JP2001332808A - Optical module and light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module and a light source device which can adjust accurately the quantity of light of luminous flux with which a photosensitive body or the like is irradiated, and is capable of miniaturization. SOLUTION: This light source device is provided with waveguides 25, 26, 27 and transmission type photoelectric transducers 41, 42, 43, and outputs of the light sources 21, 22, 23 are changed based on the quantities of lights which are detected by the photoelectric transducers 41, 42, 43. The waveguides introduce incident lights to output surfaces 25b, 26b, 27b which lights are outputted from the light sources 21, 22, 23 and enter from planes 25a, 26a, 27a of incidence. The photoelectric transducers are arranged on the output surfaces 25b, 26b, 27b, transmit luminous fluxes passing the waveguides 25, 26, 27, and detect the quantities of lights of a part of the luminous fluxes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for adjusting the output of a light source by feedback, and an optical module having a waveguide for guiding a light beam from the light source in a predetermined direction.

[0002]

2. Description of the Related Art A laser printer or a copying machine scans a light beam emitted from a light source to write on a photosensitive member. Also,
High-speed scanning can be performed by using a plurality of light beams and condensing the light at different positions in the circumferential direction of the photoconductor.

The light source is composed of a semiconductor laser as shown in FIG. The light source 17 includes an active layer 14 sandwiched between a lower clad layer 13 and an upper clad layer 15 on a substrate 12.
Are formed, and electrodes 11 and 16 are arranged on the lower surface of the substrate 12 and the upper surface of the upper cladding layer 15. Electrodes 11, 16
Light beams L1 and L2 are emitted from light emitting points 14a and 14b (14a not shown) formed on two surfaces of the active layer 14 by applying a voltage therebetween.

The light beam L1 from the light emitting point 14a is emitted toward the photosensitive member and used for writing. Light emitting point 14
The light beam L2 emitted from b is applied to a photoelectric conversion element (not shown). The photoelectric conversion element detects the amount of received light, and based on the detection result, the control unit (not shown) controls the AP.
C (Automatic Power Control) adjustment is performed.

[0005] The APC adjustment changes the driving current of the semiconductor laser to cancel the fluctuation of the light emission intensity caused by the change of the ambient temperature of the semiconductor laser. Thereby, the light source 1
The light amount of the light beam emitted from the light source 7 is made constant to prevent the deterioration of the formed image due to the fluctuation of the light amount.

However, the light beam L1 emitted from the light source 17
When the optical characteristics of an optical system such as a waveguide or an optical fiber through which the light beam changes due to the ambient temperature or the like, the APC adjustment is performed by the light beam L2 that does not pass through the optical system. Light intensity is not kept constant.

For this reason, for example, when a light source is coupled to a waveguide, if the ambient temperature changes from 20 ° C. to 80 ° C., the light quantity of the light beam after passing through the waveguide fluctuates by about 10% due to a decrease in the coupling efficiency. I do. In particular, when an image is formed by a plurality of light beams, if the difference in the light amounts of the light beams is not maintained at 5% or less, a bad image such as stripes occurs in the formed image, and thus there is a problem that a good image cannot be obtained. .

For this reason, as shown in FIG. 9, there has been proposed a light source device capable of performing APC adjustment after a light beam emitted from a light source 17 passes through an optical system. According to the figure, a light beam L1 emitted from a light source 17 composed of a semiconductor laser or the like is converted into a parallel light beam by a collimator lens 2, and a light beam L3 transmitted through a half mirror 9 is irradiated on a photosensitive member (not shown). The light amount of the light flux L4 of a predetermined ratio reflected by the half mirror 9 is detected by the photoelectric conversion element 8 including a photodiode or the like.

The control section 31 performs APC adjustment of the light source 17 based on the detection result of the photoelectric conversion element 8. This allows
The drive current of the semiconductor laser is varied to cancel the fluctuation of the light amount caused by the change of the ambient temperature of the semiconductor laser and the optical system, and the light amount of the light beam L3 after passing through the optical system is made constant. As a result, stripes and the like generated in the formed image can be prevented.

