TWI591292B - Linear light source - Google Patents

Description

Linear light source

The present invention relates to a linear light source for an image sensing module, in particular to a linear light source which can generate a predetermined illuminance distribution and form a complementary effect on an imaging lens and an image sensor, and is applied to a fax machine and a printing table. Machines, scanners and multifunction machines.

Devices or products that need to be used for recording or detecting images on the market include scanners, multifunction printers (MFPs), digital photocopiers, ATM money detectors, traveler checkers, ballot checkers, and optical models of list machines. Groups, card readers, optical identification readers, bar code recognition, fax machines, etc., however, these products require a scanning read module.

Currently the main scanning reading module is divided into CCD (C harge C ouple D evice ) and CIS (C ontact I mage S ensor ) these two mainstream architecture, both regardless of the architecture that includes a light source module, the optical lens module, the image The chip module and the motion mechanism module are sensed. When the light source module emits light and projects on the document, the light with the message is reflected through the file, the light enters the optical lens module and is imaged on the image sensor, and finally the optical signal is converted into an electronic signal through the image sensor.

Early fluorescent light source module used as a light source, such as a cold cathode fluorescent tube (CCFL; C old C athode F luorescent L amp), a halogen lamp, etc. ..., cold cathode fluorescent lamps but require additional Voltage converters and halogens and phosphors do not meet increasingly stringent environmental requirements. Since the light-emitting diode (LED; L ight E mitting D iode) has the advantage of saving, high luminous efficiency and long lifetime, in recent years have been gradually used in the light source module scans, as described in Japanese Patent JP11-232912 proposes an LED As a light source, and an LED array arranged at the rear end of the lenticular mirror, the illuminance distribution on the document is evenly distributed and applied to the scanner.

For the CIS architecture, it is expected that the light source module can emit linear light with uniform illumination. For example, Taiwan Patent No. TW579640 discloses a light collecting architecture of different scanners, which uses light collecting elements and light guiding elements to guide the light emitted by the light source to be scanned. On the file. Further, as shown in Fig. 1, a linear illuminator is disclosed in Taiwan Patent No. TW158740, in which the light source 1 is placed at one end of the rod-shaped light guiding column 2, and the astigmatism pattern 3 is disposed on a focal region of a curved surface 4 such as a concave mirror. Reflected by the surface 4 The reflected light 5 emitted by a plane is focused at a predetermined focus position 6. If the predetermined focus position is aligned with an image surface to be read, the light scattered by the astigmatism pattern will completely illuminate the image surface without wasting, so the spatial distribution of light intensity in the sub-scanning direction may be It is homogenized.

However, for the CCD architecture design, due to the influence of the focusing surface of the optical lens of the image taking lens, the light reflected at the edge of the document edge enters the image capturing lens, and after being taken by the image capturing lens, the light emitted from the edge of the image capturing lens is emitted. The intensity is weak, so that the light intensity received by the two ends of the CCD is relatively weak; this will result in a darker edge of the document image. Therefore, the CCD architecture needs to provide a similar U-shaped illumination distribution by the light source module. As shown in FIG. 2, a method is proposed in US Pat. No. 2,050,195,452. The LED array 8 is arranged at the rear end of the light guide body 7 to control the brightness of each LED, so that the illuminance of the emitted light on the document 9 to be scanned can be uniform or A U-shaped illuminance distribution is formed to replace the CCFL in a high speed scanner. However, the use of a technical means such as the use of the LED array 8 at the rear end of the light guide 7 requires many LED units and complicated control.

Another technical solution is that the light source is disposed on the end surface of the light guide body, and an end cover is disposed at the light emitting end to prevent most of the light from coming out from the near end surface, and the toothed reflecting surface is disposed on the polygonal light guiding body to The light emitted by the light source can be fully reflected to increase the utilization of the light, and the different tooth shapes are spaced from the tooth shape to adjust the light pattern after the light is emitted.

The purpose of the present invention is to provide a linear light source for an image sensing module, which is applied to a light source module of a CIS or CCD image sensor, the linear light source comprising a light guiding rod, a reflective cavity and at least one illumination source. Wherein, the light guiding rod is made of an optical material, and is provided with at least one incident surface and a single side surface, the single side surface is a light scattering structure having a feather-like rib; the light source is disposed on the incident surface of the end of the light guiding rod And emit light toward the inside of the light guide bar. When the light source emits light, the light enters the light guide bar, and the light is totally reflected by the side of the light guide bar to make the light travel inside the light guide bar. When the light reaches the scattering structure, the light is scattered due to the destruction of the total reflection phenomenon. Leaving the light guiding rod; the reflective cavity is provided with at least one light-incident opening and at least one light-emitting opening, the inside of the reflective cavity is a light reflecting surface, and the light guiding rod is placed in the reflective cavity, so that the scattered light causes the scattered light to be The light is reflected by the light reflecting surface of the reflective cavity, and finally emitted by the light emitting opening of the reflective cavity to be irradiated onto the image to be scanned. The linear light source is arranged in the axial direction of the light guiding rod by a light scattering structure. The illuminance distribution of the inline or U-shaped curve can be formed. Thereby, the image of the object can be converted by the image sensing module to form a uniform image signal.

