JPH0638002A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To automatically set a sending level corresponding to a connected line at a portable facsimile equipment or the like. CONSTITUTION:This facsimile equipment is provided with a current detection circuit 61 to detect line currents corresponding to various threshold values and a system control part 4 to switch those threshold values (Ra1-Ra4, Rb1-Rb4) and various telephone lines can be dealt with by automatically setting the suitable sending level corresponding to the difference of line resistance. Therefore, even a movable equipment can communicate in the best state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile machine, and more particularly to a facsimile machine capable of automatically setting a transmission level according to a difference in line resistance.

[0002]

2. Description of the Related Art Regarding signals transmitted from a terminal device connected to a telephone line to a line, limits such as a transmission level, a transmission voltage / current / frequency band, and a communication speed are specified.
Upon connection, it is obligatory to detect the line current in order to check whether the line is valid. The threshold value for this line current detection differs depending on the type of line (analog line / digital line) and extension / external line.
It is set for each country. Conventionally, these threshold values are uniquely determined, or the hardware is modified depending on the destination. For example, when a facsimile machine is installed, a service person sets the transmission level of a facsimile signal by measuring the line current with a dedicated jig. In addition, related to this type of device,
For example, there is JP-A-63-54894.

[0003]

In the above-mentioned prior art, since the threshold value is uniquely set in the line current detection circuit, the facsimile machine may malfunction depending on the type of line. Further, when setting the sending level, it is necessary to measure the line current successively using a dedicated jig before setting, which is troublesome. Further, in a home facsimile machine or a portable facsimile machine, even if the transmission level is set once, the transmission level must be set again when connected to another line. In particular, in a portable facsimile device, the connected line is often different each time communication is performed. In such a facsimile device, when the transmission level is fixed to the minimum value, the transmission speed may be slowed or an error may occur in the received image depending on the state of the line. An object of the present invention is to improve such problems and provide a facsimile apparatus which can automatically set a signal transmission level according to a connected line and is suitable for carrying. .

[0004]

In order to achieve the above object, the facsimile apparatus of the present invention has a means for detecting a line current by different threshold values (for example, a plurality of threshold value resistors Ra _{1 to} Ra ₄ , Rb _1). To Rb ₄ ) and means for switching the threshold value to detect the line current and setting an appropriate transmission level from the difference in the line resistance (for example, the system control unit 4),
It is characterized by supporting various telephone lines.

[0005]

In the present invention, the current detection circuit of the network control unit is provided with a plurality of threshold values, the line current of the connected line is detected by the difference in the line resistance, and the transmission level is automatically adjusted accordingly. It can be set. Therefore, it is not necessary to sequentially set the transmission level, and communication can be performed at a high signal level. Further, since the setting is performed when the main power source is turned on, even a movable facsimile apparatus can perform communication in a state suitable for the connected line.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of a portable facsimile apparatus according to an embodiment of the present invention. In FIG. 2, reference numeral 1 is a scanner for reading an original, 2 is a plotter for outputting received image data, 3 is an operation display section for an operator to operate the apparatus, and 4 is a control section for the apparatus as a whole, especially a network control section. 6
Of the current detection circuit, and the attenuator 66 switches the transmission level to a system control unit, 5 is a modem having a modulation / demodulation function, and 6 is a network control unit connected to a telephone line and transmitting data with the modem 5. .

The internal configuration of the network control unit 6 is as shown in FIG. In FIG. 1, 61 is a current detection circuit for detecting a line current, 62 is a switch for short-circuiting a resistance component after the current detection circuit 61, 63 is an OH relay for switching between a facsimile section and a telephone section, 64 is a communication transformer, and 65. Is a hybrid IC that performs 2-wire to 4-wire conversion, 6
6 is an attenuator for switching the transmission level, and 67 is a ringing signal detection circuit. In the current detection circuit 61,
Reference numeral 611 is a bridge for rectifying the line current, 612 is a Zener diode for internal protection, 613, 614 are switches for changing the current detection threshold value, and 615 is a photocoupler for current detection. In addition, Ra _{1 to} Ra ₄ , R
b _{1 to} Rb ₄ are resistors that determine the detection threshold value,
For example, Ra ₁ and Rb ₁ correspond to each other. Also, Rs
Is a resistor for adjusting a threshold value, IL is a line current, Ia and Ib are currents (IL = Ia + Ib) flowing through the resistors Ra and Rb, respectively, and VF is a photocoupler 61.
The forward voltage at 5 is shown.