[0010]

However, according to the above-described conventional light source device 10, the half mirror 9 and the photoelectric conversion element 8 are required for detecting the light amount of the light beam L1 emitted from the light source 17, so that the light source device is required. There was a problem that 10 became large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical module and a light source device capable of accurately adjusting the amount of a light beam irradiated to a photoreceptor or the like and having a small size.

[0012]

According to an aspect of the present invention, there is provided an optical module comprising: a waveguide for guiding incident light incident from an entrance surface to an exit surface; A photoelectric conversion element that transmits the light beam and detects the amount of light by a part of the light beam, and the waveguide and the photoelectric conversion element are provided integrally.

According to this configuration, the light beam incident on the incident surface is guided through the waveguide and exits from the exit surface. The light flux passes through the photoelectric conversion element and irradiates the photoconductor or the like in the middle of the waveguide or after passing through the waveguide. In the photoelectric conversion element, the light amount is detected using a light flux having a predetermined ratio of the transmitted light. As a result, by varying the amount of incident light on the waveguide according to the detected amount of light, the amount of light of the light beam after passing through the waveguide can be maintained at a predetermined value.

According to a second aspect of the present invention, in the optical module according to the first aspect, the photoelectric conversion element is provided in contact with the emission surface.

According to a third aspect of the present invention, in the optical module according to the first or second aspect,
A groove for dividing the waveguide is provided, and the photoelectric conversion element is disposed in the groove.

According to a fourth aspect of the present invention, in the optical module and the light source device according to any one of the first to third aspects, the photoelectric conversion element includes a photo diode having a pin bond of amorphous silicon. It is characterized by comprising a diode.

According to a fifth aspect of the present invention, there is provided a light source device comprising: the optical module according to any one of the first to fourth aspects; a light source for irradiating the incident surface with a light beam; A control unit for controlling the output of the light source based on the detection result.

According to this configuration, the light beam emitted from the light source enters the incident surface of the waveguide, is guided through the waveguide, and is emitted from the emission surface. The light flux passes through the photoelectric conversion element and irradiates the photoconductor or the like in the middle of the waveguide or after passing through the waveguide. In the photoelectric conversion element, the light amount is detected using a light flux having a predetermined ratio of the transmitted light. Then, by changing the output of the light source by the control unit according to the detected light amount,
The light amount of the light beam after passing through the waveguide is maintained at a predetermined value.

According to a sixth aspect of the present invention, in the light source device according to the fifth aspect, the optical module and the light source are provided integrally.

According to a seventh aspect of the present invention, there is provided a light source device, wherein: a light source; a photoelectric conversion element which transmits a light beam emitted from the light source and detects the amount of light by a part of the light beam; A control unit for controlling an output of the light source based on a detection result of the element.

According to this configuration, the light beam emitted from the light source passes through the photoelectric conversion element and irradiates the photosensitive member or the like. In the photoelectric conversion element, the light amount is detected using a light flux having a predetermined ratio of the transmitted light. Then, the output of the light source is varied by the control unit according to the detected light amount, so that the light amount of the light beam after passing through the photoelectric conversion element is maintained at a predetermined value.

According to an eighth aspect of the present invention, in the light source device according to the seventh aspect, the photoelectric conversion element is formed of a photodiode having a pin combination of amorphous silicon.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. For convenience of explanation, FIGS.
The same reference numerals are given to the same parts as. FIG.
1 is a schematic perspective view showing a light beam writing device provided with a light source device of a first embodiment. The light beam writing device 1 is mounted on a laser printer, a digital copier, or the like, and can form an image.