According to the purpose of the present invention, on the side of the light guiding rod, the radial direction of the light guiding rod can be regarded as a perfect circular shape, an elliptical shape, etc., and a single smooth surface which can be differentiated, instead of a polygonal or a plurality of curved surfaces. The cross-sectional shape makes it have the concentrating effect of the lens, which reduces the light scatter and improves the average illuminance of the light-emitting body exit surface. In addition, the purpose of the creation is to have a light-scattering structure of a feather-like rib on a single side of the light guiding rod to further improve the smoothness of the illuminance of the light emitted by the light guiding rod.

As described above, the linear light source used in the image sensing module can have one or more of the following advantages:

(1) The light guiding rod of the light-scattering structure of the feather-shaped ribs proposed by the present invention increases the fluidity of the optical material of the rib portion in the injection process, so that the optical material can completely fill the rib structure, which can improve the habit The shortcomings of the high cost and complex control of the skill shooting process.

(2) By the present invention, a light guide bar having a single side with a perfect circle, an elliptical shape, etc., can be formed in the radial direction of the light guide bar to form a illuminance distribution of the lens concentrating effect, and a linear or U-shaped shape in the axial direction. The illuminance distribution can be complemented by CIS or CCD to produce a uniform light intensity image signal, providing high resolution, high speed scanning.

The embodiments of the linear light source for the image sensing module according to the present invention will be described below with reference to the related drawings. For ease of understanding, the same components in the following embodiments are denoted by the same reference numerals.

Please refer to FIG. 3 , which is a schematic diagram of a first embodiment of a linear light source for creating an image sensing module. Please refer to Fig. 4, which is a schematic diagram of a light scattering structure having a feather-like rib on a single side of the light guiding rod of the linear light source. The linear light source 10 includes a light guiding rod 20, a reflective cavity 30 and at least one light emitting diode 40. The light guiding rod 20 is made of an optical material and has a rod-shaped structure with a circular cross section, and an incident surface 21 is provided. And a single side 22; a light emitting diode 40 is disposed on the incident surface 21 of the light guiding rod and emits light toward the inside of the light guiding rod. When the light emitting diode 40 emits light 50, the light 50 enters the light guiding rod 20. Since the refractive index of the light guiding rod 20 is greater than the refractive index of the air of 1.0, when the light emitting diode emits light, the light passes through The end incident surface 21 enters the light guiding rod 20, and since the refractive index of the light guiding rod 20 is greater than the refractive index of the air of 1.0, The light entering the light rod 20 will only refract within the critical angle without causing the light guiding rod 20 to pass through; the light 50 is totally reflected by the single side 22 of the light guiding rod inside the light guiding rod 20 When the light 50 reaches the scattering structure 23, the light 50 is scattered and leaves the light guiding rod 20 due to the destruction of the total reflection phenomenon; the reflective cavity 30 is provided with at least one light inlet opening 31 and at least one light opening 32, and the interior of the reflective cavity The light reflecting surface is disposed, and the light guiding rod 20 is placed in the reflective cavity 30, so that the scattered light is caused by the scattering structure 23 to reflect the light 50 through the light reflecting surface of the reflective cavity, and finally the light emitting opening 32 of the reflective cavity is formed. The light 50 is emitted and is illuminated on the document to be scanned.

Further, the light scattering structure of the feather-shaped ribs is mutually coupled to each of the tooth ribs, and the advantage is that the four scattered light rays 50 partially reflect the light rays 50 through the light reflecting surface of the reflective cavity in the axial direction of the light guiding rod (x direction). The ribs of the teeth again disperse the light rays 50 to form a bright line, and have a smoother distribution of the illuminance in the axial direction (z direction), and further increase the fluidity of the optical material of the rib portion in the injection process, so that the optical material is more complete. Filling the rib structure can improve the disadvantages of the high cost and complex control of the conventional art injection process.

Further, in the scanning direction (x direction), since the cross section of the light guiding rod is a perfect circular shape, an elliptical shape, or the like, the illuminance distribution forming the lens collecting effect can be provided to the image scanner. For best results, the curvature radius of the light guide bar 20 and the distance to the scanned document can be matched.

Please refer to FIG. 5 , which is a schematic diagram of a second embodiment of a linear light source for creating an image sensing module. In the present embodiment, the light guiding rod 20 is made of an optical material polymethyl methacrylate (PMMA) and has a rod-like structure of an elliptical cross section and has an incident surface 21a and an incident surface 21b at the ends. And each of the left-emitting diodes 40 and the right-emitting diodes 41; wherein, when the left-emitting diode 40 and the right-emitting diode 41 emit light 50, the light 50 enters the light-guiding rod 20 due to the light guiding. The refractive index n _{d of the} rod 20 is greater than the refractive index 1.0 of the air, and the light 50 is caused to travel inside the light guiding rod 20 by the single side 22 of the light guiding rod. When the light 50 reaches the scattering structure 23, the light is destroyed. The total reflection phenomenon causes the light 50 to scatter away from the light guide bar 20; the inside of the reflective cavity 30 is a light reflecting surface, and the light guiding rod 20 is placed in the reflective cavity 30, so that the scattered light is caused by the scattering structure 23 The light reflecting surface of the cavity reflects the light 50, and finally the light 50 is emitted from the light exit opening 32 of the reflective cavity to illuminate the image to be scanned.

