JPH1117612A - Data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive data transmitter, capable of maintaining an S/N at a level without an operational fault, at the time of restoring signals to digital signals by correcting the maximum value level and minimum value level of reception data. SOLUTION: This data transmitter is provided with an optical reception and optical voltage conversion circuit 6 for receiving data from an optical connection cable 5, an analog-to-digital converter 7 for analog-to-digitally converting the reception data and outputting parallel data and a reference signal generation and control circuit 10 for correcting the maximum value level and minimum value level of the reception data. Then, the maximum value level and minimum value level of the reception data are corrected by the reference signal generation and control circuit 10 for the correction. Thus, even in the case that a dynamic range is lowered due to degradation of the signals through attenuation of optical signals at the time of having them pass through the optical connection cable 5 and the light quantity change of a semiconductor laser by temperature change, etc., the dynamic range of the optical signals is quaranteed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copier, a printer, and a business machine such as a facsimile.
Related to data transmission devices using optical connection cables for connections with a large number of signal lines for transmitting signals, such as bus signal lines for controlling operation or transmitting information inside or between these devices It is.

[0002]

2. Description of the Related Art Conventionally, when connection using a large number of signal lines such as a bus signal line of this type is performed using an optical cable, a parallel signal is converted into a serial signal and transmitted via the optical cable. Multiplexed communication is performed by restoring or encoding a transmitted serial signal to a parallel signal to reduce the number of optical cables.

However, in this method, a serial-parallel conversion circuit and an encoding circuit are required in the transmission / reception unit.
There is a problem in that the configuration of the data transmission device becomes complicated, and the data transmission device becomes expensive. Further, in the above-mentioned conventional method, multiplex communication is performed by converting a parallel signal into a serial signal, transmitting the serial signal via an optical cable, and restoring or encoding the transmitted serial signal into a parallel signal. Therefore, when converting a parallel signal into a serial signal or when converting a serial signal into a parallel signal, the signal transmission speed decreases. Therefore, in order to prevent a decrease in signal transmission speed, high speed is required for the serial-parallel signal conversion circuit, and there is a problem that the cost is also increased in this respect. Furthermore, in the above-mentioned conventional data transmission apparatus, it has been proposed to transmit an analog signal instead of a digital signal through an optical cable in order to prevent a reduction in signal transmission speed. In the case of transmission, there is a problem that the dynamic range is reduced by the magnitude of the signal transmission amplitude due to signal deterioration due to attenuation of the optical signal when passing through the optical cable, change in the light amount of the semiconductor laser due to temperature change, and the like. there were.

Therefore, as a technique capable of solving such a problem, for example, JP-A-7-170297, JP-A-5-227243 or JP-A-8-125 is known.
No. 202 has already been proposed.

[0005] Japanese Patent Application Laid-Open No. 4-177834 discloses that
In a parallel transmission method using optical signals, a signal to be transmitted is RZ (Retu) in order to widen a dynamic range.
rnZero) and further differentiated on the receiving side.

Further, in the parallel transmission processing method according to the above-mentioned Japanese Patent Application Laid-Open No. 5-227243, a plurality of parallel input data are encoded into a transmission line code by a code conversion processing means on the transmission side.
In the optical signal parallel transmission system, which transmits the signal to the code conversion processing means on the receiving side via a plurality of optical transmission paths and decodes the parallel data in the code conversion processing means, outputs When inserting the bits required for code conversion into the input data into each sequence, the bits stored at the insertion position are moved to the new sequence, and the code is placed at the vacant bit position after the movement. A signal for conversion is inserted, and a binary signal is alternately inserted for each frame bit in the new stream, and is transmitted to the receiving side as an alternating signal for preventing the same code continuation and a frame signal.

Further, the optical parallel link according to the above-mentioned Japanese Patent Application Laid-Open No. 8-125202 discloses a transmission link for receiving an electric signal from an input line, performing electric / optical conversion and transmitting an optical signal, and a receiving link for receiving the optical signal. A receiving link for transmitting an electric signal from an output line by converting the electric signal, and an optical parallel link in which an optical ribbon fiber is used, the transmitting link includes a digital signal processing circuit board on which a skew compensation / code conversion circuit is formed; An analog signal processing circuit board on which an LD drive circuit is formed, and an LD / fiber array module connected to the optical ribbon fiber are arranged and connected in this order and sealed in a case. , A PD / fiber array module connected to the optical ribbon fiber, an amplifier circuit, and an analog signal processing circuit formed with a limiter amplifier circuit Plate and the one in which the digital processing circuit board skew compensation-code conversion circuit is formed is configured such that which was hermetically contained sealed casing is arranged connected in this order.