Now, a method of setting the four threshold levels in the current detection circuit 61 will be described. Power on
In this state, when the OH relay 63 is switched to the modem side and the switch 62 is short-circuited to close the DC loop, the line current IL, the resistance Ra (Ra _{1 to} Ra ₄ ), and the resistance Rb (Rb ₁
.About.Rb ₄ ) and the voltage VF are shown as follows, ignoring the resistance of the communication connector and the switch. IL = Ia + Ib RaIa = RbIb + VF In this embodiment, this relationship is used to set four kinds of VF (threshold level at the time of line current detection) at which the output of the current detection circuit 61 becomes low level. R
a and Rb are defined. That is, IL ₁ , Ra ₁ , Rb ₁ , I
L ₂ , Ra ₂ , Rb ₂ , IL ₃ , Ra ₃ , Rb ₃ , IL ₄ , R
a ₄ and Rb ₄ (IL ₁ <IL ₂ <IL ₃ <IL ₄ ) are set correspondingly. Then, the values of the resistors Ra and Rb are changed and the detection / non-detection of the output of the current detection circuit 61 is monitored to detect the magnitude of the line current IL. With this, since the resistance of the connected line can be known, the appropriate transmission level for the line can be determined from the attenuation level due to the line resistance.

Next, a method of automatically setting the sending level under the control of the system control unit 4 will be described. In this embodiment, when the main power supply of the facsimile apparatus is turned on, the OH relay 63 is switched to the modem side (301) and the switch 62 is short-circuited to close the DC loop, as shown in FIG. As a result, the line current IL flows. In addition,
The switching of the OH relay 63 is for avoiding the influence on the telephone side. In addition, the system control unit 4
The switches 613 and 614 are switched to sequentially set the resistances Ra and Rb (Ra _{1 to} Ra ₄ and Rb _{1 to} Rb ₄ ) (302), and the output of the current detection circuit 61 at that time is monitored (303). For example, when Ra is set to Ra ₁ , Ra ₂ and Rb is set to Rb ₁ and Rb ₂ , detection is performed, and Ra is set to Ra ₃ ,
If Ra ₄ and Rb are set to Rb ₃ and Rb ₄ and they are not detected, it is determined that the line current is between IL ₂ and IL ₃ . From this value, the resistance of the connected line is known (304), the attenuator 66 selects and sets an appropriate signal transmission level according to the attenuation level due to the line resistance (305), and then communication is performed.

[0010]

According to the present invention, by detecting the line current of the connected line by the current detection circuit having a plurality of threshold values, the transmission level is automatically set due to the difference in line resistance. Therefore, communication can be performed at a high signal level without successively setting the transmission level. Further, since the setting is performed when the main power source is turned on, even a movable facsimile apparatus can perform communication in the best state on the connected line.

[0011]

[Brief description of drawings]

FIG. 1 is a configuration diagram of a network control unit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a portable facsimile apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a transmission level setting method according to an embodiment of the present invention.

[Explanation of symbols]

 1 Scanner 2 Plotter 3 Operation Display Section 4 System Control Section 5 Modem 6 Network Control Section 61 Current Detection Circuit 62 Switch 63 OH Relay 64 Communication Transformer 65 Hybrid IC 66 Attenuator 67 Calling Signal Detection Circuit 611 Bridge 612 Zener Diode 613 Changeover Switch 614 Changeover Switch 615 Photocoupler

Claims (1)

[Claims] 1. In a facsimile apparatus that communicates via a telephone line, a means for detecting a line current by different threshold values, a line current is detected by switching the threshold values, and a transmission level is changed from an attenuation level by a line resistance. A facsimile apparatus comprising a setting means.