JPS5875370A - Modulation light forming device - Google Patents

Abstract

PURPOSE:To simplify the constitution of a modulation light forming device, by detecting the reflection of a luminous flux or the transmitted light from an object to be irradiated and applying the detected detecting output of a control means which controls a modulation light forming means in the form of the reference level. CONSTITUTION:A beam 12 given from a laser generator 11 is applied to an optical converter 13 to be modulatd in response to the voltage applied to the converter 13. Then a beam 12' is condensed through a condenser lens 17 and irradiated to a beam splitter 14 to be separated to two beams 15 and 16. The beam 16 is irradiated to an object to be irradiated, and the reflected light or transmitted light from the object is detected by a photodiode 22 and amplified by an amplifier 23 to be fed to an operational amplifier 24. At the same time, the constant voltage is applied to the other input of the amplifier 24 from a constant voltage source 26 and compared with the reference level of the output which is given from the amplifier 23 and detected by the diode 22. Based on the result of comparison, the voltage is applied to the converter 13. Thus the constitution is simplified for a modulation light forming device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modulated light forming device that forms light modulated by information on an irradiated object such as a document.

A device that illuminates a document with a constant amount of light to read information on the document, controls a light generator with the read information, and obtains modulated light that is modulated according to the information on the document is widely known. It is something that

However, such conventional devices require a part to extract information from a document and a part to modulate light based on the extracted information. This eliminates the drawbacks of the conventional tube.

Before explaining the present Ij1 in detail, first, an example in which it is applied to a copying machine will be briefly explained.

In FIG. 1, a beam 12' is modulated by a line light generating means indicated by 11 according to the voltage applied to a modulator 13, and then focused by a beam splitter 17. After separating into two beams 15 and 16, the beam 16 is placed on the condensing surface by the lens 17 and irradiated onto the document 18 having nine images. Therefore, from this document 18, the image on the document is Although it is possible to obtain reflected light 19 according to
is converted into an electric signal by the photoelectric conversion element 20 and then applied to the modulation signal forming circuit 21. This modulated signal forming circuit 21
is used to form the variable signal 111m applied to the modulator 13, and the variable X signal detected by the photoelectric conversion element 20 is at a constant level with respect to a predetermined reference level. Thus, it is a signal that controls the modulator. Therefore, if the image on the °C material is black with little light reflection, a large amount of beam will be emitted from the modulator 13.
Furthermore, if the image on the material is white with a lot of light reflection, the beam is controlled so that a small amount of the beam is emitted from the modulator 13, so the beam emitted from the modulator 13 has image information, and therefore the beam splitter The beam 15 divided by 15 can be used as it is as a beam for recording information.

To further explain the photoelectric conversion element 20 and the modulated signal forming circuit 21 with reference to FIG. 2, the photoelectric conversion element consists of a photodiode 22.
The light received at 2 is converted into an electrical signal and amplified by an amplifier 23, and this amplified signal is applied to one input terminal 25 of an operational amplifier 24. 26 is a normal foot voltage device which has a voltage selection means therein and can derive a desired voltage by switching the means, but the constant voltage from such a constant voltage device is Operational amplifier 24
is applied to the other input terminal 27 of.

Therefore, a high level signal is derived from the output terminal 28 when the signal level to the input terminal 25 becomes low, and a low level signal is derived from the output terminal 28 when the signal level to the father input terminal 25 becomes high.

Therefore, if the modulator 13 is configured so that the beam 12 is easily transmitted when the modulation signal level is high, and is difficult to transmit when the modulation signal level is low, the beam 12' can be weakened when there is a large amount of reflected light. Beam 1 if there is little reflected light
2' is controlled so that the output signal from the amplifier 1123 has a constant difference from the output voltage from the constant voltage device. (However, if there is a lot of reflected light, the level of the output signal of the amplifier 23 will be high, and if there is little reflected light, the level of the output signal of the amplifier i!823 will be low.) Therefore, the output signal from the amplifier 23 is The level is always kept at a constant level and for this reason beam 12'
The modulator 13 modulates the brightness according to the image.