[0008]

However, the prior art described above has the following problems. In other words, in the case of the parallel transmission method according to the above-mentioned Japanese Patent Application Laid-Open No. 4-177834, a method is used in which the signal is RZ-ized in order to widen the dynamic range and then differentiated on the receiving side. Need to be converted to RZ, so that not only is the configuration complicated, but also there is a problem that means for reducing the number of parallel signal lines is not considered.

Also, in the case of the systems and apparatuses according to the above-mentioned JP-A-5-227243 and JP-A-8-125202, code conversion processing and the like are performed on input data. There was a problem that the configuration became complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a simple configuration and prevent a signal transmission speed from being reduced. Of course, it can guarantee the dynamic range of the optical signal, and even if the signal is converted to analog and transmitted via an optical connection cable, it will not interfere with operation when restoring the signal to a digital signal. To S
An object of the present invention is to provide an inexpensive data transmission device capable of maintaining the / N ratio.

[0011]

In order to solve the above-mentioned problems, the invention described in claim 1 is a digital-to-analog converter that converts parallel digital data into analog data, and a digital-to-analog converter that converts the parallel digital data into analog data. Transmitting means for transmitting to the optical transmission path, receiving means for receiving data from the optical transmission path,
It is configured to include AD conversion means for converting received data received by the receiving means into digital data and outputting parallel data, and correcting means for correcting the maximum value level and the minimum value level of the received data.

With this configuration, the present invention corrects the maximum value level and the minimum value level of the received data by the correction means, thereby reducing the signal due to the attenuation of the optical signal when passing through an optical transmission path such as an optical cable. Even if the dynamic range is reduced due to deterioration or a change in the amount of light of the semiconductor laser as a transmitting means due to a temperature change, the dynamic range of this optical signal is guaranteed, and the signal converted to analog is transmitted through the optical transmission path. Even when the signal is restored to a digital signal, the S / N ratio can be maintained at a level that does not hinder the operation.

Further, according to the present invention, a digital signal is converted into an analog signal by a DA converter and passed through an optical transmission path, thereby reducing the number of signal lines in the optical transmission path and converting the digital signal into an analog signal. Is transmitted, the data transmission speed can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a data transmission apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a CP for controlling the operation of office equipment such as a copying machine, a printer, or a facsimile.
U and 2 are BUSs for transmitting data and addresses connected to the CPU 1, and 3 is a digital-to-analog converter for converting a digital signal on the BUS 2 into an analog signal. When setting the dynamic range at power-on of the above devices, all
The S signal is set to HIGH, and a signal that becomes all LOW when the minimum light amount occurs is output from the CPU 1.

Reference numeral 4 denotes a voltage-to-light conversion circuit. The voltage-to-light conversion circuit 4 includes a semiconductor laser for converting an analog signal of the digital-to-analog converter 3 into an optical signal and a drive circuit for driving the semiconductor laser. As the voltage-to-light conversion circuit 4, it is desirable to use a converter having a characteristic of changing the light intensity as linearly as possible according to the analog signal voltage.

Reference numeral 5 denotes an optical connection cable. In the embodiment of the present invention, since the attenuation of the light intensity due to the cable length is corrected, it is not necessary to use an optical fiber cable using quartz glass as the optical connection cable 5, and a plastic optical cable is used. It is enough.

Reference numeral 6 denotes a light receiving and light-to-voltage conversion circuit, and it is desirable to adopt a circuit configured to convert the voltage into a voltage as linear as possible with respect to the light intensity as in the voltage-to-light conversion circuit 4.

Reference numeral 7 denotes an analog-to-digital converter. The analog-to-digital converter 7 has REFERENCE terminals 7a and 7 for converting an analog signal into a digital signal.
b is provided for the maximum value and the minimum value. As the maximum value and the minimum value, predetermined fixed values are used when detecting the maximum light amount and the minimum light amount signal immediately after the power supply of the device is turned on, but the maximum light amount and the minimum light amount are stored in the storage unit 8, 9
After that, the values are changed to the values stored in these storage units 8 and 9.