Please refer to FIG. 6 , which is a schematic diagram of different feather rib embodiments of the light guide bar for creating a linear light source, wherein each tooth rib is connected to each other, but the tooth ribs can be different in size and spacing according to the position. In addition, the rib cross section may be a polygonal shape, a cylindrical column, a ladder column, or the like, or the rib may be a concave or convex structure.

In summary, the effect of the linear light source used in the image sensing module of the present invention is that the light guiding rod of the light scattering structure of the feather rib and the light source arranged at the entrance surface of the light guiding rod can be axially The direction (z direction) forms an in-line or U-shaped illuminance distribution, and the linearly concentrated illuminance distribution in the scanning direction (x direction) can be provided for use with high resolution and high speed scanners.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of this creation shall be included in the scope of the appended patent application.

1‧‧‧Light source placed

2‧‧‧ rod-shaped light guide column

3‧‧‧ astigmatism pattern

4‧‧‧Face mirror surface

5‧‧‧ Reflected light from the plane

6‧‧‧ Focus position

7‧‧‧Light guide

8‧‧‧LED array

9‧‧‧ Documents to be scanned

10‧‧‧Linear light source

20‧‧‧Light guide rod

21‧‧‧Incoming face of light guide rod

21a, 21b‧‧‧ incident surface

22‧‧‧Single side of the light guide rod

23‧‧‧Single side scattering structure

30‧‧‧Reflective cavity

31‧‧‧Lighting cavity entrance light opening

32‧‧‧Lighting opening of the reflective cavity

40‧‧‧Lighting diode

41‧‧‧Lighting diode

50‧‧‧Light

Figure 1 is a schematic diagram of a linear light source of the prior art applied to an image scanning module

Figure 2 is a schematic diagram of another conventional linear light source applied to an image scanning module

Fig. 3 is a schematic view showing a first embodiment of a linear light source for creating a light guide body having a feather rib

Figure 4 is a schematic diagram of a light scattering structure with a pin-shaped rib on a single side of the light guiding rod of the linear light source.

Figure 5 is a schematic view showing a second embodiment of a linear light source for creating a light guide having a feathered rib

Fig. 6 is a schematic view showing an embodiment of different feather ribs of a light guiding rod for creating a linear light source

10‧‧‧Linear light source

20‧‧‧Light guide rod

21‧‧‧Incoming face of light guide rod

22‧‧‧Single side of the light guide rod

23‧‧‧Single side scattering structure

30‧‧‧Reflective cavity

31‧‧‧Lighting cavity entrance light opening

32‧‧‧Lighting opening of the reflective cavity

40‧‧‧Lighting diode

50‧‧‧Light

Claims (9)

A linear light source, the main structure comprising: a reflective cavity, the cavity is provided with at least one light-in opening and at least one light-emitting opening, and the inner wall of the cavity is a light-reflecting surface; In the reflective cavity, the light guiding rod is a columnar structure, and includes at least one light incident surface and a side surface, wherein the side surface is a light scattering structure with a feathered rib, and the light scattering structure is used to inject the light guiding structure The light of the rod scatters the light guiding rod; the light scattering structure has a plurality of tooth ribs, each of the tooth ribs are coupled to each other, and the tooth ribs form an in-line or U-shaped illuminance along the axial direction of the light guiding rod And distributed at intervals; and at least one illumination source disposed on an incident surface of the end of the light guide rod. The linear light source of claim 1, wherein the cross-sectional shape of the long-axis direction of the light guiding rod is a single smooth curve shape that can be differentiated at one time. The cross-sectional shape of the linear light source according to the second aspect of the patent application is a perfect circle, an ellipse or an egg shape. The linear light source of claim 1, wherein the light-scattering structure of the feather-shaped ribs may be a plurality of feather-shaped ribs connected side by side. The linear light source of claim 1, wherein the plume rib cross section may be a multi-faceted or curved shape. The linear light source of claim 1, wherein the plume rib cross section may be a concave or convex structure. The linear light source of claim 1, wherein the light incident surface is a planar, curved or polyhedral structure. The linear light source of claim 1, wherein the light source may be a light emitting diode or an organic light emitting diode. A linear light source, the main structure comprising: a reflective cavity, the cavity is provided with two light-in openings and at least one light-emitting opening, and the inner wall of the cavity is a light-reflecting surface; In the reflective cavity, the light guiding rod has a columnar structure, and includes at least two light incident surfaces and a side surface, wherein the side surface is a light scattering structure having a feathered rib, and the light scattering structure is used to inject the light guiding structure. The light of the rod scatters out the light guiding rod; The light scattering structure has a plurality of ribs, each of the ribs being coupled to each other, the ribs forming an in-line or U-shaped illuminance distribution along the axial direction of the light guiding rod, and a spacing arrangement; and two illuminating The light source is disposed on a light incident surface of the two ends of the light guide bar.