JPS61186804A - Photodetector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a planar (Zolena type) detector array, and more particularly to a detector for determining the stack height or level of a paper tray. BACKGROUND OF THE INVENTION In copiers, especially high-volume copiers, it is important to monitor the amount of copy paper remaining in the copy paper tray. This avoids unnecessary interruptions in the copying operation due to lack of copy paper in the copy paper tray and the need to replenish the tray with copy paper.

As described in U.S. Pat. It is possible to do so. Numerous examples of paper detectors also
U.S. Patent No. 3,27 for a photosensitive dual layer detector
No. 8,254 is found in the prior art. In particular, a lamp as a light source and a solar cell responsive to reflected light can be used to generate a variable current proportional to the distance of the paper from the detector. The distance between the optical fiber bundle connected to the light source and the detector is ＠
All are separated by a specific angle to determine where the maximum current is obtained. This type of system is very sensitive to the distance of the paper from the detector, so the system needs to be installed with very high precision. In fiber optic sensing devices, false signals are generated simply by the transparency or paper being in a different position or on a different side along the transfer path.

In other systems, U.S. Pat.
As described in No. 5, a mechanical detector is used to detect multiple papers. The difficulty with mechanical detectors is that
They are often limited to specific paper thicknesses. If different thicknesses are used, it is necessary to make mechanical adjustments to the detector.

Other detectors, such as those shown in U.S. Pat. No. 3,778,051, use a transducer that generates a signal proportional to the thickness of the paper. A binary signal representing the thickness of the first sheet of paper delivered is compared with a signal representing the thickness of subsequent sheets. If the thickness of the subsequent paper is greater than the thickness of the initially delivered paper, a comparator generates an error signal to divert the paper from the paper feed mechanism.

Furthermore, it is also known to use a pair of receiving elements in the detector. For example, as described in Patent Application Publication No. 55-2528, it is possible to use a pair of light-receiving photodetectors and a light-emitting element with a polarizing filter to detect paper in the paper feed path. can. One of the photodetectors includes a polarizing filter to provide high and low signals for paper that is not in the path. Additionally, US Pat. No. 3,900,738 shows a method for projecting light from incoherent light sources onto two light sensing systems. The difference in output from the light sensing system represents the position of the object in the path of the light.

In US Pat. No. 3,435.24 [), the surface properties of a material are determined by the quotient of the output signals from two photomultiplier tubes. The intensity of the signal from the photomultiplier tube is determined by simultaneously measuring the transmission of energy from a single light source through small and large regions of the material of interest.

In U.S. Patent No. 4,092,068,
A single light source illuminates the surface of the material, and surface properties are determined by comparing the amount of light reflected from the surface with a pair of detectors placed at two different angles.

Additionally, as shown in U.S. Pat. No. 4,432,599, a movable optical fiber may be used with one end face facing the end faces of a plurality of mutually adjacent fixed optical fibers. It has been known. The axis of the movable optical fiber and the fixed optical fiber are such that when the movable optical fiber is placed in its initial position, an optical signal passing through the movable optical fiber at a low current passes through the entire end face to each of the fixed optical fibers. are relatively positioned to combine optical signals with an intensity equal to . This optical energy balance relationship is broken when a sensor mechanism coupled to the movable optical fiber causes a small movement of the movable optical fiber axis.

Small movements of the movable optical fiber result in an optical energy distribution between the fixed optical fibers that varies essentially linearly with displacement of the movable optical fiber. The signal generated by the energy conversion in the fixed optical fiber is converted into a corresponding electrical signal by a photodetector, and then connected to a summing amplifier and a subtraction amplifier to obtain the appropriate signal sum and signal difference. , by using the above signal sum and signal difference to give the total amount of movement of the variable optical fiber shaft.

Furthermore, in the electro-optical industry, it is common practice to set up a fiber perpendicular to the top surface of the active element when coupling the emitted light beam from a light emitting device such as a light emitting diode into the original fiber waveguide. . This is particularly required in communication applications using optical fibers. This is because it is required to couple the maximum amount of energy to the waveguide and minimize loss. Adopting such a coupling method imposes restrictions on the mounting of the light source and tends to increase the price due to the need for alignment to maximize output power. Traditionally, this top surface coupling method has been used to couple light beams to waveguides (optical fiber elements). It is not advantageous in this situation.
Components made by this method will also be required under a wide range of environmental conditions. This also makes it difficult to design a simple, low-cost detector.

