JPS5923512B2 - Photoelectric pulse generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric pulse generator used in facsimile machines, printers, and the like.

Generally, facsimile machines and printers use photoelectric lock pulse generators that determine the physical position of one bit, that is, one pixel, on a document or recording paper.

1 to 3 are views showing an example of a facsimile machine to which the present invention can be applied, in which FIG. 1 is a schematic plan view, FIG. 2 is a detailed perspective view of its scanning head, and FIG. 1 is a side view of FIG. 1 viewed from the left side.

1 to 3, 1 is a recording paper, 2 is a document, 3 is a carriage to which a scanning head 4 is attached, 5 is a guide shaft that guides the carriage 3, 6 is a motor that drives the carriage 3, and T 8 is a pulley, 8 is a drive wire (or belt) attached to the carriage 3, 9 is a pulley on which the wire 8 is hung, 10 is a pattern plate or slit plate attached to the board by an appropriate means not shown, and 11 is a slit plate. A home position (left position) sensor 12 detects the leftmost position of the scanning head 4, such as a limit switch; 12 a right position sensor similarly detects the rightmost position; 13 and 14 light sources mounted on the carriage 3; 16 is a photoelectric conversion element consisting of a photodiode, a photoconductor, a photocell, etc., which is also attached to the carriage 3; IT is a slit plate 1;
18 is a start synchronization pattern (start slit), 19 is an end synchronization pattern (end slit), 20 is a recording head portion of the scanning head 4, 21 is also an optical reading head section, 22 is a light source and light receiving element (photoelectric conversion element) part of the reading head 21, which irradiates the original 2 with light from the light source and receives the reflected light at the light receiving element; 23 is the same lens system, 24 is a slit and original pressing plate, 25 is a supply roller for recording paper 1, 26 is a supply roller for original 2, 2? is a presser plate for the recording paper 1. Note that 28 is a movable start mark, and 29 is a movable end mark.
In the recording or reading scanning method of the facsimile apparatus configured as described above, the recording paper 1 (or original 2) is run at a relatively slow speed in the y direction in FIG. (When the recording head 20 or the reading head 21 consists of a plurality of parallel head elements, each time the recording head 20 or the reading head 21 advances by a plurality of lines corresponding to the number of parallel head elements), the scanning head 4 attached to the gear ring 3 synchronizes with this. is driven by a motor 6 at high speed in the x direction from the left end to the right end, and the entire width of the recording paper 1 (original document 2) is repeatedly scanned.

As the scanning head 4 moves, the light sources 13 and 14 and the photoelectric conversion element 15, which are also attached to the gear ring 3,
16 also moves in the x direction.

Immediately after the start of the scanning head 4, the light source 13 and the photoelectric conversion element 15 start synchronizing the start synchronization pattern 1 of the slit plate 10.
When the photoelectric conversion element 15 matches the position 8, the photoelectric conversion element 15
Generates a start synchronization pulse upon receiving light from the Similarly, when the light source 13 and the element 15 coincide with the end synchronization pattern 19 just before the end of scanning, an end synchronization pulse is generated. On the other hand, the light source 14 and the photoelectric conversion element 16 are arranged so as to cooperate with the slit row 17 of the slit plate 10.
As the scanning head 4 moves, a so-called element clock pulse train is generated, which is determined by the pitch of the slit row 17 and the scanning speed of the scanning head 4. The generated clock pulses have an interval corresponding to one pixel and are used for digital processing of image information and synchronization of the scanning speeds of the transmitting system (reading system) and receiving system (recording system). The operation of generating this clock pulse will be explained in more detail with reference to FIGS. 4 to 6.

FIG. 4 shows the clock pulse generator of FIG.
1, and the light is incident on the photoelectric conversion element 16 through the slit of the slit plate 10.

Another slit plate 32 is attached to the front surface of the photoelectric conversion element 16, and this slit plate 32 is similar to the slit plate 1.
0 together with the scanning head 4 and photoelectric conversion element 16. FIG. 5 is a plan view of the slit plate 10 with the start and end pattern parts omitted, and FIG. 6 is a plan view of the slit plate 32. Both slit plates 10 and 32 have the same slit lengths Wl, W2, slit width Dl, d2, and slits 17 and 35 with slit pitches Pl and P2 (-2d1, 2d2), and are arranged so as to overlap each other in the vertical direction in FIG. 4. Slit plate 10, 32
A transparent film or a transparent glass plate coated with an opaque film (the hatched area) is used, and the pitch of the slits 17 and 35 is 0.125 mm in the case of normal 8 lines/1 m 7 n. In such a configuration,
The photoelectric conversion element 16 and the slit plate 32 are the slit plate 1
When moving relative to 0, the photoelectric conversion element 16 receives light whose intensity changes in a triangular or sinusoidal waveform, and generates an electrical signal according to the light intensity.