The light source device 10 has a built-in light source.
A plurality of light beams having different light condensing positions are emitted. Light source device 1
The luminous flux emitted from 0 illuminates the polygon mirror 3 after being collimated by the collimator lens 2. The light beam reflected by the polygon mirror 3 is scanned as the polygon mirror 3 rotates. After the scanning speed is made constant by the scanning lens 4, a desired position of the photoconductor is exposed by focusing on a photoconductor (not shown), and writing is performed.

The light beam reflected by the polygon mirror 3 irradiates the reflection mirror 5 at the leading position of each scanning line. The light beam reflected by the reflecting mirror 5 is captured by the light receiving sensor 6 so that the synchronization of the plurality of light beams can be detected.

The light source device 10 has an optical module 30 as shown in the plan view and the side view of FIGS. The optical module 30 has a lower cladding layer 2 on a substrate 24.
8 are formed, and the waveguides 25, 2
6, 27 are formed. The upper portions of the waveguides 25, 26, 27 are covered by an upper cladding layer 29.

Upper cladding layer 29 and lower cladding layer 2
8 has a lower refractive index than the waveguides 25, 26, 27. Thereby, the light beams incident from the incident surfaces 25a, 26a, 27a are confined, and the exit surfaces 25b, 26b, 27
Waveguide b. Light transmitting photoelectric conversion elements 41, 42, and 43 are coupled to the emission surfaces 25b, 26b, and 27b. Thus, the light amount can be detected by photoelectrically converting a predetermined percentage of the light beams emitted from the emission surfaces 25b, 26b, 27b.

Such an optical module 30 can be manufactured by the following method. First, 7 μm of quartz is deposited on a substrate 24 made of silicon or the like while doping fluorine by CVD to form a lower cladding layer 28. Next, 5 μm of quartz is deposited without doping by CVD. After patterning into a predetermined shape by a photolithography process, reactive ion etching is performed to form waveguides 25, 26, and 27.

Next, 7 μm of quartz is deposited while doping with fluorine to form an upper cladding layer 29. Then, the photoelectric conversion elements 4 are provided on the emission surfaces 25b, 26b, and 27b.
1, 42, and 43 are bonded with a UV curable resin or a thermosetting resin. Thereby, the optical module 30 can be obtained.

FIG. 3 is a sectional view of the photoelectric conversion elements 41, 42 and 43. A semiconductor film 63 sandwiched between transparent electrodes 51 and 52 is formed on a transparent insulating substrate 50 such as glass. The transparent electrodes 51 and 52 are formed by sputtering ITO or the like. The upper part of the transparent electrode 52 is protected by a protective insulating film 54. When a voltage is applied between the transparent electrodes 51 and 52, photoelectric conversion is performed in the semiconductor film 63.

The semiconductor film 63 includes a carrier injection blocking layer 64
P-type a-SiC: H (p-type hydrogenated amorphous silicon carbide), and i-type a-Si: H as the photoelectric conversion film 65
(Intrinsic hydrogenated amorphous silicon) and n-type a-SiC: H (n-type hydrogenated amorphous silicon carbide) are continuously formed as a carrier injection blocking layer 66 by a plasma CVD method. The thickness and film characteristics of each layer are optimized so that visible light can pass through the semiconductor film 63 and photoelectric conversion and multiplication can be performed. Further, the protective insulating film 54
Is formed of a-SiN: H (hydrogenated amorphous silicon nitride).

Although the photoelectric conversion film 65 is formed as a thin film in order to improve the light transmittance, the thin film causes deterioration in output characteristics. For this reason, the photoelectric conversion is performed by the photoelectric conversion film 65 made of a-Si: H, so that the photocurrent is multiplied and the deterioration of the output characteristics is prevented. By sandwiching the photoelectric conversion film 65 between the carrier injection blocking layers 64 and 66, light is easily transmitted and injection of carriers from the outside is prevented, so that only the photocurrent generated in the photoelectric conversion film 65 can be read. It has become.