Other difficulties associated with traditional detectors include that they often require readjustment when used in different environments, which is often complex, costly, and non-trivial.
There is a thing.

[Summary of the invention]

Accordingly, it is an object of the present invention to provide an improved stack height detector. Another object of the invention is to provide a new and improved planar detector arrangement. A further object of the present invention is to provide an array of reflective Morr optical fiber pairs for stack height detection. Yet another object of the present invention is to provide a method for fabricating a hybrid circuit that allows simple and inexpensive coupling of radiation from a chip-like component into a waveguide. Still another aspect of the present invention
One purpose is to connect several waveguides to a single light emitting diode (
The objective is to obtain a simple hybrid method for coupling to LEDs) or phototransistors.

In summary, the present invention relates to the fabrication of optical fibers for coupling the emitted light beam from a chip-like component into a plurality of waveguides and to a planar detector array made by the above method. In the above manufacturing method, the waveguide is attached to the side surface of the light emitting diode or photodiode, so the alignment of the waveguide requires only two-dimensional accuracy. The detector array includes a light source, an array of side-by-side optical fiber pairs, and an electro-optical device for converting the light into an electrical signal.

[Example of leprosy]

Other objects and advantages of the present invention will become apparent from the detailed description below, taken in conjunction with the drawings. Note that the same reference numbers refer to similar parts.

Referring now to FIG. 1, - by way of example, an electrophotographic printing apparatus is shown which sequentially moves the photoconductive surface 12 in the direction of arrow 16 through various processing steps. It has a photoconductive surface 12. At the charging location, a corona generating device 14 electrically connected to a high voltage source supplies a charge to the photoconductive surface 12 at an essentially uniform high voltage. The charged portion of photoconductive surface 12 is then advanced through exposure location 18. At exposure position 18, an original document is placed onto a transparent platen. The source material is illuminated with a lamp and the reflected light from the source material is transmitted onto the conductive surface 12.

A calm brush development system 20 moves the developer material into contact with the electrostatic latent image.

At transfer position 22, the copy sheet is moved into contact with the toner powder image. Copy paper indicated at 24 is delivered from the tray 25 to the transfer position by a paper delivery device 26. Paper delivery device 26 contacts the top sheet of the copy sheet stack. The paper feeding device 26 rotates to advance the paper from the stack (onto the feeding device 28).The conveying device 28 advances the fed holding material sheets in chronological order, and transfers the fed holding material sheets to the transfer position. The photoconductive surface 12 is brought into contact with the paper and the toner powder image is contacted.

Transfer position 22 includes a corona generator for spraying ions onto the backside of the paper. This attracts the toner powder image from the photoconductive surface 12 to the paper.

After transfer, the sheet continues to advance and is passed to a pre-heat conveyor 30 which delivers the sheet to a heating position 32. heating position 3
2 typically includes a heated roller and a backup roller to permanently fix the transferred image to the paper.

After heating, the chute passes the paper to a pick-up tray 34 where it can be picked up by the user. Also included is a cleaning mechanism 36 for removing residual toner that remains on the surface 12.

Referring to FIG. 1, there is also shown a stacked height detector 40 having a plurality of fiber optic reflective detector pairs. This sensor is preferably connected to a controller (not shown) for monitoring the height of the copy sheets in tray 25.

In FIG. 2, the configuration of a sensing device according to the invention is shown. In particular, a pair of waveguides or optical fibers 56, 58 are shown in a side-by-side arrangement. The coupled light beam from a synchrotron radiation emitting diode (not shown) travels through the optical waveguide 56 and reaches the surface 5 of the waveguide 56.
7.

The light beam propagating through the propagation waveguide 56 passes through the end face 57 of the waveguide.
, into an adjacent space, and further toward a stack of copy sheets indicated at 54 . As shown, the rays X, Y, and Z projected from the waveguide 56 are
4 and become the rays Xi, yl, zl.

The length that the optical energy is routed along the propagation waveguide 56 to the emitting surface 57 is preferably between 1 and 20ffffl+. The end dimensions of the optical waveguide are preferably comparable to the side dimensions of the LED or light emitting device in order to couple a useful amount of light flux into the waveguide.