This electrical signal is led to a waveform shaping circuit 34 via an amplifier 33, where it is shaped into a pulse waveform and output as a clock pulse. Although it is possible to generate clock pulses with just one slit 34 in the movable slit plate 32, a larger output can be obtained by providing multiple slits as shown in FIG. 6 even when the amount of light per slit is small. , usually has a shape like this. By the way, in the above-mentioned technique, in order to improve the resolution of the output clock pulse and to increase the brightness contrast of the incident light received by the photoelectric conversion element (light receiving element) 16 to obtain a clock pulse with a large amplitude, a fixed clock pulse is used. It is necessary to arrange the slit plate 10, the movable slit plate 32, and the photoelectric conversion element 16 as close as possible to reduce leakage light as much as possible.

However, since the slit plate 10 is extremely long and requires a length at least equal to the width of the original or recording paper, the slit plate 10 and the photoelectric conversion element 16 (or the light sources 13, 14, and the slit plate 32) are connected to each other over its entire length. It is extremely difficult to maintain the distances parallel to each other and at constant intervals. Therefore, when the scanning head 4 is operated, the distance between the slit plate 10 and the photoelectric conversion system (the photoelectric conversion element 16, the light sources 13, 14, or the slit plate 32) changes, and the leakage light also changes accordingly. The amount of incident light received by the conversion element 16 changes. FIG. 10A shows the output electric signal waveform of the photoelectric conversion element 16.

The output V1 of the photoelectric conversion element 16 includes a required sinusoidal component and a fluctuating voltage component d due to a change in leakage light. Further, the amplitude of the sinusoidal component itself also varies because the distance between the slit plate 10 and the photoelectric conversion system changes and the contrast received by the photoelectric conversion element changes. 1st
FIG. 0B shows the output waveform of the waveform shaping circuit 34. This circuit 34 generates a pulse waveform V2 that has a positive or zero level depending on whether the voltage waveform V1 in FIG. 10A is higher or lower than the slice level t, and this pulse is used as an element clock pulse. However, if the slice level t is lower than the voltage waveform V1, it will become a wide pulse like P1, and the slice level t will be lower than the voltage waveform V1.
It is higher than . Dropping of PO-like pulses occurs. For this reason, by adjusting the distance between the slit plate 10, the slit plate 32, and the photoelectric conversion element 16, and by adjusting the amplification degree of the amplifier 32 and the slice level of the waveform shaping circuit 34, this pulse dropout etc. can be minimized. However, the adjustment is complicated and delicate, and even so, it is not possible to completely eliminate this pulse dropout, etc. The object of the present invention is to eliminate the above-mentioned drawbacks, and by adding a simple configuration, to eliminate level fluctuations in the output electrical signal due to changes in the distance between the slit plate and the photoelectric conversion system, and to generate pulses without pulse dropout. The object of the present invention is to provide a photoelectric pulse generator obtained by the present invention.

To achieve this objective, the photoelectric pulse generator of the present invention first includes a first slit plate having a row of slits arranged at a predetermined pitch, and a second slit plate having first and second slits. It is equipped with a board. The first slit and the second slit of the second slit plate are staggered from each other by a distance shorter than the pitch, preferably within a range of A to κ pitch, in the slit row arrangement direction of the first slit plate. There is. A light source and first and second photoelectric conversion elements are arranged with the first and second slit plates in between;
The photoelectric conversion element receives light from the light source that passes through the slit row of the first slit plate and the first slit of the second slit plate, while the second photoelectric conversion element receives light from the light source that passes through the slit row of the first slit plate and the first slit of the second slit plate. It receives light that has passed through the slit row of the plate and the second slit of the second slit plate. Both slit plates are relatively moved in the direction of the slit arrangement force, and both photoelectric conversion elements output electrical signals whose phases are shifted from each other according to the shift in the distance. The outputs of both photoelectric conversion elements are differentially combined, and the combined signal waveform is shaped to obtain a target pulse train. According to this configuration, the level fluctuations included in the outputs of both photoelectric conversion elements are completely canceled out and removed, while the target sine wave signal components are out of phase with each other, so they are not canceled out but added together. After the waveform shaping process, a pulse train without dropouts can be obtained.