In the figure, the carrier injection blocking layer 64,
The photoelectric conversion film 65 and the carrier injection blocking layer 66 are p-type, i
Although the film is formed in the order of the mold and the n-type semiconductor, the reverse is also possible. As the p-type and n-type semiconductors of the carrier injection blocking layers 64 and 66, μc-Si: H (hydrogenated microcrystalline silicon) having good contact characteristics with electrodes may be used.

The photoelectric conversion elements 41, 42 and 43 may have other structures as long as they can be formed on a transparent substrate. In FIG. 3, a flat transparent insulating substrate 50 such as a glass substrate is shown.
However, it is also possible to use a prism, a lens, or the like as a substrate and manufacture a photoelectric conversion element thereon.

In FIG. 2, a light source 21 is provided on a substrate 24.
22 and 23 are formed integrally with the optical module 30. The light sources 21, 22, and 23 are composed of semiconductor lasers as shown in FIG.
26, 27 are coupled to incident surfaces 25a, 26a, 27a.

FIG. 4 is a block diagram showing the configuration of the light source device 10. The light source device 10 has a control unit 31 for controlling the outputs of the light sources 21, 22, and 23. Light sources 21, 22, 2
The light beam emitted from 3 is guided through waveguides 25, 26, and 27 and emitted, and the amount of light is detected by photoelectric conversion elements 41, 42, and 43.

The results detected by the photoelectric conversion elements 41, 42, 43 are compared with predetermined light amount data stored in the storage unit 34 by the comparison unit 32. As a result of the comparison by the comparing unit 32, when the amount of light emitted from the waveguides 25, 26, and 27 is not within a predetermined range, the driving unit 33 outputs
The drive currents of the light sources 21, 22, 23
The output of 23 is variable.

When the amount of light emitted from the waveguides 25, 26, and 27 is within a predetermined range, the driving unit 33 controls the light sources 21, 22, and 23.
Maintain the drive current of Thereby, the waveguides 25, 2
Adjustments are made so that a constant amount of light flux is always emitted from the emission surfaces 25b, 26b, 27b of the light emitting devices 6 and 27.

According to the present embodiment, the waveguides 25, 26,
27, light-transmitting photoelectric conversion elements 41, 42, and 43 capable of detecting the amount of light are disposed on the exit surface of the light module 27, and the light sources 21, 22, and 23
Even when the relative position of the optical module 30 changes and the coupling efficiency decreases, the amount of light emitted from the optical module 30 can be kept constant.

Thus, a plurality of adjacent waveguides 25,
The amount of change in the amount of light of each light beam emitted from 26 and 27 is set to 0.
Since it can be set to 5% or less (20 to 80 ° C.), the difference between the respective light amounts becomes 5% or less, and a good image can be obtained. Further, since the half mirror 9 as shown in FIG. 9 is not required, the light source device 10 can be reduced in size and space and cost can be reduced. Furthermore, the photoelectric conversion elements 41, 42, 4 are provided on the emission surfaces 25b, 26b, 27b.
3 are provided in contact with each other, so that the emission surfaces 25b, 26b, 2
7b can be protected.

Incidentally, the optical module 30 and the light sources 21, 22,
Although the light source 23 and the light source 23 are integrally formed, they may be formed separately, and an optical fiber or a prism may be coupled to the light module 30 so that the light beam from the light source is incident on the light module 30. Also, the light sources 21, 22, 2 for each of the waveguides 25, 26, 27
Although 3 is provided, the light may be branched from one light source and incident. In this case, an adjusting means for adjusting the light amount of each light beam after branching is separately required.

FIGS. 5A and 5B are a plan view and a side view showing a light source device 10 according to a second embodiment. For convenience of explanation, the same parts as those in the first embodiment shown in FIG. 2 are denoted by the same reference numerals. The difference from the first embodiment is that one photoelectric conversion element 44 is provided instead of the photoelectric conversion elements 41, 42, and 43 in order to detect the amount of light flux emitted from each of the waveguides 25, 26, and 27. That is the point. Other configurations are the same as those of the first embodiment.