According to the present invention, the optical waveguide is placed adjacent to the side surface of the ED or the butt.
) combination method is used. In this process, only two-dimensional precision is required to align the waveguide with the light emitting or receiving device. This fabrication method allows coupling of radiant energy from inexpensive chip components such as light-emitting diodes or photodetectors into waveguide elements. If non-circular waveguides are used, Assembly can be performed using conventional chip placement processes.

Referring to Figures 6a and 3b, coupling of the optical waveguide to a light emitting diode and photodetector is shown. On the hybrid substrate 64, the optical waveguide 60 is para-coupled to the LED chip or photodiode. That is, rather than coupling the waveguide to the top surface of the diode 62, side-to-side coupling between the waveguide 60 and the photodiode 62 is used.
A photodetection element such as an LED or a p-n or p-1-n diode is chosen with dimensions comparable to the waveguide material. The chip devices and semiconductors described above are adhered to substrate 64 using conventional conductive die adhesives. The waveguide can also be bonded using a similar epoxy resin. The final transmitter-receiver pair configuration must be evaluated by the level of background noise and signal crosstalk in the receiver due to transmitter proximity. Appropriate optical shielding can be provided by covering the transmitter chip with an opaque shielding material. Figures 4a and 4b show the loading and unloading surface shapes for circular and polygonal waveguide cross sections.

This type of structural combination allows pairs of optical waveguides to be made to operate side-by-side with each other. When one waveguide is used as a light flux transmission source and the other waveguide is used as a receiver, a reflection type detector is obtained. In other cases, interruptive or conductive detectors are obtained; generally the waveguide size is on the order of the chip size used for the signal source and detector. The device can therefore be made very compact and easily assembled along the edge of the board. This allows the creation of very compact sensing arrays. The resulting planar end array is compact and relatively inexpensive compared to equivalent devices made with conventional top-perpendicular bonding schemes.

As shown, there are various ways to couple the waveguides to the end faces of the emitter and detector chips.

In addition to circular waveguides such as resin optical fibers, non-circular waveguides can also be used, and various optically transparent materials such as shaped acrylic, transparent ceramics, and glass can be used. can. Furthermore, it is possible to use integrated electronic circuits through the use of Hypritz substrates. Additionally, moderate optical resolution can be obtained without using conventional optics, and high gain amplifiers can be used without noise-picking interlayers.

Referring to FIG. 5, there is shown a stacked height detector or detector array suitably supported on a substrate 70 of any suitable material, generally acrylic or the like.

Preferably, the substrate is such that the paper tray of paper tray 25 is secured to the paper tray 71 (as shown in FIG. 1). As shown, four pairs of optical fibers 72°, 74, 76, 78 are used for detecting the paper in the paper tray, and they are at 10% level, 25% level, 50% level, and 100% level, respectively. is set in the position. Each reflective fiber optic pair 72, 74, 76, 78 detects when the stack height moves above or below its location.

The resolution of 6 pairs is 4:38 microns (1,5 mil) + 1 using 76 micron (6 mil) diameter fiber pairs.
It can be as small as 6 microns (0.5 mils).

Referring to Figure @6, the basic structure of the array detector is shown, which in this example includes a pulsed current source 80 and four individual light sources 82a, 821), 82C182d. Four pairs of optical fibers are also shown at 72.74, 76.78, respectively 10%, 25%, 50%, 10
It includes a transmitting optical fiber T and a receiving optical fiber R for indicating the level of the tray at 0% capacity. The optical fiber pairs are secured in an array holder, each of the six receiving optical fibers having a respective photoconductive circuit 84a, 84b, 84c.

84d. For this configuration, the fiber length,
It should be pointed out that many variations are possible depending on the termination method and the coupling method to the type of source and detector used.

The output signals from the photodetector circuits 84a-84d may be electrically connected to a suitable display on the control console to display to the user the stacking level of the sheets in the tray.

In accordance with the present invention, a single light source is fabricated with six pairs of optical fibers and associated light detection circuitry on a single hybrid substrate 86, as shown in FIG. For simplicity, 100% capacity optical fiber pairs are excluded. A pulsed current source 80 provides pulses to a single infrared emitter 88 that serves as a light source for the optical fiber pair. The head of the detector is a vertical fiber optic array, eliminating the need for relatively longer fiber optic cables and eliminating the termination required in the implementation of individual fiber optic pairs. It is noted that the Heideritz R type board 86 is enclosed within a shielded enclosure to provide a relatively high level of EMU (electromagnetic interference) immunity.