FIG. 3 shows signal waveforms at various points when the beam 12"i is deflected in FIGS. 1 and 2 to scan over a material such as in FIG. ) As shown in (a), follow the dotted line on the document located in the black area 30.31 on the white background.
If the beam spot 32 is scanned in the direction shown in FIG. 1, the modulator is controlled so that the output of the photoelectric conversion element is constant as explained in FIGS. In the area corresponding to white, a strong beam is derived from the modulator, and in the area corresponding to white, a weak beam is derived from the modulator.In this way, the output of the photoelectric conversion element becomes approximately constant as shown in (c). As mentioned above, since the beam from the modulator contains image information, a copying apparatus can be formed by irradiating the recording medium with the beam 15.

FIG. 4 shows the above-mentioned copying apparatus in more detail.
The light is then guided to the input aperture of the transformer 36 via the reflective mirror 35. The reflecting mirror 35 is inserted to bend the optical path in order to reduce the space of the apparatus, and can be removed if unnecessary.

For the modulator 36, a known acousto-optic modulation element using an acousto-optic effect or an electro-optic element using an electro-optic effect is used.

At the modulator 36, the laser beam is subjected to strength variations according to the input signal to the modulator 36. .

Also, if the laser oscillator 34 is a semiconductor laser, a gas laser, etc., current modulation is possible. When using an internal modulation type laser that incorporates a fill element into the oscillation optical path,
The beam expander 36 is omitted and the beam is guided directly to the beam expander 37.

ii) 1 nose beam reflection from 1mia6 2-
35, the beam diameter is expanded by a beam expander 37 while the beam remains parallel. Furthermore, the laser beam whose beam diameter has been expanded is transmitted to a polyhedral rotating mirror 3 having a plurality of mirror surfaces.
8. The polyhedral rotating mirror 38 is mounted on a shaft supported by high-precision bearings (e.g. air bearings) and driven by a constant speed -k (?1lij hysteresis synchronous motor, D
The beam emitted from the beam expander is swept horizontally and is imaged as a spot on the photosensitive drum 41 by an imaging lens (or condensing lens) 40. be done. When collimated light is imaged into a spot by an imaging lens, the spot minimum diameter dmin is given by A: the entrance aperture of the imaging lens, and if f and λ are constant, increasing A will result in a smaller spot. ) II dmin is obtained.

The previously mentioned beam expander 37 is used for rounding to provide this effect. Therefore, when the required dn>in can be obtained by the beam diameter of the laser oscillator, the beam expander 37 is omitted.

A beam splitter 42 having a length that covers the entire width of the beam sweep is arranged between the photosensitive drum 41 and the imaging lens 40.

Accordingly, a portion 43 of the beam from the rotating polygon mirror 38 is irradiated onto the photosensitive drum 41, and the other portion 44 is irradiated onto a transparent glass 46 for placing materials on a document table 45. Therefore, the beam 44 moves as shown by arrow Q on the glass 46 by rotating the rotating polygon mirror 39t.

Reference numeral 47 denotes a light receiving element that receives the reflected light generated by irradiating the beam 44t on the original when the original is placed on the glass 46 and converts it into an electrical signal.

The document table 45 is moved at a constant speed in the direction of arrow P on the rail 48 by a drive device (not shown), so the glass 4
6, and while rotating the rotating polygon mirror 39,
By moving the document table 454 in the direction of arrow P, the entire document can be scanned.

At this time, it goes without saying that the photosensitive drum 41, which has a photosensitive layer over its entire surface, rotates in synchronization with the movement of the original platen 45.

The light receiving element 46 and the modulation@36 correspond to the photoelectric conversion element 20 and the optical modulator 13 in FIGS. By controlling the modulator 36 with a circuit such as
The same information as the material on the document table 45 is recorded on the photosensitive drum 41-H.

After that, the photosensitive drum 41t is processed by an electrophotographic processing process to develop the recorded information, and then the photosensitive drum 41t is printed on plain paper 47.
It is transferred to the top and fixed L7, . . . and output as a copy.

