JPS6223816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmitted light measuring device that is used in optical character reading devices and the like and measures the intensity of light transmitted through a medium.

Generally, in optical character reading devices, the intensity of light transmitted through the medium is measured to distinguish the type of medium (basis weight, etc.) and to distinguish whether there is only one medium or two or more sheets overlapped. are doing.

Conventionally, the transmitted light of a medium is reduced by the printing of characters, etc. on the medium, so it is not possible to accurately distinguish the type of medium, etc. unless the recording of characters, etc. is prohibited in the part for measuring transmitted light on the medium. However, there was a drawback that the effective usable area of the medium was reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmitted light measuring device that eliminates the influence of recording on the medium in measuring the transmitted light of the medium and can distinguish the type of medium without causing an error.

According to the present invention, there is provided a reflective light-receiving element that receives reflected light from a moving medium; A transmission light-receiving element that receives transmitted light from a narrow field of view on the medium and a time when the reflection light-receiving element starts to detect recording on the medium are corrected by the travel time required for the medium to move the predetermined distance. a memory circuit for storing the output of the transmissive light-receiving element at a time, and outputs a signal from the transmissive light-receiving element when the movement time is corrected with respect to a time when the reflective light-receiving element does not detect recording on the medium; and a switching means for outputting a signal from the storage circuit when the reflection light receiving element detects recording on the medium and when the movement time is corrected. can be obtained.

Next, explanation will be given with reference to the drawings.

Figure 1 shows a conventional optical character reader, etc.
This is a block diagram of a transmitted light measuring device used for sheet feeding detection, etc., in which 1 is a light emitting element, 2 is a moving medium with printed characters (moves in the direction of arrow a), and 3
4 is a transmissive light-receiving element, and 4 is an amplifier circuit. The light generated by the light emitting element 1 is transmitted through the moving medium 2,
It enters the transmitted light receiving element 3. The transmitted light receiving element 3 generates an output signal 101 proportional to the transmitted light, but since this signal is small, it is amplified to an appropriate level by the amplifier circuit 4 and output signal 101 is proportional to the transmitted light of the medium.
02 can be obtained. However, when the printing of characters or the like on the moving medium 2 comes onto the transmissive light-receiving element 3, the amount of transmitted light decreases, and the output signal 102 of the amplifier circuit 4 fluctuates as shown in FIG. It will no longer be possible to treat it as information.

FIG. 3 shows a block diagram of one embodiment of the present invention. Here, 1 and 11 are light emitting elements, 12 is a reflective light receiving element, 15 is a print identification circuit, 16 is a delay circuit, 1
9 outputs the output signal 102 as it is as the output signal 116 when the correction identification signal 115 is "0";
Also, when the correction identification signal 115 is "1", the output signal 10 when the correction identification signal 115 switches to "1"
This is a sample circuit that stores 2 and outputs it as an output signal 116.

The field of view of the transmissive light-receiving element 3 on the moving medium 2 is shifted from the field of view of the reflective light-receiving element 12 in the direction of arrow a, and the field of view of the transmissive light-receiving element 3 is shifted from the field of view of the reflective light-receiving element 1.
The field of view is narrower than 2.

The reflective light-receiving element 12 receives the reflected light from the medium 2 of the light emitting element 11, and when it detects printing of characters or the like on the moving medium 2 within its field of view, its output signal 113 becomes small. The print identification circuit 15 outputs an identification signal 114 that becomes "1" only while detecting this printing. This signal 114 enters the delay circuit 16, and the field of view of the reflective light-receiving element 12 and the transmission light-receiving element 17 are
The correction identification signal 11 is delayed by the time α required for the moving medium 2 to move by the distance between the fields of view.
It becomes 5. When the printing of characters or the like on the moving medium 2 comes onto the transmissive light-receiving element 3, the output signal 102 of the amplifier circuit 4 decreases as shown in FIG. 4, as described above.

At this time, that is, when the correction identification signal 115 is "1" with a delay of time α from the time when the reflective light-receiving element 12 detects printing, the printing is detected by the reflective light-receiving element 3.
The sample circuit 19 continues to output the output signal 102 of the amplifier circuit 4 as the output signal 116 after a delay of time α from the time when the detection starts. When there is no printing of characters or the like on the moving medium 2 on the transmissive light-receiving element 3, that is, when the correction identification signal 115 is "0" after a delay of time α from the time when the reflective light-receiving element 12 detects no printing, A sample circuit 19 outputs the output signal 102 of the amplifier circuit 4 as an output signal 116.

FIG. 5 is a detailed block diagram of the sample circuit 19, which will be explained along with the waveform diagram in FIG.
The detection circuit 20 generates a signal 117 having a short pulse width of "1" at the rising edge of the corrected identification signal 115, and the storage circuit 21 stores the output signal 102 when the signal 117 is "1". The analog multiplexer 23 selects the output signal 102 when the correction identification signal 115 is "0", and selects the output signal 102 when the correction identification signal 115 is "1".
1 is selected and output as an output signal 116.