In the preferred implementation, the active elements of the light source and detector are four infrared chips (one transmitter and six receivers glued to an aluminum oxide substrate).

The fiber optic waveguide is a resin fiber with a diameter of about 0-4 nvn (16 mils). Each fiber is individually
Each detector side is connected to either a transmitting or receiving diode. A fiber is tied to the side of each diode. One infrared diode functions as a transmitter with three individual fibers (one on each of the six sides) connected to each other. The receiving fibers are connected to the individual receiving diodes and also to the side ends.

Figures 8a, isb, 9a, and 9b are high-t
Figures 8a and 8b illustrate another example of an optical fiber pair fabricated on an IJ substrate. Figures 8a and 8b show a 6-position array using flexible optical fiber waveguides with circular cross-sections. 1. One transmitting LED 90 and six receiving chips 92°94.96 are shown. Connections to active devices are made through conventional silk screen conductive patterns. Figures 9a and 9b are top and front views of a 6-position array using a single-point polygonal optical waveguide with a rectangular cross section. In this embodiment, one transmitter and receiver per sensing position. It is shown.

While the invention has been illustrated and described in what is presently considered to be the preferred embodiment of the invention, many changes and modifications will be apparent to those skilled in the art. It is, therefore, to be understood that the claims are intended to cover those changes and modifications that fall within the scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a copying apparatus embodying the present invention. FIG. 2 is a block diagram for detecting the presence of a stack of copy sheets using a pair of waveguides. Figures 6a and 6b are side and top views illustrating end coupling of an LED chip and a waveguide according to the present invention. Figures 4a and 4b illustrate the ends of the reflective sensing arrangement. FIG. 5 is a diagram illustrating a stack height detector according to the present invention. FIG. 6 is a basic configuration diagram of the detector shown in FIG. 5. FIG. 7 shows a hybrid electro-optic stacked height detector according to the present invention. Figures 8a, 8b, 9a and 9b are diagrams showing modifications of the hybrid stack height detector. Reference numerals 12...Photoconductive surface 14...Corona generating device 18...Exposure position 20...Development system 22...Transfer position 24...Copy paper 25...Tray 26...Paper Sending device 28... Feeding device 32... Heating position 34... Take-out tray 36... Cleaning mechanism 54... Copy paper stack 56... Transmission waveguide 57... End surface 58... ...Receiving waveguide 60...Waveguide 62...Photodiode 64...Substrate 70...Substrate 72.74, 76.78...Optical fiber pair 80...
Pulsed current sources 82a, 82b, 82c, 82d - light sources 84a, 84b
, 84c, 84d... Photoconductive circuit 86... Hyderi r substrate 88... Infrared emitter 90... Transmission LED

Claims (3)

[Claims] (1) A detection device for detecting the amount of paper in a paper tray, comprising: an LED light source attached to a substrate; and a plurality of pairs of optical waveguides, each pair serving as a transmitting waveguide. a receive waveguide, the transmit waveguide radiating the output from the light source to the paper tray, and each of the waveguides radiates the output from the light source to the paper tray.
a pair of optical waveguides laterally coupled to one side of D; a receiver waveguide mounted on the paper tray; and a photodiode in communication with the receiver waveguide for converting the output of the light source into an electrical signal. a photodiode, each of said receiving waveguides being laterally coupled to one side of a photodiode, thereby causing said detector to determine the amount of paper in the paper tray; Detection devices, including: (2) a hybrid electro-optic sensing array including a light source for generating a radiation beam, a substrate having the light source mounted thereon, and a plurality of pairs of optical waveguides, each pair being a transmitter waveguide; and a receiver waveguide, each pair of which is fixed to the substrate, such that the emitted light flux generated by the light source is transmitted through the transmitter waveguide and incident on the receiver waveguide; A hybrid electro-optic sensing array comprising: electro-optic means in communication with a receiver waveguide for converting the emitted light flux into an electrical signal. (3) A detection device for detecting the amount of paper in a paper tray, comprising a light source attached to a substrate, a plurality of waveguide pairs, each pair including a transmitting waveguide and a receiving waveguide. a pair of waveguides, the transmit waveguide projecting the output from the light source onto the paper tray; a receiver waveguide attached to the paper tray; and electro-optic means for communicating with the receive waveguide. and electro-optical means for converting the output of the light source into an electrical signal, thereby causing the detector to determine the amount of paper in the paper tray.