Next, the printing section will be explained with reference to FIG. 5 as well. As an example of the electrophotographic process applied to this embodiment, as described in Japanese Patent Publication No. 42-23910 of the present applicant, a photosensitive plate 49 whose basic constituents are a conductive support, a photoconductive layer, and an insulating layer. The surface of the insulating layer is uniformly charged positively or negatively using Jllll's corona charger in advance, and a charge [capture Then, the surface of the insulating layer to be charged is irradiated with the laser beam 43 and, at the same time, an AC corona discharge is generated by the AC corona discharger 51 to form a pattern due to the differential pressure of the surface potential generated according to the light and dark pattern of the laser beam 43. , is formed on the surface of the insulating layer, the entire surface of the insulating layer is uniformly exposed, an electrostatic image t- is formed on the surface of the insulating layer for contrast, and further Ka
After being developed and visualized by a developing device 52 using a developer mainly composed of electrostatic image tube charged colored particles, a transfer material 5 such as paper etc.
3, the visible image is transferred using an internal or external electric field, and then the transfer gIAt is fixedly fixed by a fixing means 54 such as an infrared rung or a hot plate to obtain an electrophotographic print)*', while the transfer is After this, the surface of the insulating layer is cleaned by a cleaning device 55 to remove remaining charged particles, and the photosensitive plate is repeatedly used.

Next, in the embodiments described so far, the surface of the insulating layer of the photoreceptor, which has been uniformly charged in advance, is attenuated by AC corona discharge to attenuate the electrical charge on the surface of the insulating layer, and at the same time, the photoreceptor is irradiated with laser light. The phenomenon that occurs will be further explained in detail with reference to FIG. 6. FIG. 6 shows the state of change in the surface potential of the surface of the insulating layer of the photoreceptor.

FIG. 6(a) shows a case where the frequency of the alternating current of the alternating current corona discharge is relatively low. At this time, the potential of the surface of the insulating layer during AC neutralization can take an intermediate value t between the curve shown by the solid line and the curve shown by the dotted line due to the difference in the phase of the AC voltage. However, the laser beam is irradiated for a very short time, for example, 150 nanoseconds in this embodiment, for a specific location on the photoreceptor. For this reason, due to the difference in potential on the surface of the bonding layer when the laser beam is irradiated, the potential of the electrostatic image obtained after the entire surface is exposed is , no longer constant. Therefore, this phenomenon occurs because the entire area of the AC static neutralization area is exposed to light when applied to a copying machine, etc. Phase effects are averaged out and do not appear.

In order to eliminate the phenomenon of unevenness, when the frequency of AC static elimination is increased (Fig. 6 i:b)), the total static elimination time does not change and synchronizes with the AC frequency of the surface potential of the insulating layer. Therefore, the difference in potential between the surfaces of the insulating layer facing the laser light layer becomes smaller, and the difference in the observed image becomes negligible for practical purposes. This is explained by the equivalent path shown in . In Fig. 7, E is the voltage applied to the discharge electrode of the AC corona discharger, Re is the resistance when the corona current flows between the discharge electrode and the photoreceptor, and cp is the photoreceptor regarded as a capacitance-only load. It shows the capacitance of the photoreceptor at the time.

At this time, if the potential on the surface of the insulating layer immediately before entering AC static elimination due to -order charging is Vo, and the voltage applied to the AC corona discharge electrode is E = Eo cm (wt + #), then the voltage of the insulating layer during AC static elimination is: The surface potential is expressed as VpU+Voj -side ψ= tan-' (-1-) CpRc.

(From the simple formula, the static elimination time is given by the IN2 term on the right side, and its time constant τ is CpRc.

It also varies due to the frequency of the alternating current corona discharge.

Also, from Fig. 8, the AC static elimination time td is td='-(5) V: Drum circumferential speed ■ 1: Given by the width of the static elimination area.

Furthermore, the amount equivalent to Cp K of the equivalent path of K11711 is:
0 which is proportional to the surface area of the photoreceptor that passes through the static elimination area per unit time Cp=muv (6) Mu; proportionality constant where, cp
= Opl, Re = Re+ l If it is assumed that the static electricity is removed sufficiently under the conditions of v = v+, the time constant of static electricity removal in equation (4) is τ Karasu = Cp + Re + (7
) At this time, the amplitude of fluctuation W due to the AC discharge frequency W4
It is assumed that e is large enough to cause the amplitude Wo to cause #1 degree unevenness in the visible image. vr == Wl (Wl > wo
), and it is assumed that Wl is sufficiently small to li& that does not cause the concentration unevenness. 0 In this way, by changing the frequency of AC corona discharge, the concentration unevenness can be removed without changing the static elimination time. be able to.