Printing of characters etc. on the moving medium 2 reflects the light receiving element 1
2, when it is not detected, the correction identification signal 115 becomes "0" after a delay of time α, and the analog multiplexer 23 outputs the output signal 102 as the output signal 116. On the other hand, when the reflective light-receiving element 12 detects the printing of characters or the like on the moving medium 2, the correction identification signal 115 becomes "1" with a delay of time α, and at the rising edge of the correction identification signal 115, the detection circuit 20 outputs the signal 117. is generated, the memory circuit 21 stores the output signal 102 at that time, and while the correction identification signal 115 is "1", the signal 118, that is, when the time α is delayed from the time when the reflective light-receiving element 12 starts to detect the print. The output signal 102 of
The multiplexer 23 outputs the signal. When printing of characters or the like on the moving medium 2 is no longer detected, the correction identification signal 115 returns to "0" with a delay of time α and the analog multiplexer 23 outputs the output signal 102.
is selected and output as the output signal 115.

Since the field of view of the reflective light-receiving element 12 is wider than the field of view of the transmissive light-receiving element 3, before the print such as characters on the moving medium 2 enters the field of view of the transmissive light-receiving element 3, and after the print completely leaves the field of view of the transmissive light-receiving element 3. Until then, the signal 118 can be output as the output signal 116.

An embodiment in which the reflective light-receiving element is located in front of the transmissive light-receiving element in the moving direction has been described above, but if this order is reversed, that is, the field of view of the reflective light-receiving element 12 on the moving medium 2 is the field of view of the transmissive light-receiving element 3. from arrow a
Even if there is a deviation in the direction of , the delay circuit 16 may be connected between the amplifier circuit 4 and the sample circuit 19 instead of between the print identification circuit 15 and the sample circuit 19.

As explained above, the present invention detects a record written on a medium by a reflective light-receiving element provided apart from a transmissive light-receiving element, and when the record on the medium comes within the field of view of the transmissive light-receiving element, the recording is detected. By substituting the immediately preceding transmitted light output signal, the influence of recording on the medium is removed in measuring the intensity of transmitted light through the medium.
This has the effect of providing an output signal that is effective for distinguishing between types of media, etc. Furthermore, since the transmission light-receiving element and the reflection light-reception element each have separate fields of view, the brightness of each field of view can be adjusted independently.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example, FIG. 2 is a waveform diagram of the output signal 102 shown in FIG. 1, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a signal diagram of the signal shown in FIG. 5 is a detailed block diagram of the sample circuit 19 shown in FIG. 3, and FIG. 6 is a waveform diagram of the signals 102, 115 shown in FIG.
118 is a waveform diagram. 1, 11...Light emitting element, 2...Moving medium, 3...
...Transmission light receiving element, 4...Amplification circuit, 12...Reflection light receiving element, 15...Print identification circuit, 16...Delay circuit, 19...Sample circuit, 20...Detection circuit, 21...Storage circuit, 23 ...Analog multiplexer.

Claims (1)

[Scope of Claims] 1. A reflective light-receiving element that receives reflected light from the medium when a sheet-like medium passes near the reflective light-receiving element; a transmission light-receiving element that receives transmitted light transmitted through the medium, and a first signal output during a period in which the reflection light-reception element detects recording on the medium, and the reflection light-reception element detects recording on the medium. an identification circuit that outputs a second signal during a non-detection period; and a signal output from the identification circuit that is delayed by the time required for the medium to move from the reflective light-receiving element to the transmission light-receiving element. a delay circuit; a memory circuit that stores the output of the transmissive light receiving element when the signal from the delay circuit changes from the second signal to the first signal; and a selection circuit that selectively outputs the output from the storage circuit during the output period, and selectively outputs the output of the transmission light receiving element during the period when the delay circuit outputs the second signal. A transmitted light measuring device characterized by: 2. A transmissive light-receiving element that receives transmitted light that passes through the medium when a sheet-like medium passes through the vicinity, and a transmission light-receiving element that receives transmitted light that passes through the medium when the sheet-like medium passes near the transmitting light-receiving element; a reflective light-receiving element that receives light, and outputs a first signal during a period when the reflective light-receiving element is detecting recording on the medium, and outputs a first signal during a period when the reflective light-receiving element is not detecting recording on the medium; an identification circuit that outputs a second signal; a delay circuit that delays the signal output from the transmissive light receiving element by the time required for the medium to move from the transmissive light receiving element to the reflective light receiving element; a storage circuit that stores an output of the delay circuit when the signal from the identification circuit changes from the second signal to the first signal; and a period during which the identification circuit outputs the first signal. and a selection circuit that selectively outputs the output from the storage circuit and selectively outputs the output of the delayed light receiving element during a period when the identification circuit is outputting the second signal. Transmitted light measuring device.