Below, a case will be described in which an embodiment of the present invention is applied to a facsimile machine.

Note that the details of the scanning mechanism and the like are the same as those shown in FIGS. 1 to 5, so the explanation will be omitted and only the different points will be mainly explained. 7 to 9 show one embodiment of the present invention, in which FIG. 7 is a side view of a photoelectric conversion section, and FIG. 8 is a slit plate ( FIG. 9 is a plan view of the main part of the second slit plate (second slit plate), and shows a processing circuit for obtaining a clock pulse from the output electrical signal of the photoelectric conversion element.

In this embodiment, first, one light source 14 for clock pulse generation and a photoelectric conversion element 16 shown in FIGS. 3 and 4 are used.
Instead, as shown in FIG. 7, two light sources 14a, 1
4b and two photoelectric conversion elements 16a and 16b are provided.

In addition, as the slit plate 32, as shown in FIG.
Each slit 35 is divided into halves vertically to form a first slit row 35a, . . . and a second slit row 35b, .
Use the one formed by... Note that the fixed slit plate (first slit plate) 10 shown in FIG. 5 is used as is. The pitch P3 of the slit rows 35a and 35b is equal to the slit pitch P1 of the slit plate 10, and the slit length of the slit row 35a and the slit row 35b are equal to each other.
The length W3, which is the sum of the slit lengths, is equal to the slit length W1 of the slit plate 10.
3(d1-D3).

As a feature, the slit rows 35a and 35b have D3/2 (-P
3/4) (see Fig. 8).
The light source 14a and the photoelectric conversion element 16a are arranged mainly in the upper part of the slit row 17 and facing the slit row 35a in FIG. They are arranged facing each other (see Figure 7).

Regarding the scanning head movement direction, the photoelectric conversion elements 16a and 16b are located at almost the same position (more precisely, at the slit 35, respectively).
a and 35b). Note that the light sources 14a, 14b1 and the photoelectric conversion element 16
a, 16b and the slit plate 32 are attached to the scanning head gear link 3 in the same manner as in the prior art, and are adapted to move together with the scanning head 4 in the x direction. In Figure 9, 36
a and 36b are photodiodes corresponding to the photoelectric conversion elements 16a and 16b, 37a and 37b are load resistances thereof, and 38
is a differential amplifier, and 34 is a waveform shaping circuit.

During operation, when the scanning head moves in the x direction (slit arrangement direction), the photoelectric conversion element 16a receives light from the light source 14a that passes above the slit 17 and through the slit 13a, and generates a substantially sinusoidal waveform indicated by Va in FIG. generates electrical signals.

Similarly, the photoelectric conversion element 16b is connected to the slit 1 from the light source 14b.
7 and 35b, it generates a substantially sinusoidal electrical signal delayed by k phase from a, as shown by b in FIG. These a and Vb are the load resistance 3 in FIG.
It is shown as the voltage appearing at 7a and 37b. If the fixed slit plate 10, the movable slit plate 32, and the photoelectric conversion elements 16a, 16b are
Assuming that the interval changes, the voltage levels Va and b fluctuate as shown in FIG. 11 due to the accompanying change in leakage light and contrast, but the tendency of the fluctuation is the same for both.

This corresponds to the slits 35a and 35b in the scanning direction x.
This is because the photoelectric conversion elements 16a and 16b are located at almost the same position. Both output voltages A and b are applied to the differential amplifier 38, and as a result, the above fluctuation components are completely canceled out, while the sine wave signal component is out of phase (90 degrees), so
Without being canceled out, a sine wave Va-b (c in FIG. 11) delayed by κ phase (45 degrees) with respect to a appears on the output side of the differential amplifier 38. The signal Vc from which the variation has been removed in this way is shaped by the waveform shaping circuit 34,
V in Fig. 11 is on the output side.

As shown in Figure 3, it is possible to obtain clock pulses without dropouts. d According to this embodiment, the resolution of the clock pulse train is increased,
It is also effective in increasing the scanning speed of the head.