Next, when the circumferential speed of the drum is y 2 tl v4 == vl, t#! Then, CIh=αCpI −4 static elimination time tf ta,='=-L=”LaυV! α
vI α td・=1 1 Therefore, the static electricity removal time τ must be Oα Therefore, in order to sufficiently remove static electricity within tdm, the static electricity removal time constant τ1Cp1@RC1 τt=Cp*@Rct= = Q water α α It can be seen that it is necessary to use Equation 11. Actually, changing the RCt is achieved by changing the distance between the discharge electrode wire and the photoreceptor. At this time, the AC corona discharge The amplitude W1 of the fluctuation caused by the frequency is as follows, and the wt(D condition for W2 = WI is determined as W) Cp * Rc = wt CP + Rct
According to formula a, in order to prevent unevenness of the original image, it is necessary to apply an AC corona circumference number greater than a certain value, and that value is proportional to the circumferential speed of the drum.

In this example, the circumferential speed V of the drum is 30 cm/kai,
Width of static elimination area 3caX 30CAs Capacitance C of photosensitive plate
a5PF/a11, AC static elimination current is 75 μm rms,
It was carried out at a voltage of 7 kV, a frequency of f ij I KHz, and an electrostatic contrast of about 5 oov. The development is done using liquid 'iJL.
g1 and reversal development was performed. From these experiments, it was possible to remove the unevenness of the image under the condition that the frequency f of AC static elimination was satisfied. That is, it means that the pitch according to the frequency of AC corona discharge on the photosensitive drum A is 9.3 mm. Therefore,
The effects of the above four formulas are achieved under increasingly general conditions.

P is a constant determined by the capacitance of the photoreceptor, the width of the static elimination area, the development conditions, etc., and was 0.03 in the above example.

As still another example, the present applicant's Japanese Patent Publication No. 42-19
An electrophotographic electrostatic image forming process such as that described in Japanese Patent No. 748 is applied. That is, a photosensitive plate having a conductive support, a photoconductive layer, and an insulating layer as basic components is used, and the surface of the insulating layer is uniformly positively or negatively charged in advance by a first corona discharge, and the photoconductive layer and the surface of the insulating layer, or
A charge of opposite polarity to the charged polarity is captured inside the photoconductive layer, and an alternating current corozo discharge is applied to the charged surface to attenuate the charge on the surface of the insulating layer. The process is the same as that of the first embodiment except for the steps of irradiating a laser beam, forming an image 1 on the surface of the distribution insulating layer according to the brightness of the laser beam, and then developing the electrostatic Va.

The photoreceptor and laser oscillator used in the first and second embodiments were as follows. Combination A a) Laser oscillator He-No gas laser wavelength 632.8 m, U) Photoreceptor activated by sea bream Add 90 g of oxidized cadmium oxide, 90 g of vinyl chloride, and a small amount of thinner.
It is applied to a thickness of about 70μ by spraying onto aluminum foil of 0μ. Next, a microphone film with a thickness of about 25 μm was adhered to the photoconductive M surface using adhesive to obtain a photosensitive plate, and then KI! IJ photoconductor A sound photoconductor wound around a drum. In the case of this photoreceptor, the charge polarity of the first charge is positive.

Combination B a) Laser oscillator He Cd laser wavelength 441.6 mμ Port) A Ta layer with a thickness of about 1μ is vacuum deposited on the photoreceptor aluminum substrate, and further a Ta layer with a thickness of 90μ containing Te containing 15% is vacuum deposited. In the case of this photoreceptor whose surface is coated with transparent insulating resin to a thickness of about 30 μm and cured, the first charging polarity is negative.

Furthermore, various laser light guides currently announced or to be announced in the future also include the Ml and JII20#
Applicable to imaging processes.