According to the present embodiment, each of the waveguides 25, 2
When detecting the amount of light emitted from 6, 27, the amount of each emitted light can be detected by the light receiving element 44 by the following procedure. That is, the light source 21 is turned on, and the light source 2 is turned on.
By turning off the light sources 2 and 23, light amount control for the waveguide 25 is performed based on the light amount detected by the light receiving element 44. Next, the light source 22 is turned on, the light sources 21 and 23 are turned off, and the light receiving element 44 is turned on.
The light quantity control for the waveguide 26 is performed based on the detected light quantity.
Next, the light source 23 is turned on, the light sources 21 and 22 are turned off, and the light amount control for the waveguide 27 is performed based on the light amount detected by the light receiving element 44. Thereby, the light amount of the light beam emitted from the optical module 30 can be kept constant.

Next, FIGS. 6A and 6B are a plan view and a side view showing a light source device 10 according to a third embodiment. For convenience of explanation, the same parts as those in the above-described second embodiment shown in FIG. 5 are denoted by the same reference numerals. The difference from the second embodiment is that a groove 30a for dividing the waveguides 25, 26 and 27 is formed in the optical module 30, and the photoelectric conversion element 44 is formed in the groove 30a.
It is a point that is arranged inside. Other configurations are the same as in the second embodiment.

The groove 30a can be formed by dicing or etching after the formation of the optical module 30. Then, the photoelectric conversion element 44 is fitted into the groove 30a and bonded with a UV curable resin or a thermosetting resin. Therefore, by forming the groove 30a in the vicinity of the emission surfaces 25a, 26a, and 27a, the amount of light substantially equal to the light emitted from the waveguides 25, 26, and 27 can be detected by the photoelectric conversion element 44. The same effect as in the embodiment can be obtained. Further, the positioning of the photoelectric conversion element 44 becomes easy, and the number of assembly steps can be reduced. In addition, as in the first embodiment, an independent photoelectric conversion element may be provided for each of the waveguides 25, 26, and 27.

FIG. 7 shows a light source device 1 according to a third embodiment.
It is a schematic block diagram which shows 0. The above-mentioned collimator lens 2 shown in FIG. The light beam L1 emitted from the light source 17 composed of a semiconductor laser is converted into a parallel light beam by the collimator lens 2, and the light beam L3 transmitted through the photoelectric conversion element 44 similar to the first to third embodiments is irradiated on a photoconductor (not shown). You. The photoelectric conversion element 44 photoelectrically converts a part of the light beam that has passed through the collimator lens 2 and detects the amount of light.

The control section 31 performs APC adjustment of the light source 17 based on the detection result of the photoelectric conversion element 44. Thereby, the drive current of the semiconductor laser is varied, and the fluctuation of the light amount caused by the optical system such as the collimator lens 2 and the change of the ambient temperature of the semiconductor laser is canceled to keep the light amount of the light beam L3 after passing through the optical system constant. To As a result, stripes and the like generated in the formed image can be prevented.

According to the present embodiment, similarly to the first embodiment, since the half mirror 9 is not required for the above-described conventional light source device 10 shown in FIG. 9, the light source device 10 is downsized to save space. And cost reduction can be achieved.

[0049]

According to the present invention, by disposing a transmissive photoelectric conversion element capable of detecting the amount of light on the exit surface of the waveguide, the relative position between the light source and the optical module due to a change in ambient temperature or the like is obtained. , The light emitted from the optical module can be kept constant.

As a result, it is possible to reduce the amount of change in the amount of light of each light beam emitted from a plurality of adjacent waveguides, and to reduce the difference between the amounts of light, thereby obtaining a good image. . Further, since a half mirror is not required unlike the related art, the size of the light source device can be reduced and the cost can be reduced.

In the case where the light quantity of the light beam passing through a plurality of waveguides is detected by a common photoelectric conversion element, the positioning of the photoelectric conversion element is performed by disposing the photoelectric conversion element in a groove for dividing the waveguide. And the number of assembling steps can be reduced.