Generally, the output of a photoelectric conversion element increases as the amount of light it receives increases. Therefore, even if the received light intensity is the same, the faster the scanning speed is, the lower the output voltage is, and the slower the scanning speed is, the higher the output voltage is. Therefore, if the speed changes, the output will also change. However, in this embodiment, such output fluctuations accompanying speed fluctuations are also detected as in-phase components, and these are canceled out and removed, making it possible to achieve higher speeds. In addition, when the speed is increased, the output level decreases as described above, but as the so-called noise bias component due to leakage light is removed, the relative ratio between the maximum level and minimum level of the effective signal component changes. This results in the same effect as increasing the contrast of the input light. Furthermore, since the widening portion due to leakage light in the output signal is removed, the waveform is sharpened and the resolution is improved. In the embodiment described above, the first slit 35a and the second slit 3
5b was set as (k)P(90), but this is not limited to this, as long as it is sufficiently short compared to the period of the above fluctuation (Fig. 10 A (7) Vb), this fluctuation can be Since they can be canceled out, it is clear that similar effects can be achieved.

However, if it is extremely short and, for example, the sine wave phase difference between voltages a and b in FIG. (1) In the embodiment, a deviation of about P is required at the minimum. The amount of shift is (K)P(phase difference 18
0 required), the effective sine wave component is the differential amplifier 3
8, the period of the noise component due to leakage light is sufficiently longer than that (in other words,
With this degree of deviation, the fixed slit 10 and the movable slit 3
Since there is almost no change in the distance between the two, they cancel each other out almost completely, and a good result is obtained. Therefore,
It is desirable that the amount of deviation be selected within the range of 1 to 3 P.
In the above embodiment, the case where a plurality of slits 35a and 35b are provided has been described, but the slit 35
It is clear that the same application is possible even when one each of a and 35b is provided.

Further, in the above embodiment, two light sources 14a and 14b are provided, but a single light source common to both photoelectric conversion elements 16a and 16b may be used. The light sources 14a, 14b may not be mounted on the scanning head gear link but may be a single stationary light source extending the entire length of the fixed slit plate 10.

In the above embodiment, although the length of the slit plate 32 is shorter than that of the slit plate 10, both slit plates have the same structure,
The slit plate 10 and the photoelectric conversion elements 16a, 16b may be fixedly arranged, and only the slit plate 32 may be moved together with the head gear link. Photoelectric conversion element 16a,
16b is also two stationary photoelectric conversion elements extending over the entire length of the fixed slit plate 10, and the light source 14a
and 14b may be moved.

Furthermore, the slit plate 32 has two slit rows 35a and 35.
In addition to "b", three or more adjacent columns may be shifted from each other.

In short, the present invention includes at least two slit rows arranged with a predetermined phase shift from each other in the slit arrangement direction of at least one slit plate, and at least two photoelectric conversion elements that receive light from each slit row. The main idea is to move the slit plate and these photoelectric conversion elements relatively in the slit arrangement direction, and to differentially synthesize the electric signals generated from both photoelectric conversion elements at this time. As detailed above, according to the photoelectric pulse generator of the present invention, even if the distance between the slit plate for clock pulse generation and the photoelectric conversion element changes as the two move, it is not affected by the change. This provides excellent effects, such as being able to obtain an electrical signal whose fluctuations are canceled out and removed, and by extension, obtaining a clock pulse train without pulse dropouts.

[Brief explanation of drawings]

1 to 6 schematically show a photoelectric clock pulse generator for facsimile for explaining the present invention. FIG. 1 is a plan view thereof, FIG. 2 is a perspective view of the scanning head, and FIG. Its left side view, FIG. 4 is a photoelectric conversion unit and output electric signal processing circuit diagram, FIG. 5 is a plan view of the fixed slit plate, FIG. 6 is a plan view of the movable slit plate, and FIGS. The figures schematically show an embodiment of the present invention, in which FIG. 7 is a side view of a photoelectric conversion section, FIG. 8 is a plan view of a fixed slit plate, FIG. 9 is an electrical signal processing circuit diagram, and FIG. 10 is a diagram of an electric signal processing circuit. and FIG. 11 is an electrical signal waveform diagram for explaining its operation. 10, 32...Slit plate, 14a, 14b.
...Light source, 16a, 16b...Photoelectric conversion element, 17, 35a, 35b...Slit row.

Claims (1)

[Claims] 1 a light source, a first slit plate having a row of slits arranged at a predetermined pitch, a second slit plate having first and second slits with a predetermined phase difference smaller than the slit pitch, a first photoelectric conversion means that receives light from a light source through the slit row of the first slit plate and the first slit of the second slit plate; the slit row of the first slit plate and the second slit plate; a second photoelectric conversion means for receiving light from the light source through a second slit; a means for relatively moving the first and second slit plates in the slit arrangement direction; A photoelectric pulse generator comprising: means for differentially synthesizing the outputs of the converting means; and means for shaping the output waveform of the synthesizing means to obtain a pulse output.