus, the amount of light can be modulated. The U-shaped compound lens 30 shown in FIG. 14 is manufactured by resin molding on the SLED light emitting portion using a U-shaped stamper created by wet etching a glass substrate using a U-shaped mask opening. However, the light amount can also be modulated by changing the U-shaped mask opening dimensions, that is, the opening length, width, and the positional relationship between the U-shaped vertical opening and the horizontal opening.

  Further, when the lens is not a U-shaped shape as shown in FIG. 15 but a normal substantially circular shape, the lens diameter and the radius of curvature are slightly changed, or the shape is changed to be slightly elliptical. It is possible to modulate the amount of light.

  These are all determined by the design of the photomask, and can be realized with high accuracy without increasing the cost.

  The self-scanning light-emitting element array chip of the present invention can be used as a light source of an optical writing head used in an optical printer, a facsimile machine, a copying machine or the like.

FIG. 20 shows an example of an optical writing head using the self-scanning light emitting element array chip of the present invention. A plurality of light emitting element array chips 71 in which light emitting elements are arranged in a row are mounted on the chip mounting substrate 70 in the main scanning direction, and on the optical path of light emitted from the light emitting elements of the light emitting element array chip 71. An erecting equal-magnification rod lens array 72 that is long in the main scanning direction is fixed by a resin housing 73. A photosensitive drum 74 is provided on the rod lens array 72. Further, a heat sink 75 for releasing heat of the light emitting element array chip 71 is provided on the base of the chip mounting substrate 70, and the housing 73 and the heat sink 75 are fixed by a fastener 76 with the chip mounting substrate 70 interposed therebetween. ing.

  Next, an optical printer using such an optical writing head will be described. A basic structure of the optical printer is shown in FIG.

An optical writing head 200 is installed in the optical printer. A photoconductive material (photosensitive member) such as amorphous Si is made on the surface of the cylindrical photosensitive drum 202. The drum rotates at the printing speed. The photoreceptor surface of the rotating drum is uniformly charged by the charger 204. Then, the optical writing head 200 irradiates the photosensitive member with the light of the dot image to be printed, neutralizes the charging where the light hits, and forms a latent image. Subsequently, toner is applied to the photosensitive member by the developing unit 206 in accordance with the charged state on the photosensitive member. Then, the toner is transferred onto the sheet 212 sent from the cassette 210 by the transfer unit 208. The sheet is heated and fixed by the fixing device 214 and sent to the stacker 215. On the other hand, the drum that has been transferred is neutralized over the entire surface by the erasing lamp 218, and the remaining toner is removed by the cleaner 220.

  Such an optical writing head can be used not only for printers but also for facsimile machines and copying machines. FIG. 22 shows the basic structure of a facsimile or copying machine. The same constituent elements as those in FIG. 21 are denoted by the same reference numerals.

  Light is emitted from the light source 224 to the read original 222 conveyed by the paper feed roller 230, and the reflected light is received by the image sensor 228 via the imaging lens 226. Based on the output of the image sensor 228, the light emitting element array 232 of the optical writing head 200 is turned on, and the photosensitive drum 202 is irradiated via the rod lens array 234. Printing on the paper 212 is as described for the optical printer.

It is an equivalent circuit diagram of a self-scanning light emitting element array chip. It is a figure which shows the pattern of a self-scanning light emitting element array chip. It is a figure which shows the typical structural example of the light emitting element array, refractive index distribution type | mold rod lens array, and photosensitive drum which are used for the conventional optical printer. It is a figure which shows the state of the light ray to the photosensitive drum at the time of using the conventional light emitting element array with a lens. It is a figure which shows the shape of a light emission part area | region. It is a figure which shows the shape of a compound lens. It is a partially enlarged view of a light emitting element array provided with a compound lens array. It is a figure which shows the pattern of a light emission part array. It is a graph which shows the relationship between a light quantity and an electric current. It is a graph which shows the light quantity of the 1st-128th light emission part. It is a figure which shows simply the drive circuit of a light emission part array. It is a figure which shows a linear regression line. It is a figure which shows the dimension of the area of a light emission part. It is a figure which shows the Example which changes the area of a light emission part. It is a top view of the state which formed the compound lens in the light emission part of a SLED chip. It is a figure which shows preparation of the SLED chip with a lens. It is a top view of the quartz glass substrate with Cr film which patterned the opening array. It is a graph showing the change of the lens light transmission efficiency when the formation position of a compound lens is shifted to x direction. It is a graph showing the change of the lens light transmission efficiency when the formation position of a compound lens is shifted to ay direction. It is a figure which shows the structure of an optical writing head. It is a figure which shows the basic structure of an optical printer. It is a figure which shows the basic structure of a facsimile or a copying machine.

Explanation of symbols

14 Power supply wiring 26 Light emitting portion 27 Electrode 30 Compound lens 102 Cr film 104 Aperture 130 Stamper 200 Optical writing head

Claims (8)

A light emitting element array comprising a plurality of light emitting elements arranged in the main scanning direction;
A lens array composed of microlenses provided on the light emitting portion of each light emitting element;
Each light emitting element includes at least one power supply line extending in the main scanning direction for supplying current from a power supply bonding pad;
By reducing farther the position displacement amount in the main scanning direction and the center of each microlens corresponding to the center and the light-emitting portions of the light emitting portion from the bonding pad, of each of the microlenses as the distance from the bonding pad Self-scanning light-emitting element array chip with increased light transmission efficiency . A light emitting element array comprising a plurality of light emitting elements arranged in the main scanning direction;
A lens array composed of microlenses provided on the light emitting portion of each light emitting element;
Each light emitting element includes at least one power supply line extending in the main scanning direction for supplying current from a power supply bonding pad;
By reducing farther positional deviation amount in the sub-scanning direction perpendicular to the main scanning direction and the center of each microlens corresponding to the center and the light-emitting portions of the light emitting portion from the bonding pad, away from the bonding pad A self-scanning light emitting element array chip in which the light transmission efficiency of each microlens is increased according to A light emitting element array comprising a plurality of light emitting elements arranged in the main scanning direction;
A lens array composed of microlenses provided on the light emitting portion of each light emitting element;
Each light emitting element includes at least one power supply line extending in the main scanning direction for supplying current from a power supply bonding pad;
A self-scanning light-emitting element array chip in which the light transmission efficiency of each microlens is increased as the distance from the bonding pad is changed by changing the shape of the microlens as the distance from the bonding pad is increased . Applying resin to a plurality of light emitting elements arranged in the main scanning direction;
Forming a microlens on the light emitting element by pressing a molding die against the resin and forming the resin into the shape of the microlens; and
Including
The mold used in the forming step of the microlens is at least in the main scanning direction or the sub-scanning direction between the center of each light emitting portion of the plurality of light emitting elements and the center of each microlens corresponding to each light emitting portion. A method of manufacturing a self-scanning light-emitting element array chip, comprising a recess that can be shaped so that the amount of positional deviation on one side decreases as the distance from the bonding pad increases. Optical writing head having a self-scanning light-emitting element array chip according to any one of claims 1-3. An optical printer comprising the optical writing head according to claim 5 . A facsimile comprising the optical writing head according to claim 5 . A copying machine comprising the optical writing head according to claim 5 .

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