Reference numeral 8 denotes a storage unit for the minimum light amount, and 9 denotes a storage unit for the maximum light amount.

Reference numeral 10 denotes a correction reference signal generation and control circuit which supplies a signal to the CPU 1 for outputting a maximum light amount generation signal and a minimum light amount generation signal to the bus 2 after power is turned on. When a signal is not output to the bus 2 for more than one minute, the correction reference signal generation and control circuit 10 detects the signal and outputs the same signal as when the power is turned on. The optical connection cable 5 and the optical reception and optical voltage conversion circuit 6 are configured to correct the characteristic change due to the temperature.

Numeral 11 denotes a maximum light amount signal and a minimum light amount signal stored in the minimum light amount storage unit 8 and the maximum light amount storage unit 9, and the analog-to-digital converter 7 based on these signals.
Is a digital-to-analog converter for generating a reference voltage.

Reference numeral 12 denotes a receiving-side CPU bus on which the signal restored by the analog-to-digital converter 7 is placed.

In the above configuration, the data transmission apparatus according to this embodiment has a simple configuration as described below, and it is of course possible to prevent the signal transmission speed from being reduced. That is, the dynamic range of the optical signal is guaranteed, and even if the signal converted into an analog signal is transmitted through an optical connection cable, the S / N ratio is maintained at a level that does not hinder operation when the signal is restored to a digital signal. It has become possible.

That is, in the above data transmission apparatus, FIG.
As shown in (1), when office equipment such as a copier, a printer, or a facsimile is turned on (step 1), C
The PU 1 generates a trigger signal for generating the maximum light amount (step 2), and sends the trigger signal for generating the maximum light amount to the digital-to-analog converter 3 via the bus 2.
Output to Then, this digital-to-analog converter 3
Outputs an analog signal for generating the maximum light amount to the voltage-light conversion circuit 4, and the voltage-light conversion circuit 4 generates the maximum light amount (step 3).

The maximum light quantity signal converted into an optical signal by the voltage light conversion circuit 4 is transmitted to the light receiving and light voltage conversion circuit 6 through the optical connection cable 5, and is converted into a voltage signal corresponding to the maximum light quantity signal. . The maximum light amount signal converted into the voltage signal is converted into a digital signal by the analog-to-digital
The maximum light amount is stored in the storage unit 9 via the bus 12 (step 4).

Next, the CPU 1 generates a trigger signal for generating the minimum light amount (step 5), and outputs the trigger signal for generating the minimum light amount to the digital-to-analog converter 3 via the BUS 2. Then, the digital-to-analog converter 3 outputs an analog signal for generating the minimum light amount to the voltage-light conversion circuit 4, and the voltage-light conversion circuit 4 generates the minimum light amount (step 6).

The minimum light quantity signal converted by the voltage light conversion circuit 4 into an optical signal is transmitted to the light receiving and light voltage conversion circuit 6 through the optical connection cable 5 and is converted into a voltage signal corresponding to the minimum light quantity signal. . The minimum light amount signal converted into the voltage signal is converted into a digital signal by the analog-to-digital
-Stored in the minimum light amount storage unit 8 via the BUS 12 (step 7).

Thereafter, the correction reference signal generation and control circuit 10 outputs data and address signals from the CPU 1 via the bus 2 to the digital-to-analog converter 3, which converts the data and address signals into analog signals. Outputs data and address signals to the voltage-to-light conversion circuit 4,
When the voltage-to-light conversion circuit 4 converts the signal into an optical signal and outputs the signal to the optical connection cable 5, the CPU 1 outputs a signal corresponding to the maximum light amount and the minimum light amount to the BUS 2 after the power is turned on. A signal is provided (step 8). The correction reference signal generation and control circuit 10 converts the signals corresponding to the minimum light amount and the maximum light amount stored in the minimum light amount storage unit 8 and the maximum light amount storage unit 9 by the digital-analog converters 11 and 11. The analog signals are converted into analog signals, and the signals corresponding to the minimum light amount and the maximum light amount converted into the analog signals are output as voltage values to reference (ref) terminals 7 a and 7 b of the analog-to-digital converter 7. A window for converting the analog signal into a digital signal is controlled (step 9).