It is important to devise a combination of photoreceptors with spectral sensitivity characteristics that are matched to each laser wavelength.

As a laser, Ar gas laser rz Ar+Krz (visible) semiconductor laser dye laser Infrared laser beam double-wave conversion using a nonlinear crystal (YAG laser, semiconductor laser), etc. can be used.

In the present invention, such a copying apparatus is further provided with a beam detector as shown at 56 in the fourth wJ, and this beam detector 56 is composed of a small entrance slit and a photoelectric conversion element (for example, a PIN diode) with a variable response time. .

Beam detector 56#i, swept laser beam 430
Using this detection signal, the start timing of the input signal to the modulator 36 for outputting information from a computer or the like to the photosensitive drum is determined. As a result, it is possible to reduce the error in the division accuracy of each reflecting surface of the polyhedral rotary mirror 38 and the synchronization deviation of horizontal signals due to one rotation unevenness to seven wide widths, and to obtain high-quality images. The permissible range of accuracy with which water is sprinkled on the driving Tanabata 39 is increased, and it can be manufactured at a lower cost.

In a copying device configured in this way, an electronic method is required to record data signals sent in the form of electrical signals from an electronic computer, etc., on a single recording medium by superimposing them on information obtained from the above-mentioned materials. The driving mode of the optical modulator is changed according to a binary signal from a computer.

To explain in more detail with reference to FIG. 9, (however, the members with the same numbers as those in FIG. 2 are made of the same members), 9E has two levels like a binary signal, and , shows a device for superimposing serially sent data signals with information on gains and losses from data 18.

Reference numeral 60 indicates an application terminal for applying a binary data signal such as a dual-speed signal, and the binary data signal applied from this terminal is applied to a switch 61.
It controls the

That is, this switch has a contact piece 62 and a contact point 63a.

63b, but when a signal indicating 9 black is applied to the terminal 60, for example "1", the contact piece 62 and the contact 6
3b is connected, and when a signal indicating white, e.g.
The contact 63b is connected to the constant voltage source 64, and the contact piece 62 is connected to the optical modulator 13. Therefore, the constant voltage from the constant voltage source 64 is applied to the contact piece 6.
2 and the contact 63m are connected, and the contact piece 62 and the contact 63b are connected by making the voltage equal to the voltage derived from the output terminal 28 when the beam 16 is irradiated to the black part on the document 18. This allows the beam 15 to perform the exposure necessary to draw black on a photosensitive drum (not shown).

In other words, when a signal corresponding to black arrives from the terminal 60, the constant voltage determined by the constant voltage source 64 is optically changed by forcibly connecting the contact piece 62 and the contact point 63b.
By applying the voltage to the IllIl circuit 13, and otherwise connecting the contact piece 62 and the contact 63at-, control is performed as explained in FIG.

Although omitted in the recording apparatus shown in Fig. 1.2.9, the beam emitted from the optical transformer 13 is repeatedly deflected in one direction (X direction), and The terminal 60 is configured to move in a direction (Y direction) perpendicular to the deflection of the beam on the material, so that the entire area on the material is scanned by the beam. As mentioned above, a signal from a computer or the like is applied to the data signal forming apparatus.A brief explanation of the data signal forming apparatus shown in the first .theta. drawing will now be given. In FIG. 9, the information from the electronic computer applied to the terminal 60 is directly 1i.
The information is input to the interface circuit 66 of this apparatus in a specified format via a storage medium such as a magnetic tape or a magnetic disk. Various instructions from computer 77 are decoded and executed by instruction depth circuit 67.

Data is stored in data memory 68 in fixed amounts.

In the case of character information, the format of l-data is given as a binary code, and in the case of graphic information, it is given in pixel units that make up a figure, or data of lines that make up a figure ( (so-called vector data). These modes are specified in advance of the gator, and the instruction execution circuit 67 controls the data memory '68 and line data generator 69t to process data according to the specified mode. A line data generator 69 generates final data for one scanline.