Further, according to the present invention, the amount of light emitted from the light source is detected by the transmission type photoelectric conversion element after passing through the optical system such as the waveguide and the collimator lens.
Then, based on the detection result, the output of the light source can be varied to adjust the light amount of the light beam transmitted through the photoelectric conversion element to be constant. Therefore, the formed image is maintained well, and a half mirror as in the related art is not required. Therefore, the light source device can be downsized to save space and reduce costs.

Further, according to the present invention, by forming a photoelectric conversion element by a photodiode having a pin bond of amorphous silicon, it is possible to transmit a light beam and easily detect the light amount of a predetermined ratio of the light beam.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a light beam writing device including a light source device according to a first embodiment of the present invention.

FIG. 2 is a plan view and a side view showing the light source device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of a photoelectric conversion element of the light source device according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of the light source device according to the first embodiment of the present invention.

FIG. 5 is a plan view and a side view showing a light source device according to a second embodiment of the present invention.

FIG. 6 is a plan view and a side view showing a light source device according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram illustrating a light source device according to a fourth embodiment of the present invention.

FIG. 8 is a perspective view showing a conventional light source.

FIG. 9 is a configuration diagram showing a conventional light source device.

[Explanation of symbols]

 Reference Signs List 1 light beam writing device 2 collimator lens 3 polygon mirror 4 scanning lens 5 reflection mirror 6 light receiving sensor 9 half mirror 10 light source device 11, 16 electrode 12 substrate 13 lower cladding layer 14 active layer 15 upper cladding layer 21, 22, 23 light source Reference Signs List 24 substrate 25, 26, 27 waveguide 28 lower cladding layer 29 upper cladding layer 30 optical module 31 control unit 32 comparison unit 33 driving unit 34 storage unit 41, 42, 43, 44 photoelectric conversion element 51, 52 transparent electrode 54 protective insulation Film 63 semiconductor film 64, 66 carrier injection blocking layer 65 photoelectric conversion film

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01S 5/026 H01L 31/02 DF term (reference) 2C362 AA43 AA45 AA53 AA54 DA08 2H047 KA04 KA12 MA07 RA04 5F073 AB13 AB15 AB21 AB25 AB27 AB29 BA07 FA02 FA06 GA03 GA12 GA18 GA37 GA38 5F088 AA03 AB04 AB05 BA15 BA20 BB10 CA02 DA01 FA04 GA02 HA12 JA14 5F089 AA02 AA10 AB20 AC30 BC16 CA15 GA10

Claims (8)

[Claims] A waveguide for guiding incident light incident from an entrance surface to an exit surface; and a photoelectric conversion element that transmits a light beam passing through the waveguide and detects the amount of light by a part of the light beam; An optical module, wherein the waveguide and the photoelectric conversion element are provided integrally. 2. The optical module according to claim 1, wherein said photoelectric conversion element is provided in contact with said emission surface. 3. The optical module according to claim 1, wherein a groove for dividing the waveguide is provided, and the photoelectric conversion element is disposed in the groove. 4. The optical module according to claim 1, wherein said photoelectric conversion element comprises a photodiode having a pin bond of amorphous silicon. 5. An optical module according to claim 1, wherein said light source irradiates a light beam onto said incident surface.
A light source device comprising: a control unit that controls an output of the light source based on a detection result of the photoelectric conversion element. 6. The light source device according to claim 5, wherein the optical module and the light source are provided integrally. 7. A light source, a photoelectric conversion element that transmits a light beam emitted from the light source and detects a light amount by a part of the light beam, and outputs an output of the light source based on a detection result of the photoelectric conversion element. A light source device comprising: a control unit that controls the light source. 8. The light source device according to claim 7, wherein the photoelectric conversion element is formed of a photodiode having a pin bond of amorphous silicon.