The window control at the time of converting an analog signal into a digital signal in the analog-to-digital converter 7 is performed, for example, as shown in FIG. When the minimum light amount value stored in the storage unit 8 is B, the maximum light amount value stored in the maximum light amount storage unit 9 is A, the minimum light amount value of the analog signal is b, and the maximum light amount value of the analog signal is a. , The analog signal is multiplied by (AB) / (ab) and converted to a digital signal.

After the dynamic range control operation and the like are completed, the CPU 1 starts transmitting a normal operation signal (step 10).

The CPU 1 constantly checks the operation status of the CPU bus 12 (step 11).
If the transmission of the data to the second light source is stopped for a predetermined time (for example, one minute) (Step 12), the process returns to Step 2, and a trigger signal for generating the maximum light amount is generated again. The calibration operation up to 9 is repeated again. This is to correct the dynamic range or the like if the data transmission is stopped for a predetermined time (for example, one minute) or more because the dynamic range or the like may have changed again.

As described above, in the above embodiment, the digital-to-analog converter 3 for converting the parallel data from digital to analog, the voltage-to-light conversion circuit 4 for sending the converted data to the optical connection cable 5, the optical connection cable 5, an optical receiving and optical voltage converting circuit 6 for receiving data from the analog-to-digital converter 5, an analog-to-digital converter 7 for converting the received data from analog to digital and outputting parallel data, and correcting the maximum value level and the minimum value level of the received data. Since the correction reference signal generation and control circuit 10 is configured to include the correction reference signal generation and control circuit 10, the correction reference signal generation and control circuit 10 corrects the maximum value level and the minimum value level of the received data so that the optical connection cable 5 is passed. Signal degradation due to optical signal attenuation at the time, or changes in the light intensity of the semiconductor laser due to temperature changes, etc.
Even if the dynamic range is reduced, the dynamic range of the optical signal is guaranteed, and even if the signal converted into an analog signal is transmitted through the optical connection cable 5, there is no problem in operation when the signal is restored to a digital signal. It is possible to keep the S / N ratio at a level.

The present invention also provides a digital-to-analog converter 3 for converting parallel data from digital to analog, a voltage-to-optical converter 4 for sending the converted data to an optical transmission line,
Since it has an optical reception and optical voltage conversion circuit 6 for receiving data from the optical connection cable 5 and an analog-to-digital converter 7 for converting the received data from analog to digital and outputting parallel data, the digital signal is converted into an analog signal. By passing the data through the optical connection cable 5, the number of signal lines can be reduced, and the data transmission speed can be improved by an amount corresponding to the conversion into the analog signal and the transmission of the data.

[0036]

According to the present invention, DA conversion means for DA conversion of parallel data, transmission means for transmitting the converted data to an optical transmission path, reception means for receiving data from the optical transmission path, and reception data Is configured to include AD conversion means for AD-converting the data and outputting parallel data, and correction means for correcting the maximum value level and the minimum value level of the received data. Not only can be prevented from becoming slower, but also assures the dynamic range of the optical signal and restores the signal to a digital signal even if the signal was converted to analog and transmitted via an optical connection cable. S / N to a level that does not hinder operation
A data transmission device that can maintain the ratio can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a data transmission device according to the present invention.

FIG. 2 is a flowchart showing an operation of the embodiment of the data transmission apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing a state of correction of a data signal.

[Explanation of symbols]

1 CPU, 2 buses, 3 digital / analog converter,
4 voltage light conversion circuit, 5 light connection cable, 6 light reception and light voltage conversion circuit, 7 analog-digital converter, 8
A storage unit for the minimum light amount, a storage unit for the maximum light amount, a reference signal generation and control circuit for correction, a digital-to-analog converter, and a CPU bus on the receiving side.

Claims (1)

[Claims] 1. A digital-to-analog converter for converting parallel digital data into analog data, a transmitter for transmitting the data converted by the digital-to-analog converter to an optical transmission line, and a receiver for receiving data from the optical transmission line. Means, AD conversion means for converting received data received by the receiving means into digital data and outputting parallel data, and correcting means for correcting the maximum value level and the minimum value level of the received data. Data transmission equipment.