That is, when data is given as a character code, the character pattern is read out from the character generator 7o,
Either line up the character pattern for one line and buffer it, or buffer the character code for one line and sequentially read the character pattern from the character generator 7゜ to create one tough 2
Data f for modulating 4 frames of laser light: Created sequentially. Even when the data is graphical information, the data for the scan line is converted to scan line data and the data for sequentially modulating the laser beam for the l line scan is generated. A line buffer 71 and a line buffer 72 each consisting of a shift register or the like having a number of bits appropriate for the number of pixels are alternately supplied manually under the control of a buffer switch control circuit.

Furthermore, line buffer 71 and line buffer 72
The data is sequentially output one bit at a time for one scan sheet as a beam detection signal sound trigger signal from the beam detector 73, and is applied to the switch 61 shown in FIG. While one reflective surface scans the photosensitive drum along a line perpendicular to the rotational direction, data corresponding to 1 and 24 times stored in the line buffer is applied to the switch 61. Data signals are read out alternately from the line buffers 71 and 72 under the control of the buffer switch control circuit 76. In other words, when the line is overflowing from one side of the line buffer, it is being written to the other line buffer.

With this method, when the rotating polyhedral mirror sweeps over the photosensitive drum and the distance between one reflecting surface and the next reflecting surface is very short, the 01 scan line can be applied to the modulator without missing any data. Before scanning, the photosensitive drum continues to rotate at a constant speed and moves by an appropriate scan line interval.As described above, according to the present invention, the following light can be modulated with an extremely simple configuration. In Although,
The present invention is not limited to the embodiment shown in FIG. 1.2, but the embodiment V shown in FIG.
It is possible to apply it.

That is, as shown in FIG. 11(a), the beam transmitted through the material 18i is the light i! 17, it may be detected by the conversion element 20,
Also, the condenser lens 17 is connected to the beam splinter 14 and the document 18.
The condenser lens may be placed between the two, or the condenser lens may be omitted altogether.

j! In this case, as shown in FIGS. 11(b) and 11(c), the material may be irradiated with a beam that has passed through the beam sinter 14, and in this case, the light 'mz as shown in FIGS.
The light reflected from the material 18 by the converter 20 may be detected, or the light transmitted therethrough may be detected.

In the embodiments (b) and (c), the condenser lens 1
7-ray plexus! It may be placed between the 1m device 13 and the beam splinter 14- or between the beam splinter 14 and the material 18, or may be omitted.

In addition, in the embodiments shown in Figures 1 and 11 (a), (b), and (c), when a laser generator 11 whose generated beam intensity can be controlled by a control signal is used, in other words, the modulation function is When a laser generator (for example, a current modulated laser) having a laser beam is used, the output of the modulation signal forming circuit 21 can be applied directly to the laser generator, thereby eliminating the optical modulator.

As described above, the present invention enables a light tube modulated by information on an irradiated object such as a document to be obtained with a simple configuration.

[Brief explanation of the drawing]

1II is a block diagram 2 showing the modulated light forming device according to the present invention, 1112a11 is a block diagram 2 showing the modulated light forming device according to the present invention in more detail, (#lI3 Figures (a), (b), (c) ) is an explanation showing the operation of each part in FIG. Waveform diagrams for explanation, #g7 to 8 are equivalent circuits and enlarged explanatory diagrams when AC charge removal is performed on the photoreceptor, and FIG. 9 is the present invention I!1
IIt-A block diagram showing a data signal forming device in FIG. 1θ, and FIGS. 11(a), (b),
(C) is a block diagram showing a recording device to which the present invention can be applied. Here, llq laser generator, 13 is an optical modulator, 14 is a beam splitter, 18 is a document, 2o is a photoelectric conversion element, 2
1 is an optical modulation signal forming circuit, 22-line photodiode, 2
4-channel operational amplifier, 26° 64 is a constant voltage power supply, 61 is a switch, and 64 is a reference voltage device.

Claims (1)

[Claims] A modulated light forming means whose output light amount is controlled in response to the application of a modulation signal, a scanning means which scans an irradiated object with the output light from the modulated light forming means, a reflection of the luminous flux from the irradiated object, or A modulated light forming device comprising: a detection means for detecting transmitted light; and a control means for controlling the modulation means so as to bring the detection output of the detection means to a reference level.